All Thrusts Chits 01.001 Chang CS 6/08/2009 09:24 Thrust 01 On the rotation (p. 11?), you may want to generalize the "rotation driven by ICRF mode conversion" to "rotation driven by ICRF." The statement is too narrow. Rotation can be driven by ICRH only. 01.002 Buttery Richard 6/08/2009 09:41 Thrust 01 Need to give some indication of which things US in particular should focus on (rather than leave to other partners) 12.001 Jarboe Tom 6/08/2009 11:29 Thrust 12 Needs a comment, on the first page, on theme 12s relation to 9, 10, and 11 as Mike explained in his talk. 14.001 Jarboe Tom 6/08/2009 11:53 Thrust 14 Add "Develop" to the beginning of title. Seems like this thrust might belong in theme 3. 18.001 intrator tom 6/08/2009 14:00 Thrust 18 just to amplify on the question on (paraphrased) "why bother spreading out our resources on tangents to mainstream approaches?" Especially since themes 1-4 call out physics and engineering, vs theme 5 that calls out configurations. response could include ... we need some game changers, and there is a long list (eg disruptions, magnet cost, simple geometry, lithium, no center stack, engineering simplicity and modularity that follows from simply connected, eases super conducting magnet implementation… ) 04.001 Hawryluk Richard 6/08/2009 14:24 Thrust 04 I would highlight in the issue of H-mode confinement the importance of understanding not only the L to H power threshold but the H to L power threshold. This may be more important or at least as important for ITER. 18.002 intrator tom 6/08/2009 14:29 Thrust 18 I like a figure that displays frc, st, rfp, tmak, sphmak, stellarator, in 3D shaping vs ext magnetization vs aspect ratio cube. I would place spheromak and perhaps rfp and frc (translated ones primarily) at larger 3D character. There is likely a continuum albeit sparsely populated between tokamak and stellarator of 3D ness. And 3D issues are important for all approaches. 04.002 Hawryluk Richard 6/08/2009 14:36 Thrust 04 There has been considerable work on using ICRF to condition SC tokamaks. That should be mentioned since it may mean that we do not need to develop variable frequency ECH. 11.001 Lipschultz Bruce 6/08/2009 14:45 Thrust 11 - There is almost no basis for use of P/R as a scaling parameter. I suggest dropping the reference to that and leave the scaling from ITER (x5 power through the separatrix if no additional radiation in the pedestal). - In addition to the various divertor options mentioned I believe just increasing divertor area a la expanded boundary makes sense. It is probably simpler to achieve than the various divertor options mentioned. 01.003 Callis Richard 6/08/2009 15:38 Thrust 01 The validation of integrated modeling may need the measurement of plasma parameters at a 2D or even 3D level. Some discussion should be included for this effort. This does not need to be a burning plasma relevent diagnostic but something to support the base plasma physics understanding. 11.002 Lipschultz Bruce 6/08/2009 15:38 Thrust 11 - This and other thrusts argue that Li is compatible with the high temperature walls one wants for thermal conversion efficiency in a reactor (550-1000C). I can possibly be convinced that people will be clever and be able to get the Li to flow across the magnetic field. On the other hand I find it difficult to believe that the erosion rate of Li won't be enormous. Please define what the gross erosion rate is for Li as a function of temperature and compare to C and W. Some estimate of the net erosion both in the divertor and first wall would be good too. 01.004 Callis Richard 6/08/2009 15:41 Thrust 01 It was briefly mentioned about sensors, but engineering sensors (not physics diagnostics) are a real challenge for burning plasma devices beyond ITER and should not be overlooked. 01.005 Goldston Rob 6/08/2009 15:42 Thrust 01 This thrust would be somewhat more compelling if there were a preliminary prioritized list of diagnostics in the thrust, perhaps just a few for now, as a step along the path of your plan to evaluate and then prioritize. 01.006 Morley Neil 6/08/2009 15:42 Thrust 01 Thrust 13 also contains some mention of development of engineering diagnostics for PFC, blankets, etc compatible with the fusion environment.Even if these are developed separately from various magnetic and plasma diagnostics, certainly the various techniques for neutron irradiation effects in materials, signal transmission, etc. could be common elements and should be noted. Also, do you envision using a facility like an CTF that is doing various steady state, technology testing to moderate fluence, also as a test environment for diagnostics? I think this should be mentioned too. Thanks... 01.007 Hawryluk Richard 6/08/2009 15:43 Thrust 01 Make sure that the thrust highlights that investments in diagnostics have a high scientific benefit to cost ratio. 01.008 Peng Martin 6/08/2009 15:43 Thrust 01 What is the assumed working relationship between the research thrust and the ITER diagnostic plan? What are planned in ITER? What are missing in your view. What are the priorities in addition to what ITER Project is planning? 01.009 Taylor Tony 6/08/2009 15:45 Thrust 01 Topic "combined" thrust You indicated this was a combined thrust from Theme 1 and Theme II. The presentation seemed focused on ITER. Are there not requirements and therefore efforts needed to address measurements under the constraints of higher neutron flux? 01.010 Marmar Earl 6/08/2009 15:47 Thrust 01 As part of the prioritization and subsequent development of new/improved diagnostics, it will be important to coordinate efforts with those of other parties (Europe, Japan and Australia, for example) to avoid redundant efforts. 01.011 Dorland Bill 6/08/2009 15:49 Thrust 01 Given certain constraints on time, money and real estate for new diagnostics, the prioritization process described in this thrust will be most successful if it is strongly coupled to the theory, simulation and validation elements of Thrust 6. 02.001 Dorland Bill 6/08/2009 16:02 Thrust 02 The suggested ties to 17 are real, but greatly overshadowed by the rest of the story. Namely, the whole point of thrust 17 is to avoid having to do all the hard work of thrust 2. This is by far the dominant interaction between these thrusts, I think. 02.002 Callis Richard 6/08/2009 16:04 Thrust 02 Owing to the sensitivity of insulating materials to the neutrons, interior coils are problematic in reactors like DEMO. If 3D coils are needed an element of the research plan should be to evaluate how close to the plasma the 3D coils need to be and what response times are required. 02.003 Morley Neil 6/08/2009 16:10 Thrust 02 You mention thrusts 9-12, but thrust 13 which includes the tritium breeding blanket and integrated first wall is one of the components that must take heat and EM load. A linkage here is probably important -- thin walled ferritic steel blanket full of liquid metal must be shown to take these loads and may help set your goal posts. They may also limit the response time of control systems by interposing large conducting structures between your sensor, coils, and the plasma. 02.004 Goldston Rob 6/08/2009 16:13 Thrust 02 I believe that the capability to predict disruptions is a big problem. My understanding is that JT-60U saw no signals whatsoever in advance of their high-beta disruptions. I think it is important to describe how difficult this problem is, and the status of the work to date, not just include it in a to-do list. 06.001 Greenwald Martin 6/08/2009 16:13 Thrust 06 Test of chit system 02.005 Goldston Rob 6/08/2009 16:16 Thrust 02 You can include the Thrust 12 device as a place to test disruption avoidance at Demo-relevant heat flux, with Demo-relevant first-wall components, and long-pulse / high duty factor. Probably much higher duty factor than planned for the Asian devices. Note that CTF/FDF is not a place to test this technology, since it cannot survive lots of disruptions. 02.006 Reiman Allan 6/08/2009 16:17 Thrust 02 It would be helpful to have a set of benchmarks to assess where we are in terms of disruptions, and to measure progress in dealing with disruptions. For this purpose, a few reactor-relevant equilibria should be targeted. Given the limited pulse lengths available on present day tokamaks, the equilibria should be run repeatedly to get a measure of the disruption frequency. It would not be unreasonable to devote a day of run time to repeatedly running some of these cases for 20 or 30 shots. Methods of avoiding and mitigating disruptions could be tested in this context as they are developed. 02.007 Boozer Allen 6/08/2009 16:17 Thrust 02 On viewgraph 13: Inventions and theoretical investigations are required to before disruption prediction and avoidance concepts can be tested. Said differently, concepts must be developed before they can be tested. At present there are few concrete suggestions especially for methods of ways of steering the plasma away from disruption prone regimes while maintaining high performance. The basic talk was very good. 02.008 Baylor Larry 6/08/2009 16:20 Thrust 02 No mention is made of the required reliability of the tools used to avoid and/or mitigate off normal events. Some mention of this seems warranted to make clear the engineering difficulty of implementing such systems. 02.009 Chan Vincent 6/08/2009 16:25 Thrust 02 I am surprised to hear the statement that we cannot "postdict" disruptions. There has been extensive work in understanding disruptions caused by approaching stability boundaries e.g. due to lock modes, NTMs and RWMs. Significant work has been done in validating the physics against experiments. We should be able to predict hence avoid or mitigate such instabilities. The more relevant question is what fraction of the disruptions in tokamaks is caused by "predictable" instabilities and what fraction is caused by accidental "junks" falling off the wall? And whether disruptions caused by "junks" can be mitigated? It seems to me this question can be answered with some dedicated effort within reasonable time. 02.010 Reiman Allan 6/08/2009 16:27 Thrust 02 I have been told that because disruptions do not cause problems on DIII-D, there is little incentive for operators to make any effort to avoid them. This greatly decreases the value of the disruption database on DIII-D. If the operators were asked to attempt to avoid disruptions on all shots where it is possible to do so without compromising the other goals of those shots, that would immediately render the DIII-D disruption database more valuable. Statistics on disruptivity in various regimes would become meaningful. The remaining disruptions could be analyzed as to causes, with a view to further reducing the incidence of disruptions. One could look at the data to determine whether precursors were present, or whether the imminence of the disruptions could have been detected in some other way. This would allow us to assess whether it is reasonable to expect that we will be able to avoid or mitigate disruptions. 03.001 Hill David 6/08/2009 16:34 Thrust 03 validation of models doesn't seem to count on data from present experiments at a level consistent with ongoing efforts. seems to focus on theory + diagnostic development, awaiting testing in a burning plasma. 03.002 Hawryluk Richard 6/08/2009 16:37 Thrust 03 Beta_alpha of 1-3% sounds high, since beta in ITER is 2-3%. How is beta_alpha defined? 02.011 Reiman Allan 6/08/2009 16:38 Thrust 02 There is a great deal of overlap between thrusts 2, 5 and 8. It would appear that they should logically be merged to form two thrusts. 02.012 Wesley John 6/08/2009 16:41 Thrust 02 The issue that some disruptions may not be 'predictable' is raised. It is arguable that all disruptions owed to internal causes should be predictable in the sense that some advance warning of onset is possible; questions do exist whether prediction lookahead time for certain internal causes will be sufficient for some avoidance or slow-acting mitigation methods. With regard to external causes, eg falling micro or macro objects, velocities are low enough that there may be sufficient 'initial interaction time' to be able to actuate 'fast mitigation' schemes. Such considerations put a premium on minimal detection + actuation delay strategies / technologies. 03.003 Zarnstorff Michael 6/08/2009 16:44 Thrust 03 In your figure of Vfast/VAlfven vs rho*-fast, where does the JT-60U data lie? With their NNBI, I would have thought they would have a higher Vfast/VAlfven than shown for the large tokamaks. 04.003 Hill David 6/08/2009 16:45 Thrust 04 Seems like wall conditioning would belong under thrusts 10 or 11 03.004 Hubbard Amanda 6/08/2009 16:45 Thrust 03 Please be sure that the impact of fast ion loss events on the first wall is considered, and appropriate activities to assess and mitigate highlighted. Didn't come through clearly in the talk, and it is explicitly not included in Thrust 2. 01.012 Peng Martin 6/08/2009 16:45 Thrust 01 About disruptions, in the summary and in the presentation on thrust 2, the proposed actions do an excellent job on controlling instabilities that cause disruptions and mitigating the impact in case of disruptions. However, it is relative light in describing the research needed to avoid disruptions in the first place, or to avoid them to the level that ensures reliable plasma and machine operations, in ITER and other prospective fusion devices. Such research could include studies and identification of relatively stable plasmas which have been shown to only have slow plasma instabilities that are readily controlled. Further, in the absence of control, only relatively gentle disruptions would occur that are readily subject to mitigation. Such research, together with that on the well-described instability control, would map out the knowledge for the continuum from "disruption-prone" to "disruption-free", needed to design Demo to manage disruptions with confidence. 04.004 Goldston Rob 6/08/2009 16:51 Thrust 04 Have you estimated the heating power density from ECDC? One needs rather high heating power to raise the surface temperature enough to desorb T. I would be a bit surprised if 1 MW did the job, but maybe the spot size is small enough. 02.013 Wesley John 6/08/2009 16:52 Thrust 02 ITER current = 9 - 15 MA is a 'game modifier' with regard to achieving soft landing disruption avoidance or rapid shutdown disruption mitigation without inducing high levels of runaway electron.current. DM tests in present low-current and moderate-current tokamaks (eg JET) will not necessarily be definitive for ITER. ITER will be a 'first-of-kind' test of ability to avoid/mitigate disruptions while limiting or avoiding excess RE. Successful resolution of this issue in ITER is essential for DEMO with less-robust PFC designs. Ability to test various DM/RE-Avoidance methods in ITER plus PFC robustness is critical. 01.013 Rognlien Tom 6/08/2009 16:52 Thrust 01 Dave, In the Thrust 1 presentation today, you noted a connection to various other Thrusts toward the end. However, these were limited to the first 6 Thrust, whereas diagnostics are spread through many others. For example, Thrust 9 on the "Boundary Plasma" has an important diagnostic-needs component that I will mention tomorrow. In the final document, it will be useful to connect to other relevant Thrust needs. -Tom 04.005 Callis Richard 6/08/2009 16:53 Thrust 04 With respect to ICRF antennas,a topic not mentioned is the effect on antenna performance from deposited erosion products. Does this lead to impurity transport, voltage stand-off degradation etc.? What about ICRF coupling and plasma antenna gap relationships. The proposed localized gas puffing may not be practical because of the large throughput required. 03.005 Meade Dale 6/08/2009 16:55 Thrust 03 As I recall calculations by Gorelenkov et al in 2004 showed that TAE stability in ITER was strongly affected by fast ions from NB injection. In a Demo-like plasma (Hi Palpha/Pext) externally supplied fast ions will be absent. I suggest that this thrust discuss this limitation on the ability of ITER to fully resolve alpha-driven TAE-like instabilities. 04.006 Hill David 6/08/2009 16:57 Thrust 04 Even though we understand the ECH propagation and absorption, is the energy confinement for ECH-heated plasmas understood well enough that we can predict performance in ITER? Should this be part of this thrust? 02.014 nygren richard 6/08/2009 17:02 Thrust 02 The technology requirements in regard to gas injection, pellets, etc. are embedded in the control of transients but do not seem to be explicitly called out at the level of the one pagers. 04.007 Goldston Rob 6/08/2009 17:06 Thrust 04 In what ways would the new facility you are discussing be significantly different from the three Asian tokamaks? It seems that having a fourth such machine, much later than those three, would be overly redundant. 03.006 Chan Vincent 6/08/2009 17:11 Thrust 03 In a burning plasma, the strong alpha heating will result in very high background D and T temperatures. This should have a stabilizing effect on Alfven instabilities due to the strong ion Landau damping. This effect cannot be studied on existing facilities with NBI or ICRH created fast ions. However, it may be simulated using strong ECRH in a high density plasma where electrons and ions are equilibrated with isotropic distributions. 04.008 Rasmussen David 6/08/2009 17:11 Thrust 04 Regarding attributes for a "new" facility. One approach that could separate a US facility from EAST, KSTAR and JT-60 could be to push the auxiliary power density. This would imply a modest size device and a lot of investment in heating power. If it was to be ITER relevant or (alpha relevant) it would need a means to get a significant fast ion population. Power ramp up and power ramp down (to avoid disruptions) could be part of the program. 04.009 Zarnstorff Mike 6/08/2009 17:14 Thrust 04 Why does the US need to build a new facility of this sort, instead of partnering with KSTAR, EAST, or JT-60SA? If you start designing such a facility now, won't KSTAR, EAST, and JT-60SA have an insurmountable head-start by the time such a US facility was operating? 05.001 Zarnstorff Mike 6/08/2009 17:28 Thrust 05 For this to be useful, you must include an additional requirement: your solution must be consistent with burning at plasma Q~20. I.e., the fraction of external current drive must be low, ideally ~10-20% of the total current, and the external heating must be no more than ~18% of the total plasma heating (for Q=20). Also, there must be a requirement on the maximum variations in the plasma reactivity. E.g, clearly, 100% variations must cause additional problems and not be allowed. What is the acceptable variation? 05.002 Zarnstorff Mike 6/08/2009 17:29 Thrust 05 Cross-connects: you should note that Thrust 17 is attempting to accomplish the same goal, but using other techniques (3D shaping). 05.003 Baylor Larry 6/08/2009 17:32 Thrust 05 An important aspect of controlling a burning plasma is controlling the isotopic mix (D/T)as mentioned in your talk. Perhaps this should be included in "Active control" of your 1 pager. 05.004 Reiman Allan 6/08/2009 17:37 Thrust 05 I thought that the presentation was much improved from the draft thrust write-up. The thrust now is about advanced tokamaks, which does make a reasonable thrust. The one sentence summary should be modified accordingly. 02.015 Callen Jim 6/08/2009 17:42 Thrust 02 Your viewgraphs are better than the 6 pager. The description on pages 5 to 6 of the 6 pager give a good description of what to do and how the U.S. is well-positioned for research in this area. But your one-pager does not include these issues. Shouldn't the one-pager end with a strong "punch-line" about what should be done and the possible U.S. role? 05.005 Greenwald Martin 6/08/2009 17:42 Thrust 05 There is an implicit assumption that the only reactor relevant regime is with beta_n well above the no-wall limit. There may be a solution at higher Bt, high q, high beta_p, but with only modest beta_n. This requires spending more on the magnets, but may result in a much more robust configuration. This option should be investigated... 05.006 Boozer Allen 6/08/2009 17:47 Thrust 05 If the other thrusts were carried out, what would be missing that this thrust would develop? Control of pressure, current drive, and rotation must be done with little power. Inventions in this area must be made before they can be tested, and they need to be shown to be credible by theoretical modeling. The question of how good can the performance can be is misleading. A certain level of performance is required; one must show that it is credible that these performance levels can be achieved. I would agree with Ron Parker that of the three legs sensors, algorithms, and actuators the algorithm issue is so simple compared to the other two that putting the three together is misleading. 05.007 Peng Martin 6/08/2009 17:51 Thrust 05 Great thrust and description. Since controllability is a function of proximity to know instabilities and limits, I recommend the inclusion in the thrust research that characterizes the science of controllability starting from parameter regimes relatively far away from these limits, and develop the science while approaching them progressively. 02.016 Wesley John 6/08/2009 17:51 Thrust 02 Also applies for Thrust 5. Even 'normal' fusion power and current shutdown in ITER is acknowledged to be a delicate coordinated action and control sequence. Faster, but not rapid shutdown for disruption avoidance without itself causing disruption looks even more difficult, and successful disruption avoidance or retreat strategies that work in present medium-scale tokamaks may or may not be similarity successful for ITER (or DEMO). Research for T2 and T5 need to assess extrapolation of technologies and strategies to ITER and DEMO. 02.017 nygren richard 6/08/2009 17:53 Thrust 02 I suggest that we all use the term "off-normal" only for events that are truly outside the expected operation, such as unexpected failures of components, as would be of interest for a safety analysis. 05.008 intrator tom 6/08/2009 17:55 Thrust 05 Active feedback and control is a good idea, maybe the only alternative for unstable regimes. The parable of the jet fighter plane being dynamically unstable but actively controlled is interesting. On the other hand active control of any system is not compatible with failsafe design. As a machine builder with a lot of hardware experience, I try to stay away from scenarios like this. The safety and reliability standard for a jet fighter is very different (casualties will be pilots and the crash target) from a nuclear facility that is possibly near a population center like a city (where there is a catastrophic downside to system failure). Do we really want this solution? In general simple technology is preferred if we have the option. 02.018 nygren richard 6/08/2009 17:55 Thrust 02 I would suggest that the implied technology in terms of RF antennae and equipment such as launchers for killer pellets and massived gas injection be clearly identified as enabling technology. 05.009 Berk Herb 6/08/2009 17:55 Thrust 05 If we seriously want to base our fusion concepts on operating above passive stability limits we need a good base of experiments that demonstrate such control. This can be done in present day tokamak experiments if feedback tools are to be developed to operate above passive limits. Thus if the concept is worthy, there is a need to document the improvements and reliability achieved by working significant above passive stability limits. Demonstrating this may give credibility to an aggressive feedback direction to planned work on ITER and Demo above passive stabilization limits. 04.010 Temkin Richard 6/08/2009 21:34 Thrust 04 The talk by Ron Parker and Craig Petty presented specific advocacy for these ideas: “Ensuring that ITER will efficiently achieve its objectives requires a high level of support by the US tokamak program. This requires: In the near term, investing in the domestic tokamaks, e.g., with additional HCD and diagnostics, enabling a focused program of research addressing key ITER issues; In the longer term, constructing and operating a new US tokamak -- an ITER Satellite Facility.” This advocacy is missing from both the one pager and the six-pager. It should be in both documents. This statement also should be prominent in the write-ups: “Much of the research required for extending the pulse length on ITER, and indeed for carrying out the research outlined in this thrust, can be initiated on the existing domestic tokamaks with enhanced capabilities. As a first step, this can be accomplished by approximately doubling the ECH power on DIII-D, the NBCD power on NSTX, and the LHCD on 04.011 Temkin Richard 6/08/2009 21:39 Thrust 04 Ron Parker said in the Thrust 4 talk, under facility requirements: “As a first step, this can be accomplished by approximately doubling the ECH power on DIII-D, the NBCD power on NSTX, and the LHCD on Alcator C-Mod. This is an excellent idea. I wonder why Ron did not also advocate ECH for NSTX and for Alcator C-Mod? A major Bernstein Wave Heating program was proposed for NSTX in recent years, but not funded. I would include that. ECH for Alcator would also be interesting. 05.010 Temkin Richard 6/08/2009 21:59 Thrust 05 Thrust 5 describes the future need for the Control Systems that would be used to operate the auxiliary systems. This is an interesting topic and the presentation by Alan Turnbull was very thoughtful (and entertaining.) But, this is putting the cart before the horse. We need direct advocacy of the auxiliary systems themselves, and advocacy at a high level! The important technologies for heating, current drive, fueling, etc. must be developed well beyond present day capabilities to meet future needs. We need Thrust 5 to cover the need for the enabling technologies and auxiliary systems. They are not covered in the other thrusts! The Theme 2 write-up on the research needs for auxiliary systems, including plasma heating research needs, is excellent. The research needs for auxiliary systems were supposed to be included in one of the thrust areas, specifically as a major part of Thrust 5. Thrust 5 is called “Develop and Demonstrate the Enabling Science and Technology For Controlling and Su 05.011 Temkin Richard 6/08/2009 22:07 Thrust 05 I would not use the word “actuator” to describe the plasma control systems such as heating, fueling, etc. The word “actuator” is ordinarily used to describe “a mechanical device for moving or controlling a mechanism or system.” Using the word “actuator” will really confuse people, especially non-fusion people. I would replace “actuator” with a specific device or devices such as “heating and fueling system.” I would make the replacement everywhere in the Task 5 write-ups, both the one-pager and the six-pager. 06.002 hill David 6/09/2009 09:11 Thrust 06 When experiments work closely with theorists to validate codes, it would seem that this is exactly the type of "case study" mentioned in Martin's talk today. Things that come to mind are comparisons between GYRO and detailed transport measurements (such as the effort on DIII-D which has been ongoing for a number of years, or efforts on NSTX). Similarly, there have been ongoing efforts to compare RF or ECH heating codes with experiment, comparing SOL models such as UEDGE against a wide variety of edge diagnostics, work on rotation physics comparing with MHD codes such as MARS-F, and comparisons of TAE mode structure measurements with simulation. So, I don't understand what is being advocated. Is it some central administration? It is an official adoption of some new efforts to add to the present mix? Is it funding for new efforts to build codes to replace existing codes? Since we are a fusion science program, programs are already stressing physics understanding using simulation. 06.003 Callis Richard 6/09/2009 09:18 Thrust 06 It appears that this thrust only covers plasma physics. Is there not a place in this thrust for model development for predicting better materials for the first wall and structural material. 06.004 Chang CS 6/09/2009 09:19 Thrust 06 Dear Martin, On page 12, another big part of computer science is data management. 06.005 Ji Hantao 6/09/2009 09:22 Thrust 06 In some areas, such as magnetic reconnection, space and astrophysical community have specific strengths in terms of theory and simulations. I strongly suggest that we add a component in this thrust to collaborate and interact with them in a mutually beneficial way. 06.006 Peebles Tony 6/09/2009 09:25 Thrust 06 Generally your talk strongly supported the need for innovation in diagnostics and presents a balanced approach to development of validated predictive models. However, your VG on resources (VG #12) seems very biased towards the "needs" of the theory/ computational research activity. For example, 7 of your list of 11 resources are theory/ computaional, 1 on diagnostics, 2 experimental facilities and 1 on analysts. This projects a, perhaps unintended, but biased perspective especially in light of the fact that computational resources have increased significantly in recent whereas funding for measurement innovation has been stagnant for at least 10 years. 01.014 Chang CS 6/09/2009 09:26 Thrust 01 It seems to me that emphasis on the self-consistent study between the waves driven by, and sitting on, the energetic particles and their self-organizing interaction with the background plasma equilibrium and turbulence could be upgraded. This issue is not easy to handle at the moment, but should become important as we think about ITER and DEMO. 06.007 Marmar Earl 6/09/2009 09:30 Thrust 06 Should this thrust be broadened to include technology? 03.007 Ji Hantao 6/09/2009 09:31 Thrust 03 I found that most activity described in this thrust is duplicated in Thrust #8. In fact, the main activity of #8 depends on the outcome of this thrust. I think we should seriously consider to combine these two thrusts in a more coherent and coordinated thrust. 06.008 Humphreys Dave 6/09/2009 09:37 Thrust 06 I see a strong focus on the flow of data from experiments to codes for the validation mission, which is of course essential. But the need for significant effort to enable the output of the thrust to be used by experimentalists, control designers, etc... isn't so clear. See for example the summary slide for a good illustration of the focus and direction of data flow in the thrust. What I think is missing is an entirely separate activity to adapt the validated codes so they can produce specific model forms and other results as needed by these customers. This is an element of computational modeling research plans that is traditionally neglected, or in cases when it is pursued, has not been very successful in the fusion community (e.g. NTCC). I suggest that it is important to make more explicit in the thrust description the intent to do the substantial and costly work to make the results of thrust 6 highly usable and tailored to the needs of experimentalists and other customers. 07.001 CALLIS RICHARD 6/09/2009 09:38 Thrust 07 This thrust does not cover the issues in regards to the 3D coils that may need to be inside the vacuum vessel to control VDEs, ELMs and RWMs. These coils have severe radiation requirements as well as challenging cooling needs. Everything has to be compatible with remote naintenance requirements. 07.002 Callis Richard 6/09/2009 09:44 Thrust 07 Is there an issues in using ceramic insulation material, with the ceramic material losing it's insulating properties under neutron fluence. Does sample testing need to be performed? 06.009 Hill David 6/09/2009 09:45 Thrust 06 What is meant by coordination? The discussion of this thrust does not recognize the substantial ongoing coordinated effort comparing theory/simulation and experiment in many areas (core, edge, rf, transport, fast ion stability and transport, MHD stability, and rotation physics). More resources are needed for this field, and the idea of getting support and respect for "analysts" is urgently needed. However, the emphasis on "coordinated" implies that what is really needed is better top-down management or a new upper level management structure. 05.012 Milora Stan 6/09/2009 09:46 Thrust 05 Amanda made the point that power density scales like beta^2 B^4. But it scales first and foremost like n^2T^2. Since T is essentially the same for ITER and DEMO it practically only scales like n^2. And n will need to be a factor of 2 at least higher for DEMO than ITER(already a challenge) because the power density needs to be 5 higher. We have not really faced the issue of high density control/sustainment in our experimental programs. Given the importance of the issue, the lack of attention to it in any detail in either thrusts 5 and/or 8 is surprising. A proper treatment of the issue would include theory, simulation, experiments and enabling technology. It should build on Thrust 4. 08.001 hill david 6/09/2009 10:05 Thrust 08 The core-edge coupling part of this thrust seems to overlap nearly completely with thrust 12. The combination of these two thrusts seems to imply that two separate experiments are needed, both with high confinement neutron-producing cores (either by short pulse DT or longer pulse DD operation) and appropriate PFCs. Is this what we mean? 12.002 Hill David 6/09/2009 10:07 Thrust 12 This thrust seems to overlap nearly completely with core-edge coupling part of thrust 8. The combination of these two thrusts seems to imply that two separate experiments are needed, both with high confinement neutron-producing cores (either by short pulse DT or longer pulse DD operation) and appropriate PFCs. Is this what we mean? 08.002 Marmar Earl 6/09/2009 10:23 Thrust 08 What is the expected schedule for construction and operation of the proposed US D-T facility relative to that of ITER? Does this machine operate operate in parallel with ITER, or after substantial D-T experience on ITER? 02.019 Wesley John 6/09/2009 10:49 Thrust 02 Need/intent to develop and test a 'broad portfolio' of disruption prediction means, plasma and hardware in present expts should be more explicitly stated. One or two prediction means is unlikely to be effective for all types and causes of disruption, and 'voting' or redundant predictions may be important to minimize false positives. Final complement and deployment for ITER TBD. 02.020 Wesley John 6/09/2009 11:05 Thrust 02 Need a range of ITER qualified mitigation strategies and/or hardware, plus effective mitigation capabilities for 'target' plasmas ranging from low-current to full-current OH, heated and burning full-current plasmas (9-15-17 MA) and during-shutdown lower-energy plasmas. Also after-thermal-quench 'already-disrupted' plasmas. RE threat may be common to all; methods for mass delivery or other RE mitigation may differ. Action/delay times may differ. Need some statement on this 'range of mitigation strategies' and likely need for multiple means 'on-ready' for ITER. 09.001 CALLIS RICHARD 6/09/2009 11:08 Thrust 09 All electromagnetic waves used to heat and drive current in the plasam, must traverse throught the SOL. This thrust only covered the ICRF range of frequencies. The thrust should be expanded to cover the frequencies of Lower Hybrid 4 - 9 Ghz and ECH 150 -250 GHz. In these areas there are issues of wave=plasma coupling,deposits on mirrors and launchers, power handeling issues, etc. 08.003 Goldston Rob 6/09/2009 11:16 Thrust 08 The full set of upgradabilities that you have listed are greater in every respect than those of the original ITER, which itself cost twice what the present ITER costs. While we are not discussing price in detail, we need to have a sense of what you are talking about here. You need to present at least a cartoon idea of what you are talking about to make this worthy of consideration. What magnet technology are you discussing? What HH factors are you assuming to achieve your goals? What are you assuming about insulator lifetime (FIRE was already beyond the known limits)? What kind of PFC technology are you considering that could support this mission? Making a fog of options is not adequate for consideration. You need to show the scale/scope of at least one compelling concept that could be upgraded to all of these other missions. 05.013 Temkin Richard 6/09/2009 11:25 Thrust 05 I put in a previous chit describing issues with this thrust. I want to make it clear that my suggestion is that this thrust either be completely rewritten or be revised to a very major extent. 06.010 Brower David 6/09/2009 11:29 Thrust 06 it has often been said…. “Equilibrium reconstruction codes are only as good as the measurements that constrain them”. This led to the demand for detailed measurements of equilibrium parameters in the plasma core over the past 10-15 years. Same is true for development of simulation codes, predictive models and validation procedures, …. Critical nature of the measurement component must be made clear. One-page thrust contains 7 proposed action items, including... 5 related to theory/codes/validation, 1 related to experiments and 1 related to measurements. Perhaps a bit out of balance...... 09.002 Chan Vincent 6/09/2009 11:34 Thrust 09 A promising control of the edge pedestal performance is the use of strong shaping. It can potentially improve the stability of the edge MHD modes thereby allowing high pedestal compatible with small ELMs or ELM-free operation. This mechanism can be tested in existing facilities with dedicated experiments. I note that this was missing in the summary presentation. 10.001 nygren richard 6/09/2009 11:35 Thrust 10 Replace the term "off-normal" with "transient." "Off-normal" will imply accident scenarios to some people outside fusion. 10.002 Baylor Larry 6/09/2009 11:41 Thrust 10 Is a new PMI test facility capable of handling tritium necessary or can deuterium be sufficient to understand retention in a ITER/DEMO divertor like environment? 10.003 hill david 6/09/2009 11:51 Thrust 10 are we ready to proceed with such a facility? Is there agreement as to what to build? 10.004 Hill David 6/09/2009 11:55 Thrust 10 Testing for compatibility in existing experiments would seem to be critical, but is given minimal attention in this thrust. 10.005 Whyte Dennis 6/09/2009 11:56 Thrust 10 Don: Nice job overall to motivate a more aggressive program in this area. Two main comments. The presentation implied that PISCES is the only test-stand facility we have in the US, and that we lack in areas of testing tritium, alpha damage and in-situ PMI diagnosis. I'll point out that we have TPE which is basically PISCES with tritium. Alpha damage and In-situ PMI using ion-beam analysis with a plasma present is available in the relatively new DIONISOS facility, the subject of invited talk at the last PSI conference. Both of these facilities have unique features in the worldwide PSI test stand area. I know you had limited time to present the US capabilities, but I think showing that we have a good base of US facilities and expertise to expand from actually makes this thrust more compelling. Secondly, it is necessary to emphasize the critical role that modeling has in this area. This enables "transfer" of the knowledge gained in the test-stands to the confinement world. 10.006 nygren richard 6/09/2009 12:03 Thrust 10 Suggestion - use "W fuzz" as an example where the surface conditions that we will see in ITER result drive changes in the surface morphology. Whether or not we expect to see W fuzz in a tokamak, the eperiments show that there will be a strong driving force to alter the surface significantly. 10.007 nygren richard 6/09/2009 12:03 Thrust 10 Suggestion - use "W fuzz" as an example where the surface conditions that we will see in ITER result drive changes in the surface morphology. Whether or not we expect to see W fuzz in a tokamak, the eperiments show that there will be a strong driving force to alter the surface significantly. 10.008 nygren richard 6/09/2009 12:09 Thrust 10 If we believe that actively-cooled internal components will be needed for RF systems and other ICs, then this should be more clearly stated and presents both an engineering challenge to met as well as a need for some restructuring in the internal coordination of the fusion program in that this also reenforces the need for stronger integration of the design, fabrication, testing and deployment path for PFCs and ICs. 04.012 Wesley John 6/09/2009 13:01 Thrust 04 The are many connections between the normal aspects of plasma initiation, ramp-up, equilibrium burn and ramp-down and the 'alternate' evolutions associated with response to hardware and plasma abnormalities and disruption avoidance. The plasma anomalies can in turn arise from lack or limitation of control capabilities (out of actuator range, insufficient power, bad algorithm) or unforeseen plasma perturbations. In the end, an integrated cross-thrust (Super-Thrust) effort that combines scenario, actuators, control (system and algorithms) and intelligent reaction plus active-in-scenario guidance to minimize 'variance' will be needed. Not advocating combining thrusts; just mutual support. 10.009 nygren richard 6/09/2009 13:07 Thrust 10 Addendum to previous chit: The point, perhaps not clear before, is that the W fuzz cannot be discounted because one might not expect it to from in a tokamak. The driving force will be present due to the conditions and we can expect some type of rearrangement of the surface morphology that will likely be important in the erosion process and how the surface responds to transient heat loads. 10.010 Hill David 6/09/2009 13:09 Thrust 10 Seems like 10 and 11 both aim to develop solutions to the PFC issues, one looking at the materials and one looking at divertor configurations. Seems like ideal candidates for consolidation using definition of thrust: multi-faceted attack on an important issue for fusion. 10.011 Hill David 6/09/2009 13:10 Thrust 10 Seems like 10 and 11 both aim to develop solutions to the PFC issues, one looking at the materials and one looking at divertor configurations. Seems like ideal candidates for consolidation using definition of thrust: multi-faceted attack on an important issue for fusion. 11.003 Hill David 6/09/2009 13:10 Thrust 11 Seems like 10 and 11 both aim to develop solutions to the PFC issues, one looking at the materials and one looking at divertor configurations. Seems like ideal candidates for consolidation using definition of thrust: multi-faceted attack on an important issue for fusion. 11.004 Hill David 6/09/2009 13:14 Thrust 11 Impact of naturally occurring SOL currents on liquid metal divertors should be considered. 10.012 Temkin Richard 6/09/2009 13:23 Thrust 10 The discussion of RF antennas as Internal Components is specialized to ICRF antennas. For example, the Thrust 10 six page write-up says: “Reliable performance of RF antennas/launchers is needed. Many of the issues concerning the interaction of the near field of the antenna/launcher with the scrape off layer plasma (SOL) are not well understood.” The write-up should also reference other RF launchers, including EC launchers. More work is needed on EC launchers as well as on ICRF launchers. This should be a simple change to write up. 11.005 Wong Clement 6/09/2009 13:31 Thrust 11 Based on the presentation: Good presentation with focus on the divertor design. In the 6 pager, please make sure that discussion on the issues of cooling the FW is included. The FW is removing >80% of the thermal power for DEMO and at the same time the heat flux distribution is uncertain. For coolant heat transfer enhancement approach, the use of internal channel roughening should be included for the FW design. At the same time, the combination of internal channel roughening and other methods like jets should be included in future development. It is too early to narrow on a few selected helium-cooled heat transfer enhancement options. University programs can sure make contributions in helium-cooled heat transfer enhancement in the future. 11.006 Ji Hantao 6/09/2009 13:33 Thrust 11 Free-surface liquid metal flow in a magnetic field is a relatively unexplored area of research. What are properties of MHD turbulence of such flow, including flow drag and heat transport? I suggest that in addition to the comprehensive test stand described in the thrust, I suggest to add a research component on these basic physics understandings using a combination of theory, simulation and small-scale experiments. This component is important to give us a firm base for any further applications to fusion environments. 10.013 Temkin Richard 6/09/2009 13:34 Thrust 10 Thrust 10 should identify the advantages of novel concepts for Internal Components, and encourage the development of such components. The one page write-up now says: “Can fabrication techniques guarantee robust PFC and IC designs and acceptably low failure rates?” I would add to this: “Can new, innovative concepts for the ICs reduce the power loading and increase the reliability?” I propose this change since EC launchers are actively pursuing such innovative concepts. One specific innovative concept involves the use of mixtures of microwave modes that can be end fired from a waveguide and steered remotely, thus eliminating the plasma facing mirror. This innovative idea was presented at the Theme 3 Workshop and is mentioned in the full write up of Theme 3. The one page write-up for Thrust 10 should reflect the need for innovative new ideas. 08.004 Ji Hantao 6/09/2009 13:35 Thrust 08 "Self-heated plasma" and "strongly-coupled plasma" are used interchangably. I suggest to use "self-heated plasma" only since "strongly-coupled plasma" is being used elsewhere to describe different kinds of plasmas. 12.003 Hill David 6/09/2009 13:38 Thrust 12 With regard to long-pulse component reliability, there has been a lot of mention of experience from Tore Supra regarding development of hot spots and ultimate component failures. As I recall, these were due to undetected defects in fabrication, rather than unexpected heat flux. These undetected defects came to light only gradually, perhaps due to gradual delamination of components. Such failures were attributed to inadequate pre-installation qualification. Thus, it would seem that off-line testing/qualification is more relevant than testing in tokamaks. 12.004 Callis Richard 6/09/2009 13:44 Thrust 12 How do you account for edge Alpha affects on PFCs if you do not run in DT? 12.005 Marmar Earl 6/09/2009 13:48 Thrust 12 Liquid lithium is mentioned as a possible plasma facing material. However, in the stated temperature range (500 to 1000 C), the vapor pressure of Li is very high (around 50 torr at 1000 C). Is liquid Li a credible option for the proposed facility (and by extension for DEMO or a reactor)? 12.006 Hill David 6/09/2009 13:53 Thrust 12 Won't the integrated testing require a high confinement core plasma? Is this compatible with hydrogen operation? Won't it have to have same kinds of ELMs and edge pedestal and core transport as high confinement plasmas in order to validate the integrated operation? If so, won't this mean DD operation and subsequent neutron activation? Are there agreed upon (but fusion power proponents) possible solutions that will be tested? If not, does it make sense to begin design of such a facility now? 12.007 Taylor Tony 6/09/2009 13:54 Thrust 12 CLARIFICATION I understand that the facility called for here is primarily a "integration" facility. New materials and there properties will be developed in 10, optimial configurations will be developed in 11, and ELM suppression will be perfected in 2. Do these other activities precede thrust 12 - Does 12 need to wait on these other tasks? 09.003 Jarboe Tom 6/09/2009 13:56 Thrust 09 Present modeling seems to be broken up into four regions: PMI, edge, pedestal, and Core. These regions all provide boundary conditions for their neighbors. Since boundary conditions are so important we need self-consisent boundary conditions. This will only be achieved by integrating the modeling of all four regions. We need to do a whole experiment model with PMI BC calculated self-consistantly. 13.001 Cohen Sam 6/09/2009 14:00 Thrust 13 Once DEMO starts operating with D-T, how long will it take for the reprocessing system to extract as much tritium in a day as is burnt in a day ( or as fueled in a day)? 02.021 Taylor Tony 6/09/2009 14:05 Thrust 02 After listening to thrusts 9, 10 11, & 12, It is clear that ELM suppression techniques are assumed to have been developed elsewhere in thrust 2. Thrust 2 seems to imply heavy reliance on non-axisymmetric fields as a viable ELM suppression technique ---- Yet there have been some comments that ELM suppression by RMP coils may not be credible for DEMO. It is my opinion that removing the impulsive heat and particle fluxes from repetitive ELMs is the hihgest priority task for "taming the plasma material interface." Therefore, I think thrust 2 should add to the ELM suppression effort "exploration of innovative techniques" for ELM control with high pedestal pressure. 13.002 Lipschultz Bruce 6/09/2009 14:09 Thrust 13 I think your emphasis of liquid metals was with respect to test blanket modules. But you also mention divertors and other areas. Please make it clear when you talk about flowing Li that you mean TBMs and not divertors. Li and other flowing liquid metals make sense for TBMs but are unlikely to make sense in a reactor for PFCs given the high temperatures where their evaporation rate rises to levels rivaling the highest incident ion fluxes in the divertor. 10.014 Youchison Dennis 6/09/2009 14:12 Thrust 10 Is the training/education of test facility operators (test engineers)retained in the 6-pager for both new & existing facilities? 11.007 Ji Hantao 6/09/2009 14:12 Thrust 11 With regard to basic properties of free-surface liquid metal flows, there are quite some details that have been worked in Thrust #13 where liquid metal duct flows were described. There are important commonalities with free-surface MHD. I recommend to interact with that thrust on these aspects. 13.003 Ulrickson Mike 6/09/2009 14:18 Thrust 13 A question was raised in the thrust 13 talk about whether technology development required for this thrust should be done in thrusts 10-12 or in thrust 13. While this development might be able to be done in thrust 13 it will be done more cost effectively in thrusts 10-12 where the development can be done without all the complications of the full nuclear issues. The nuclear regulatory requirements will greatly constrain the ability to try configurations and increase the cost of maintenance. A step by step approach is more effective. Without the science foundation of thrusts 10-12 (and possibly 9) the probability of success of thrust 14 is small. 13.004 Greenwald Martin 6/09/2009 14:19 Thrust 13 I want to endorse your step by step "science based" approach. It seems to me that this is right way to go for technical reasons and more likely to be attractive to policy makers. The tension between our missions as a science program or as an energy program is resolved appropriately with this approach. (I note that thrust 14 is organized along similar lines.) 13.005 wong Clement 6/09/2009 14:25 Thrust 13 This is in respond to the comment by Rob Goldston. There is no reason for us to assume that CTF should be designed to take 1 disruption per year. This is the wrong approach of work out the problem. The approach that most of us are recommending is to do our best to avoid and mitigate disruption and Type-I ELMs. However at the same time, as a conservative engineering measure, we will have to develop disruption tolerance surface, to take care of a few disruption for the case of un-expected disruptions. This could be a minor point, but it has significant difference on the approach we go about to find the solutions to handle disruption and Type-I ELMs. 13.006 Hill Dave 6/09/2009 14:31 Thrust 13 There seems to be a lot in common between thrust 13 and 14 in terms of materials, radiation damage, and components. Should these be combined? If not, text needs to better differentiate the research. 14.002 Hill David 6/09/2009 14:31 Thrust 14 There seems to be a lot in common between thrust 13 and 14 in terms of materials, radiation damage, and components. Should these be combined? If not, text needs to better differentiate the research. 14.003 Greenwald Martin 6/09/2009 14:37 Thrust 14 I wanted to reiterate my comment w/r to thrust 13 and endorse your step by step "science based" approach. It seems to me that this is right way to go for technical reasons and more likely to be attractive to policy makers. The tension between our missions as a science program or as an energy program is resolved appropriately with this approach. 04.013 Peng Martin 6/09/2009 14:44 Thrust 04 Various disruption loads for CTF (including its first stage scientific R&D implementation called FNSF), estimated according to the ITER physics basis for disruptions, are much smaller than those estimated for ITER. These are well documented in the IAEA FEC2008 paper FT/P3-14. The reasons for these results are obvious, that the FNSF stored plasma and magnetic energies are an order of magnitude smaller than those of ITER, over a plasma linear scale size that is 1/5 that of ITER. As a result, FNSF will unfortunately not be a good facility for testing DEMO-relevant disruption mitigation science and technology compared to ITER. It is recommended that such information be included the Thrust 13 documentation. 13.007 Goldston Rob 6/09/2009 14:48 Thrust 13 There is a kind of chicken-and-egg problem with respect to disruption and CTF. For example, in Ted Strait's talk at the Theme III workshop, he indicated that a VDE in FDF would be 2.2x worse than in ITER, and of course ITER needs a thick Be/Cu/steel first wall. Laila El-Guebaly and Rene Raffray submitted a white paper to the Theme IV workshop which, in referring to ARIES FS first wall designs, indicated: "ITER-type VDEs could deposit up to 60 MJ/m2 in 0.2 sec. Not even one VDE can be accommodated based on such severe VDE parameters." They also indicate that "There is no practical means to enhance the breeding of the DCLL blanket if the off-normal events require adding more than 1-2 mm FS on the FW." 14.004 Hsu Scott 6/09/2009 15:23 Thrust 14 I found it striking that the need for an IFMIF-class facility was not directly emphasized in this thrust nor any of the other related thrusts. A materials qualification capability is clearly needed before we can build a FDF/CTF. The US has an opportunity to go forward with this by leveraging on existing accelerators, such as the 800 MeV proton accelerator at Los Alamos. We could essentially carry out IFMIF's mission many years sooner at a fraction of the cost. This is needed to accelerate the pace of fusion energy development. 11.008 Youchison Dennis 6/09/2009 15:32 Thrust 11 Limit thrust#10 activities to PMI (first 10 microns of pfc surface) Thrust #11 should address power and particle effects deeper than 10 microns. 12.008 Buttery Richard 6/09/2009 15:36 Thrust 12 Absence of DT option seems puzzling. Logic of previous thrusts is that dpa may change the materials properties, therefore it seems odd to start by ruling out any kind of D-T phase – particularly when the device will need remote handling. Surely should retain an option on some kind of DT phase? Your argument seemed to be about need for shielding for high fluence operation could be constraining. But even in D-D you will need R-H, and machine will make T as well, which needs handling. 12.009 Buttery Richard 6/09/2009 15:37 Thrust 12 Please define how far this thrust goes beyond what can be achieved in Asian devices (up to 100s, metal walls). How crucial is the extra bit. 05.014 Wesley John 6/09/2009 15:38 Thrust 05 Disruption avoidance actions (the 'A' in PAM) will comprise a specialized 'control' response that may combine a number of 'standard' magnetic and control and fueling/pumping actions, plus possible specialized actions such as modest impurity injection, etc. not part of 'stationary-state control'. A wide range of outcomes, ranging from full recovery to Thrust 4 conditions to a fast plasma shutdown 'scram' (ideally not as fast as mitigation) can be envisioned. Avoidance scenarios must be tested. Separation from the other Thrust 2 activities is not acceptable. 11.009 Buttery Richard 6/09/2009 15:42 Thrust 11 Principal of divide between 10 and 11 seems OK, but practically there are clear overlaps - eg on transients and needs for integrated test facilities in each thrust. Need to draw line more carefully... Should materials part of thrust 10 be merged into a new nuclear+heat materials thrust with 14 - and rest of thrust 10 into 11? >> ONE STRONG THRUST TO RESOLVE MATERIALS. 10.015 Buttery Richard 6/09/2009 15:42 Thrust 10 Principal of divide between 10 and 11 seems OK, but practically there are clear overlaps - eg on transients and needs for integrated test facilities in each thrust. Need to draw line more carefully... Should materials part of thrust 10 be merged into a new nuclear+heat materials thrust with 14 - and rest of thrust 10 into 11? >> ONE STRONG THRUST TO RESOLVE MATERIALS. 14.005 Buttery Richard 6/09/2009 15:42 Thrust 14 Should materials part of thrust 10 be merged into a new nuclear+heat materials thrust with 14 - and rest of thrust 10 into 11? >> ONE STRONG THRUST TO RESOLVE MATERIALS. 03.008 Buttery Richard 6/09/2009 15:45 Thrust 03 This needs a clear experiment programme highlighting. Also consider merging as subset of thrust 8 as facilities to address this physics are the same as those specified in 8. 04.014 Buttery Richard 6/09/2009 15:47 Thrust 04 The biggest risk to ITER achieving its scenarios si the absence of NNBI and possibly viability of ICRH. Therefore add a fall back with a bullet for developing and assessing ECRH dominant scenarios, augmented by edge rotation from tangential positive ion beams. 13.008 Raman Roger 6/09/2009 15:52 Thrust 13 The goal of fusion research is to burn fuel and produce power. Controlling fusion plasma discharges simply does not mean control current and heat the plasma. In an ignited system no external heating is needed. In a high bootstrap current fraction discharge the plasma will generate a substantial part of its own current. The more this self driven current is the more efficient is the reactor. Thus, capability for precise fueling is a powerful profile control tool. Another benefit of core fueling is increased tritium burn-up (hence less amount of it trapped in walls) and reduced burden on the pumping and tritium processing systems. While there are on-going programs for various other means of control (current, ELMs, RWMs, NTMs), there is no program in the US or internationally to develop precision core fueling capability. This is a severely lacking capability needed for a Demo and quite possibly for the AT phase of ITER. So it should not be hidden in the thrust descriptions under the genera 15.001 Youchison Dennis 6/09/2009 15:53 Thrust 15 This is an important thrust for the advancement of engineering science! One of the major impediments is the dis-similar and proprietary file formats that limit the interoperability of design codes. Can this issue be addressed by the US government and/or international standards organizations in a timely manner? Is there a strategy on how to standardize on file/data formats? 15.002 Goldston Rob 6/09/2009 15:59 Thrust 15 It seems to me that the DT machines we are discussing are designed in order to make ourselves happy. We want to make lots of tritiium. We want to show that the bootstrap current profile is consistent with alpha heating. But everyone outside of this room only wants electricity from us. It seems to me that we should consider extending the requirement for a CTF (whether an ST, AT or CS) to include net electricity production. This means that Q_eng needs to be somewhat greater than unity, say 1.3, so that 100 MWe would be put on the grid, perhaps with 30% duty factor. 16.001 Hill David 6/09/2009 16:06 Thrust 16 All research elements outlined, except #6, are those of larger aspect ratio tokamaks. Some issues (such as divertor heat flux) are not unique to the ST, but just reflect the consequences of design choice in going to a smaller radius tokamak. Proposed high-beta is only modestly higher than conventional tokamaks. Most importantly, it is limited by the same physics effects. Present ST-CTF proposals move to A~2, which is very close to "conventional" tokamak experience. So, rather than unique physics that must be investigated separately from the "conventional" tokamak, shouldn't the work here be folded into that of Thrust 5 or 8? 10.016 Allain Jean-Paul 6/09/2009 16:07 Thrust 10 Many surface response codes used in erosion/re-deposition modeling of PMI effects rely and have used extensively particle-beam (e.g. ion, atomic, etc...) test facilities (e.g. UTIAS, IPP, IIAX, others...). Both in the talk and the 6-pager very little was mentioned on a need to upgrade/integrate/add such facilities in the context of both materials and computational code development. I think we need to be more explicit about the need for such facilities as critical pieces to the PMI effort. 16.002 Hill David 6/09/2009 16:11 Thrust 16 The ST has very high divertor heat flux because of its small major radius. Are liquid metal divertors unique to the ST? That is, does the ST uniquely allow use of liquid metal divertors? Is the divertor physics of the ST unique as compared to conventional tokamaks? If so, how and at what aspect ratio do these difference appear? 16.003 Whyte Dennis 6/09/2009 16:12 Thrust 16 Why is relative increase in pulse length limited to 3 orders of magnitude as a goal? For ST-CTF as demonstrated goal this would suggest from today's ~ 1 s --> 1e5 (day) to 1e6 seconds (~weeks). This issue could have implications to heating/CD choices at low-A. 06.011 McKee George 6/09/2009 16:23 Thrust 06 In response to Dave Hill's comment ("Aren't we doing this already"): this thrust needs to emphasize that the validation effort requires a level of rigor that, frankly, is not often achieved in fusion science today. Confidently extrapolating models/simulations to BP/ITER experiments requires the more rigorous validation process that is envisioned for this thrust. 09.004 Allain Jean-Paul 6/09/2009 16:28 Thrust 09 Current materials surface response codes are challenged by predicting a strongly-coupled interface boundary with the plasma. These codes are limited to mostly Monte Carlo BCA(binary collision approx.)-techniques that only partially predict the materials evolution induced by its coupling with plasma. For example, none of the current materials surface codes can predict the morphology materials mixing evolution evidenced in PISCES-B studies. There should be a more explicit need articulated in this thrust for development and more frequent use of atomistic simulation tools (e.g. MD, AMD, QMD, ab-initio, etc...) in the context of materials surface evolution under plasma exposure. This development is non-trivial and will require significant resources. This effort is critical since the material surface response remains a boundary condition to erosion/re-deposition codes discussed in this thrust. 16.004 Buttery Richard 6/09/2009 16:28 Thrust 16 It undersells the CTF to pull it out into its own path and thrust - it has much wider relevance and value. So this thrust should be more explicitly about a full package to establish the physics basis for the CTF (including design studies), rather than just the ST specific research lines - though these would form a major part of this. Title should therefore change as well. 16.005 Taylor Tony 6/09/2009 16:29 Thrust 16 As presented, the physics motivation for this thrust does not seem well founded. Clarification on the title What does "reduced aspect ratio" mean in the title? On the last page, you showed a figure that goes from NSTX to NSTX-U to CTF. It is my understanding that the aspect ratio incrases with each. What I expected from the title was an effort that explored unique physics that might be obtained as the aspact ratio became smaller and smaller -- say like 1.2 - 1.3. Buttery's comment is worth considering -- physics basis for CTF. The physics is less unique as you move toward aspect ratio of 2, but the motivation and the representation of what is planned is much clearer. 16.006 hill david 6/09/2009 16:29 Thrust 16 The idea that we need special, untested high-current connections and new high current, low-voltage generators to produce the toroidal field in the ST, suggests significant technological risk. So too do the high divertor heat loads and startup and current drive requirements in overdense plasmas. Do these challenges negate the advantages of the ST for the CTF mission? Does the R&D cost to address these issues offset proposed cost savings with ST CTF devices? 16.007 Greenwald Martin 6/09/2009 16:29 Thrust 16 The research program described in this thrust is important and interesting, however I wonder why it is not integrated with other thrusts that are looking at the same issues. Maintaining the fiction that an ST is anything other than a low aspect ratio tokamak needlessly multiplies categories violating the principle of Occam's razor. Specifically it makes the overall MFE program less rather more clear by obscuring common themes. 05.015 Raman Roger 6/09/2009 16:31 Thrust 05 The goal of fusion research is to burn fuel and produce power. Controlling fusion plasma discharges simply does not mean control current and heat the plasma. In an ignited system no external heating is needed. In a high bootstrap current fraction discharge the plasma will generate a substantial part of its own current. The more this self driven current is the more efficient is the reactor. Thus, capability for precise fueling is a powerful profile control tool. Another benefit of core fueling is increased tritium burn-up (hence less amount of it trapped in walls) and reduced burden on the pumping and tritium processing systems. While there are on-going programs for various other means of control (current, ELMs, RWMs, NTMs), there is no program in the US or internationally to develop precision core fueling capability. This is a severely lacking capability needed for a Demo and quite possibly for the AT phase of ITER. So it should not be hidden in the general thrust descriptions under th 07.003 Sawan Mohamed 6/09/2009 16:37 Thrust 07 Superconductors (e.g. Nb3Sn) are limited to ~1e19 n/cm2 fast neutron fluence due to degradation in Jc. At this level, the absorbed dose in organic insulators is ~1e10 Rads which is the limit for cyanate ester/plyimides. How high a fluence can HT SC take? It is important to develop superconductors that can tolerate higher fluences otherwise developing more radiation resistant organic insulators or ceramic insulators will be useless or not needed. 17.001 Callis Richard 6/09/2009 16:51 Thrust 17 There was no mention if the technology needed for heating plasmas was in hand. If not what are the issues and challenges? 17.002 Parker Ron 6/09/2009 16:55 Thrust 17 Why have you not mentioned completing NCSX as the first step in your plan? NCSX was cancelled for political purposes, but maintained strong scientific support in the community. We have a new DOE administration, so why shy away from bringing up its completion as a way of jump starting a major US stellarator program? 17.003 Lipschultz Bruce 6/09/2009 17:00 Thrust 17 The thrust is well written, covering optimizing steallarators and ELM control. However, it seems to be missing a study of what is the minimal 3D winding one could add to a tokamak to slow down disruptions in tokamaks (as current ending transients occur in Stellarators) to a reasonable period which lowers heat loads. 17.004 Peng Martin 6/09/2009 17:04 Thrust 17 It appears scientifically necessary for thrust 17 to clarify the nature of compact quasi-symmetric stellarator configurations being "disruption-free", particularly for those that carry substantial toroidal bootstrap plasma current. If disruption free operation is already guarranteed based on existing data and understanding, the proposed research on intermediate new stellarator experiments will aim to carry out confinement research for a plasma free of disruption worries. If disruption free operation still needs to be tested and verified in intermediate new stellarator experiments, the proposed research should include the determination of the parameter regimes that are indeed free of disruptions. 13.009 Baylor Larry 6/09/2009 17:26 Thrust 13 This thrust writeup seems overly detailed on tritium breeding and lacking other fuel cycle aspects. The areas of fueling, pumping, and exhaust processing also have significant challenges to go to a FNSF/DEMO. 16.008 Raman Roger 6/09/2009 17:57 Thrust 16 For the ST to realize its potential (so that it is simply not a low aspect ratio tokamak), the end result should be a simpler machine with much less auxiliary systems than a tokamak. This means: 1) complete elimination of the solenoid so that this space could be used to improve the reliability of the TF center leg, and 2) operation at very high levels of the bootstrap current fraction. At very high levels of the plasma self driven current, only a small amount of external RF power is needed to make up for the balance of current not produced by the plasma. This leads to a simpler system with the auxiliary input power reduced to low levels. This also means that the internal pressure profile still needs to be controlled to maintain the high bootstrap current fraction. A precision fueling system can do this by controlling the density profile (A system based on neutral beams are not suitable for a reactor because of neutron streaming through the large NB port openings and the higher recircul 04.015 Callis Richard 6/09/2009 17:57 Thrust 04 There is no mention in the fueling discussion if the fueling can reach the core to replace the DT burnup. Are high speed pellets or some other means of fueling needed? 17.005 intrator tom 6/09/2009 18:01 Thrust 17 I wanted to point out that there is at least one other potentially fusion relevant concept that is capable of steady state operation without disruptions. It is not toroidal, and fully axisymmetric, ie not 3D. This is the magnetic mirror, possibly of the Gas Dynamic Trap type (GDT). The GDT relies on being sufficiently collisional so that ions are scattered into the loss cone and make its ion velocity distribution isotropic. This eliminates the usual mirror velocity space (loss cone) instabilities. 06.012 Ulrickson Mike 6/09/2009 18:10 Thrust 06 Much (most) of the development of models of the SOL is described and will be done under thrust 9. Thrust 6 should reference input from thrust 9 for the SOL portion of the integrated model formation. 18.003 Raman Roger 6/09/2009 18:11 Thrust 18 Chit 1) over the past 20 years, the tokamak program has consistently built larger and larger machines that helped it to rapidly develop the concept. Is the FRC/Spheromak program sufficiently aggressive to consider the construction of a machine much larger than present machines as the next step? Because these concepts do not have expensive TF coils and much less auxiliary systems than tokamaks, the cost of a much larger FRC or spheromak would still be quite low compared to a comparably sized tokamak. Chit 2) historically these programs have also been instrumental in educating students (who have then gone on to work on larger fusion projects), much more so than large tokamak programs. Clearly a much larger well trained fusion work force is needed in the ITER-era. This quite valuable benefit to fusion research should appear someplace in the document. 08.005 Hawryuk Richard 6/09/2009 22:05 Thrust 08 For their steady state, ITER operates at betan ~3, which is above the no-wall limit according to the RWM studies that were performed. 14.006 Berk Herbert 6/09/2009 22:18 Thrust 14 The issue helium entrainment appears to be very basic in degrading the plasma facing material, both for the energetic helium impinging on the plasma facing material and the neutrons producing transmutations deeper within the support structure. What directions are being considered to enable the material to maintain its integrity for a sufficient length of time during reactor operation. 10.017 Wong Clement 6/10/2009 07:49 Thrust 10 Please add W. Wampler to contributor’s list, if not already done to the latest version. 01.015 Hubbard Amanda 6/10/2009 07:51 Thrust 01 Dave, A belated comment. I like the thrust and its expression. But I must say that in the presentation, and more importantly in the Thrust writeup, the balance between Themes I and II is significantly skewed to Theme I and ITER. All should realize that this Thrust is joint between Themes I and II, in fact it was originally proposed by Theme II at the GA workshop, but we suggested that it would be sensible to broaden to include Theme I given the commonality of issues. This means not only meeting ITER's needs, but preparing to meet the harder challenge of fusion reactors. I do not argue with ITER being a priority, but not the only one. Jim Terry wrote a very clear and compelling summary of the additional needs for the Theme II chapter,a. I suggest more of this flavour and content be incorporated into the Thrust writeup - in particular the Introduction and Actions. Just visually, seeing ITER in nearly every sentence of the chapter (at least six per paragraph) seems like ove 10.018 Wong Clement 6/10/2009 07:51 Thrust 10 Thrust 99 Due to the focus of Thrust 10 (surface materials) and 11 (innovation), together they have missed to emphasize the significant gap on the need for the development of robust high performance and disruption tolerant (both thermal and structural) PFC components. 11.010 Wong Clement 6/10/2009 07:52 Thrust 11 VG #1 The Thrust has the wrong title, because the need is much more than innovations. It gives the wrong impression to the reader and the authors of the thrust, leading to too much on innovation and not enough on basics. Suggest simply calling it Improved Power and Particle Handling, or Innovative and Broad base Development of Power and Particle Handling. 16.009 Sheffield John 6/10/2009 08:33 Thrust 16 In the TAP committee we agreed that the goal of ST research was to prepare for the possibility to a CTF (component test facility). As a group we did not support the notion that the ST was a good DEMO candidate. The title of Thrust 16 should be changed to reflect this. 06.013 Berry Lee 6/10/2009 08:40 Thrust 06 To balance issues, reliability of ECH (invessel, tubes, xmission system) and of NBI performance should be mentioned--no actions required. It should be noted that: 1. ITER, because of size, beta field is qualitatively different from present machines and is largely single pass. 2. Ill understood possibilities for flow drive are possible with ICRH. 12.010 Navratil Jerry 6/10/2009 08:44 Thrust 12 This 'integration' thrust assumes that PMI effects are separable from effects of nuclear damage - but data shown in presentations of Thrust 10 and 11 indicate this is not correct. The surface and material characteristics of the PFCs are strongly affected by neutron damage. 04.016 Berry Lee 6/10/2009 08:48 Thrust 04 To balance issues, reliability of ECH (invessel, tubes, xmission system) and of NBI performance should be mentioned--no actions required. It should be noted that: 1. ITER, because of size, beta field is qualitatively different from present machines and is largely single pass. 2. Ill understood possibilities for flow drive are possible with ICRH. 06.014 Berry Lee 6/10/2009 08:51 Thrust 06 Ignore previous chit--used wrong thrust #. 16.010 Hazeltine16 Richard 6/10/2009 08:58 Thrust 16 I would find it difficult to explain to an outsider why the exploration of one parameter, among the many describing a tokamak, deserves its own thrust. Do we need another thrust about triangularity? The ST program would make much more sense if it identified a clear, special mission, as it did in the TAP report. 18.004 Martin Piero 6/10/2009 09:09 Thrust 18 I propose to select a limited number of keywords, to be listed at the beginning of the document and to be used throughout it. They may help a continue focusing of the reader on our key points. As in John Sarff presentation, I'd try to stress as much as possible to 'linking' role and the contact toward other configurations that low-B configuration (RFP in particular) have. 07.004 El-Guebaly Laila 6/10/2009 09:16 Thrust 07 What is the present (and future) cost of HTS magnets? 09.005 Brower David 6/10/2009 09:33 Thrust 09 One of the proposed action items for THRUST 9 is to Develop and Deploy New Diagnostics. However, when reading the words expanding on this proposal in the the 6 page thrust description, it only requests more extensive sets of existing diagnostics; (1) various types of mechanical probes, (2) Thomdson scattering, and (3) spectroscopy and the manpower to operate them. The thrust may be better served by identifying the plasma parameters that need to be measured and the resolution required but not specifying the technique to make these measurements. This would leave the thrust open to new diagnostic ideas and measurement innovation. 09.006 Brower David 6/10/2009 09:41 Thrust 09 One of the proposed action items for THRUST 9 is to Develop and Deploy New Diagnostics. However, when reading the words expanding on this proposal in the the 6 page thrust description, it only requests more extensive sets of existing diagnostics; (1) various types of mechanical probes, (2) Thomdson scattering, and (3) spectroscopy and the manpower to operate them. The thrust may be better served by identifying the plasma parameters that need to be measured and the resolution required but not specifying the technique to make these measurements. This would leave the thrust open to new diagnostic ideas and measurement innovation. 12.011 Garofalo Andrea 6/10/2009 09:52 Thrust 12 Thorough integrated testing would seem to require testing the effects of DEMO-level neutron damage, therefore requiring operation with a high performance DT core. Then, this thrust looks a lot like the first stage of a Thrust 8 facility. Flexibility and ease of maintenance already must be included in a Thrust 8 facility design. The perturbation to Thrust 8 from including Thrust 12 seems minimal. 13.010 Yoder Graydon 6/10/2009 09:54 Thrust 13 There needs to be more words regarding safety in this thrust area. At least some of the data and codes developed in this thrust will be used for safety arguments and in the licensing process. Safety needs to be integrated throughout the program. 05.016 Chan Vincent 6/10/2009 09:54 Thrust 05 The oral presentation came across as a "brute-force" approach to push the plasma against its natural physics tendencies. I think that approach will fail. A much better approach is to develop an appropriate set of control tools to assist the plasma to reach an optimized self-organized state. The optimized state(s) should be identified through research in scientific understanding. This philosophy needs to be stated up front. 13.011 Yoder Graydon 6/10/2009 09:59 Thrust 13 Although the modeling and code efforts are now integrated in thrust 15, this is an important aspect of thrust 13, and some discussion of how the data/models/codes will be developed and used should be included in the discussion of thrust 13 as well. 13.012 Patton Brad 6/10/2009 10:07 Thrust 13 Discussion of safety and RAMI need to be added to Thrust 13 or a new Thrust area needs to be established to address these overarching issues essential to the success of the program. 13.013 Yoder Graydon 6/10/2009 10:22 Thrust 13 Development of instrumentation necessary for control and monitoring of power extracton systems is another element of this thrust that might be better integrated. 05.017 Brower David 6/10/2009 10:35 Thrust 05 Three elements required for control are 1) sensors, 2) actuators and 3) control algorithms. Emphasis in 6 page thrust is largely on 2) and 3). Importance of 1) or needs for 1) are largely neglected. 14.007 Peng Martin 6/10/2009 10:36 Thrust 14 The statement that material irradiation data is absent or inadequate for the initial test modules in FNSF is not consistent with the facts broadly reported in the literature. The status of the knowledge relevant to thrust 14 in this regard: For FS (at >DBTT) in test modules and GlidCop (<300oC) in TF center post, material damage data are available for FNSF for up to ~10 dpa, assuming for both He/dpa ~ 10 appm/dpa and swelling limit of ~100 appm He. For FS radiation creep rupture, coefficient of k ~ 0.5x10-6/MPa-dpa shows that for 10 dpa, there is plenty of MPa margin in practical designs to stay within an elongation of 0.1% due to radiation induced creep. These facts should be included in the content of Thrust 14. 13.014 Patton Brad 6/10/2009 10:39 Thrust 13 Discussion of applied research on measurement techniques should be added. Successful R&D in the tritium measurements would provide significant contributions to advancing the fusion fuel cycle. Advances in real-time tritium monitoring are essential to understanding the fuel cycle phenomena in the R&D stage and in the follow on monitoring and control of FNSF and DEMO. It is recommended an aggressive R&D effort be directed at measurement of tritium distributions in the full fusion environment. 13.015 Goldston Rob 6/10/2009 10:45 Thrust 13 There is a kind of chicken-and-egg problem with respect to disruption and CTF. For example, in Ted Strait's talk at the Theme III workshop, he indicated that a VDE in FDF would be 2.2x worse than in ITER, and of course ITER needs a thick Be/Cu/steel first wall. Laila El-Guebaly and Rene Raffray submitted a white paper to the Theme IV workshop which, in referring to ARIES FS first wall designs, indicated: "ITER-type VDEs could deposit up to 60 MJ/m2 in 0.2 sec. Not even one VDE can be accommodated based on such severe VDE parameters." They also indicate that "There is no practical means to enhance the breeding of the DCLL blanket if the off-normal events require adding more than 1-2 mm FS on the FW." 18.005 Cohen Sam 6/10/2009 10:49 Thrust 18 Following up on Mike Mauel's comments about stressing the transformative aspects of CTs, place more emphasis on advanced fuels in CTs, to overcome some of the major materials issues of D-T burning and tritium breeding. 12.012 Meade Dale 6/10/2009 11:19 Thrust 12 The terms Demo-relevant, Demo-like are used to describe the regimes of interest for this thrust. What is meant by Demo-like? It seems that only the power density is Demo-like. There are numerous other important physical variables: pedestal temperature and temperature, scrape-off temperature and density, scrape-off width and length, collisionality at the pedestal and in the scrape-off, geometry and mirror ratio in the scrape-off for parallel transport, fuel species mix, etc. Are these additional parameters Demo-like? Demo-like for the edge core coupling implies a Demo-like core – are the ρ∗, ν∗ and β in the core similar to Demo? 12.013 Meade Dale 6/10/2009 11:23 Thrust 12 The term high performance is used to characterize the plasma condition needed to address this thrust. High performance has two parts – high confinement (ntau for high Q) and high power density(beta^2B^4). Are both needed to address this thrust? 11.011 cohen sam 6/10/2009 11:25 Thrust 11 Add statements in this thrust how some alternate confinement devices, e.g. FRC and spheromkas, offer opportunities for innovations in energy extraction while stellarators have even more constraints. 14.008 Peng Martin 6/10/2009 11:34 Thrust 14 The statement that material irradiation data is absent or inadequate for the initial test modules in FNSF is not consistent with the facts broadly reported in the literature. The status of the knowledge relevant to thrust 14 in this regard: For FS (at >DBTT) in test modules and GlidCop (<300oC) in TF center post, material damage data are available for FNSF for up to ~10 dpa, assuming for both He/dpa ~ 10 appm/dpa and swelling limit of ~100 appm He. For FS radiation creep rupture, coefficient of k ~ 0.5x10-6/MPa-dpa shows that for 10 dpa, there is plenty of MPa margin in practical designs to stay within an elongation of 0.1% due to radiation induced creep. These facts should be included in the content of Thrust 14. 16.011 maingi rajesh 6/10/2009 11:50 Thrust 16 The action elements of the 1 pager have too much information for target audience. Suggest first two elements wording be streamlined: • Extend studies of STs to much lower collision frequency and smaller gyroradius in upgraded facilities • Extend ST experiments to near burning-plasma conditions, in a new long-pulse facility with higher BT (1.5 – 2.5T) and non-inductive startup capability (following chit addresses next 2 bullets) 16.012 maingi rajesh 6/10/2009 12:02 Thrust 16 Please clarify and streamline last 2 bullets of 1 pager: Does this entail a high Bt, short pulse facility with a test stand for magnet development? • A potentially advantageous option divides studies based on pulse length and BT, addressing high field magnet technology on test stands, or in a relatively short-pulse device studying current initiation and sustainment techniques only available at higher BT, disruption physics and impact, and impulsive heat loads. Long pulse studies would be conducted in a second, lower field (1.5T < BT< 2T) device generating continuous, high temperature plasmas. How would you do the bullet below: design study? Build a range of facilities? • Evaluate whether reduced aspect ratio can improve fusion characteristics of stellarators and RFPs at high pressure. Connect near-unity A research in STs with compact torus research. 18.006 McLean Harry 6/10/2009 13:07 Thrust 18 Suggestion for second paragraph to bring out innovative character at modest cost without criticizing mainline approaches. ...Research on multiple configurations provides a vital and healthy scientific approach to grow and validate fusion science over a wide range of plasma conditions. add While generally/often regarded/recognized as more speculative than mainline tokamak research, exploring this wider range of plasma conditions and technologies used to produce them expands opportunity for scientific discovery, breakthrough, and innovation, often at very modest cost. /add Also, low-field configurations exhibit magnetic self-organization processes resembling those in astrophysical plasmas. They thus... 15.003 Cohen Sam 6/10/2009 13:18 Thrust 15 Consider the following RAMI issue: Say a 1st generation fusion reactor has an availabilituy of 50%. That is bad, if the plant is 2 GWe and provides all of a city's electrical power. BUT, if there are 1000 2 MWe plants ( advanced fuel FRCs naturally) then the 50% availability, though bad might be tolerable, both because not all the power is gone (at any one time) and because repairs can be made quicker on the smaller cleaner plants. 13.016 maingi rajesh 6/10/2009 13:24 Thrust 13 There is an apparent 1:1 overlap between the testing of PFCs and Internal Components in this thrust and thrust 11. This topic is the sole mission of thrust 11. Suggest that the PFC and IC testing in dedicated test stands be ceded to thrust 11, while integration of the components remains in this thrust. The overlap then would be in concept development portion, which would be shared between the two thrusts. 08.006 Zarnstorff Michael 6/10/2009 13:37 Thrust 08 It doesn't seem to be in a chit, but the Thrust write-ups need to indicate the interconnection and dependencies on other thrusts. For Thrust 8, it seems to me that there is a dependence on the results from Thrust 5, 17, 12(?), and 16(?). There may be others, since Thrust 8 is a penultimate integration. 10.019 Youchison Dennis 6/10/2009 14:02 Thrust 10 An important component of this thrust should be upgrade of existing test facilities to include synergistic testing effects. This may require combinations of existing systems, sharing of diagnostics, the addition of entirely new diagnostics or expanded capabilities, and continued support of existing test stands. 03.009 Cohen Sam 6/10/2009 14:25 Thrust 03 This thrust focussed exclusively on alphas in tokamaks. The ICC devices may have much different effects from a fast alpha population. For example , half the alphas formed in FRCs will likely be lost through the (p_phi > 0) loss cone. The remaining will comprise/drive a current and a radial potential will develop. What effect will these have on stability and confiment? Will TAE modes exist in a device that has no toroidal field? There are no banana orbits in FRCs. How does this affect alpha losses and instabilities? 03.010 Chang CS 6/10/2009 14:43 Thrust 03 This chit was originally sent to thrust 1 at 9:30 on 6/9/09. Redirected to thrust 3 (Hooks) It seems to me that emphasis on the self-consistent study between the waves driven by, and sitting on, the energetic particles and their self-organizing interaction with the background plasma equilibrium and turbulence could be upgraded. This issue is not easy to handle at the moment, but should become important as we think about ITER and DEMO. 01.016 intrator tom 6/10/2009 14:44 Thrust 01 there is no mention of diagnostic or measurement needs for the Innovative confinement concepts, or alternate concept devices. there may be some differences for example smaller magnetic field, or much larger magnetic field in compression schemes, larger beta, non tokamak geometry for access. Many clever plasma diagnostics have been conceived and developed on small plasma machines, and later advanced in sophistication to the point where they were fielded on large facilities (eg reflectometry, two color interferometers, electrostatic probes for edge diagnostics, microwave and visible scattering for fluctuations). 06.015 Buttery Richard 6/10/2009 15:06 Thrust 06 I am skeptical about needs to "coordinate" more - we don't want to risk turning this into a giant management activity with standards and interfaces - at expense of the extremely powerful sharp focus US efforts have on scientific deliverables of their modelling projects. 12.014 Peng Martin 6/10/2009 15:43 Thrust 12 This chit is put in now, as suggested by the leaders of the Thrust 12 discussion. Thrust 12 should have adequate clarity regarding the uncertainties of success of an integrated PFC solution obtained using a DD toroidal facility, when it is operated in a full fusion nuclear environment for the first time. Examples of potential or likely failure include: The synergistic radiation induced interactions of combined materials in a PFC under expected full operating conditions, which is identified in thrust 14 as a critical research contribution enabled by thrust 13. Thus, a worthy PFC, be it born of thrust 12 or other research thrusts, will have to be tested and its likely failure mechanisms discovered and understood, solutions developed (or re-developed), and re-tested in a full environment. 12.015 Peng Martin 6/10/2009 16:06 Thrust 12 Thrust 12 needs to be clear regarding the research capabilities required to carry out the research promised. An example: Thrust 12 promises the capability of delivering 10^6 s accumulated plasma operaton under high heat flux toroidal integrated high confinement conditions. It therefore require a divertor that are proven to survive 10^6 s total operation while handling a peak heat flux of 10 MW/m2 or higher, to begin the promised research in thrust 12. Thrust 12 therefore needs to be clear about requiring such divertor solutions, as an example, perhaps born of other thrusts, to deliver on its promises. 13.017 nygren richard 6/10/2009 16:50 Thrust 13 Neil - reminder: Lookover/add comments re engineering diagnostics. Non-nuclear and nuclear component test facilities may have greataer demands and more challenging requirements for engineering diagnostics than DEMO where there is an expectation fors operating in a quiescent regime and showing robustness and efficiency. 06.016 Callen Jim 6/11/2009 08:46 Thrust 06 To me this is potentially one of the most important and scientifically promising of the thrusts. However, I still feel very strongly that this Thrust 6 on V&V needs to conclude with a "punchy action item" which indicates something specific that administrators and OFES/DoE planners could endorse and develop a program to do something about. I can understand why you do not want to choose a particular area to focus on. However, it seems to me you could propose that a "prototype" program(s) could/should be developed and tested -- e.g., by arranging for a proposal solicitation (>~ $2M/yr?) for a few year V&V activity in an area of the proposers choosing. PROPOSED ACTION ITEM FOR THRUST 6: To develop an effective framework for implementing these ideas, one or more prototype V&V activities should be developed and enfranchised with real resources in the aforementioned areas over a multi-year time frame for one or more of the 8 indicated "case study" activities on page 2 of the six page 08.007 McKee George 6/11/2009 09:59 Thrust 08 The mission initially presented for Thrust 8 (specifically, section 1B) offered a compelling vision that would achieve not only the Thrust 8 goals, but also embrace the objectives of several thrusts from ReNeW. Unfortunately, I couldn't attend the breakout meeting due to obligations to other thrusts, but the results of that discussion seem to have downgraded the original mission. I would simply encourage this thrust to revert to the original, ambitious goals of pursuing an integrated approach to the complex core-edge coupling problem via a long-pulse DT experiment. 11.012 Ying Alice 6/11/2009 10:38 Thrust 11 Originally submitted via email Tue, 09 Jun 2009 17:58 Eastern time (EH) Two distinct power handling concepts (LM and He-cooled)were mentioned in this thrust. Is the author?s intent to develop both concepts simultaneously? Are there criteria to be used to differentiate one concept from the other in terms of R&D strategy and time line? 11.013 Wong Clement 6/11/2009 12:07 Thrust 11 Originally submitted to thrust 99 on 6/10/09 8:00 VG #1 The Thrust has the wrong title, because the need is much more than innovations. It gives the wrong impression to the reader and the authors of the thrust, leading to too much on innovation and not enough on basics. Suggest simply calling it Improved Power and Particle Handling, or Innovative and Broad base Development of Power and Particle Handling. VG # 2 The presentation and therefore corresponding writing needs to identify deficiencies in PFC development including necessary helium test loops, test stands, fabrication with RAFM steel, CCGT and robust and disruption tolerant (both thermal and structural effects) PFC designs. We also need to include design margins. 11.014 Wong Clement 6/11/2009 12:08 Thrust 11 VG # 3 On the disadvantages, the list should also indicate that the piping arrangement which is especially difficulty for the FW and inboard components. This helps to highlight the difficulties in designing for large FW components while meeting all the routing, heat removal and low pumping requirements. VG # 6 Under innovation should add “twisted tapes” and “2-D and 3-D surface roughening”. Actually there could be other new and combination of options. VG # 7 For a major cooling option for fusion power development, VG # 7 actually indicates the inadequacy of helium cooled development and limited development participants in the last 16 years, mostly from SBIR, which naturally focused on break through innovations like refractory alloys and porous media. A much broader base and fundamental support, like from universities and industries will be needed. 11.015 Wong Clement 6/11/2009 12:09 Thrust 11 VG # 8 All refractory metal heat sink…is not the correct indicator of necessary development. We will need a refractory metal surface and even the indicated examples shown later have transitional piece to RAFM steel or ODFS. A more straightforward option of planar refractory metal surface e.g. W, joining to ODFS and then RAFM steel and then to coolant channels should be considered for both FW and divertor designs. For lower temperature helium coolant at ~350-400 C, the ODFS is to bring the surface temperature up to 700 C such that the W surface could be maintained to >700 C, which is necessary to maintain the toughness of the W-alloy under neutron irradiation. VG # 20 Recommendations should add the need for broader base support and to enhance the training of a new generation of heat removal engineers and scientists. 16.013 Peng Martin 6/21/2009 16:19 Thrust 16 This one-page reads very well. Thanks for providing another opportunity to improve the final draft. I recommend dropping the word "aggressively". I agree with the earlier chits on the need to focus more on the TAP Tier-1 issues, and would like to suggest a further improvement to the additional goal, which is "to aggressively pursue improvements to advance the ST for energy production", by dropping this word. This is because that a "fusion nuclear science and technology component testing device" already aimes at establishing the knowledge needed to harness fusion power, ie, to produce energy. The two elements of the goal are therefore at least equally important. This can be conveyed simply by dropping "aggressively." 04.017 Temkin Richard 6/22/2009 17:59 Thrust 04 Previously, the thrust said: Develop wall cleaning techniques that are compatible with high stationary toroidal magnetic fields. Investigate feasibility of tunable gyrotrons for EC cleaning. In this version, it has been changed to: Develop wall cleaning techniques that are compatible with large, stationary magnetic fields; The earlier language made sense and matched the disucssion. I would suggest as a possible option that still fits in the available space: Develop wall cleaning techniques that are compatible with large, stationary magnetic fields. Investigate feasibility of tunable gyrotrons for EC cleaning.