News and Events

U.S. Burning Plasma Organization eNews

October 31, 2020 (Issue 148)


USBPO Mission Statement: Advance the scientific understanding of burning plasmas and ensure the greatest benefit from a burning plasma experiment by coordinating relevant U.S. fusion research with broad community participation.

CONTENTS

Director’s Corner
C.M. Greenfield
Research Highlights
Contact and Contribution Information  

Director’s Corner

Chuck Greenfield, US BPO DIrector

ITER assembly continues

The ITER Organization has posted a video showing the tokamak assembly process at https://www.iter.org/news/videos/545. Although in its early stages, the process is underway. Currently, the lower cylinder of the cryostat is being welded to the cryostat base, and additional components continue to arrive on the ITER site and are being prepared for installation.

You are here.

The IAEA fusion team has put together a new Fusion Device Information System(https://nucleus.iaea.org/sites/fusionportal/Pages/FusDIS.aspx), an interactive map giving information on fusion devices worldwide. It’s fascinating to see the geographical extent of fusion research on six continents as well as the diversity of concepts and mix of public and private facilities.

How we can support the ITER research plan

A recently published ITER Technical Report (ITR-20-008) lists areas where further research is needed to prepare for execution of the ITER Research Plan. The report, entitled “Required R&D in Existing Fusion Facilities to Support the ITER Research Plan,” can be downloaded from the ITER Technical Reports web site at https://www.iter.org/technical-reports. The USBPO Research Committee reviewed an earlier version of this list in late 2019 and early 2020 to identify impactful research topics that could be done within the US Fusion Energy Sciences program. We will review the ITER Organization’s updated version to adjust our recommendations prior to posting them on the USBPO website.

ITER Organization signs cooperation agreement with Canada

Starting when ITER begins operating with Deuterium-Tritium fuel in the mid-2030s and continuing for the entirety of its Fusion Power Operation phases, it will consume most of the world’s tritium supply. On October 15, the ITER Organization signed a memorandum of understanding with Canada, where 19 of the world’s 31 CANDU fission reactors are operated. This is important because these reactors are the main producer of tritium, which decays with a 12-year half-life and so is not found in useful quantities in nature. In addition to opening up these reactors as a supply for ITER’s fuel, this also provides access to Canada’s extensive expertise in handling tritium.

Research in Support of ITER contributed oral session at the Memphis Cyberspace APS-DPP
Conference

As you’ve no doubt already heard, the APS Division of Plasma Physics annual meeting will now be held remotely. We hope you’ll tune in for the 13th annual contributed oral session on
“Research in Support of ITER,” organized by the USBPO. This will be session CO07 (
https://meetings.aps.org/Meeting/DPP20/Session/CO07), on Monday afternoon November 9 at 2PM CST.

Larry Baylor (ORNL)

US

Research on Disruption Mitigation Enabled by Shattered Pellet Injection Systems on DIII-D, JET, and KSTAR in Support of ITER

Woong Chae Kim (NFRI)

Korea

Progress of Disruption mitigation with SPI and integration of real-time diagnostics for DECAF in KSTAR

Dmitrii Kiramov (Texas)

US

Pellet sublimation and expansion under runaway electron flux

Yipo Zhang (SWIP)

China

Progress in Disruption Mitigation on the HL-2A tokamak

Charlson Kim (SLS2)

US

NIMROD Shattered Pellet Injection Simulations

Michael Faitsch (MPI)

Germany

Broadening of the power fall-off length in a high density, high confinement H-mode regime in ASDEX Upgrade

Curtis Johnson (Auburn)

US

Diagnosing metastable populations in fusion edge plasmas using collisional-radiative modeling constrained by experimental observations with extrapolation to ITER parameter space

Nikolai Gorelenkov (PPPL)

US

Microturbulence-mediated route for stronger energetic ion transport and Alfvénic mode intermittency in ITER-like tokamaks

Christian Kiefer (MPI)

Germany

ASDEX Upgrade experiments and validation of theoretical transport models for the prediction of ITER PFPO-1 plasmas

Mireille Schneider (ITER)

France

Simulation of heating and current drive sources for various scenarios of the ITER Research Plan using the IMAS H&CD workflow

Emmi Tholerus (CCFE)

UK

Scenario development of ITER ELMy H-mode hydrogen plasma

Kathreen Thome (GA)

US

Changes in Impurity Transport with Applied Torque in DIII-D ELMy H-mode Plasma

Sun Hee Kim (ITER)

France

Assessment of access to ITER steady-state operation using CORSICA

Zhang Bin (ASIPP)

China

The dominant electron heating with low torque towards ITER baseline on EAST

Andrea Garofalo (GA)

US

High betaP for ITER Q=10 and Q=5 missions

 

Research Highlight

Energetic Particles (Leaders: Cami Collins and Aaron Bader)

The upcoming JET D-T campaign is right around the corner, giving us an important opportunity to study alpha particle physics. In this month’s highlight, Dr. Phillip Bonofiglo and team are preparing to make fast ion loss measurements that will be used to validate energetic particle transport models needed for reliable projection and interpretation of burning plasma in ITER and future reactors.

Simulating Energetic Particle Losses on JET for Model Validation

P. J. Bonofiglo1, M. Podestà1, V. Kiptily2, V. Goloborodko3, R. B. White1, F. E. Cecil4, and JET Contributors

1Princeton Plasma Physics Laboratory, Princeton, NJ, USA

2Culham Centre for Fusion Energy of UKAEA, Culham Science Center, Abingdon, UK

3Kyiv Institute for Nuclear Research, Kyiv, Ukraine

4Colorado School of Mines, Golden, CO, USA

 

Author email: pbonofig@pppl.gov

In order to achieve steady state conditions in a burning plasma reactor, the transport and confinement of energetic particles, such as alphas, must be well understood.1 Many mechanisms have been discovered that result in increased transport and, ultimately, losses of energetic particles.2-4 This, in turn, degrades plasma performance and reduces heating. This is particularly relevant for the necessary alpha heating in tokamak reactors and the upcoming JET DT-campaign in spring/summer of 2021.5 To better understand the confinement properties of energetic particles, models have been constructed to mimic the various loss mechanisms and fast ion response.6 This work confirms the validity of a transport model on JET plasmas through the integration of a synthetic fast ion loss detector for experimental comparison.

JET contains an array of Faraday cup fast ion loss detectors as a part of its advanced diagnostic suite, shown in Figure 1, which is sensitive to MeV energy lost ions.7 Lost ions enter the top apertures of the Faraday cups and penetrate an alternating stack of thin conductive foils and insulators. Ions deposited on the conductive foils are read as a current measurement while ions stopping in the insulators are ignored, yielding an energy resolution for impingent ions. Recent enhancements to the diagnostic’s hardware and data acquisition have resulted in enhanced measurements of MHD induced fast ion losses in JET deuterium plasmas.8 As such, we have

A picture containing arrow

Description automatically generated

Figure 1: (a.) Faraday cup fast ion lost detector array denoting the Z=0 midplane, poloidal direction (), toroidal direction (), and the cup housings or “pylons.” (b.) A blown-up Faraday cup depicting the series of alternating conductive foils and insulators.

chosen to implement the JET Faraday cup array in an energetic particle transport model for validity testing and to supplement experimental measurements.

Our model consists of the widely used transport code TRANSP [9], the Hamiltonian guiding-center particle motion code ORBIT [10] with the “kick” feature [11] capable of calculating the energetic particles’ change in their constants of motion as a response to a supplied perturbation, and an ad-hoc integration code which calculates particles’ reverse trajectories from the Faraday cups back to the plasma region. First, a reference TRANSP run is performed constrained by experimental measurements. This establishes a magnetic equilibrium and initial fast ion distribution for use. At present, JET deuterium plasmas with NBI+ICRH heated deuterons, as well as the accompanying DD-fusion products, have been examined in lieu of alpha particles. Typical TRANSP runs yield an insufficient number of fast ions in the RF-heated tail, i.e. of MeV energy, to be statistically relevant for synthetic loss analysis. As such, the plasma state from TRANSP is used in the stand-alone NUBEAM+TORIC portion of TRANSP and ran repeatedly to build upon the fast ion distribution.

Using the TRANSP produced equilibrium, full particle trajectories are integrated backward from the detector into the plasma giving an exact loss distribution which is used to bias the TRANSP produced distribution and provide markers for particles in ORBIT. Particles in ORBIT are seeded from the TRANSP fast ion distribution in a Monte-Carlo fashion with small variations in R, Z, pitch, and energy. The variations from the original distribution are used to combat two problems: 1. the TRANSP distribution is the confined distribution while the reverse-integrated distribution only encompasses losses, so no overlap exists, and 2. the conflation between the full-orbit reverse integration code and the guiding-center code ORBIT is broken. Seedings that do not overlap the loss distribution are discarded while ones that do are provided markers with a weight equal to the fast ion density from the TRANSP simulation. ORBIT then calculates the resulting fast ion motion as a response to a supplied perturbation. When particles reach within a Larmour radius of the wall, the particle is stopped with a random gyrophase. The resulting, final, ion position is checked against an “installed” detector geometry in ORBIT for synthetic detection. Lastly, the energy of the collected ion is compared to that simulated in the SRIM code [12] which calculates the ion deposition within the foil stack. The marker weights for the particles are then summed to produce a relative flux for comparison to measurement. In summary, the energetic particle flux from TRANSP has been converted to a synthetic flux in ORBIT by biasing against the reverse-integrated loss distribution, tracking the fast ion trajectory as a response to a supplied instability to the detector geometry, checking the deposition energy, and summing across all collected particles. Mathematically, this is expressed in the below equation where the denote the Kronecker delta function with respect to the reverse-integrated distribution and SRIM deposition.

 

where

and

 

The model was tested against a long-lived kink mode in a JET deuterium discharge with 25 MW NBI and 6 MW ICRH heating. Faraday cup loss measurements are clearly visible in response to the kinks for comparison to the model results. Using an analytical representation for the kink modes from [13] and [14], the resulting ORBIT losses biased by the reverse-integrated distribution are visible in Figure 2.

Figure 2 highlights the successful reproduction of losses to the detector geometry shown in Figure 1 and the poloidal distribution of losses. Translating the marker weights to synthetic flux, the relative foil signals can be calculated. Also, the model allows the deconstruction of foil signals by ion species of which the detector is incapable. The distribution of the synthetic ion signal across the foils is shown in Figure 3 along with a table showing the foil sensitivities for a given ion species as calculated by the SRIM code.

Diagram

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Figure 2: Lost ion orbits produced from the TRANSP+ORBIT-kick model for a long-lived kink mode in JET in the full poloidal plane, (a.), and zoomed in to the uppermost pylons, (b.). Red denotes detected particles, orange particles impacted the detector housing, green particles impacted the limiter, and blue hit the wall.

Foil

Proton (MeV)

Deuteron (Mev)

Triton (MeV)

1

0.0-0.49

0.0-0.49

0.0-0.50

2

0.68-0.96

0.79-1.10

0.84-1.20

3

1.10-1.32

1.35-1.60

1.48-1.76

4

1.45-1.65

1.78-2.00

2.00-2.35

 

Figure 3: Distributions of synthetic lost ion signal across each foil where foil 1 denotes the plasma-most foil, and foil 4 is the deepest foil in the stack. The table on the right denotes the receptive deposition energy for each foil by ion species. Note: The DD-triton birth energy occurs within the measurable range of foil 2 and the DD-proton birth energy is larger than foil 4’s depth.

The general trends of the signals agree with measurements but, at present, overpredict the losses. The authors believe this could be due to poor statistics in the deuteron losses, possible additions of prompt losses, or inaccuracy of the simulated kink amplitude. Work is ongoing to remedy these possible sources of error in our simulation. Overall, the implementation of a model utilizing the TRANSP and ORBIT-kick codes has been successfully commissioned for a JET deuterium plasma utilizing forward and backward integration methods. Successful loss measurements, both real and synthetic, have been made from which future work will focus on reconciling measured vs. simulated fluxes, looking forward to JET’s DT-campaign.

Acknowledgements

This work is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, and has been authored by Princeton University under Contract Number DE-AC02-09CH11466 with the U.S. Department of Energy. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

References

1A. Fasoli, C. Gormenzano, H. L. Berk, B. Breizman, S. Briguglio, D. S. Darrow, N. Gorelenkov, W. W. Heidbrink, A. Jaun, S. V. Konovalov, et al., Nucl. Fusion 47, S264 (2007).

2W. W. Heidbrink and G. J. Sadler, Nucl. Fusion 34, 535 (1994).

3W. W. Heidbrink, Phys. Plasmas 15, 055501 (2008).

4W. W. Heidbrink and R. B. White, Phys. Plasmas 27, 030901 (2020).

5R. J. Hawryluk, Rev. Mod. Phys. 70, 537 (1998).

6M. Podesta, M. Gorelenkova, N. N. Gorelenkov, and R. B. White, Plasma Phys. Control Fusion 59, 095008 (2017).

7D. S. Darrow, S. Baumel, F. E. Cecil, V. Kiptily, R. Ellis, L. Pedrick, and A. Werner, Rev. Sci. Instrum. 75, 3566 (2004).

8P. J. Bonofiglo, V. Kiptily, A. Horton, P. Beaumont, R. Ellis, F. E. Cecil, M. Podesta, and JET Contributors, Rev. Sci. Instrum. 91, 093502 (2020).

9R. J. Hawryluk, “An empirical approach to tokamak transport”, in Physics of Plasmas Close to Thermonuclear Conditions, (Brussels: CEC) vol 1, pp 19-46 (1980).

10R. B. White and M. S. Chance, Phys. Fluids 27, 2455 (1984).

11M. Podesta, M. Gorelenkova, and R. B. White, Plasma Phys. Control Fusion 56, 05503 (2014).

12srim.org

13R. Farengo, H. E. Ferrari, P. L. Garcia-Martinez, M. -C. Firpo, W. Ettoumi, and A. F. Lifschitz, Nucl. Fusion 53, 043012 (2013).

14D. Kim, M. Podesta, D. Liu, and F. M. Poli, Nucl. Fusion 58, 082029 (2018).

 

Calendar of Burning Plasma Events

Many upcoming meetings are being impacted by the COVID-19 situation. We suggest that you not rely too heavily on the schedule below – it is best to check with the meeting organizers before making any plans.

2020

JET DT-campaign (https://www.burningplasma.org/resources/ref/Web_Seminars/Litaudon-JET-%202019-05-02-vf.pdf)

JT-60SA First Plasma (http://www.jt60sa.org/)

Nov 9-13, 2020

62nd Annual Meeting of the APS Division of Plasma Physics

Remote only

 

Nov 15-19, 2020

Technology of Fusion Energy (TOFE) 2020

Chicago, IL Virtual

 

Nov 16-20, 2020

ITER International School

Marseille, France

 

Dec 6-10, 2020

47th International Conference on Plasma
Science (ICOPS)

Singapore Virtual

 

Dec 14-17, 2020

High Temperature Plasma Diagnostics
Conference

Santa Fe, NM Virtual

 

Dec 16-17, 2020

Fusion Power Associates 41st Annual Meeting and Symposium

Washington, D.C. Virtual

 

 

2021

Jan 24-29, 2021

International Conference on Plasma Surface Interactions

Jeju, South Korea Virtual

May 10-15, 2021

28th IAEA Fusion Energy Conference (FEC2020)

Nice, France

June 21-25, 2021

EPS 47th Conference on Plasma Physics

Sitges, Spain

Sep 7-10, 20201

25th Joint EU-US Transport Task Force
Meeting

York, UK

 



See the author list of E. Joffrin et al. 2019 Nucl. Fusion 59 112021

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