U.S. Burning Plasma Organization eNews
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. GreenfieldContact and Contribution Information
Director’s Corner
Chuck Greenfield, US BPO DIrector
Life and fusion research continue…
I hope you are staying safe and healthy.
Like many of you, working at home has become a “new normal.” But work
progresses on ITER and on our large domestic facilities (DIII-D and NSTX-U),
and we’re all learning to be productive while working remotely. The bright
side to this is that we’re developing capabilities now that may be quite
valuable when ITER starts operating and many of us are participating from
thousands of miles away.
Research in Support of ITER contributed oral session at the Memphis
Cyberspace APS-DPP Conference
The thirteenth annual Research in Support
of ITER session has now been organized (see below). Thanks to everybody who
requested a slot; unfortunately, we couldn’t accept all of the proposals for
this 15-talk session. As you’ll notice, we have assembled quite an
international session for this year’s meeting.
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 this interesting and informative session.
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 |
USBPO
Council
You may remember that we held an election for the
USBPO Council a while back, as three members’ terms expired: Ted Biewer (ORNL), David Newman (Alaska), and Gary Staebler (GA). I’d like to express my gratitude to Ted,
David, and Gary for their service during their terms. Each year we select four
new members; two by election and two by appointment. I’m happy to announce that
Emily Belli (GA) and Greg Wallace (MIT) were the winners. In addition, Diane
Demers (Xantho Technologies) and David Rasmussen
(ORNL) have jointed the Council as appointed members.
With these changes, the 2020 USBPO Council is as
follows:
Emily Belli |
GA |
2022 |
Troy Carter (Chair) |
UCLA |
2020 |
Diane Demers |
Xantho |
2022 |
Jim Irby |
MIT |
2021 |
George McKee |
Wisconsin |
2020 |
Raffi Nazikan (Vice Chair) |
PPPL |
2021 |
Francesca Poli |
PPPL |
2021 |
David Rasmussen |
ORNL |
2022 |
Don Rej |
LANL |
2020 |
Terry Rhodes |
UCLA |
2021 |
Uri Shumlak |
Washington |
2020 |
Vlad Soukhanovskii |
LLNL |
2020 |
Greg Wallace |
MIT |
2022 |
11th ITER International
School: The Impact and Consequences of Energetic Particles on Fusion Plasmas
The
11th ITER International School has been rescheduled for November
16-20, still at Aix-Marseille University as originally planned. The subject of
this year’s school is “The Impact and Consequences of Energetic Particles on
Fusion Plasmas.” There is, of course, some uncertainty about whether the school
can proceed on this schedule and whether US people will be able to travel to
France by November.
As
previously announced, we are still hoping to send 16 students from the US,
supported by USBPO scholarships. In addition, about a half-dozen US researchers
are on the agenda as speakers.
The
recipients of the 2020 IIS scholarships are:
Gurleen Bal (UCLA) |
Genevieve DeGrandchamp
(UCI) |
Jonah Duran (U Tenn
Knoxville) |
Kenneth Gage (UCI) |
Alvin Garcia (UCI) |
Daniel Lin (UCI) |
Gabriel Player (UCI) |
Quinn Pratt (UCLA) |
Aaron Rosenthal (MIT) |
Alex Saperstein (Columbia) |
Kamil Sklodowski
(UCLA) |
Elizabeth Tolman (MIT) |
Jeff Lestz
(Princeton/UC Irvine) |
Philip Bonofiglo
(PPPL) |
Noah Hurst (Wisconsin) |
Alex Tinguely
(MIT) |
More
details on this ITER International School are available or forthcoming at https://iis2020.sciencesconf.org/
ITER tokamak assembly begins
Even
with COVID-19 restrictions, work is proceeding on the assembly of the ITER
tokamak. For the last few years, I’ve been sharing photos of buildings. It was
exciting to watch them going up, but now the tokamak building has been
completed and turned over to the ITER Organization to move into the next phase:
Tokamak assembly.
The
first major component, the cryostat base, was inserted into the tokamak pit on
May 26. Many large components, including the first poloidal and toroidal field
coils, have already arrived at the ITER site. The first completed vacuum vessel
sector is in transit.
Meanwhile,
meetings at ITER are either delayed or being held remotely. The ITER Council
recently held a remote meeting, and the Science and Technology Advisory
Committee, of which I am a member, is preparing to hold a meeting remotely in September.
The
first piece of the ITER Tokamak, the cryostat base, was lowered into the tokamak
pit on May 26. Photo courtesy of the ITER Organization.
Research Highlight
Diagnostics (Leaders: Max Austin and
Calvin Domier)
This month’s highlight is from the diagnostic group at
University of California, Davis discussing the latest in state-of-the-art edge
microwave plasma diagnostic instrumentation.
This team has led the development for more compact and robust elements
to use in both passive and active microwave systems to provide electron
temperature and density measurements for next step fusion devices.
System-on-chip technology: game changer
for burning plasma diagnosis*
Guanying Yu1, Yilun
Zhu1, and Neville Luhmann1
1University
of California, Davis
Author e-mail: amzhu@ucdavis.edu
Microwave-based
measurements have found broad application in magnetic fusion plasma diagnostics
and are expected to be widely employed in burning plasma experiments due to
their numerous advantages and applications including minimal port access
requirements, co-locating interferometer, reflectometer, radiometer, and
scattering systems for burning plasma physics studies and real-time feedback
plasma control. In many state-of-the-art systems, each device-level function is
performed by a separate component. Diagnosticians then typically assemble a
functional instrument by connecting these packages together with short sections
of waveguide resulting in the common expression of waveguide “plumbing”. In
contrast, the cutting-edge microwave integrated chip (IC) technology provides
breakthrough opportunities to enhance diagnostics’ capabilities in fusion
science and survive the harsh radiation environment. Integrated circuit
technology facilitates combining many bulky microwave components onto a single,
tiny piece of semiconductor substrate, as shown in Figure 1. The front-end
microwave sensor is built on a square millimeter level chip instead of the suitcase-size
waveguide approach. The System-on-Chip approach has demonstrated excellent
shielding performance against environmental interference, significant mixing
efficiency (over 30x boost), and new accessible physics areas. Furthermore, the
IC itself is able to be mass produced, making for a bench-stock of consistent
and yet inexpensive replacement circuits that can be swapped out with minimal
effort—clearly an advantage in burning plasmas where experimental resources,
diagnostic access, and run-time are at a premium!
A demo version
of System-on-Chip microwave diagnostics was successfully deployed for DIII-D
Electron Cyclotron Emission Imaging (ECEI) measurements in 2019. The new ECEI system is now used for 2D
pedestal temperature imaging with high spatial and temporal resolution. High
confinement (H-mode) plasmas are accompanied by a quasi-periodic crash event
(ELMs) at the plasma edge, which poses a detrimental transient heat load to the
plasma facing materials. Resonant Magnetic Perturbations (RMPs) have been
widely applied in experimental tokamak devices to control the ELMs, but the
physics mechanism of RMP-ELM control is still not fully understood. Enhancing
plasma edge transport appears to be key to constraining the plasma edge in this
stable operating region that is free from ELMs. RMPs are predicted to drive
small magnetic islands in the plasma edge that may enhance edge transport by
guiding the electrons parallel to the island magnetic field lines.
Additionally, the RMP changes the plasma flow at the edge, which may
destabilize certain turbulent phenomena that may also enhance the edge
transport. For the latter case, the
DIII-D W-band [75-110 GHz] ECEI, upgraded with the latest high signal-to-noise-ratio
receivers, has been commissioned to measure the electron radiation temperature
()
fluctuation excited by low-k (k
<0.3)
turbulence and
reveal clues to understanding the physics of
RMP ELM suppression.
In DIII-D
discharge 179328, an increasing RMP is applied to the plasma to achieve ELM
suppression. RMP strength
coil current; and the ELMs are measured via
the
signal.
The significant increase in the ECEI spectrum coherence signifies strong
turbulence. The cross phase describes the
turbulence phase velocity as ~ 15 km/s in the ion diamagnetic direction in the
lab frame. The capability of obtaining the cross power spectrum and cross phase
allows us to perform more detailed physics studies to correlate profile changes
with fluctuation characteristics.
Benefiting from
the system-on-chip mixing technology, ECEI is not only a fluctuation
diagnostic, but also measures the equilibrium electron temperature. When the
ELMs are suppressed in the same discharge, the plasma edge is not static, but
exhibits quasi-periodic pulsations every ~10 .
The pulsations, seen in Fig 3(a)(b), are confirmed with both the heat flux
diagnostic IRTV and the uncalibrated
diagnostic ECEI. Each peak in the IRTV heat
flux coincides with one valley in the pedestal temperature in the time domain.
Due to the high signal quality of ECEI, the turbulence amplitude (Fig. 3(c)) is
separately measured with short time windows at all of the peaks and valleys of the
IRTV heat flux. We found that the turbulence is strongly correlated with energy
transport in the plasma edge, as the turbulence power is significantly stronger
at the IRTV heat flux peaks than that at the valleys.
Implementing
microwave diagnostics on reactor plasma will require a slight increase in
operating frequencies above 160 GHz, mandating further technology developments.
However, there are considerably more serious issues raised by the harsh
radiation and high temperature environment. ITER will be the first magnetic
confinement fusion machine to produce net fusion power and will generate
radiation levels, i.e., neutrons and gamma rays, that are much higher than
present-day tokamaks. Consequently, there is a need to develop more robust electronics
with higher performance and capability to reliably measure the desired data. A major improvement in robustness, as well as
performance and capability, is to switch to gallium nitride (GaN) semiconductor devices, which are wide bandgap
materials (3.39 eV versus 1.43 and 1.11 for GaAs and Si, respectively). GaN semiconductor devices have been shown to provide high
power, high breakdown voltages, and low noise beyond 200 GHz. UC Davis will
develop key strategic GaN based chips (75-110 GHz and
above) that will advance the capabilities of microwave diagnostics including radiometers,
reflectometers, and scattering. This
work will transform current microwave measurement capabilities while ensuring
continued U.S. leadership in burning plasma diagnostic expertise.
* This work was supported by the US DoE under Grants DE-FG02-99ER54531
and DE-FC02-04ER54698.
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 (/resources/ref/Web_Seminars/Litaudon-JET-%202019-05-02-vf.pdf) |
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JT-60SA First Plasma (http://www.jt60sa.org/) |
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Sep
20-25, 2020 |
Virtual |
|
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Oct 12-16, 2020 |
Theory
of Fusion Plasmas Joint Varenna- |
Varenna or Lausanne |
|
Nov
9-13, 2020 |
Remote
only |
|
|
Nov 15-19, 2020 |
Chicago, IL |
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Nov
16-20, 2020 |
Marseille,
France |
|
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Dec 6-10, 2020 |
Singapore |
|
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Dec
13-17, 2020 |
Santa
Fe, NM |
|
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Dec 16-17, 2020 |
Washington, D.C. |
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Jan
24-29, 2021 |
Jeju, South Korea |
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May 10-15, 2021 |
Nice, France |
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