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 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. Podestà 1, V.
Kiptily2, V. Goloborodko3, R. B. White1, F. E.
Cecil4, and JET Contributorsâ€
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
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.
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 transportâ€, 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
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JET DT-campaign (https://www.burningplasma.org/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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Nov
9-13, 2020 |
Remote
only |
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Nov 15-19, 2020 |
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Dec 6-10, 2020 |
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Dec
14-17, 2020 |
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Dec 16-17, 2020 |
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2021
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Jan
24-29, 2021 |
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May 10-15, 2021 |
Nice, France |
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June
21-25, 2021 |
Sitges, Spain |
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Sep 7-10, 20201 |
York, UK |