Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

The Us d-t facility, studied in 1b, would perform focused research on creating high-performance
fusion plasmas in the strongly coupled regime to provide the core plasma physics approaching
demo conditions. The coupled plasma transport and mhd at high pressure, high density, and
high self-driven current, exceeding that possible on iteR, would be explored. The heating and
current drive sources would be used to establish these plasmas, and new and more effective control
tools would be sought and developed. The demo parameters would be pursued simultaneously
to the extent possible. self-consistent core/scrape-off layer/divertor plasmas would be established,
potentially at higher flux densities than those in iteR, and the supporting elements of
fueling and pumping for particle control, power handling, multi-level feedback control with disruption
avoidance would be established on the multiple current profile redistribution time scale.
The studies in 1b would determine the possible extensions of this facility to other fusion nuclear
science missions.
2. Existing program activities that contribute to this Thrust and should be supported and
expanded.
Activity 2a: Continue to pursue the program on US tokamak (and ST) facilities to establish
the simultaneous high-performance plasma parameters (b N , f BS , P rad,core , etc.) in nonburning
D-D plasma.
in the very near-term, present tokamaks in the Us should pursue upgrades to heating and current
drive systems, as well as pulse extension to a few current profile redistribution times. These
non-burning d-d plasma devices should identify attractive plasma configurations for iteR and
beyond. The access to combinations of high beta, high noninductive plasma current, high bootstrap
fraction, high fast particle content, long pulse lengths, other dimensionless plasma parameters,
and a mix of external control tools varies among the Us tokamaks. The results of the Us (and
international) experiments will need to be combined to establish a more universal physics basis.
Using the varied tools on the Us devices, the requirements for plasma current profile and radiated
power fraction control can be explored (Thrust 5).
Activity 2b: Take advantage of the Asian long pulse non-burning D-D tokamaks for
longer pulse lengths, all four heating and current drive sources for flexibility in plasma
configurations, and control system development. Examine areas where existing device
program plans for the Asian devices could be enhanced or expanded to provide a greater
physics database, and seek to establish a strong collaboration to pursue this.
The main new d-d devices planned over the next 20 years are the long pulse asian tokamaks —
kstaR (korea), east (china), and Jt-60sa (Japan). The focus of the asian tokamaks is d-d operation
for pulses ranging from 100 to 1000 s, which provides > 2-5 current relaxation times. in
addition, the plasma configurations of interest are high noninductive current fraction plasmas
(targeting 100%, and high bootstrap current fraction), and high beta pushing above the no-wall
limit. kstaR and east will utilize all four main tokamak heating and current drive systems
(neutral beams, ion cyclotron, electron cyclotron, and lower hybrid), which will give them considerably
greater flexibility than any single Us tokamak in exploring plasma configurations, while
Jt-60sa will use neutral beams and electron cyclotron sources only. development of more so-
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