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

4. based on the outcome of actions 1-3, a new experiment capable of demonstrating the
integration of confinement, current sustainment, active control of mhd stability, and
boundary control is essential to establish the scientific basis for an RFP burning plasma.
This could be a two-stage, upgradeable facility that first emphasizes the integration of
confinement and current sustainment at moderate plasma current. a 2 ma first stage
could attain sufficiently high-S to robustly test confinement scaling, ac current drive,
and the hybrid scenario. The second stage will push performance at the 4 ma level to
test confinement and current-drive up to S=10 9 and r* less than 1% with fully integrated
boundary control and near-burning plasma conditions. The pulse length requirement
for both stages will demand active control of resistive wall modes (RWms). high-power
plasma control using mW-level neutral beams and radiofrequency are required, and the
experiment must be well-diagnosed to validate our understanding of the important
physical processes.
similar to the RFP, spheromaks have shown transient control of magnetic fluctuations leading to
electron temperature of 0.5 kev and core energy confinement time of 10 ms. continuous sustainment
compatible with good confinement has not been demonstrated and is a focus of near-term
activities. at present there are no large-scale experiments that can address this issue or other limits
to confinement. The development path shown in Figure 2 will fill this gap, facilitate innovation
to increase formation efficiency, and address technology needs.
1. Upgrades of existing and construction of new ce-level experiments will foster innovation
in formation and current drive studies. With support from analytics and computation,
formation experiments will investigate methods for exceeding the flux amplification and
current multiplication factors obtained in past experiments. They will also improve our
understanding of mhd activity excited by ac current drive and refluxing techniques for
steady, quasi-steady, and pulsed operation.
Figure 2. CE spheromaks emphasize innovation to address specific needs prior to PoP development.
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