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

7. extend St performance to near-burning-plasma conditions.
Present and upgraded st facilities can go far in developing the knowledge base needed for st fusion
nuclear science applications. a factor of five to ten reduction in collisionality and increase
in pulse duration should be achievable by doubling of the field, current, and heating and current
drive power in upgraded st facilities with a modest increase in aspect ratio (a ≥ 1.3 → 1.5). depending
on results from upgraded st facilities and the worldwide tokamak research program, a
new st device with increased performance and capabilities may be needed to support the design
and operation of a low-a device suitable for fusion nuclear science applications.
actions:
• Further reduce collisionality to near-burning-plasma conditions to assess: current drive
for ramp-up and sustainment at high current, core and pedestal transport, mhd stability,
Pmi solutions.
• operate a high-performance st for very long pulse lengths with actuators relevant to
a high neutron fluence environment to assess: (1) sustained plasma current drive and
profile control, reliable disruption prediction, avoidance, and mitigation for integrated
st conditions; and (2) compatibility of sustained high performance with high power
and particle exhaust mitigation techniques, with equilibrated divertor and first-wall
conditions and low hydrogenic retention.
• test high-field, long pulse magnets under conditions directly relevant to st applications.
Summary of Thrust 16
The Thrust elements provide a comprehensive set of research actions to advance the st configuration
to be ready to contribute to fusion nuclear science applications. These actions also enable
access to a unique plasma parameter regime of high normalized plasma pressure, low collisionality,
and low aspect ratio. This Thrust enhances the understanding of compact alternative magnetic
configurations, expands the understanding of conventional aspect ratio tokamaks including
iteR, and develops capability necessary to prepare for a fusion demo.
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