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

• assess computationally, on test stands, and in fusion experiments, the interactions
between elms and liquid metal PFcs.
• similarly, assess the interactions between liquid metal PFcs and disruptions, runaways,
and fast lost-ions.
• develop techniques to flow liquid in the presence of time varying magnetic fields.
• address tritium retention issues.
• assess the compatibility of liquid metal surfaces with high-performance plasmas in small,
medium and large experimental facilities.
plaSMa ModiFicatioN By auxiliaRy SyStEMS:
RESEaRch REquiREMENtS
Overall goal: Establish the physics and engineering science of auxiliary systems that can provide power,
particles, current and rotation at the appropriate locations in the plasma at the appropriate intensity.
key gaps identified by the 2007 Fesac panel included 1 :
gap: Plasma Heating — even in high-gain plasma, some level of auxiliary plasma heating may
be required for startup, sustainment or instability control. This needs to be achieved precisely and
efficiently. new systems and technologies have to be developed or expanded to meet the requirements
of demo.
gap: Plasma Current Drive — For steady-state operation the plasma current will have to be
produced in a nonpulsed (noninductive) manner, and owing to the low current drive efficiencies
of most noninductive means, a high fraction of internally generated current (bootstrap current)
is desirable. however, high-performance plasmas with high bootstrap currents are susceptible to
instabilities, where tearing modes create zones of zero or low bootstrap current.
gap: Fueling and Exhaust Control — operation of demo steady state for weeks or months
at a time, at high fusion power production, requires that the fuel concentration in the core of the
plasma be adjustable and renewable.
gap: Rotation Control — to optimize plasma confinement in high-beta plasmas, edge rotation
improves performance by producing radial velocity shear, which acts to stabilize micro-turbulence
and thereby improves plasma confinement.
Presently four heating and current drive actuators, electron cyclotron (ech, eccd), neutral beam
injection, ion cyclotron (icRF) and lower hybrid current drive (lhcd) are employed widely and
are either already incorporated into the iteR design or seriously being considered. Pellets and gas
puffing will be employed for fueling. For demo a reduced set of actuators is envisioned. successful
operation on iteR will go a long way to qualifying the set necessary for demo. For steadystate
at scenarios, including the advanced operation phase of iteR, aimed at demo and be-
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