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

• sufficient heating with little torque injection to approach the sustained h-mode conditions
with dominant electron heating and dimensionless parameters anticipated for iteR.
• sufficient mix of heating power to vary the effects of fast ions, thermal particles, and
radiofrequency power on the h-mode pedestal, plasma rotation, and flow shear.
• sufficient current drive power to access sustained safety factor profiles that approximate
the main iteR operational scenarios and drive ≥ 50% of the total plasma current.
• Pulse length many times the resistive diffusion time.
• extended capability to measure electron and ion-temperature fluctuations, and high
spatial resolution profile diagnostics (e.g., improved current profile diagnostics) to
support research in h-mode threshold and sustainment, including transient conditions.
• enhanced ability to control particles at the plasma edge and fuel in the plasma core to
resolve the remaining physics issues in heating and fueling for application to iteR.
• methods to mitigate or suppress edge localized modes in low-collisionality plasmas.
• Radiative divertor operation.
• ability to determine adequate methods for wall preparation and cleaning.
addressing the critical issues for iteR identified in this Thrust requires a focused and well-coordinated
research plan. to obtain maximum productivity from the domestic program in addressing
iteR issues, the three Us tokamaks should be upgraded to realize as many of the noted attributes
as possible. Where appropriate, particularly in the area of pulse length extension, partnerships
should be formed with new international tokamaks. on the longer term, it is essential to address
the issues confronting iteR in a device with scenario capability that permits — and indeed requires
— development of integrated solutions. The ability of the world tokamak program to provide
the platform(s) for developing integrated solutions needs to be evaluated. if the capability of
planned and existing tokamaks falls short of those needed for developing integrated solutions,
construction of a new domestic facility should be undertaken. such a facility could be compatible
with the high-priority goals in other thrusts, e.g., Thrust 8.
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