PPT Slide

Current Drive with Non-zero Edge Density

• So far, CD requirements have been assessed for well-aligned

equilibria where the edge density, nea, is set to zero.

In reality, a non-zero nea is required for divertor operation, and may

naturally exist in an H-mode outer plasma region.

• In a plasma equilibrium with fixed pressure profile, raising nea

(with p’=0) may reduce the edge bootstrap current implying

a larger edge seed current to be driven externally.

• Higher ne and lower Te near the edge often leads to less efficient

local current drive.

• It is therefore necessary to examine the impact of a non-zero edge

density on the RFCD requirements.

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