Fusion Science and Technology / Volume 50 / Number 4 / November 2006 / Pages 503-507
Accumulation of impurity injected for reduction of heat load to the divertor plates was of great concern with a peaked density profile. Applicability of impurity injection to a burning plasma with a peaked density profile was investigated for various impurity accumulation levels using the A-SSTR2 design parameters. Impurity transport analysis indicated that the argon density profile twice as peaked as the electron density profile can yield acceptable radiation profile even with a peaked density profile. The required confinement improvement factor over the IPB98(y,2) scaling slightly increased from 1.4 with the flat density profile to 1.5 with the peaked electron density profile at ne(r/a = 0)/ne(r/a = 0.7) ~ 3. When the argon density profile was determined by neoclassical transport, the radiation loss in the core plasma intensively increased with the peaked density profile, which requires higher confinement enhancement factor of 1.9 at ne(r/a = 0)/ne(r/a = 0.7) ~ 3.