Calculation of the bootstrap current profile for the TJ-II stellarator

Abstract

Calculations of the bootstrap current for the TJ-II stellarator are\npresented. DKES and NEO-MC codes are employed; the latter has allowed, for the\nfirst time, the precise computation of the bootstrap transport coefficient in\nthe long mean free path regime of this device. The low error bars allow a\nprecise convolution of the monoenergetic coefficients, which is confirmed by\nerror analysis. The radial profile of the bootstrap current is presented for\nthe first time for the 100_44_64 configuration of TJ-II for three different\ncollisionality regimes. The bootstrap coefficient is then compared to that of\nother configurations of TJ-II regularly operated. The results show qualitative\nagreement with toroidal current measurements; precise comparison with real\ndischarges is ongoing.\n