1 - Nuclear Sciences and Applications - IAEA

324 DONNE et al.
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FIG. 1. Short term effects of high voltage current pulse (a,b). The thermal part of the electron distribution
function shows an increase in Te (c) and ne (e) in the centre of the plasma, while at the edge
(r/a = 0.7) cooling (d) and rarefaction If) occur. Both effects disappear in about 50 ps. A tail population
with Te up to 3 keV (g) and ne up to 10 19 m~ 3 (h) is observed at r/a = 0.7 m, for 10 to 15 ins only.
follows after thermalization on a much longer time-scale, x^n^r,,,^); [2,3].
After an initial stable formation of the current skin (the first 3 |is), a rapid
broadening towards the center follows later during current rise, possibly due to a
mixture of resistive modes [4]. In this phase the plasma is compressed with
considerable heating. After removal of the additional current, the current density
profile has become narrower. The excess energy stored in the poloidal magnetic
field is gradually released during the relaxation in about 2 ms. The above