An attempt to mitigate disruptive plasma current decay in relation to vacuum vessel electrical aspects

In order to search for techniques to mitigate disruptions, the characteristics of disruptive Ip decays were tested for (1) low and high vacuum vessel loop resistance Ωv conditions, and (2) scrape-off layer (SOL) plasma to vessel current (halo current) control. These tests were to manipulate the SOL current. Case (1) had the advantage of lower loop voltage V1 without an increase of the force due to the eddy current, in comparison with high Ωv conditions. In case (2), the Ip decay rate was reduced by suppressing the SOL current. The core plasma current and the shell effect during the first phase, in which magnetic axis and core plasma still exist with the closed flux surfaces, were enhanced, which is effective in mitigating disruptive Ip decay. (author). 12 refs, 7 figs