Filling stellarator with laser-produced plasma

Laser-produced plasma was applied to a Stellarator whose main radius is 50 cm, which has helical conductors of l = 2 and 3, and rotational transformation is 0.5 to 0.6. Specifically, the details of the process for filling the Stellarator with plasma are elucidated. Major conclusions are as follows: The rotational transformation inherent to the Stellarator did not function in the time-region before plasma ring formation, and the significant toroidal drift and particle loss arose. On the other hand, the rotational transformation became effective, and the toroidal drift and particle loss were suppressed after plasma ring formation. For this reason, overall particle trapping efficiency was about 10 % in one-position plasma production. Thus, the multi-position ( 2 or 4 positions) plasma production was tried in a torus as one of the methods to suppress the particle loss by functioning rotational transformation before the loss starts due to drift, and the trapping efficiency can be improved up to about 50 % in 4-position simultaneous production. (Wakatsuki, Y.)