Metal Impurity Behaviour in DIVA Determined Using a Blow-Off Technique

Abstract

We obtained clear evidence of metal impurity behaviour in DIVA by using a blow-off technique. The impurity in plasma was found to have a constant velocity of (2–3)·10³ cm/s which is much less than the injected velocity of 10⁵ cm/s. Confinement times of metal impurity of about 1 and 4 ms in the peripheral and central region respectively were obtained. The particle balance is represented as the reflected rate 78%, the reducted rate by the divertor action 16%, and the accumulated rate 6%. Major disruption was forced by injecting a large amount of gold atoms.