Pulse Discharge Cleaning for Open-Ended Systems

A significant improvement in plasma parameters (ion temperature and electron temperature) has been achieved through the use of pulse discharge cleaning in the mirror machine, RFC-XX-M, in Nagoya, Japan. The essence of this technique is to use pulsed-off-resonance ion cyclotron heating (10-ms duration every 10 s), gas puffing, and electron cyclotron heating preionization in conjunction with baking (to 100 to 150°C) in order to prepare the machine surfaces for full-power normal experimental shots. It was also found that RFC-XX-M could operate at nearly full parameters without titanium gettering after discharge cleaning, whereas without discharge cleaning and titanium gettering it is difficult to sustain a plasma.