Fusion Science and Technology / Volume 52 / Number 4 / November 2007 / Pages 1061-1065
Technical Paper / Plasma Engineering and Diagnostics
A 21S metastable helium atomic beam injector was studied for a beam probe of electric field diagnoses, which is applicable to high electric potential region in Inertial Electrostatic Confinement Fusion (IECF) plasmas where a solid probe can hardly be utilized. With deuterium background gas (~0.1Pa) which is the minimum operation pressure of the IECF devices, the beam density was found to decrease ten times lower than beam density without background gas because of collisional effect. Also, plasma parameters in a-magnetron-discharge-based exciter were evaluated by means of Langmuir probe and emission spectroscopy. These results strongly imply a high excitation rate of ~10-4 into 21S metastable state.