Retention and Desorption of Discharge Gases in Wall Materials Used for Large Helical Device
In the Large Helical Device, the control of particle recycling is one of important issues. Glow discharge cleanings (GDC) have been conducted to control the particle recycling in LHD. In order to simulate such the particle behavior, the glow discharge apparatus was fabricated, and retention and desorption of hydrogen and helium GDC gases were examined for stainless steel liner and graphite sample. The retained amount of hydrogen was one or two orders of magnitude larger than that of helium in both the wall materials. The helium ion impact desorption was observed to be effective to reduce the hydrogen retention. On the other hand, hydrogen ion impact was ineffective to reduce the helium retention. It was also seen that the impurities at the top surface of 316L SS was removed during GDC for only several hours.
真空 46(11), 795-798, 2003-11-20
The Vacuum Society of Japan