High-resolution mass spectrometric analysis of gases released from graphite during sequential helium and deuterium glow discharge cleanings

Abstract The amounts of helium ( 4 He) and deuterium (D 2 ) retention/release on a graphite wall during sequential 4 He and D 2 glow discharge cleanings have been evaluated using the high-resolution quadrupole mass spectrometer. A large amount of D 2 was retained on the graphite wall and/or released from the wall during these discharges. At a wall temperature of 300°C, the total amount of 4 He released during a 15 min D 2 glow discharge was much smaller than the amount of D 2 retained on the wall. Thermal desorption experiments showed that the graphite sample, exposed to the 4 He glow discharge, retained a very small amount of 4 He which desorbed at around 150°C.