RESIDUAL-GAS PRESSURES IN SEALED FUSED-SILICA GLASS AMPOULES

The residual gas pressures in sealed and annealed ampoules made from S ilica glass have been determined using different methods including a M cLeod gauge. It has been found that the gas build-up in the ampoule is mainly the result of the ampoule heat treatment; the amount of gas re leased and trapped during sealing the ampoule under vacuum is much les s. The pressures in the ampoules after heat treatment range from a few mTorr to a few Torr, depending on the silica glass and on the outgass ing and annealing procedures.