Investigation by techniques of electron stimulated desorption of the merits of grow discharge cleaning of the surfaces of vacuum chambers at the CERN intersecting storage rings

Abstract

To provide surface cleaning of the CERN intersecting storage rings, in which the pressure is below 10 −10 torr over a 2 km length of mostly elliptical pipe (160 X 52 mm), ion bombardment during a glow discharge has been utilized. The discharge in argon at a pressure of about 3 × 10 −2 torr was carried out intermittently in the course of a 15 h bake-out at 300°C. Subsequent electron scrubbing enabled the electron desorption efficiency of the surface of the ISR vacuum chambers to be reduced by two to three orders of magnitude. Information is given on the apparatus used and the procedure adopted, together with a discussion of the diagnostic technique and a consideration of the action of the discharge cleaning.