10 October 2003S. DeBarger PEP-II Vacuum Failures PEP-II Machine Advisory Committee

S. DeBarger 10 October 2003 Elliptical Vacuum Valve Failure On 23 Jan 03, LER elliptical vacuum valves, PR02 VACV 1153 & PR02 VACV 3044 would not fully open following 2 Hour ROD. Both valves had damage to their RF seals and actuating mechanisms. The valves were removed and replaced with spool pieces. Failure is attributed to deficiencies in the design of the RF shields, compounded by a workmanship defect in one valve. Beam Time Lost hours Current Status Valves repaired by VAT using existing RF seal design. Spare valve installed at VACV 3044 location. Gap rings at this location have been replaced with gap rings of the correct size. Existing elliptical and round valves show heating by the beam. This is not adequately measured.

S. DeBarger 10 October 2003 LER Frangible Link On 19 Apr 03, pressure at the IP became elevated. Beam was unrunnable due to high LER Backgrounds. Leak discovered on upstream LER Frangible Link. Several attempts to VacSeal were short-lived; finally the leaking bellows module was replaced. During replacement of the leaking bellows, a second bellows module was found to have damaged RF fingers. Both bellows were replaced with spares and reinstalled. Failure is attributed to mishandling of the bellows during or after installation, causing the RF fingers to lose contact with the beampipe. It is possible that corrosion also played a part in the failure. Beam Time Lost47.50 hours Current Status New spare modules being fabricated using existing design New bellows restraints for transportation & for normal operation to be designed and fabricated

S. DeBarger 10 October 2003 Mystery Pressure Bump Near IP On 26 Apr 03, pressure at the IP became elevated. During leakchecking, pressure improved. No leak was located. Lots of speculation … could this be the first appearance of a problem that would resurface? Beam Time Lost hours

S. DeBarger 10 October 2003 LER Arc 1 Pumping Chamber On 9 May 03, pressure near PR02 VP1151 rose. Leakchecking revealed a leak in a weld prep on the pumping chamber aluminum extrusion. Attempts to seal the leak with VacSeal or to establish a guard vacuum were unsuccessful. Replaced the leaking chamber on 17 May 03. Beam Time Lost48.50 hours Current Status Chamber to be repaired

S. DeBarger 10 October 2003 Q2 Chamber On 27 Jun 03, pressure began to rise at the IP. Initial attempts to leakcheck did not locate a leak. By 4 Jul 03, the pressure had risen to the level. Additional leakchecking revealed a water-to- vacuum leak in the Forward Q2 chamber. Radial Ion Pump PR02 VP3012 failed on the 29 th, possibly related to leakchecking activities. Failure traced to a crack in the water-cooled mask due to a material defect Beam Time Lost 50.1 hours Current Status Chamber replaced with older version of the same chamber After removal, discovered that the NEG pump had been overheated at some time, damaging the NEG material Chamber repair appears not to be an option Evaluating the performance of the installed chamber and comparing to future running scenarios