Changkun Dong

Physics Department, Old Dominion University, Norfolk, VA 23606

Applied Research Center, Jefferson Lab, Newport News, VA23606

Ganapati Myneni

Jefferson Lab

Newport News VA 23606

Recent technological improvements in turbo pumps make them very attractive for UHV/XHV applications. The major deterrent for such use is the necessity of a backing mechanical pump (such as a scroll or a diaphragm pump). Extended operation of a wide range turbo pump without a backing pump has been recently demonstrated¹. This has been accomplished with a 13-liter volume that was initially evacuated with a sorption pump and then was valved off. The main difficulty with this system is getting to low partial pressure of hydrogen. A sputter-ion pump is an alternative-backing pump for the turbo pumps. We have built a small XHV pumping system with a Varian V70LP 70 liter turbo pump backed by a Varian VacIon Plus 20 liter Sputter-ion pump. In this paper the performance characteristics of this pumping system are reported.

1. Peter Weber et al. JVST A 1996 14(5) 2695-2698