Test results of pre-production prototype distributed ion pump design for the PEP-II asymmetric B-Factory collider

We have built and tested a plate-type pre-production prototype distributed ion pump (DIP) for the PEP-II B-Factory High Energy Ring (HER). The design has been simplified from an earlier design to use less materials and to reduce overall costs. Penning cell hole sizes of 15, 18, and 21 mm have been tested in a uniform magnetic field of 0.18 T to optimize pumping speed. The resulting final DIP design consisting of a 7-plate, 15 mm basic cell size anode was predicted to give the best pumping speed results for the actual varying magnetic field of the HER dipole. A description of the final optimized DIP design will be presented along with the test results of the pumping speed measurements.