STUDY OF THE POST EXTRACTION ACCELERATION GAP IN THE ISIS H − PENNING ION SOURCE ∗

The RAL Front End Test Stand (FETS) is being con-structed to demonstrate a chopped H−beam of up to 60 mA at 3 MeV with 50 pps and sufficiently high beam quality for future High Power Proton Accelerators (HPPA). The injection energy into the RFQ will be in the range of 60 to 70 keV whereas the standard ISIS H − Penning ion source operates at 35 keV, therefore the post extraction acceler-ation voltage must be increased. In order to finalize the design of the FETS post extraction system, a study is be-ing conducted on the Ion Source Development Rig (ISDR) at ISIS. This study shows how beam transport is affected by different post extraction acceleration voltages and gap lengths. Beam current and 4 dimensional profile measure-ments are presented along with theoretical calculations