Controlling the shape of the ISIS H? penning ion source beam pulse

The Penning ion source serving the ISIS Pulsed Spallation Neutron and Muon facility routinely delivers 55 mA beam of negative hydrogen ions (H?) in 250 µs pulses at 50 Hz repetition rate. Front End Test Stand (FETS) specifications require 60 mA, 2 ms, Hz. Extending discharge pulse length to 2.2 ms will need overcome observed current droop caused by thermal transients long operation. Recent experiments 25 have demonstrated square up 1.2 with permanent magnet version 100 1.65 same equipped a double-width extraction slit. Droop was compensated ramping during pulse. physical phenomena underlying its countermeasures are discussed, further technical developments that necessary reach FETS described. In addition, various experimental shapes H? were achieved controlling accelerated through 70 MeV linac. technique allows almost arbitrary shaping for injection studies into 800 rapid cycling proton synchrotron.