Solution to the Transverse Phase Space Time Dependence Problem with LAMPF's High Intensity H+ Beam

The 750 keV H+ beam at LAMPF has a transverse phase space time dependent transient during the first 200 ps of each 750 μs long macro-pulse. The time dependence is documented in an earlier report. Further studies indicate that the time dependence is due to space charge neutralization resulting from secondary emission of electrons produced by collisions of the H+ and H
₂
+ beams on the transport walls. One of several possible solutions has been tested and has proven successful in eliminating the time dependence of the beam entering the linac.