LANSCE Linac RF Performance for a Long Pulse Spallation Source

Abstract

The present LANL Long Pulse Spallation Source (LPSS) design consists of a 1 MW neutron spallation target fed by a pulsed proton beam from the Los Alamos Neutron Science Center (LANSCE, formerly LAMPF) accelerator. This proton beam would have a repetition rate of 60 Hz and a pulse length of 1 ms for a duty factor of 6%. An average/peak currentof 1.25 mA/21 mA would be required foran 800 MeV beam to provide this power at this duty factor. The spallation target would reside in Area A and use the H+ beam. The LANSCE accelerator would also be required to simultaneoulsy deliver H- beams to the Manual Lujan Jr. Neutron Scattering Center (MLNSC) and Weapons Neutron Research (WNR) facility. Presently LANSCE delivers 16.5 mA peak of H+ beam at 120 Hz, with a 625 {mu}S beam pulsewidth; H- beams are also accelerated for MLNSC and WNR. In Nov. 1995, linac operation shifted to LPSS pulse parameters, except for the peak curent which remained at 16.5 mA. In addition to delivering 800 kW H+ proton beam to physics production targets, H- beams were simultaneously delivered to customers for the PSR feeding MLNSC and to researchers using WNR. Performance of the RF powerplants for the 201.25 MHz drift tube linac 805 MHz side coupled linac, and associated electronics is described. Conclusion of the experiment is that the LANSCE linac can be upgraded through modest improvements to drive a 1 MW LPSS.