J-PARC H ion source and space-charge neutralized LEBT for 100-mA high energy and high duty factor LINACs

Ueno, Akira  

In July 2019, a 3 GeV 920 kW beam was accelerated for 10.5 hours in the J-PARC. During the operation, the H ion source and LINAC was operated with the beam duty factor (BDF) of 1.25% (0.5 ms25 Hz) and the ejected beam intensities of 58 and 50 mA, respectively. Separately, they were stably operated with the BDF of 1.5% (0.6 ms25 Hz) and the ejected beam intensities of 72 and 60 mA, respectively. Based upon the 100-mA and BDF 5% (1 ms50 Hz) H ion source operation on a test-stand, the possibility of the 100-mA high energy and high duty factor LINACs with a radio frequency quadrupole LINAC with an injection energy higher than 64 keV is presented. The unexpectedly effective space-charge neutralization effects in the low energy beam transport are also presented. Furthermore, the transverse emittance improvements by about 8% with the shortest beam extractor are presented.