Tuning of RF amplitude and phase for the separate-type drift tube linac in J-PARC

Shen, G.; Ikegami, Masanori*

In the beam commissioning of J-PARC linac, the RF set-point has been determined for 15 SDTL modules based on a beam experiment. In the beam-based tuning, a phase scan method is employed with the concept of phase signature matching. The obtained phase scan curve shows an excellent agreement with that from a numerical model, and the tuning accuracy of 1 deg in phase and 1 % in amplitude is achieved with a sufficient margin. In the phase scan tuning, the range of phase scanning is restricted to two critical regions to avoid the unfavorable influence from debunching. An analogous scheme has successfully been applied to the RF set-point tuning for bunchers and debunchers. The tuning goals for these cavities are set to 5 deg in phase and 5 % in amplitude. The tuning goal is expected to be met for those cavities, while the debuncher tuning is to be confirmed by directly monitoring the debuncher functions.