Vacuum tube operation analysis under multi-harmonic driving and heavy beam loading effect in J-PARC RCS

Yamamoto, Masanobu   ; Nomura, Masahiro  ; Shimada, Taihei ; Tamura, Fumihiko   ; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Toda, Makoto*; Yoshii, Masahito*; Schnase, A.*

A magnetic alloy loaded cavity is used to generate multi-harmonic rf voltage in J-PARC RCS. However, a vacuum tube operation analysis under the multi-harmonic driving is very complicated because many variables should be solved with a self consistency. At the conventional operation analysis, a hand work by tracing the constant current curve of the tube was performed, or an appropriate single harmonic wave form was assumed. We have developed a numerical analysis code which calculates the vacuum tube operation automatically and it realizes the multi-harmonic vacuum tube operation analysis. The code is verified at the high power beam acceleration test and we confirm the calculation results are consistent with the measurement ones. We can calculate the vacuum tube operation precisely by using the code, and it will contribute to improving the quality of the beam in the high intensity proton synchrotron.