WEP30 　ポスター②　 8月30日 14号館1441教室 13:30-15:30

Multi-cavity field emission at STF-2 accelerator in KEK

○Prakash Joshi (SOKENDAI), Toshihiro Matsumoto, Shinichiro Michizono, Yasuchika Yamamoto, Takahiro Oyama (KEK, SOKENDAI)

At the superconducting RF test facility (STF) in KEK, 10 MW multi-beam klystron pulsed by a modulator of repetition rate 5 Hz drives RF power of 1.3 GHz into the superconducting (SC) cavities. The average accelerating gradient of 9 SRF cavities is 33.0 MV/m and the maximum allowable beam energy of the facility is 500 MeV. In December 2022, an experiment was conducted where neutron and gamma radiation levels are measured both upstream and downstream by tuning eight cavities. The measured data were compared to field emissions from each cavity. A model assuming that electrons generated by field emission are accelerated through multiple cavities was applied and discussed. The key finding emphasizes the significant influence of multi-cavity FE over a single cavity, with the help of FE losses occurring within the cavity itself, in the neighboring cavity, upstream and downstream according to tuning & detuning of a cavity, and finally accumulating at the closed gate valves.