Electromagnetic design of the prototype spoke cavity for the JAEA-ADS linac

Tamura, Jun  ; Kondo, Yasuhiro   ; Yee-Rendon, B. ; Meigo, Shinichiro   ; Maekawa, Fujio  ; Hasegawa, Kazuo; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Konomi, Taro*

The Japan Atomic Energy Agency (JAEA) is proposing an accelerator-driven subcritical system (ADS) as a future project to transmute long-lived nuclides to short-lived or stable ones. In the JAEA-ADS, a high-power proton beam of 30 MW with the beam energy of 1.5 GeV and with the beam current of 20 mA at an exit of the accelerator is required with sufficient reliability. Furthermore, the linac needs to be operated in a continuous wave (CW) mode in order to be compatible with the reactor operation. Since a normal conducting structure raises a difficulty in cavity cooling under the CW operation, a superconducting linac would be a suitable solution. As the first step toward the complete design of the JAEA-ADS linac, we are planning to demonstrate a high-field measurement by manufacturing a low-beta prototype spoke cavity. For the cavity development, we designed the prototype cavity. By the electromagnetic simulation, we obtained good cavity performance comparable with the modern spoke cavities.