RF 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 (SC) 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 prototype spoke cavity. It will provide us an insight for the development of the low-beta SC cavity. It will also enable us to acquire valuable information such as the accelerating gradient under the stable operation. In this symposium, the RF design of the prototype cavity including multipacting analysis is presented.