Development of a compact 325 MHz proton interdigital <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>H</mml:mi></mml:math>-mode drift tube linac with high shunt impedance
Pengfei Ma, Rongnian Tang, Ye Yang, Shu-xin Zheng, W. B. Ye, M. W. Wang, W. L. Liu, B. C. Wang, Qingzi Xing, Changtong Du, H. Y. Zhang, Jian Li, Xiangfeng Guan, X. W. Wang, Zeyuan Wang, M. Qiu
Abstract
This paper describes the construction, rf measurement and tuning, rf conditioning, and beam commissioning of a compact 325 MHz interdigital $H$-mode (IH) drift tube linac (DTL) with modified KONUS (Kombinierte Null Grad Struktur, combined zero-degree structure) beam dynamics at Tsinghua University. This IH-DTL accelerates a proton beam from 3 MeV to 7 MeV in about 1 m. With a high rf frequency of 325 MHz, the cavity is designed to be compact while retaining a high average gradient of $4\text{ }\text{ }\mathrm{MV}/\mathrm{m}$. The efficient shunt impedance $Z{T}^{2}$ is $101\text{ }\text{ }\mathrm{M}\mathrm{\ensuremath{\Omega}}/\mathrm{m}$. The beam test results show good agreement with the beam dynamics design. The developed compact IH-DTL can be applied to the injectors of medical proton machines.