Beam dynamics, RF measurement, and commissioning of a CW heavy ion IH-DTL

A 53.667 MHz CW (continuous-wave) heavy ion IH-DTL has been designed for the SSC-LINAC injector of HIRFL-CSR (Heavy Ions Research Facility at Lanzhou-Cooling Storage Ring). It accelerates ions with maximum mass-to-charge ratio of 7.0 from 143 to 295 keV/u. Low-power RF measurement of the IH-DTL1 has been taken to investigate the RF performance and the quality of the electric field distribution on the beam axis. The measured $Q_0$ value and the shunt impedance are 10,400 and 198 M$\Omega$/m, respectively. The electric field distributions on and around the beam axis were evaluated and compared with the design value. By a new approach, the dipole field component is also estimated. The beam dynamics simulation using measured field distribution was presented in this paper. Based on the dynamics analysis in both transverse and longitudinal phase space, the field distribution can meet the design requirement. Finally, the RF conditioning and very first beam commissioning on the IH-DTL1 were finished. The beam test results agree well with the simulation results; what's more, the property of the variable output beam energy about the separated functions DTL was verified.