Development of a Radio-Frequency Quadrupole Accelerator for the HL-2A/2M Tokamak Diagnostic System

In order to figure out the migration and deposition of impurities on the first wall of HL-2A/2M tokamak, Peking University and Southwestern Institute of Physics are co-developing a deuteron RFQ as part of the in situ ion-beam diagnostic for the material. The RFQ, which operates at 162.5 MHz, is designed to accelerate a 10-mA deuteron beam from 40 keV up to 1.5 MeV. Key design considerations and the final design parameters are presented. The RFQ has been conditioned at a 1% duty factor for 80 h at RF cavity power of 55 kW. The specific shunt impedance of the cavity is 221 kΩ·m by measuring the bremsstrahlung spectrum. The intrinsic Q-value after the high-power tests measured by the Ring-Down method is 13,780. Beam commissioning has been taken place during the first half of 2021, and the beam measurements include beam current and energy of 2H+ ion. A 10 mA 2H+ beam was successfully accelerated through the RFQ.