Theoretical and experimental studies on 104 MHz ladder IH-RFQ accelerator

To study feasibilities of RFQ-based ion implantation and accelerator mass spectroscopy (AMS), a 104 MHz ladder type IH radio-frequency quadrupole (Ladder IH-RFQ) accelerator has been developed. According to beam dynamics design, it is able to accelerate ions with mass-to-charge ratio up to 14 from 2.9 keV/u to 35.7 keV/u. As a specific feature, the output beam energy spread is as low as 0.6% realized by using internal discrete bunching method. A rod-type RFQ structure, i.e. ladder IH-RFQ is adopted, taking advantage of its mechanical stability and symmetric inter-electrode field. Power test shows that specific shunt impedance of the constructed cavity reaches 178 kΩ m. During the beam commissioning, 210 μA 4He+ beam has been obtained, and the transmission efficiency is better than 70% at current of several tens μA. The ladder IH-RFQ is proved to be very suitable for operating frequency above 100 MHz for light ions.