It is difficult to accelerate a high intensity heavy ion beam because the upper limit of the beam current in an RFQ (Radio Frequency Quadrupole) linac depends on the applied voltage at the RFQ electrode and the strength of the space charge effect. A multi-beam RFQ linac, with multiple beam-channels accelerating several beams in parallel in one cavity, and utilizing multiple beams to decrease the space charge effect can be used to achieve a higher beam current. In order to demonstrate that a four-beam IH-RFQ (Interdigital H-type RFQ) linear accelerator is suitable for high-intensity, heavy ion beam acceleration, we have developed a four-beam prototype.
A four-beam IH-RFQ cavity was fabricated according to design parameters obtained from our previous detailed simulations. Low-power RF property measurements of the fabricated four-beam IH-RFQ cavity were carried out with a network analyzer. After the low-power RF property measurements, we performed a high-power test and an acceleration test.