B+ beam tests of the 'modified' cw 4-rod RFQ

The development of the 'modified' 4-rod RFQ linac system has been completed and a series of beam acceleration experiments demonstrated the specified performance of the RFQ linac. The RFQ accelerates light and medium ions to MeV energies for irradiation applications. The linac operates in cw mode at 34 MHz, relatively lower resonant frequency compared with most of the existing proton RFQs. The RFQ cavity withstands up to 50 kW cw rf power. He+, N2+, C+ and B+ ions were successfully accelerated to their goal energies of 84 keV/u: 0.334 MeV, 1.17 MeV, 1.00 MeV and 0.92 MeV, respectively. The maximum beam currents measured at the RFQ output were 32, 13, 220 and 330 pμA for He+, N2+, C+ and B+, respectively with the beam transmission over 80%. (author)