R.L. Poirier, R. Baartman, P. Bricault, K. Fong, S. Koscielniak, R. Laxdal, A.K. Mitra, L. Root, G. Stanford, D. Pearce (The Isak Group at TRIUMF)
The ISAC 35 MHz RFQ is designed to accelerate ions of A/q =< 30 from 2keV/u to 150keV/u in cw mode. The RFQ structure is 8 meter long and the vane-shaped rods are supported by 19 rings spaced 40 cm apart. An unusual feature of the design is the constant synchronous phase of -25 deg. The buncher and shaper sections are eliminated in favor of an external multi-harmonic buncher. All 19 rings are installed with quadrature positioning of the four rod electrodes aligned to +/- 0.08 microns. Relative field variation and quadruple asymmetry along the 8 meters of the RFQ was measured to be within +/- 1%. Early operation at peak inter-electrode voltage (75kV) was restricted by the rapid growth of dark currents due to field emission: the nominal operating power of 75 kW increased to 100 kW in a few hours. A program of high power pulsing, followed by cw operation have all but eliminated the problem leading to a successful 150 hour test at full power. Successful beam test results show a strong confirmation of the beam dynamics and rf design as well as the rf engineering. The results of rf and beam tests will be reported.
Comments or Questions to