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CW Performance of the Triumf 8 Meter Long RFQ for Exotic Ions

R. L. Poirier·R. Baartman·P. Bricault·K. Fong·S. Koscielniak·R. Laxdal·A. K. Mitra·L. Root·G. Stanford·D. Pearce
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Abstract

The ISAC 35 MHz RFQ is designed to accelerate ions of A/q up to 30 from 2keV/u to 150keV/u in cw mode. The RFQ structure is 8 meters 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; 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 mm. 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 confirm beam dynamics and rf designs.

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R. L. Poirier, R. Baartman, P. Bricault, K. Fong, S. Koscielniak, R. Laxdal, A. K. Mitra, L. Root, G. Stanford, D. Pearce. 2000-08-22. CW Performance of the Triumf 8 Meter Long RFQ for Exotic Ions. https://arxiv.org/abs/physics/0008210

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