A novel beam focus control at the entrance to the ANU 14UD accelerator
Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia
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Published online: 19 December 2013
Tandem electrostatic accelerators often require the flexibility to operate at variety of terminal voltages to cater for various user needs. However beam transmission will only be optimal for a limited range of terminal voltages. This paper describes a focussing system that greatly expands the range of terminal voltages for optimal transmission. This is achieved by controlling the gradient of the entrance of the low-energy tube providing an additional controllable focusing element. Up to 150 kV is applied to the fifth electrode of the first unit of the accelerator tube giving control of the tube entrance lens strength. Beam tests to confirm the efficacy of the lens have been performed. These tests demonstrate that the entrance lens control eliminates the need to short out sections of the tube for low terminal voltage operation.
© Owned by the authors, published by EDP Sciences, 2013
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