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arXiv · 1701.00300

Beam-induced Back-streaming Electron Suppression Analysis for Accelerator Type Neutron Generators

Cory Waltz·Mauricio Ayllon·Tim Becker·Lee Bernstein·Ka-Ngo Leung·Leo Kirsch·Paul Renne·Karl Van Bibber
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Abstract

A facility based on a next-generation, high-flux D-D neutron generator has been commissioned and it is now operational at the University of California, Berkeley. The current generator design produces near monoenergetic 2.45 MeV neutrons at outputs of 10^8 n/s. Calculations provided show that future conditioning at higher currents and voltages will allow for a production rate over 10^10 n/s. A significant problem encountered was beam-induced electron backstreaming, that needed to be resolved to achieve meaningful beam currents. Two methods of suppressing secondary electrons resulting from the deuterium beam striking the target were tested: the application of static electric and magnetic fields. Computational simulations of both techniques were done using a finite element analysis in COMSOL Multiphysics. Experimental tests verified these simulation results. The most reliable suppression was achieved via the implementation of an electrostatic shroud with a voltage offset of -800 V relative to the target.

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Cory Waltz, Mauricio Ayllon, Tim Becker, Lee Bernstein, Ka-Ngo Leung, Leo Kirsch, Paul Renne, Karl Van Bibber. 2017-01-02. Beam-induced Back-streaming Electron Suppression Analysis for Accelerator Type Neutron Generators. https://arxiv.org/abs/1701.00300

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