Neutron production using a pyroelectric driven target coupled with a gated field ionization source

Abstract

Abstract.A palm sized, portable neutron source would be useful for widespread implementation of detection systems for shielded, special nuclear material. We present progress towards the development of the components for an ultracompact neutron generator using a pulsed, meso-scale field ionization source, a deuterated (or tritiated) titanium target driven by a negative high voltage lithium tantalate crystal. Neutron production from integrated tests using an ion source with a single, biased tungsten tip and a 3x1 cm, vacuum insulated crystal with a plastic deuterated target are presented. Component testing of the ion source with a single tip produces up to 3 nA of current. Dielectric insulation of the lithium tantalate crystals appears to reduce flashover, which should improve the robustness. The field emission losses from a 3 cm diameter crystal with a plastic target and 6 cm diameter crystal with a metal target are compared.

Nanofabrication of arrays of silicon field emitters with vertical silicon nanowire current limiters and self-aligned gates

“…Using this structure they reported a reduction in the electrostatic field across the insulator between the gate electrode and the substrate, leading to a dramatic decrease in the charge injection and an improvement of device reliability [16,17]. Furthermore, the increase in the insulator thickness while keeping the gate aperture the same made the structure more amendable to field ionization at relatively low voltage, a physical process that requires more intense electrostatic fields [16][17][18]. In this work, the aspect ratio is increased to >50:1 while the gate aperture is reduced to 350 nm and the oxide thickness increased to 10 μm, dramatically reducing the electrostatic field across the gate insulator thereby reducing time dependent dielectric breakdown (TDDB) and hence increasing lifetime [19,20].…”

Analysis of slope-intercept plots for arrays of electron field emitters

“…1 They are also used in ion sources, for example field ionization sources for neutron generators. [2][3][4][5][6] In all cases, it is important to be able to characterize the field emitter samples, which can be done using electron field emission experiments, see for example Ref. 7.…”

A model study of the role of workfunction variations in cold field emission from microstructures with inclusion of field enhancements

“…Next, the two-dimensional current density, as given in equations (10), was obtained as a function of the local electric field. Emitters with the same 10 μm height but different halfwidths of 0.5 nm, 2 nm and 10 nm were used for the calculations.…”

“…Electron emission from cathodes can provide high current densities (several kA cm −2 ) for a variety of applications such as high power microwave generation [1][2][3], free electron lasers [4], pumping of excimer lasers [5], in the plasma physics arena [6], and for surface modifications and material processing [7,8]. Field emitters also play an important role in vacuum electronics [9], and as sources for neutron generators [10,11]. Field emission is attractive (e.g.…”