Application of Doppler spectroscopy inH2to the prediction of experimentalD(d,n)3Hereaction rates in an inertial electrostatic confinement device

Abstract

In our previous paper, we developed an optical measurement for absolute densities of fast (tens of keV) H ions in an abnormal hollow cathode discharge of hydrogen in the units to tens of mTorr pressure range. We apply this method to a cylindrically symmetric inertial electrostatic confinement (IEC) discharge of hydrogen using the Doppler spectrum of Halpha. We predict neutron production rates for an equivalent discharge of deuterium and compare these with experimental values under the separate conditions of constant deuterium gas pressure (approximately 6 mTorr) and voltage (30 kV). Our predictions capture the variation of production rates with dc current (10-50 mA) and agree with experiment to within an order of magnitude. The applicability of this diagnostic to the cylindrical IEC discharge is thus demonstrated, with our results supporting the theory that the discharge is dominated by energetic neutrals emerging from the cathode apertures.