Brief Communications
Feasibility of a low-voltage discharge in pure molecular hydrogen
F. G. Baksht,
V. G. Ivanov Ioffe Institute, St. Petersburg
Abstract:
The feasibility of initiating a low-voltage discharge in pure (free of readily ionizable impurity) molecular hydrogen is studied theoretically. A discharge with cathode fall
$\varphi_1$ = 10 V, interelectrode gap
$L$ = 2 cm, and total hydrogen concentration
$N^{(0)}_{\mathrm{H}_2}\approx$ 2
$\times$ 10
$^{15}$ cm
$^{-3}$ is considered by way of example. The plasma parameters, including concentration
$N_{\mathrm{H}^-}$ of negative hydrogen ions H
$^-$, are calculated. The concentration of H
$^-$ ions is maximal in the near-anode plasma and may reach
$(N_{\mathrm{H}^-})_{\mathrm{max}}\approx$ 0.5
$\times$ 10
$^{12}$ cm
$^3$. Concentration
$N_{\mathrm{H}^-}$ can be increased severalfold by introducing a small amount of cesium into the discharge,
$N^{(0)}_{\mathrm{Cs}}\le$ 10
$^{13}$ cm
$^{-3}$. Cesium ionizes completely and concentrates in narrow near-electrode layers, which are depleted with the plasma in the purely hydrogen discharge. The discharge modifications studied in this work may be of interest as low-voltage volume plasma sources of H
$^-$ ions under conditions when a high concentration of cesium in the source plasma is undesirable.
Received: 26.09.2013
Fulltext:
PDF file (153 kB)
