A simple source for the production of continuous cold plasmas and intense line spectra associated with a particular gas is described in its application to helium. Plasma densities and temperatures have been measured spectroscopically. When using helium or neon gas the device becomes an intense source of ionizing radiation for studies of the chemical reactions induced by the ionizing ultraviolet. The intensity of this radiation has been measured with reasonable accuracy by very simple photocells which are easily constructed in the laboratory and are only sensitive to vacuum-ultraviolet radiator; more than ${10}^{16}$ 584-Å photons per second are emitted by a 30-W source. The mechanism is via ion-electron recombination from a 1660°K plasma of ∼${10}^{13}$ ions/${}_{}{}^3{}_{}{}^{}\mathrm{cm}$ density.

• Received 23 March 1964

DOI:https://doi.org/10.1103/PhysRev.135.A1247