Absorptions in the afterglows of high-frequency rare-gas discharges and their interpretation in terms of the paired-electron gas plasma

Abstract

A study of absorptions in the afterglows of four rare gases following long-pulse high-frequency electrodeless discharge energization is reported in the pressure range 0.05 to 1.5 Torr. It is found that the phenomena can be interpreted using the revised model for the pair gas previously applied to magnetized plasmas. The absorptions occur when the measuring cavity resonant frequency is the same as the oscillatory frequency of a population of aggregated pairs. Excited states are formed as a result of the absorptions. Electron densities calculated on this premise are found to be close in magnitude to mean densities derived from the cavity method. The pair aggregation numbers,n–, vary from 1 to 5 at low power to from 2 to 7 at high power. The method of energization of the pulsed discharges is changed into a low-current arc discharge and found to produce a free-electron gas in the afterglow which does not exhibit absorptions. The same result is obtained in xenon gas by increasing the power input into the electrodeless discharge to maximum values (~2kW peak). The resultant increase in electron density in xenon causes the destruction of the paired gas which is replaced by a free-electron gas. The absorptions disappear, showing that they are caused by the paired gas. The destruction of the pair gas in xenon by increase of electron density enables a trial to be made of a possible binding mechanism for the pairs, the spin magnetic potential, Vs. A simple calculation for Vs is made and from this the maximum pair gas density, nM, in each of the four rare gases is calculated. This leads to a determination for the radius of the xenon atom from results at two pressures as 2.9 and 3.0.10-10m.