Dreierstoßrekombination in abklingenden Niederdruckentladungen

Abstract

For certain conditions the afterglow of low pressure discharges can be dominated by three body recombination. These conditions — electron densities of about 10¹² cm⁻³ and electron temperatures of about 500 °K— are realized 20 μsec after switch off of the discharge for gas pressures (hydrogen) between 2 and 6 mTorr. In this pressure range the energy transfer from the electrons via the ions to the neutrals and subsequently to the wall is high enough to permit a decay of the electron temperature to low values before the electron density has decreased appreciably.

A theoretical model demonstrates that the electron density decaydn _e/dt∼n ³_e f(T _e) is in good approximation equivalent todn _e/dt=const·n ²_e for a certain range of time and of parameters. This proportionality is observed. The measured values of the constant differ from the calculated ones by about 15%.