Recombining processes in a steady plasma flow penetrating into hydrogen gas

Abstract

A numerical investigation of recombining process in a high-temperature plasma flow in a quasi-steady state (electron temperature about 10 eV, electron density about 1014 cm-3 and flow velocity about 106 cm s-1) was performed under gas contact cooling conditions using the collisional-radiative model, in which gas cooling is mainly due to surrounding gas particles freely coming into the plasma column. The calculation has shown that the electron temperature relaxes in accord with experimental results and also that the occurrence of the recombining region and the inverted populations almost agree with the experimental ones. Atomic processes responsible for gas cooling are discussed.

Spectroscopic study of a supersonic plasma jet generated by an ICP torch with a convergent-divergent nozzle

“…In our approach, we consider the continuum emission being comprised only of the electron-ion contributions (2) and ( 3), and we assume pLSE. We put T ex = T e and use the upper level Saha equation (5) to express population of a chosen atomic level. In this case both the line and continuum emission coefficients depend on the square on n e and the resulting lineto-continuum ratio depends only on the electron temperature.…”

“…If radiative decay is important, it depopulates mainly lower levels [1]. In strongly recombining plasma, when electron temperature is low while electron number density keeps sufficiently high, a population inversion of excited states may occur, which can even lead to the conditions favourable for a lasing action [3][4][5]. On the other hand, if a drop of the pressure, and thus the temperature, is not so big and the flow is supersonic, some of the processes become frozen and the number densities of particles do not follow correspondingly changes in the temperature.…”