On the electron temperatures and densities in plasmas produced by the 'torche a injection axiale'

摘要

The election temperature and the electron density of plasmas created by the "Torche a Injection Axiale" (TIA) are determined using Thomson scattering. In the plasma with helium as the main gas, temperatures of around 25 000 K and densities of between0.64 and 5.1 x 10~(20) m~(-3) are found. In an argon plasma the electron temperature is lower and the electron density is higher: 17000 K and around 10~(21) m~(-3) respectively. From these results it can be established that the ionisation rates of both plasmas are much larger than the recombination rates, which means that the plasmas are far from Saha equilibrium. However, deviations from a Maxwell electron energy distribution function, as reported for the "Microwave Plasma Torch" (MPT), are not found in the TIA. The excitation and ionisation power of the TIA appears to be stronger than that of the MPT.