Spectroscopic measurement of electron temperature in helium arc plasma

The intensities of the neutral helium spectral lines emitted from helium plasma produced by the energetic arc have been measured, and the population densities of the energy levels of neutral helium have been calculated from them. Electron temperature could be deduced from them, since the distribution of the measured population densities above the fifth principal quantum number was Maxwellian. Discharge conditions of helium arc were as follows; helium pressure at 10^-2 torr, currents of 100, 150, and 240 amp., and magnetic field strength of 3540 gauss. In these cases the electron temperatures of 0.19, 0.34, and 0,34 ev respectively were obtained. It was considered from the radial intensity distribution of neutral helium lines that the measured electron temperatures were the values around the arc column. (author)