Temperature Parameters from Negative Bands of Nitrogen under Excitation by Electron Impact

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Abstract
In a field-free space, temperature determations along the axis of the discharge tube have been carried out from measurements on the intensity distribution of the negative bands of nitrogen under different excitation conditions. The indicated temperatures were compared with the true gas temperatures directly measured by a thermoelement and found to be the same. From a heat conduction consideration, a theoretical formula has been derived in terms of Bessel functions, which gives calculated values in good agreement with the experimental results. The variation of temperature with gas pressure was determined and it was found that the change of the thermal conductivity of the gas within the experimental range could account for the results. The temperature variation with current under different positions of the tube was ascribed to the effect of convection currents. The indicated temperature was experimentally proved to be independent of the accelerating potentials from 20 volts to 800 volts. The non-transference of energy between electrons and molecular rotation was attributed to the large difference of the masses of the electrons and nitrogen molecules.