Tests of features of field-acceleration models for the extraordinary selective H Balmer α broadening in certain hydrogen-mixed plasmas

The results of the 656.3 nm Balmer α line measurements, recorded as a function of position in the cell, direction relative to the electric field, strength of the electric field, and pressure from He/H2 (95/5%) as well as Ar/H2 (95/5%) DC glow-discharge plasmas with needle electrodes support the conclusion that field-acceleration models (FAMs) are not valid to explain selective broadening in hydrogen-mixed plasmas. The reflector capabilities of the cathode that are necessary to explain the symmetrical profile in FAM were removed by using needle-like electrodes. The peak shape remained symmetrical. The role of the gas matrix as a reflector or divertor was tested by varying the gas pressure more than two orders of magnitude. The nondirectional, isotropic peak shape remained the same. The broadening was observed throughout the cell and was independent of angle with respect to the field; thus, it did not depend on the field strength. This was also confirmed by directly varying the applied voltage and observing no effect on the broadening. Nor, do FAM predict that selective, excessive H broadening was only observed for helium and argon mixed plasmas, but not for xenon. In contrast, a chemical reaction with energy release that produces broadening of H that is time dependent, nondirectional, position independent, selective to H, Gaussian Doppler, often two orders of magnitude in excess of the electron temperature, and specific to plasmas with atomic hydrogen and a catalyst (Ar+ and He+ in this study) including those formed chemically explains the data in total.