Measurements of Swarm Parameters in Chlorine-Bearing Molecules.

摘要

Precision measurements of swarm parameters have been measured over an extended range of electron mean energy in chlorine-bearing gases relevant to the xenon chloride excimer laser system. These measurements were accomplished using a pulsed drift tube specifically designed to handle corrosive gases. Experimental measurements of electron drift velocity, attachment and ionization coefficients together with positive and negative-ion mobilities have been made in pure HC1 over the range of E/N (ratio of electric field to gas number density) from 3 to 300 x 10 to the -17th V/sq cm. A set of electron collision cross sections has been derived which is consistent with the measured swarm parameters. Combination of this set of cross sections with the known set for nitrogen has resolved an apparent discrepancy in the attachment rate coefficient between the present measurements and other measurements in HC1/N2 mixtures. Measurements of warm parameters in pure CC14 have been made over the range of E/N from 300 to 950 X 10 to the -17th V/sq cm. Measurements of electron drift velocity were possible only over the limited range of E/N from 850 to 950 X 10 to the -17th V/sq cm. The lack of sufficient data in CC14 prevented a meaningful derivation of a cross section set for CC14. Considerable effort was extended to obtain swarm data in pure C12. Attempts to achieve a higher yield photocathode than a semi-transparent gold cathode are documented. A new louvered photocathode was designed. Together with higher intensity UV exciting sources, usable current waveforms were finally recorded in C12. The results of a literature search on swarm parameters and electron impact cross sections are summarized for C12 and BC13. (Author)