Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygen — iodine lasers

Abstract

A volume self-sustained discharge (VSD) in iodides (C3H7I, C4H9I) and in their mixtures with SF6, N2, and O2 in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field. Additions of SF6 or N2 to the iodides improves the stability and homogeneity of the SIVD, while adding up to 300 % (relative to the partial iodide pressure) of O2 to these mixtures has only an insignificant effect on the discharge stability. The possibility of SIVD initiation was modelled experimentally in a 1.5-L discharge volume. For the C4H9I:O2:SF6=0.083:0.25:0.67 mixture at a pressure of 72 Torr, the specific energy input into the discharge plasma ranged up to 130 J L-1 in this geometry. A conclusion was drawn that the SIVD is promising for the production of atomic iodine in the pulsed and repetitively pulsed operating regimes of a chemical oxygen — iodine laser.