Self-initiated volume discharge in mixtures of SF6 with hydrocarbons to excite nonchain hf lasers

摘要

The paper studies a self-sustained volume discharge without preionization-self-initiated volume discharge (SIVD) - to excite non-chain HF lasers on SF$-6$/-C$-2$/H$-6$/ mixtures. Once initiated by a local discharge gap breakdown, SIVD is found to propagate then over the whole gap normally to the applied electric field through successively starting diffuse overlapping channels at a voltage close to the quasi- stationary value. With forming new channels, the current through those previously originated decreases. The volume occupied by SIVD tends to expand with increasing the energy released within the discharge plasma, whereas a discharge bounded by a dielectric surface shows a simultaneous increase both in burning voltage and current. All these features combined allow a concept to be put forward of the existence of certain restriction mechanisms depending on the specific energy released and not permitting the total deposited energy to pass through a single channel. It is suggested that SF$-6$/ dissociation by electron impact and the electron attachment to vibrationally excited SF$-6$/ molecules are just those mechanisms. Simple analytical models have been developed allowing these mechanisms to be qualitatively described.