THE EFFECT OF VIBRATIONAL-EXCITATION OF MOLECULES ON THE EVOLUTION OFTHE STREAMER CHANNEL

The effect of gas heating caused by the nonresonant character of the V V-exchange on the dynamics of the streamer channel is studied analytic ally with allowance for both the nonsteady character of the distributi on function and the electron excitation of vibrational molecular state s. It is shown that, for dipole-molecule gases, the heating due to the anharmonicity of the VV processes can substantially increase the tran slational temperature, which can, in turn, lead to the onset of ioniza tion instability in the streamer channel and a conversion of the strea mer into a spark. An analytical expression for the fraction of vibrati onal energy converted into the thermal energy is obtained. In the prop osed analytical model, this expression is used to describe both the st reamer dynamics and the condition under which the streamer goes over t o a spark.