An axisymmetric electric discharge as a means for remote heating of gas and for ignition of combustible gas mixture

Experimental and theoretical investigations are performed of gasdynamic phenomena accompanying a ring electric discharge excited in air at atmospheric pressure. It is experimentally demonstrated that the discharge generates a toroidal (three-dimensional) shock wave which cumulatively converges toward the axis. A mathematical model is constructed, which describes the process of focusing of the toroidal shock wave. The results of measurements of shock-wave processes accompanying the discharge are in good agreement with the calculation results; this enables one to estimate the gas temperature which may be attained in the region of cumulative convergence at some distance from the ring center. Results are given of first experiments in the excitation of a ring shock wave in a combustible gas mixture (stoichiometric mixture of CH$_4$:O$_2$).