Analysis of the results of a laboratory experiment on the observation of a runaway electron avalanche in air under high overvoltages

Analytic estimates and numerical computations are carried out to test the concept of a laboratory experiment on the demonstration of a runaway electron (RE) avalanche and RE-induced air breakdown under high overvoltages. It is shown that the development of an RE avalanche is impossible under the conditions of the given laboratory experiment. The experimentally observed distinct tail of the picosecond RE pulse, which was interpreted as the RE avalanche induced by the primary RE peak, is very weakly pronounced in the numerical experiment. Only the initial stage of the RE avalanche could be observed in the laboratory experiment; however, according to the numerical results, the fraction of REs in it is too small (as compared to the number of electrons in the primary peak) for the secondary REs to appreciably affect the breakdown process.