First observations of runaway breakdown phenomenon in laboratory experiments

Microwave electron cyclotron resonance discharge in air is studied in a tim e-varying magnetic mirror trap. The obtained experimental data demonstrate a rapid increase in the number of fast electrons with wide energy spectrum (1-300 keV). It is followed by strong flashes of gamma photons and associat ed secondary optic emission. The experimental results are interpreted as th e first observation in a laboratory of the runaway breakdown phenomenon, wh ich plays a significant role in a thunderstorm atmosphere. (C) 1999 Publish ed by Elsevier Science B.V. All rights reserved.