An experimental investigation of an avalanche of relativistic runaway electrons under normal conditions

The development of avalanches of relativistic runaway electrons is investigated in an experiment similar to the classical Townsend experiment, but in the relativistic energy region. A large-scale laboratory setup is developed with an operating voltage of up to 1.2 MV, which is a chamber with flat electrodes separated by a segmented insulator. A sensitive collector method of analyzing the spectra of high-energy electrons is developed, which is used in electron detectors with a large collecting surface. The multiplication of relativistic electrons in the air is investigated at voltages of up to 1.0 MV. The initial stage of a relativistic electron avalanche is realized for the first time. The results of measurements agree with the results of Monte Carlo simulation.