Features of gas discharge in narrow-gap micropattern gas detectors at a high level of alpha-particle background

Preliminary results of research into electron multiplication in micropattern gas detectors (MPGDs) at a high level of alpha-particle background are presented. This work has expanded the borders of understanding of the streamer mode nature. It is seen as a complex of electrostatic and electromagnetic interactions which begin the appearance of the precursor in plasma state. In an inter-electrode gap, plasma oscillations occur which are accompanied by longitudinal elastic waves of ionization, which can reach the cathode surface with an induced negative charge. With the release of this charge, due to the previously established conducting channel, there is a strong pulse accompanied by emission due to the recombination of positive and negative ions and a thin cord or streamer. With the aim of protecting the MPGDs from spark breakdown at a high-level alpha-particle background, the following gas composition of buffer, cooling, and electronegative components is offered: 70% He + 28% CF₄ + 2% SF₆.