Methods for measuring electron concentration in shock waves

The current state of research on measuring the electron concentration in low-temperature plasma in the vicinity of a strong shock wave, which simulates the conditions of the descend spacecraft entry into the Earth’s atmosphere is considered. Various physicochemical processes leading to the formation of low-temperature plasma both ahead of the shock wave front and in the shock-heated gas are analyzed. A critical review of various plasma diagnostic methods is made, their advantages and disadvantages are noted. An analysis of numerous experimental data on measuring the electron concentration in various shock-heated gases under various conditions was carried out.