Microwave Method of Tubular Plasma Density Measurement for Relativistic Microwave Oscillator

The method for determining the absolute plasma density in sources that create plasma in the strong magnetic field using the electron beam has been developed and tested. The results of plasma density measurements in the source of tubular plasma used in research on plasma relativistic microwave electronics are presented. It was shown that at time of switching-on plasma maser, for discharge currents of 5, 9, and 20 A, the plasma densities were (3 ± 0.3) × 10¹², (5.5 ± 0.6) × 10¹², and (9.5 ± 1) × 10¹² cm^–3, respectively. Comparison with the probe measurements previously performed, as well as with the numerical calculations made using the KARAT code, showed good agreement between the results of microwave measurements and numerical calculations, while the measurement error did not exceed 15%. The results of probe measurements much stronger deviate from the results of microwave measurements, which is associated with the presence of the strong magnetic field in the plasma source.