Microwave beatwave excitation of electron plasma wave and high energy electron production

Two X-band microwave beams with a slightly different frequency and the maximum output power of 50 kW are injected into a target plasma antiparallel to each other through a standard horn, The resonant excitation of an electron plasma wave is observed when the difference in frequency between counterstreaming microwaves is equal to the electron plasma frequency. The excited wave propagates in the same direction as the higher-frequency microwave with a wave length which satisfies the resonance condition of wave number. The wave amplitude grows with an increase in incident microwave power, and reaches the density perturbation delta n/n(0) of approximately 3.2 % at the incident microwave power of 40 kW and beat frequency of 600 MHz. A small amount of high-energy electrons with the speed of 27 eV are observed in the high-power region of incident microwave.