Measurement of self and mutul impedances of two coupled cylindrical antennas in a hot plasma

The self and mutual impedances of two coupled cylindrical antennas embedded in a hot plasma have been measured. A large volume of hot plasma was provided by a mercury-arc discharge. Pairs of monopoles with various lengths were embedded in the plasma volume and excited by r.f. signals. The experimental results show that, near the plasma frequency, the self and mutual impedances undergo rapid changes as the plasma density is varied. The effect of an electroacoustic wave on the self impedance is not very outstanding. However, this wave has a significant effect on the mutual impedance, as can be evidenced by the appearance of electroacoustic resonances (Tonks-Dattner resonances) in the mutual-impedance curves.