Experimental results of plasma antennas

Summary form only given. Considerable progress has been made on plasma antennas of which the major advances are: operation at higher plasma densities in the steady state, considerable reduction of power consumption and reduction of noise from the electrical current, which generates the plasma. We have performed experiments concerning transmission and reception, stealth, reconfigurability, shielding, protection from electronic warfare, mechanical robustness, mechanical reconfigurability, plasma waveguides and noise reduction of plasma antennas. In the past, our plasma tubes were ionized by steady state DC current. If the tubes are ionized by extremely short bursts of DC current, we find that the plasma is produced in an extremely short time of about 2 microseconds. However, the plasma persists for a much longer time of about 1/100 second. This is the reason why fluorescent lamps can operate on 60 or 50 Hz electric power. In the new mode of operation, we observe that the plasma density produced by the pulsed power technique is considerably higher than the plasma density produced by the same power supplied in the steady state, which produces two beneficial results: we can operate at much higher plasma densities and at several giga Hertz. In addition, we can operate during the long, non-current carrying phase, which should not have noise generated by current-driven instabilities. We have also operated our plasma antennas at several megawatts using a spark-gap-driven separate RF power supply. We find that even at very high power levels, the plasma antenna operates as efficiently as a metal antenna. We also find that with the proper operating mode, the plasma antenna will not ignite even in the presence of a megawatt RF field. In conclusion, our recent inclusion of a pulsed power supply for our plasma tubes provides reduced noise, higher steady state DC plasma density and reduced power consumption. There are possibly minor problems because of a slight plasma density fluc- uation during the pulsing cycle, which will be addressed in the future work