Experimental Measurements of Power Extraction Circuits For Mobile Ionospheric Heating*

A mobile heater for ionospheric modification studies will require a new megawatt class RF source operating with an antenna array that is 1/20 the area of HAARP [1]. In order to deliver an effective power density comparable to that of HAARP, the total source power must be in the range of 16 MW, thus demanding highly efficient sources [2]. The source design we are currently pursuing utilizes a grid-less electron gun that uses a mod-anode to turn a thin annular beam on and off in class D operation. The beam is passed through a decelerating gap and its kinetic energy is extracted using a tunable resonant circuit that presents a constant impedance over the frequency range of 3–10 MHz, such that the beam is almost decelerated at all frequencies.