Simulations & Experiments of Constant Impedance Tunable Power Extraction Circuit for Mobile Ionospheric Heating

The power extraction circuit in an lOT (Inductive Output Tube) is a resonant circuit made of actual inductors and capacitors at low frequencies (3–10 MHz) due to the size limitation of a cavity. To build a mobile, low frequency range, high power sources for ionospheric heating with high efficiency and tunability, we need a constant impedance to decelerate the beam at all frequencies [1]. This paper discusses the design and construction of pi-circuit for two different gun designs: 70kV - 30A & 20 kV - 1A guns [2]. While the tunability is achieved by variable capacitors, the high efficiency is limited by the internal resistance of the inductor in the pi-circuit.