Highly Efficient Micro Cathode

Busek Company, Inc. proposes to develop a micro thermionic cathode that requires extremely low power and provides long lifetime. The basis for the cathode is a Barium impregnated dispenser cathode. The innovation will be the heating technique. We are proposing to heat the cathode to emission temperatures through radio frequency induction heating. The current state of the art micro cathodes utilize a resistive heater typically operated by passing a DC or AC current through a small refractory wire, heating the wire through ohmic heating. This requires significant sized wires and mechanics that create a heat sink through the leads, greatly increasing the power required to heat the cathode. Alternative development programs for micro cathodes have proposed utilizing lasers to heat the backside of the cathode. The drawback for this method of heating is the low power efficiency of state of the art lasers.In support of our proposed concept, Busek has recently developed an innovative RF generation circuitry that leads to applications like the proposed. The circuit is highly efficient and load variant tolerant. During Phase I we will design, build and test a model cathode with integrated induction heater coil and RF generator. Phase II will optimize the design and develop a commercial cathode for applications such as sensors, traveling wave tubes or micro ion engines.