HARMONIC GENERATION USING THE VARACTOR CAPABILITIES OF THE PLASMA SHEATH.
Final technical rept.,
PURDUE UNIV LAFAYETTE IND SCHOOL OF ELECTRICAL ENGINEERING
Pagination or Media Count:
A study was made of large signal, high frequency phenomena occurring in a slightly ionized plasma contained within a set of concentric, metallic coaxial cylinders. An rf equivalent circuit is developed wherein the sheath is represented by a voltage dependent capacitor in parallel with a voltage dependent resistor, the pre-sheath by a collisionless loss element, and the plasma region by a series resistor and inductor. It is found that when the sheath is thin compared to the radius of the inner cylinder, the voltage dependence of the sheath capacitor reduces to form identical with that of an abrupt junction varactor diode, so that the plasma capacitor is properly called a plasma varactor. As an application of the plasma varactor, frequency doubling using standard semiconductor varactor techniques is attempted. The resultant peak conversion efficiency is found to be 31.6 at a drive frequency of 142mc and input power of .42w. It is shown that the sheath conductance is responsible for this low conversion efficiency relative to that obtainable from a semiconductor varactor, and it is suggested that the use of a lower temperature discharge plasma, such as cesium, should result in a substantial improvement. Author
- Electrical and Electronic Equipment
- Plasma Physics and Magnetohydrodynamics