Plasma impedance and electron density in a pulsed laser channel

Abstract

The representation of plasma impedance of gas laser discharge and spark gap channels by an inductance–capacitance (Lp−Cp) tank circuit has been useful in describing the frequency response of a pulsed superradiant laser charging circuit. The impedance matching of these plasma channels can lead to resonant narrowing of the laser pulsewidth in superradiant nitrogen lasers. Using fluid equations to model the electron and ion plasmas, the impedance of plasma channels is formulated. This derived impedance supports the phenomenological Lp−Cp tank circuit configuration, and provides the means to calculate the inductance and capacitance in terms of the plasma density and discharge dimensions. Conjugating this model with the pulse width narrowing via plasma impedance matching, the electron density at the very moment of lasing in a superradiant gas laser channel can be estimated by using the measured Lp and Cp.