PLASMA ELECTRON DENSITY MEASUREMENT WITH A FEEDBACK OSCILLATOR

A new method is described to measure average plasma number density using a feedback oscillator. This simple technique is applicable for electron densities ne≤1010 cm-3 and has the novel feature that it can be calibrated to read the density directly on a digital frequency counter. Using an argon plasma, density measurements are made and good agreement is found with independent Langmuir probe data. The feeeback oscillator technique essentially measures the dielectric constant and thus has a wide range of application. © 1968 The American Institute of Physics.