Quantitative Microplasma Electron Number Density Measurement by Coherent Microwave Rayleigh Scattering

In this paper, a method for quantitative measurement of electron number density in a microplasma by coherent microwave Rayleigh scattering is described. Coherent microwave Rayleigh scattering reaches its maximum when the microwave frequency is at its resonance frequency. The resonance frequency depends on the electron number density in the microplasma and the electron-neutral and Coulomb collisional frequencies. When a subnanosecond microwave pulse illuminates the microplasma, the average electron number density can be measured from the frequency analysis of microwave scattering. The technique will be able to quantitatively measure subnanosecond-resolved electron number density evolution in the microplasma.