Description
One of the main defining characteristics of a plasma is the electron density. Conventional electron density diagnostic techniques, such as Langmuir probes or Thomson scattering are generally relatively invasive. As an alternative, Microwave Cavity Resonance Spectroscopy (MCRS) can be used as a minimally invasive diagnostic technique for the electron density. MCRS relies on measuring the eigenfrequency of a cylindrical cavity using microwaves. As the permittivity of the medium inside the cavity changes, the eigenfrequency of the cavity shifts.
This work will give an overview of the working principles of MCRS, and highlights three of its key capabilities across various applications. First, its high temporal resolution is demonstrated through measurements on pulsed plasmas. Second, a method for obtaining qualitative spatial information is shown using nanodusty plasma experiments and FEM simulations. Finally, the high sensitivity of MCRS is illustrated through the characterization of an electron beam.