Diagnostic Development for E-Beam Excited Air Channels. Microwave Cavity Reflection Interferometer for Single-Pulse Transient Conductivity Measurements

摘要

A technique is described for measuring real and imaginary conductivity histories in a single pulse using the microwave cavity perturbation technique. The method can be used even when the perturbations are large, e.g., when the frequency shift is larger than the FWHM of the cavity resonance and/or when the cavity Q changes significantly. We demonstrate the use of the technique to measure laser photoionization yields in a high pressure buffer gas. It will also be particularly useful to measure afterglow conductivity decays for electron beam channels from single-pulse accelerators. Keywords: Plasma diagnostics; Microwave techniques; Conductivity measurements; Electron beams. (jhd)