Advances in Impedance Probe Applications and Design in the NRL Space Physics Simulation Chamber

Impedance probe measurements are made at ionospheric (F-region) plasma conditions ( $n_{e}\approx 10^{4}$ – $10^{6}$ cm $^{-3}$ and $\lambda _{D}\approx 1$ –10 cm) created in the Space Physics Simulation Chamber at the Naval Research Laboratory. Measurements of probe-plasma impedance are used to provide comparative data and identify possible problems, with the goal of developing flight-capable diagnostics for sounding rocket experiments. The ability of the diagnostic technique to infer electron density and plasma potential in an ionospheric plasma is demonstrated with laboratory measurements. In addition, preliminary data from prototype instruments built in our laboratory are presented.