Mutual impedance experiments are a type of active, in-situ plasma diagnostic. They have shown their effectiveness by providing measurements of the electron density and temperature onboard Earth ionospheric missions, and later onboard the Rosetta cometary mission. Such instruments measure the mutual electrical impedance between two electric antennas embedded in the plasma to be diagnosed. The mutual impedance is itself a function of the plasma parameters, such as the plasma density and electron temperature. Current state-of-the-art numerical models of the measured mutual impedance provide access to these plasma parameters, under the assumption of an unmagnetized plasma. However, the magnetic field is expected to significantly impact mutual impedance measurements performed in magnetized plasma such as, e.g., in the magnetosphere of Mercury and Ganymede, respectively targeted by the BepiColombo and JUICE missions.

The goal of this work is to extend mutual impedance instrumental models in order to take into consideration the effects of the magnetic field present in such magnetized planetary plasmas, to support those exploratory space missions. This is achieved by combining two complementary approaches: instrumental modeling and laboratory experiments. 

First, we have developed and validated a new numerical model, based on the calculation of the electric potential emitted by a spherical, point-like electric antenna in a magnetized, homogeneous, Maxwellian plasma. This new instrumental model is used to compute synthetic mutual impedance spectra and assess the impact of the electron magnetization on the instrumental response. We discussed plasma density and temperature diagnostics from the analysis of these synthetic mutual impedance spectra. 

Second, the plasma density diagnostic is used to analyze experimental results obtained in the controlled environment of the LPC2E plasma chamber PEPSO, which experimental setup has been upgraded for this study.