Floating Potential Peturbations due to Micro-Meteoroids Impacts : Theory and Application to STEREO/WAVES data

Abstract:

In-situ observation of dust grains from various origins is continuously performed by space missions equipped with radio instruments. These measurements consist in observations of voltage pulses, or their spectral signature. It has for long been proposed that one of the mechanisms able to produce these pulses is the recollection by the spacecraft of electric charges generated by impact ionization.

Here for the first time, on the basis of this charge recollection assumption, a complete theoretical model of how pulses are generated is proposed. This model makes it possible to reproduce the precise shape of a voltage pulse, including the sometimes observed "voltage undershoot" following the pulse, knowing the local plasma parameters.

We use the data provided by S/WAVES and show that it strongly supports the model proposed. Even though other processes may be responsible for radio pulses generation, we show here that recollection process is unambiguously observed.

The model proposed is an important step forward, in that it enables us to reproduce the shape, timescales and amplitudes of pulses generated by dust impacts in various space environments. Such a model can be used to infer the dust-detection abilities of different radio instruments onboard different spacecraft, including future missions Solar Orbiter and Solar Probe Plus.