Design of a space plasma detection circuit based on a floating power supply

Plasma detection payloads installed on satellites enable high-precision in situ measurement of ionospheric plasma parameters. This kind of equipment has been deployed on multiple scientific observation satellites. They interact with electrons and ions in the plasma by applying voltage to their sensors, thereby enabling the measurement of plasma parameters. However, satellites operating in space plasma environments may experience significant reference-ground potential shifts due to satellite surface charging effects. This creates a large potential barrier between the plasma and the satellite, potentially rendering probe-based plasma detection methods ineffective. This issue is particularly severe for microsatellites. To address this issue, a floating power supply is proposed. It can synchronously adjust the supply voltage of a precision operational amplifier operating at low voltage based on the voltage applied to a sensor. The designed space plasma detection circuit based on the floating power supply integrates a current-voltage conversion circuit, a differential proportional operation circuit, and the floating power supply circuit. When using this detection circuit, a wider voltage range can be applied to a sensor to precisely measure currents ranging from nanoampere to microampere levels. This detection circuit effectively reduces the measurement error caused by reference-ground potential offset. Space plasma simulation experiments show that, under different offset conditions used to emulate satellite charging, the designed circuit can preserve complete I-V characteristic curves by supporting wide-range scanning. This lays the foundation for detecting high-precision plasma parameters and meets the stability requirements for complex space environment detection.