Prelude-Sat Electron Emitter (PSEE): A compact, low power electron emitter for planetary instrumentation.

The Prelude-Sat Electron Emitter (PSEE) is a compact, low-power carbon nanotube-based electron source developed to enable active spacecraft potential control and plasma diagnostics onboard nanosatellites. Designed for the Prelude-Sat CubeSat mission, which aims to investigate ionospheric disturbances associated with seismic activity, PSEE provides controlled electron emission to mitigate spacecraft charging effects that hinder electric field and Langmuir probe measurements in low Earth orbit. The emitter features a vertically aligned carbon nanotube cathode with a dual-grid extraction system and analog electronics capable of sub-millisecond response times and logarithmic current sensing over more than three orders of magnitude. Housed in a 40 × 40 × 32 mm3 aluminum casing, PSEE operates with a maximum power consumption of 330 mW. Laboratory validation demonstrates stable electron emission from nanoamperes to over 10 μA and accurate real-time tracking of 60 ms stepped voltage sweeps representative of Langmuir probe operation. These results confirm that PSEE fulfills the requirements for active charge control and high-sensitivity plasma measurements on miniaturized platforms, making it a strong candidate for future CubeSat missions and space instrumentation.