Multi-Needle Langmuir probe

Numerous Langmuir probes have flown in space, used to measure plasma properties, and their design has scarcely changed since they were first invented back in 1924: a series of voltages is applied to the probe, and the collected currents are used to identify properties of the plasma, such as electron and ion density, and temperature. This multi-needle Langmuir Probe (m-NLP) from Eidsvoll Electronics and the University of Oslo instead extends a quartet of miniature cylinders, each set to a different, but fixed, voltage, producing a much narrower spatial resolution – down to less than two metres.