(as described by the QB50 mission)
The multi-Needle Langmuir Probe instrument works by measuring the current collected individually from four needle probes, placed in front of the satellite’s shock front. The collected current is converted to voltage, filtered, digitalized and then sent to the central telemetry (TM) system.
By using data from four fixed-bias Langmuir needle probes, sampled at the same time, the plasma electron density can be derived with high time resolution without the need to know the electron temperature and the spacecraft potential. With the selected needle probe design and the estimated electron densities, the instrument is to be capable of measuring currents ranging from 1 nA to 2 μA.
The m-NLP system consists of one data acquisition PCB, one PCB which acts as the mounting plate for the miniaturized Langmuir Probes, one aluminium top plate and an integrated electron emitter on top.