Particle Detectors
PCD
The purpose of the Potential Control Device (PCD) on EQUATOR-S is to reduce the spacecraft potentials to a few volts, levels sufficiently low to allow plasma particle measurements down to very low energies. For this purpose, the PDC emits beams of 6 keV indium ions to compensate the positive charging that would otherwise exist under most circumstances. The emission principle is field evaporation and ionisation of the liquid metal covering a needle by applying a high voltage. Beam currents are variable and can either be set to fixed values, or are adjusted automatically based on the electron energy spectrum measured by the 3DA instrument that is transmitted to PCD in real-time. PCD is identical to the ASPOC instrument developed for CLUSTER. See: http://www.mpe-garching.mpg.de/EQS/eq-s-instruments.html