| definition |
- 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
|
