The low energy electron and ion spectrometers on the AUREOL-3 satellite - The SPECTRO experiment

The SPECTRO instruments on AUREOL-3 have been designed to measure auroral particle energy spectra, angular distributions and mass spectra in the energy range 0.01-21 keV/Q. The measurements are done with several spherical electrostatic analyzers and channel electron multipliers. The ROBE spectrometer, with 9 viewing axes, gives the two dimensional distributions of both electrons and positive ions from 0.1 to 21 keV with 1.6 sec resolution, and with good energy and angular resolution. Two TBE analyzers measure the fluxes of particles aligned with the geomagnetic field down to energies as low as 10 eV. In addition, two ion mass spectrometers are included for the measurement of the ion composition in the range 0.1-14 keV/Q and 0.8-50 a.m.u. in 64, 32, or 4 mass channels. All the instruments of the SPECTRO experiment are controlled by an onboard calculator, which gives a wide choice of operating modes. This paper explains the operation and the method used to calibrate these instruments, and gives some of the inflight results.