Energetic ion mass spectrometer

A new type of spectrometer for space application has been developed and tested in the laboratory which measures separately, mass/charge and the three-dimensional velocity distribution of incident ions. The instrument has relatively high resolution (m/Δm = 600 amu/m) and allows rapid measurement of the four-dimensional set: mass/charge, speed, elevation angle, and azimuth angle. The basic components include: (1) a sector magnet which serves as a momentum/charge filter with a very wide angular acceptance, (2) an electrostatic deflector which spreads the momentum-analyzed ion beam according to energy/charge (or mass/charge), (3) microchannel plate detectors with position sensitive readout, and (4) a set of grids with variable applied voltage to accelerate or decelerate the incident ions before they enter the analysis part of the instrument. For application in a comet environment an electrostatic mirror would be used to reflect ions into the instrument while preventing dust from entering the field of view.