LOW-ENERGY NEUTRAL-ATOM IMAGING TECHNIQUES FOR REMOTE OBSERVATIONS OFTHE MAGNETOSPHERE

Recent developments in the detection of neutral atoms mill enable cons truction of space-based imagers that may reveal the global structure a nd dynamics of the terrestrial magnetosphere. The principal technical challenge of imaging low-energy neutral atoms having energies <30 keV is separating them from the intense uv background, to which their dete ctors are sensitive, with minimal loss of trajectory and energy inform ation. Three instrument concepts for separating low-energy neutral ato ms from the background uv are discussed: neutral-atom ionization via t ransmission through an ultrathin carbon foil and subsequent electrosta tic deflection, uv grating polarizers and attenuators, and high-freque ncy shutters. Hardware associated with each of these concepts is mated to a detector section that provides trajectory, coincidence, and, if required, time-of-flight measurements.