Global spectroscopy and imaging of atmospheric x-ray bremsstrahlung: instrumentation and initial results from the PEM/AXIS instrument aboard the u

摘要

Abstract: The Atmospheric X-ray Imaging Spectrometer (PEM/AXIS) aboard NASA's Upper Atmosphere Research Satellite (UARS) provides continuous horizon to horizon images, both day and night, of the 3 to 100 keV x ray flux emitted from the top of the atmosphere. AXIS achieves a spatial resolution to better than 100 km using a 1 dimensional array of 16 passively cooled silicon detectors. The primary purpose of this instrument is to provide a global monitor of electron energy input to the upper atmosphere. The intensity and energy distribution of electrons precipitating into the atmosphere can be inferred from the x-ray bremsstrahlung spectra. The resulting images and spectra are also a rich source of information on the structure and dynamics of the magnetosphere. AXIS is part of the Particle Environment Monitor (PEM) investigation on UARS, launched 12 September 1991 into a 585 km by 57$DGR inclination orbit. We describe the design, development, and calibration of AXIS and provide an assessment of its excellent on-orbit performance. The unique capabilities of x-ray imaging spectrometers are demonstrated through an analysis of specific examples from October and November 1991. Important new developments for follow-on instruments also are described. !10