Abstract
Micropore optics have recently been implemented in a lobster eye geometry as a compact X-ray telescope. Fields generated by rare-earth magnets are used to reduce the flux of energetic electrons incident upon the focal plane detector in such a setup. We present the design and implementation of the electron diverters for X-ray telescopes of two upcoming missions: the microchannel X-ray telescope onboard the space-based multiband astronomical variable objects monitor and the soft X-ray instrument onboard the solar wind magnetosphere ionosphere link explorer. Electron diverters must be configured to conform to stringent limits on their total magnetic dipole moment and be compensated for any net moment arising from manufacturing errors. The two missions have differing designs, which are presented and evaluated in terms of the fractions of electrons reaching the detector, as determined by relativistic calculations of electron trajectories. The differential flux of electrons to the detector is calculated, and the integrated electron background is determined for both designs.
Highlights
X-ray telescopes use grazing incidence optics to focus photons onto a detector
We present the design and implementation of the electron diverters for X-ray telescopes of two upcoming missions: the microchannel X-ray telescope onboard the space-based multiband astronomical variable objects monitor and the soft X-ray instrument onboard the solar wind magnetosphere ionosphere link explorer
There is an asymmetry in the results: the orientation of the magnetic field deflects a small number of electrons emerging from the upper right and lower left Micropore Optics (MPOs) inward, to the detector; at the lower right and upper left MPOs, the field direction is reversed so that electrons can reach the detector by completing a circular orbit at lower energies, or through the magnetic null at high energies
Summary
Micropore Optics (MPOs) reflect X-rays from the walls of regular arrays of microscopic square channels Such a geometry requires a direct line of sight from the focal plane to the immediate space environment of the telescope, allowing charged particles (either trapped in the magnetic field of the Earth or comprising solar wind, etc.) to reach the detector directly. The MXT is a lobster eye optic made up by MPOs arranged in a 5 × 5 grid for a focal length f = 1.125 m and 64′ × 64′ Field Of View (FOV), limited by the CCD detector. Two electron flux densities are indicated: the peak of the observation period occurring during a coronal mass emission and the ambient time average excluding elevated transients
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