DeflectorShield: magnetic shielding for laser communications

In order to simultaneously characterize and mitigate spacecraft laser communication (lasercom) system performance degradation by electric propulsion (EP) plumes, we propose to develop a magnetic deflector to protect the reflective telescopes typical of lasercom systems from erosion by charge-exchange (CEX) ions. Since beam intensity losses due to absorption and Rayleigh scattering are negligible for the typical EP plume densities, sputtering is the dominant degradation mechanism for on-orbit lasercom. The DeflectorShield uses permanent magnets to set up a magnetic field perpendicular to the optical axis, deflecting CEX ions into the telescope tube before they strike the primary mirror. We will use the magnetostatic code MagNet 6.0? to design a proof-of-concept magnetic deflector, sized to fit a commercially-available reflective telescope. Phase-I will also be used to develop a build, test and evaluation plan for Phase-II. Experiments in Phase-II will compare the optical performance degradation of two telescopes (one protected, one unprotected) at opposite locations in the wings of a Hall thruster plume, permitting the separation of erosion and re-deposition effects. These experiments will permit iterative validation and improvement of the baseline design.