The radiation environment for the LISA and MiniSTEP missions and test mass charge control Original Research Article

A limiting disturbance that affects high-precision weak-force experiments in space using proof-masses, such as MiniSTEP (MINImal Satellite Test of the Equivalence Principle) and LISA (Laser Interferometer Space Antenna), is due to charging of the proof-masses. Charging by an ambient flux of high-energy protons is inevitable in any orbit. Estimates of charging rates have been computed using Monte Carlo particle-transport codes with semi-empirical particle flux models for the MiniSTEP and LISA geometries. Disturbance mechanisms involving the proof-mass charge are reviewed and the critical design parameters are identified. A technique for charge control based on photoelectric emission is briefly described.