Impacts of Hot Space Plasma and Ion Beam Emission on Electrostatic Tractor Performance

A recent proposed technique for geostationary debris mitigation is the electrostatic tractor. The tug vehicle approaches a debris object to within 20 m and emits a focused electron beam onto it. This results in a negative charge on the debris and a positive charge on the tug vehicle. Used in conjunction with low thrust, the electrostatic force is used to tow a debris object into a disposal orbit. In this paper, the impacts of geomagnetic storm activity on the charging of tug and debris are considered. The influence of electrons emitted from the debris (photoelectrons and secondary electrons) on tug charging is also considered. Both of these phenomena yield improved electrostatic tractor performance. The simultaneous emission of an electron and ion beam by the tug is also considered to improve tractor performance and enable charge transfer for scenarios where it fails when only an electron beam is used. The theoretical maximum electrostatic force that is possible with simultaneous emission is computed, and the results indicate that emitting both an electron and ion beam enables smaller tug vehicles to tow larger objects that could not otherwise be towed with only an electron beam.