Electric propulsion (EP) thrusters range from low thrust attitude control thrusters, to moderate thrust engines for station keeping, to high thrust engines for orbit raising and interplanetary flight. All systems which emit charged particles to create thrust are covered by these requirements, including:
• field-emission electric propulsion (FEEP) thrusters;
• gridded ion engines (e.g. radio-frequency and Kaufmann);
• electrodynamic thrusters (e.g. Hall effect);
• magneto-plasma dynamic thrusters.
Neutralising electron or neutral plasma emitters form an integral component of many of these systems and are considered in the same design and testing process. In addition, neutralizers can be used to control spacecraft potentials arising from natural causes. Hence, these requirements cover neutralizers, including:
• plasma contactors;
• FEEP neutralizers;
• electron beam emitters;
• heated filament emitters.
For EP systems that emit uncharged particles, e.g. electro-thermal systems, most of the requirements of this document are not relevant. However, they do emit contaminants and neutral plasmas that can affect electrostatic interactions outside the spacecraft and so are covered by this standard in these respects.