An ion thruster (1) and a method for providing trust is disclosed. The ion thruster comprises a sputtering magnetron (2), a target (3) arranged at the sputtering magnetron, and a second electrode (4). During a first pulse, the target is at a negative potential (U.sub.HiP) with respect to a second electrode and a plasma is sustained whereby atoms are sputtered from the target and at least a portion thereof become ionised by the plasma. During a second pulse, a reversed potential (U.sub.rev) is applied between the target and the second electrode. This increases the potential of a volume of the plasma adjacent to the target, which in turn accelerates ions in a direction away from the target. Thereby, thrust is provided.

The disclosure further relates to a computer program and a computer readable medium, as well as a spacecraft comprising the ion thruster.

A propulsion system for a spacecraft includes at least one chemical propulsion engine, at least one electrical propulsion engine, and a propellant feed system that includes a propellant supply system including at least one tank to store a common propellant. The propellant supply system is configured to deliver a controlled flow of the common propellant to both the chemical propulsion engine and the electrical propulsion engine. Also disclosed is the use of a common propellant in a spacecraft and a method of providing a common propellant to an electrical and a chemical propulsion engine.

A propulsion system for a spacecraft includes at least one electrical propulsion engine comprising at least one neutraliser; and a pressurant gas system comprising a pressurant gas which is fed directly into the at least one neutraliser.

A neutralizer suitable for use in an ion engine comprises a halogen gas source and an electrode tube comprising an inlet opening connected to the halogen gas source for supplying a halogen gas provided by the halogen gas source into the electrode tube, a discharge space for generating a plasma from the halogen gas supplied into the electrode tube, and an outlet opening for discharging the plasma generated in the discharge space and free electrons from the electrode tube. An electron emitter is arranged in the discharge space of the electrode tube, which is at least partially made of tungsten, a tungsten alloy or a tungsten composite material containing at least one of iridium, rhenium, ruthenium, rhodium and osmium.

Methods and apparatuses for emitting electrons from a hollow cathode are provided. The cathode includes a plasma holding region configured to hold a plasma, a gas supply source configured to supply gas to the plasma holding region, and an orifice plate disposed on a periphery of the plasma holding region. The orifice plate comprises a plurality of openings constructed to receive electrons from the plasma. The plurality of openings decouple gas conductance and electrical conductance across the orifice plate. The diameters of the plurality of openings are within a range of 20%-60%, inclusive, of a diameter of a circular opening with an area equal to a sum of the areas of the plurality of openings.

A Hall thruster includes an annular discharge region and an annular cathode concentric to the annular discharge region.

A heaterless hollow cathode provides electron emission current in an electric space propulsion system. A mechanical, thermal, and electromagnetic design of the cathode apparatus is presented, and a method of operation for rapid ignition and stabilization of the cathode is provided. The keeper of the cathode apparatus has a thickness change which reduces the flow of heat away from the cathode's emitter assembly. The method for heating the emitter assembly includes controlling applied voltages so that the current flowing from the emitter assembly to the keeper is maintained at a predetermined fixed value. By this method, damage to the electron emitting surfaces of the emitter assembly by electric arcing and/or by depletion of dopant materials is avoided.

A field emission neutralizer is provided. The field emission neutralizer includes a bottom plate and a field emission cathode unit located on the bottom plate. The field emission cathode unit includes a substrate, a shell located on the substrate, a cathode emitter located inside the shell, a mesh grid insulated from the cathode emitter, and a shielding layer insulated from the mesh grid. The cathode emitter includes a cathode substrate and a graphitized carbon nanotube array. The graphitized carbon nanotube array is in electrical contact with the cathode substrate. The graphitized carbon nanotube array is fixed on a surface of the substrate body, and the carbon nanotubes of the graphitized carbon nanotube array are substantially perpendicular to the cathode substrate.

A field emission electron source and a method of manufacturing the same. A field emission electron source comprises an emitting electrode and an extractor gate electrode. The emitting electrode comprising a plurality of particles with nanosharp protrusions. The extractor gate electrode comprises a metal. The extractor gate electrode is formed in a same plane as the emitting electrode. The extractor gate electrode is formed surrounding the emitting electrode. A method of manufacturing a field emission electron source comprises forming an emitting electrode comprising a plurality of particles with nanosharp protrusions using a direct ink writing (DIW) printer. The method comprises forming an extractor gate electrode comprising a metal using the DIW printer.

A field emission neutralizer is provided. The field emission neutralizer comprises a bottom plate and at least one field emission cathode unit located on the bottom plate. The field emission cathode unit comprises a substrate, a shell located on the substrate, a mesh grid, a shielding layer insulated and spaced from the mesh grid, and at least one cathode emitter located inside the shell, and insulated and spaced from the mesh grid. The cathode emitter comprises two cathode electrode sheets and a graphitized carbon nanotube structure, the graphitized carbon nanotube structure comprises a first portion and a second portion, the first portion is clamped between the two cathode electrode sheets, and the second portion is exposed outside of the two cathode electrode sheets.