A propulsion unit (10) for a spacecraft is described. The propulsion unit (10) comprises a centrally arranged cathode (20), a concentric anode (30), an injection point (60) for injecting a propellant (50) between the central cathode (20) and the concentric anode (30), an acceleration coil system (100) and a vectoring coil system (110) for expelling a plasma plume (75) from a nozzle (115). A plurality of superconducting coils (120, 125) is arranged about the concentric anode (30) for creating a magnetic field (B) between the central cathode (20) and the concentric anode (30) and directing the plasma plume (65) from the nozzle (115).

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 magnetic pole structure for a Hall thruster is provided. The magnetic pole structure includes: multiple wide-envelope outer magnetic pole components, a magnetic bridge, a pagoda-shaped inner magnetic pole component, a top plate, and a bottom plate, where the multiple wide-envelope outer magnetic pole components are arranged on an outer edge of the Hall thruster, symmetrical about the pagoda-shaped inner magnetic pole component, and enclose a semi-open structure; the magnetic bridge is located between each of the wide-envelope outer magnetic pole components and the pagoda-shaped inner magnetic pole component; the bottom plate is attached to a bottom part of each of the wide-envelope outer magnetic pole components and a bottom part of the pagoda-shaped inner magnetic pole component; and the top plate is attached to an upper part of each of the wide-envelope outer magnetic pole components.

A Hall thruster is configured to reduce or eliminate pole erosion by electrically tying the cathode to the thruster chassis body. The electrical connection controls the ion energy hence reducing erosion at the pole. In a different configuration, the cathode is biased by a power supply, allowing further control of the ion energy and the elimination of pole erosion, thus increasing the thruster's operational lifetime.

A plasma accelerating apparatus includes: a cathode (11) configured to supply electrons to a plasma acceleration region; an anode (12); a power supply (13) configured to apply a voltage between the cathode and the anode; a supply port (14) arranged on an outer circumference side of the cathode to supply a propellant to the plasma acceleration region; and a first magnetic field generator (15) configured to generate a first axial direction magnetic field in the upstream side region of the plasma acceleration region to suppress electrons supplied from the cathode from heading for the anode. Thus, the plasma accelerating apparatus and the plasma accelerating method having high thrust efficiency is provided.

A satellite propulsion system and methods of operating the same include a first ionization stage and a second acceleration stage. The first ionization stage has a plasma source configured to produce an arc discharge and emit a preliminary plasma. The plasma source includes an external magnetic field configured to magnetize the arc discharge. The second acceleration stage has an accelerator positioned in series with the plasma source. The accelerator is configured to accelerate the preliminary plasma out through the accelerator, thereby creating an accelerated plasma flow. The application of an activation threshold voltage to the accelerator results in a surge in system performance parameters.

Disclosed is a miniaturized plasma propulsion device with minimized surface area of the thruster walls exposed to the plasma and, as a result, reduced plasma-surface interactions including a set of segmented electrodes to facilitate the following improvements compared to relevant existing technologies: 1) control of the plasma flow including focusing of the plasma plume 2) increase of the thrust 2) reduction of inefficiencies associated with the electron cross field current, and 3) mitigation of low frequency oscillations. The electrodes affect all these actions when a DC or modulated voltage is applied to one or all of them with the same or different amplitudes, with the same or different frequencies or phases which are all optimized to realize the best performance through changes in the acceleration and/or ionization regions. In addition, the applied voltage to the main electrodes may also be modulated.

A cusped-field thruster for a space system, wherein the cusped-field thruster comprises: at least two substantially annular permanent magnets arranged in an antipolar manner, wherein a magnetic pole piece is formed between the permanent magnets, and an anode, which comprises a permanent-magnetic material. The cusped-field thruster is configured such that a cusp is formed in a region adjacent to the anode of the cusped-field thruster.

A plasma accelerating apparatus includes: a cathode (11) configured to supply electrons to a plasma acceleration region; a anode (12); a power supply (13) configured to apply a voltage between the cathode and the anode; a supply port (14) arranged on an outer circumference side than the cathode to supply a propellant to the plasma acceleration region; and a first magnetic field generator (15) configured to generate a first axial direction magnetic field in the upstream side region of the plasma acceleration region to suppress that the electrons supplied from the cathode head for the anode. Thus, the plasma accelerating apparatus and the plasma accelerating method having high thrust efficiency can be provided.

A Hall effect thruster arranged inside a wall and including a magnetic circuit and an electric circuit including an anode, a first cathode, and a voltage source. The magnetic circuit and the electric circuit are arranged in such a manner as to generate magnetic and electric fields around the wall. In every meridian section, the magnetic circuit presents an upstream magnetic pole and a downstream magnetic pole arranged at the surface of the wall and spaced apart from each other; and the anode and the first cathode are situated on either side of the upstream magnetic pole.