GB2609465A

GB2609465A - Thrust vectoring system

Info

Publication number: GB2609465A
Application number: GB2111165.3A
Authority: GB
Inventors: Clayson Thomas; Stokes Mark
Original assignee: Magdrive Ltd
Current assignee: Magdrive Ltd
Priority date: 2021-08-03
Filing date: 2021-08-03
Publication date: 2023-02-08
Also published as: GB202111165D0

Abstract

A thrust vectoring system (140, figure 1), 340 for a plasma thruster, comprising a plurality of aligned coils (160), 360 configured to be proximal to a plasma source. The aligned coils receive an electric current, generating a magnetic nozzle (190) to direct plasma from the plasma source to create thrust. At least one steering coil (175), 375, 385 receives an electric current to generate a steering magnetic field, deflecting the plasma. A controller (150) controls direction and magnitude of current through the at least one steering coil, adjusting direction and magnitude of plasma deflection to control the direction and/or magnitude of the thrust from the plasma source. A method of vectoring thrust from a plasma thruster comprises generating a magnetic nozzle to direct plasma in a first direction, generating a steering magnetic field in a second direction transverse to the first direction, and adjusting the magnitude and direction of the generated steering magnetic field to adjust the magnitude and direction of the deflection of the plasma.

Description

Thrust vectoring system

Field of the invention

The present disclosure relates to a thrust vectoring system for a plasma thruster, such as 5 a pulsed plasma thruster for use as primary or secondary propulsion means for space vehicles and satellites.

Background

Pulsed Plasma Thrusters (PPT) are an example of an electric propulsion means and are one of the most simple, reliable and trusted propulsion systems ever made. These types of thruster use electronic circuitry that stores energy in a capacitor bank and cyclically discharges it producing pulsed high voltage arcs (some thousands of volts) on the surface of a propellant bar, causing its vaporization, dissociation (known as the ablation process) and ionization. The resulting gas is accelerated partly by the Lorentz force and partly thermally resulting in the generation of thrust.

PPTs have been in use since the 1960s, and although they typically have a low efficiency (typically around of less than 10%) they are used due to their incredibly high reliability. This is due to the absence of tanks, piping, and moving parts. They have found particular 20 applicability in smaller satellites, such as a CubeSat (10 x 10 x 10 cm).

However, a challenge with such satellites is that due to the presence of manufacturing defects or manufacturing tolerances, there may be a misalignment between the propulsion means and the centre of mass of the satellite, which can result in a rotation of the satellite.

The attitude of such satellites may therefore need to be adjusted to counter this rotation. Additionally, and/or alternatively, due to the presence of an increasing number of satellites in orbit, the orbit of a satellite may need to be adjusted to avoid collision.

WO 2015/082739 describes an example of a system for vectorizing the thrust of a plasma thruster that uses three rigid circular conducting coils, all having the same radius, thickness and width. Each of the coils is slightly offset from the other by an angle, and altering the current through each coil can adjust the thrust vector created. However, a disadvantage of such a system is that it will only work with plasmas of the right conditions. So if the -2 -density is too high, or a different material used, it may not work.

WO 2019/229286 describes an example of an electrodeless plasma space engine with a U-shaped geometry.

Summary of the invention

Aspects of the invention are as set out in the independent claims and optional features are set out in the dependent claims. Aspects of the invention may be provided in conjunction with each other and features of one aspect may be applied to other aspects.

In a first aspect of the disclosure there is provided a thrust vectoring system for a plasma thruster, comprising a plurality of aligned coils configured to be located proximal to a plasma source, wherein the plurality of aligned coils are arranged to receive an electric current to generate a magnetic nozzle to direct plasma from the plasma source to create thrust, and at least one steering coil configured to receive an electric current to generate a steering magnetic field to deflect the plasma. The thrust vectoring system further comprises a controller configured to control the direction and magnitude of current through the at least one steering coil to adjust the direction and magnitude of the deflection of the plasma to control the direction and/or magnitude of the thrust from the plasma source.

The magnetic nozzle generated by the plurality of aligned coils has a longitudinal axis that may be coaxial with the plurality of aligned coils. The steering magnetic field may have a primary axis that is at an angle to, for example transverse to, for example orthogonal to, the longitudinal axis of the magnetic nozzle generated by the plurality of aligned coils. For example, the primary axis of the steering magnetic field may be at an angle of between 45 and 135 degrees relative to the longitudinal axis of the magnetic nozzle, for example at an angle of between 70 and 110 degrees It will be understood that to generate a steering magnetic field to deflect the plasma, the at least one steering coil may be positioned at an angle relative to the plurality of aligned coils, for example transverse to the plurality of aligned coils, but not necessarily at right angles to the plurality of aligned coils (for example, the at least one steering coil may be at an angle of between 45 and 135 degrees relative to the plurality of aligned coils, for -3 -example at an angle of between 70 and 110 degrees), although in some examples the at least one steering coil may be positioned orthogonally to the plurality of aligned coils.

The plurality of aligned coils and/or the steering coil may be magnetic coils, for example in the sense that they may be configured to produce a magnetic field in the event that a current is applied to them. In some examples the aligned coils may be magnetic coils in the sense that they comprise permanent magnets. The plurality of aligned coils may be configured to confine and guide plasma, for example by generating a magnetic nozzle to confine and guide plasma.

The at least one steering coil may comprise a pair of opposing steering coils positioned transverse to the plurality of aligned coils. The pair of steering coils may be perpendicular to the plurality of aligned coils. The pair of opposing steering coils may be coaxial with each other.

The plurality of aligned coils may be coaxial with each other. For example, the plurality of aligned coils may be coaxial with each other along a first axis in a first plane, and wherein the at least one steering coil has a central axis in the first plane. For example, the plurality of aligned coils may be coaxial with each other along a first axis in a first plane, and wherein the pair of opposing steering coils may be coaxial with each other in the first plane and orthogonal to the plurality of aligned coils.

The plurality of aligned coils may comprise a first coil proximate to the to the plasma source, and a last magnetic coil distal to the plasma source, and wherein the at least one 25 steering coil may be proximate to the last magnetic coil. In some examples the at least one steering coil has a central axis aligned with the last coil.

The at least one steering coil may comprise two pairs of opposing steering coils, wherein each pair may be positioned transverse to the plurality of aligned coils. For example, the 30 two pairs of opposing steering coils may be orthogonal to each other.

The thrust vectoring system may be configured for use with a pulsed plasma thruster. The thrust vectoring system may be configured for use with a hollow cathode thruster. -4 -

In another aspect of the disclosure there is provided a method of vectoring thrust from a plasma source such as a plasma thruster, the method comprising generating a magnetic nozzle to direct plasma in a first direction from a plasma source, wherein the magnetic nozzle has a longitudinal axis and the first direction is a direction parallel to the longitudinal axis; generating a steering magnetic field in a second direction transverse to the first direction of the magnetic nozzle to deflect the plasma; and adjusting the magnitude and direction of the generated steering magnetic field to adjust the magnitude and direction of the deflection of the plasma.

Generating the steering magnetic field in a second direction transverse to the first direction of the magnetic nozzle may comprise generating the steering magnetic field perpendicular to the first direction of the magnetic nozzle.

Generating the steering magnetic field in a second direction perpendicular to the first direction of the magnetic nozzle may further comprise generating the steering magnetic field perpendicular to the first direction and in the same plane as the longitudinal axis of the magnetic nozzle.

Generating a magnetic nozzle in a first direction may comprise applying an electric current to a plurality of aligned coils.

Generating a steering magnetic field transverse to the first direction of the magnetic nozzle to deflect the plasma may comprise generating a steering magnetic field proximate to the outlet of the plurality of aligned coils, wherein the plurality of aligned coils comprises a first coil proximate to the plasma source, and a last coil distal from the plasma source, and wherein the outlet of the plurality of aligned coils corresponds to a region proximate to the last coil distal from the plasma source.

Generating a steering magnetic field transverse to the first direction of the magnetic nozzle may comprise applying an electric current to at least one steering coil.

Generating a steering magnetic field transverse to the first direction of the magnetic nozzle -5 -may comprise applying an electric current to a pair of opposing steering coils arranged transverse to the plurality of aligned coils to deflect the plasma.

In some examples the method may comprise proportionally reducing the electric current 5 applied to one of the pair of steering coils in response to increasing the electric current applied to the other of the pair of steering coils.

In some examples the method may comprise applying an electric current to one of the steering coils in a direction opposite to the direction of electric current applied to the other 10 of the steering coils.

In some examples the method further comprises generating a second steering magnetic field in a third direction orthogonal to the second direction of the first steering magnetic field and orthogonal to the first direction of the magnetic nozzle.

In some examples generating the second steering magnetic field comprises generating the second steering magnetic field in the same plane as the longitudinal axis of the magnetic nozzle, and wherein generating the first steering magnetic field comprises generating the first steering magnetic field in the same plane as the longitudinal axis of the magnetic nozzle but in a direction orthogonal to that of the second steering magnetic field.

In another aspect there is provided a computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the method described above.

In another aspect there is provided a data carrier signal carrying the computer program product.

In another aspect there is provided a satellite such as a CubeSat comprising the thrust 30 vectoring system described above.

Drawings Embodiments of the disclosure will now be described, by way of example only, with -6 -reference to the accompanying drawings, in which: Fig. 1 shows a schematic plan view of an example thrust vectoring system in combination with a plasma source; Fig. 2 shows a perspective view of an example thrust vectoring system; Fig. 3A shows a colour map of the magnitude of a magnetic field generated by a thrust vectoring system such as the system of Fig. 2; Fig. 33 shows a plot of the magnetic field lines of Fig. 3A; Fig. 4A shows a colour map of the magnitude of a magnetic field generated by a thrust vectoring system such as the system of Fig. 2; Fig. 43 shows a plot of the magnetic field lines of Fig. 4A; Fig. 5A shows a colour map of the magnitude of a magnetic field generated by a thrust vectoring system such as the system of Fig. 2; Fig. 53 shows a plot of the magnetic field lines of Fig. 5A; Fig. 6 shows a perspective view of another example thrust vectoring system; Fig. 7 shows a process flow chart of an example method of vectoring thrust from a plasma source; and Fig. 8 shows a plan schematic view of an example controller.

Specific description

Embodiments of the disclosure relate to a thrust vectoring system for a plasma thruster. The thrust vectoring system may be coupled to or used with a source of plasma, such as a pulsed plasma thruster. For example, the thrust vectoring system may be used with a Hollow Cathode Thruster (HCT) as will be described in more detail below. It will be appreciated that the thrust vectoring system described herein may be used with satellites, and in particular small satellites such as CubeSat.

In summary, the thrust vectoring system comprises a first means for generating a first magnetic field for confining, guiding and accelerating plasma from the plasma source. The means for generating a first magnetic field may generate a magnetic nozzle to guide and funnel the plasma from the plasma source in a first direction to provide thrust. The thrust vectoring system also comprises a second means for generating a second magnetic field for deflecting the plasma in a second direction that is transverse to the first direction. -7 -

The operating procedure is as follows: by circulating electric currents through the coils, a magnetic field is generated whose magnetic line tubes form a convergent-divergent magnetic nozzle. The average current that is circulated by the coils generates an applied magnetic field capable of magnetizing, confining and guiding the expansion of the motor plasma.

An example thrust vectoring system 140 is shown in Fig. 1 in use with a plasma source 100, which in this example is a Hollow Cathode Thruster (HCT), although it will be understood that embodiments of the disclosure may be used in combination with other plasma sources such as a Helicon plasma thruster, a gridded ion thruster or a Hall thruster. Preferably the thrust vectoring system is configured for use with a pulsed plasma thruster (P PT).

As noted above, an example of a suitable plasma thruster may be a Hollow Cathode Thruster (HCT). HCTs have been successfully employed as plasma sources in electric thrusters for many years. Ion and Hall thrusters that utilize an electron discharge to ionize the propellant gas and create the plasma in the thruster require a cathode to emit the electrons. In addition, thrusters must neutralize the ion beam leaving the thruster by providing electrons emitted from a cathode into the beam. The properties of the cathode material, the physical configuration of the hollow cathode, and structure of the cathode plasma determine, to a large extent, the performance and life of both ion and Hall thrusters.

The example Hollow Cathode Thruster (HCT) 100 shown in Fig. 1 comprises a cathode comprising a hollow refractory tube 115 with an orifice plate 117 on the downstream end. The tube 115 has an insert 111 in the shape of a cylinder that is placed inside the tube 115 and pushed against the orifice plate 117. This insert 111 is an active electron emitter, and it can be made of several different materials that provide a low work function surface on the inside diameter in contact with the cathode plasma. The cathode tube 115 is wrapped with a heater 107 (a co-axial sheathed heater is shown in Fig. 1 with a heat shield 109 surrounding the heater 107) that raises the insert 111 temperature to emissive temperatures to start electron discharge. The electrons emitted from the insert 111 ionize gas propellant 105 injected through the cathode tube 115 and form a cathode plasma 125 -8 -from which the discharge-current electrons are extracted through the orifice 113 into the thruster plasma 130.

Hollow cathodes may be enclosed in another electrode called a keeper electrode 103 5 which is shown in Fig. 1. The major functions of the keeper electrode 103 are to facilitate turning on the cathode discharge, to maintain the cathode temperature and operation in the event that the discharge or beam current is interrupted temporarily, and to protect the cathode orifice plate 117 and external heater 107 from high-energy ion bombardment that might limit the cathode life. The keeper electrode 103 is normally biased positive relative 10 to the cathode tube 115, which either initiates the discharge during start-up or reduces the ion bombardment energy during normal operation.

The thrust vectoring system 140 is shown adjacent and coupled to the plasma source 100. The thrust vectoring system comprises a first means for generating a first magnetic field 160 in a first direction, and a second means for generating a second (steering) magnetic field 175 in a second direction transverse to the first direction. The first means 160 and the second means 175 are coupled to a controller 150 and also a (not shown) power source, which may be a battery. In the example shown the plasma source 100 is also coupled to the controller 150, although it will be understood that in other examples the plasma source 100 may be independently controlled. The first means may be a conductive coil (or a plurality of coils), for example comprising a plurality of turns of a conducting wire, configured to generate a magnetic field through the application of an electrical current. The second means 175 may additionally or alternatively be a conductive coil (or a plurality of coils), for example comprising a plurality of turns of a conducting wire, configured to generate a magnetic field through the application of an electrical current.

In the example show the first means for generating a first magnetic field 160 is elongate and has a longitudinal axis L aligned with (for example, coaxial with) the longitudinal axis of the plasma source 100. The first means for generating a first magnetic field 160 may comprise a plurality of conducting coils. The plurality of conducting coils may be coaxial with each other along a first axis (for example a longitudinal axis of the first means for generating a first magnetic field 160), for example coaxial with each other along a first axis in a first plane. In the example shown, the longitudinal axis of the first means 160 is coaxial -9 -with the longitudinal axis of the cathode tube 115 and in the same plane as the plasma source 100. In the example shown the first means for generating a first magnetic field 160 comprises a plurality of aligned identical repeating circular coils all having the same size and all coaxial with each other. In the example shown the plurality of aligned coils are also 5 equally spaced, however it will be appreciated that the spacing may vary, for example so that the aligned coils are closer to each other for example closer to the plasma source. However, it will be understood that in other examples the first means for generating a first magnetic field 160 may comprise a plurality of coils but of different shapes and/or sizes. It will also be appreciated that instead of or in addition to coils, the means for generating a 10 magnetic field may be U-shaped, for example coils formed in a U-shape configuration.

The second means for generating a second (steering) magnetic field 175 may also comprise at least one conducting coil. The at least one conducting coil may be the same shape and size as one of the coils of the plurality of coils of the first means for generating a first magnetic field 160, or the at least one conducting coil may be larger or smaller, for example the at least one conducting coil of the second means for generating a second magnetic field 175 may have a larger or smaller radius than the coils of the first means for generating a first magnetic field 160, and/or may have more or less turns. In the example shown, the second means for generating a second magnetic field is also a conducting coil, of approximately the same size and geometry of one of the conducting coils of the first means for generating a first magnetic field 160. In the example shown the second means for generating a second magnetic field 175 is in the same plane as (for example, the centre of the second means for generating a second magnetic field 175 is in the same plane as the centre of the first means for generating a first magnetic field 160), but perpendicular to, the first means for generating a first magnetic field 160. It will also be appreciated that instead of or in addition to coils, the means for generating a magnetic field may be U-shaped, for example coils formed in a U-shape configuration.

The first means for generating a first magnetic field 160 may have a proximal portion arranged proximate to the plasma source 100, and a distal portion distal to the plasma source 100. The second means for generating a second magnetic field 175 may be arranged proximate to the distal portion of the first means for generating a first magnetic field 160. In the example shown, the first means for generating a first magnetic field 160 -10 -comprises a plurality of conducting coils. A first, proximal, conducting coil is arranged proximate to the plasma source 100, and centred around the orifice 113. A last, distal, conducting coil is arranged distal to the plasma source 100. The second means for generating a second magnetic field 175 is arranged proximate to and perpendicular to the distal conducting coil. This may help to improve the deflection that may be obtained by the second means for generating a second magnetic field 175, and the effect that this has on the directed plasma and thereby its impact and efficacy at thrust vectoring.

The first means for generating a first magnetic field 160 is configured to create a magnetic nozzle 190 to direct, for example accelerate and guide, the thruster plasma 130 emitted from the plasma source 100 and cause acceleration via the Lorentz force. The first means for generating a first magnetic field 160 is configured to do this by passing an electric current through a conductor, such as a conducting coil.

The second means 175 for generating the second (steering) magnetic field is configured to generate a steering magnetic field to deflect the magnetic nozzle 190 to vector the thrust created by the directed plasma via the Lorentz force. The second means 175 is also configured to do this by passing an electric current through another conductor, such as a conducting coil. The aim of the magnetic fields for directing plasma is to achieve thrust vectoring by changing the direction and therefore the strength of the magnetic field generated by the second means 175.

The controller 150 is configured to control the second means 175 to vary or adjust the magnitude and direction of the second magnetic field to provide control of the degree of 25 deflection of the magnetic nozzle 190 so that manoeuvrability may be controlled. In the example shown in Fig. 1, only one second means 175 for generating the second magnetic field is shown, and the degree of deflection can be varied in both directions (i.e. towards the second means 175 and away from the second means 175) by varying the direction of current passed through the second means 175 for creating the second magnetic field. 30 Although only one second means 175 for generating the second magnetic field is shown in Fig. 1, in some examples the second means 175 may comprise a plurality such as a pair of means, for example a pair of conductors configured to be placed either side of the magnetic nozzle generated by the first means for generating a first magnetic field 160 to aid in deflecting and guiding the emitted and directed plasma. In some examples the second means 175 may comprise a plurality of equally spaced conductors, for example three conductors (such as coils) arranged in a triangular pattern around the generated magnetic nozzle for deflecting the magnetic nozzle created by the first means 260 and the plasma.

For example, as shown in Fig. 2 the second means 275 comprises a pair of wound coils placed either side of the first means 260 for deflecting the magnetic nozzle created by the 10 first means 260.

Fig. 2 shows another example thrust vectoring system 240, with many features in common with the example shown in Fig. 1. It will be understood that the thrust vectoring system 240 shown in Fig. 2 could be used with the plasma source of Fig. 1.

The example thrust vectoring system 240 in Fig. 2 four static electromagnetic coils (green) forming the first means for generating a first magnetic field 360, and two steering electromagnetic coils (blue and red) forming the second means for generating a second magnetic field 275. The plurality of aligned coils of the first means for generating a first magnetic field 260 are coaxial with each other along a first axis in a first plane, and wherein the pair of opposing steering coils forming the second means for generating a second magnetic field 275 are coaxial with each other in the first plane and orthogonal to the plurality of aligned coils of the first means for generating a first magnetic field 260. The pair of opposing steering coils forming the second means for generating a second magnetic field 275 are proximate to a distal coil of the plurality of coils forming the first means for generating a first magnetic field 260, with the pair of opposing steering coils forming the second means for generating a second magnetic field 275 centred around the distal coil, such that the pair of opposing steering coils forming the second means for generating a second magnetic field 275 are centred on the distal coil of the first means for

generating a first magnetic field 260.

In some examples the method may comprise proportionally reducing the electric current applied to one of the pair of steering coils forming the second means for generating a -12 -second magnetic field 275 in response to increasing the electric current applied to the other of the pair of steering coils. Proportionally adjusting the current through a pair of steering coils in this way may help improve the steering and thus vectoring of the plasma. In some examples, the method may comprise applying an electric current to one of the steering coils in a direction opposite to the direction of electric current applied to the other of the steering coils. This may further act to help improve steering and thus vectoring of the plasma.

Examples of the thrust vectoring system 240 shown in Fig. 2 in use are illustrated in Figs. 10 3A to 5B.

With only the static (green) coils on, a linear field is generated as shown in Figs. 3A and 3B. This example uses a 20 mm radius coils, each with a current x turns of 2000 A. A linear field within the coil, and a diverging one to the left. Plasma will be ejected with an 15 average velocity in the -x direction, which produces thrust in the +x direction.

The steering coils can be used to bend the diverging magnetic field lines in either direction as shown in Fig. 4A to 5B. The magnitude of bending (and thus level of thrust vectoring) can be accurately controlled by varying the current through the steering coils. Figs. 3A, 4A and 5A show a colour map of the magnitude of the magnetic field generated by the first and second means for generating magnetic fields 260, 275. Figs. 3B, 48 and 5B show the corresponding field lines generated by the same means shown in corresponding Figs. 3A, 4A and 5A. The magnetic nozzle 390 generated by the plurality of aligned coils of the first means for generating a first magnetic field can be seen in Fig. 33 as can its longitudinal axis L. The plots in Figs. 4A to 5B use a current x turns of 3000 A in the steering coils (which have the same dimensions as the static coils). The plasma will approximately follow the field lines, and thus the plasma can be accurately vectored (for example, steered upwards or downwards in the plane of the plots shown in Figs. 4B and 56) by controlling the current though the steering coils forming the second means for generating a second magnetic field 275. The effect on the magnetic nozzle 390 by the second means for generating a second magnetic field 275 can be seen in Figs. 46 and 46 -the second means for generating a -13 -second magnetic field 275 can be seen to alter and deflect the magnetic field lines of the magnetic nozzle 390 in the vicinity of the second means for generating a second magnetic field 275.

Steering the plasma in the way has two major benefits when used with spacecraft: /. It can be used to apply a torque on the spacecraft, allowing a single propulsion system to be used both for providing thrust and attitude control (i.e. turning the spacecraft).

2. It allows the propulsion system to maintain attitude in the case of an off-center center of mass -particularly useful in the case of spacecraft with deployable solar panels and boons.

It will of course be appreciated that the system may naturally extend to three dimensions by including more steering coils.

Fig. 6 shows another example thrust vectoring system 340, with many features in common with the examples shown in Figs. 1 and 2. It will be understood that the thrust vectoring system 340 shown in Fig. 6 could be used with the plasma source of Fig. 1.

Fig. 6 shows a four steering coil arrangement which allows for both pitch and turn control. Three coils would also be possible (for example, equally positioned around the static coils forming the first means for generating a first magnetic field 260 when viewed in the longitudinal axis of the first means for generating a first magnetic field 260), as would higher numbers of coils (which adds additional redundancy). When three or more coils are used, it will be understood that in some examples the method may comprise proportionally adjusting the current in the coils relative to the current through the other coils. For example, if the current in one of the coils is increased by a quantity x, then the current through the other coils may be reduced correspondingly by the same quantity x.

In the example shown in Fig. 6, in addition to the second means for generating a second magnetic field 375, there is a third means for generating a third magnetic field 385 comprising another pair of opposing steering coils, such that the thrust vectoring system 340 of Fig. 6 comprises two pairs of opposing and orthogonal steering coils, wherein each -14 -pair is positioned transverse to the plurality of aligned coils forming the first means for generating a first magnetic field 360. In the example shown the third means for generating a third magnetic field 385 is also proximate to the last coil of the plurality of aligned coils forming the first means for generating a first magnetic field, and in line with the second means for generating a second magnetic field 375. In some examples, however, the relative positioning of the third means for generating a third magnetic field 385 may differ, for example the third means for generating a third magnetic field 385 may be proximal or distal of the second means for generating a second magnetic field 375 relative to the plasma source 100.

Fig. 7 shows a flow chart of an example method of using the thrust vectoring system, for example the thrust vectoring system of any of Figs. 1 to 6. In Fig. 7 the method 700 comprises generating 701 a magnetic nozzle to direct plasma in a first direction from a plasma source (for example, by controlling the first means for generating a first magnetic field 160, 260, 360, for example by controlling the controller 150 shown in Fig. 1), wherein the magnetic nozzle has a longitudinal axis and the first direction is a direction parallel to the longitudinal axis; generating 703 a steering magnetic field in a second direction transverse to the first direction of the magnetic nozzle to deflect the plasma (for example, by controlling the second means for generating a second magnetic field 175, 275, 275 and/or or the third means for generating a third magnetic field 385 as shown in Fig. 6, for example by controlling the controller 150 shown in Fig. 1); and adjusting 705 the magnitude and direction of the generated steering magnetic field to adjust the magnitude and direction of the deflection of the plasma.

Generating the steering magnetic field in a second direction transverse to the first direction of the magnetic nozzle may comprise generating the steering magnetic field perpendicular to the first direction of the magnetic nozzle. For example, this may comprise controlling the second means for generating a second magnetic field 175, 275, 375 by controlling the controller 150.

Generating the steering magnetic field in a second direction perpendicular to the first direction of the magnetic nozzle may further comprise generating the steering magnetic field perpendicular to the first direction and in the same plane as the longitudinal axis of -15 -the magnetic nozzle.

Generating a magnetic nozzle in a first direction may comprise applying an electric current to a plurality of aligned coils. For example, this may comprise controlling the first means 5 for generating a first magnetic field 160, 260, 360 by controlling the controller 150.

Generating a steering magnetic field transverse to the first direction of the magnetic nozzle 15 may comprise applying an electric current to at least one steering coil.

Generating a steering magnetic field transverse to the first direction of the magnetic nozzle may comprise applying an electric current to a pair of opposing steering coils arranged transverse to the plurality of aligned coils to deflect the plasma.

In some examples the method may comprise proportionally reducing the electric current applied to one of the pair of steering coils in response to increasing the electric current applied to the other of the pair of steering coils.

In some examples the method may comprise applying an electric current to one of the steering coils in a direction opposite to the direction of electric current applied to the other of the steering coils.

In some examples such as in the example shown in Fig. 6 the method further comprises generating a second steering magnetic field in a third direction orthogonal to the second direction of the first steering magnetic field and orthogonal to the first direction of the magnetic nozzle. For example, this may comprise controlling the third means for generating a third magnetic field 385 by controlling the controller 150.

-16 -In some examples generating the second steering magnetic field comprises generating the second steering magnetic field in the same plane as the longitudinal axis of the magnetic nozzle, and wherein generating the first steering magnetic field comprises generating the first steering magnetic field in the same plane as the longitudinal axis of the magnetic nozzle but in a direction orthogonal to that of the second steering magnetic field.

It will be understood that while in some examples the first means for generating a first magnetic field and/or the second means for generating a second magnetic field comprise conducting coils configured to generate a magnetic field through the application of an electrical current, in some examples permanent magnets may be used. For example, the position and/or orientation of the permanent magnets relative to the magnetic nozzle may be controlled. For example, the position and/or orientation of the second means for generating a second (steering) magnetic field may be controlled (for example by the controller) to control the direction of thrust.

Fig. 8 is a functional block diagram of a computer system 1200 suitable for implementing one or more embodiments of the present disclosure. For example, the computer system 1200 may provide the functionality of the controller 150 shown in Fig. 1. The computer system 1200 includes a bus 1212 or other communication mechanism for communicating information data, signals, and information between various components of the computer system 1200. The components include an input/output (I/O) component 1204 that processes a user (i.e., sender, recipient, service provider) action, such as selecting keys from a keypad/keyboard, selecting one or more buttons or links, etc., and sends a corresponding signal to the bus 1212. It may also include a camera for obtaining image data. The I/O component 1204 may also include an output component, such as a display 1202 and a cursor control 1208 (such as a keyboard, keypad, mouse, etc.). The display 1202 may be configured to present a login page for logging into a user account or a checkout page for purchasing an item from a merchant. An optional audio input/output component 1206 may also be included to allow a user to use voice for inputting information by converting audio signals. The audio I/O component 1206 may allow the user to hear audio. A transceiver or network interface 1220 transmits and receives signals between the computer system 1200 and other devices, such as another user device, or a service -17 -provider server via network 1222. In one embodiment, the transmission is wireless, although other transmission mediums and methods may also be suitable. A processor 1214, which can be a micro-controller, digital signal processor (DSP), or other processing component, processes these various signals, such as for display on the computer system 1200 or transmission to other devices via a communication link 1224. The processor 1214 may also control transmission of information, such as cookies or IP addresses, to other devices.

The components of the computer system 1200 also include a system memory component 1210 (e.g., RAM), a static storage component 1216 (e.g., ROM), and/or a disk drive 1218 (e.g., a solid-state drive, a hard drive). The computer system 1200 performs specific operations by the processor 1214 and other components by executing one or more sequences of instructions contained in the system memory component 1210. For example, the processor 1214 can run the applications 200, 500 described above.

It will also be understood that the modules may be implemented in software or hardware, for example as dedicated circuitry. For example, the modules may be implemented as part of a computer system. The computer system may include a bus or other communication mechanism for communicating information data, signals, and information between various components of the computer system. The components may include an input/output (I/O) component that processes a user (i.e., sender, recipient, service provider) action, such as selecting keys from a keypad/keyboard, selecting one or more buttons or links, etc., and sends a corresponding signal to the bus. The I/O component may also include an output component, such as a display and a cursor control (such as a keyboard, keypad, mouse, etc.). A transceiver or network interface may transmit and receive signals between the computer system and other devices, such as another user device, a merchant server, or a service provider server via a network. In one embodiment, the transmission is wireless, although other transmission mediums and methods may also be suitable. A processor, which can be a micro-controller, digital signal processor (DSP), or other processing component, processes these various signals, such as for display on the computer system or transmission to other devices via a communication link. The processor may also control transmission of information, such as cookies or IP addresses, to other devices.

-18 -The components of the computer system may also include a system memory component (e.g., RAM), a static storage component (e.g., ROM), and/or a disk drive (e.g., a solid-state drive, a hard drive). The computer system performs specific operations by the processor and other components by executing one or more sequences of instructions contained in the system memory component.

Logic may be encoded in a computer readable medium, which may refer to any medium that participates in providing instructions to a processor for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. In various implementations, non-volatile media includes optical or magnetic disks, volatile media includes dynamic memory, such as a system memory component, and transmission media includes coaxial cables, copper wire, and fibre optics. In one embodiment, the logic is encoded in non-transitory computer readable medium. In one example, transmission media may take the form of acoustic or light waves, such as those generated during radio wave, optical, and infrared data communications.

Some common forms of computer readable media includes, for example, floppy disk, flexible disk, hard disk, magnetic tape, any other magnetic medium, CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, RAM, PROM, EPROM, FLASH-EPROM, any other memory chip or cartridge, or any other medium from which a computer is adapted to read.

In various embodiments of the present disclosure, execution of instruction sequences to practice the present disclosure may be performed by a computer system. In various other embodiments of the present disclosure, a plurality of computer systems 600 coupled by a communication link to a network (e.g., such as a LAN, WLAN, PTSN, and/or various other wired or wireless networks, including telecommunications, mobile, and cellular phone networks) may perform instruction sequences to practice the present disclosure in coordination with one another.

It will also be understood that aspects of the present disclosure may be implemented using hardware, software, or combinations of hardware and software. Also, where applicable, -19 - the various hardware components and/or software components set forth herein may be combined into composite components comprising software, hardware, and/or both without departing from the spirit of the present disclosure. Where applicable, the various hardware components and/or software components set forth herein may be separated into sub-components comprising software, hardware, or both without departing from the scope of the present disclosure. In addition, where applicable, it is contemplated that software components may be implemented as hardware components and vice-versa.

Software in accordance with the present disclosure, such as program code and/or data, may be stored on one or more computer readable mediums. It is also contemplated that software identified herein may be implemented using one or more general purpose or specific purpose computers and/or computer systems, networked and/or otherwise. Where applicable, the ordering of various steps described herein may be changed, combined into composite steps, and/or separated into sub-steps to provide features described herein.

The various features and steps described herein may be implemented as systems comprising one or more memories storing various information described herein and one or more processors coupled to the one or more memories and a network, wherein the one or more processors are operable to perform steps as described herein, as non-transitory machine-readable medium comprising a plurality of machine-readable instructions which, when executed by one or more processors, are adapted to cause the one or more processors to perform a method comprising steps described herein, and methods performed by one or more devices, such as a hardware processor, user device, server, and other devices described herein.

In the context of the present disclosure other examples and variations of the apparatus and methods described herein will be apparent to a person of skill in the art.

Claims

-20 -CLAIMS: 1. A thrust vectoring system for a plasma thruster, comprising: a plurality of aligned coils configured to be located proximal to a plasma source, 5 wherein the plurality of aligned coils are arranged to receive an electric current to generate a magnetic nozzle to direct plasma from the plasma source to create thrust; and at least one steering coil configured to receive an electric current to generate a steering magnetic field to deflect the plasma; and a controller configured to control the direction and magnitude of current through the 10 at least one steering coil to adjust the direction and magnitude of the deflection of the plasma to control the direction and/or magnitude of the thrust from the plasma source.
2. The thrust vectoring system of claim 1 wherein the at least one steering coil comprises a pair of opposing steering coils positioned transverse to the plurality of aligned 15 coils.
3. The thrust vectoring system of claim 2 wherein the pair of opposing steering coils are coaxial with each other.
4. The thrust vectoring system of any of the previous claims wherein the plurality of aligned coils are coaxial with each other.
5. The thrust vectoring system of claim 4 wherein the plurality of aligned coils are coaxial with each other along a first axis in a first plane, and wherein the at least one 25 steering coil has a central axis in the first plane.
6. The thrust vectoring system of claim 4 as dependent on claim 3 wherein the plurality of aligned coils are coaxial with each other along a first axis in a first plane, and wherein the pair of opposing steering coils are coaxial with each other in the first plane and 30 orthogonal to the plurality of aligned coils.
7. The thrust vectoring system of any of the previous claims wherein the plurality of aligned coils comprises a first coil proximate to the to the plasma source, and a last -21 -magnetic coil distal to the plasma source, and wherein the at least one steering coil is proximate to the last magnetic coil.
8. The thrust vectoring system of claim 7 wherein the at least one steering coil has a central axis aligned with the last coil.
9. The thrust vectoring system of any of the previous claims wherein the at least one steering coil comprises two pairs of opposing steering coils, wherein each pair is positioned transverse to the plurality of aligned coils
10. The thrust vectoring system of claim 9 wherein the two pairs of opposing steering coils are orthogonal to each other.
11. The thrust vectoring system of any of the previous claims configured for use with a 15 pulsed plasma thruster.
12. The thrust vectoring system of any of the previous claims configured for use with a hollow cathode thruster.
13. A method of vectoring thrust from a plasma thruster, the method comprising: generating a magnetic nozzle to direct plasma in a first direction from a plasma source, wherein the magnetic nozzle has a longitudinal axis and the first direction is a direction parallel to the longitudinal axis; generating a steering magnetic field in a second direction transverse to the first 25 direction of the magnetic nozzle to deflect the plasma; and adjusting the magnitude and direction of the generated steering magnetic field to adjust the magnitude and direction of the deflection of the plasma.
14. The method of claim 13 wherein generating the steering magnetic field in a second direction transverse to the first direction of the magnetic nozzle comprises generating the steering magnetic field perpendicular to the first direction of the magnetic nozzle.
15. The method of claim 14 wherein generating the steering magnetic field in a second -22 -direction perpendicular to the first direction of the magnetic nozzle further comprises generating the steering magnetic field perpendicular to the first direction and in the same plane as the longitudinal axis of the magnetic nozzle.
16. The method of any of claims 13 to 15 wherein generating a magnetic nozzle in a first direction comprises applying an electric current to a plurality of aligned coils.
17. The method of claim 16 wherein generating a steering magnetic field transverse to the first direction of the magnetic nozzle to deflect the plasma comprises generating a steering magnetic field proximate to the outlet of the plurality of aligned coils, wherein the plurality of aligned coils comprises a first coil proximate to the plasma source, and a last coil distal from the plasma source, and wherein the outlet of the plurality of aligned coils corresponds to a region proximate to the last coil distal from the plasma source.
18. The method of claim 16 or 17 wherein generating a steering magnetic field transverse to the first direction of the magnetic nozzle comprises applying an electric current to at least one steering coil.
19. The method of claim 18 wherein generating a steering magnetic field transverse to 20 the first direction of the magnetic nozzle comprises applying an electric current to a pair of opposing steering coils arranged transverse to the plurality of aligned coils to deflect the plasma.
20. The method of claim 19 comprising proportionally reducing the electric current 25 applied to one of the pair of steering coils in response to increasing the electric current applied to the other of the pair of steering coils.
21. The method of claim 19 or 20 comprising applying an electric current to one of the steering coils in a direction opposite to the direction of electric current applied to the other 30 of the steering coils.
22. The method of any of claims 13 to 21 further comprising generating a second steering magnetic field in a third direction orthogonal to the second direction of the first -23 -steering magnetic field and orthogonal to the first direction of the magnetic nozzle.
23. The method of claim 22 wherein generating the second steering magnetic field comprises generating the second steering magnetic field in the same plane as the longitudinal axis of the magnetic nozzle, and wherein generating the first steering magnetic field comprises generating the first steering magnetic field in the same plane as the longitudinal axis of the magnetic nozzle but in a direction orthogonal to that of the second steering magnetic field.
24. A computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the method of claims 13 to 23.
25. A data carrier signal carrying the computer program product of claim 24.