Hall thruster, heat exchange unit, rocket, artificial satellite, and space probe

Abstract

[Problem] To provide novel features. [Solution] One aspect of the present invention sets forth a Hall thruster provided with an anode, a vaporization chamber, and a passage formation part. The anode is configured to supply a propellant to a predetermined position in order to generate a propulsive force. The vaporization chamber is configured to vaporize the propellant on the inside thereof. The passage formation part forms a first passage, a second passage, and a third passage. The first passage is configured to guide the propellant to the inside of the vaporization chamber. The second passage is configured to guide, of the propellant having been guided to the vaporization chamber, a predetermined amount of the propellant to the anode. The third passage is configured to guide, of the propellant having been guided to the vaporization chamber, the propellant other than the predetermined amount to the outside of the Hall thruster.

Description

Hall thruster, heat exchange unit, rocket, artificial satellite, and space exploration vehicle

[0001] The present invention relates to a Hall thruster, a heat exchange unit, a rocket, an artificial satellite, and a space exploration vehicle.

[0002] Patent Document 1 discloses a technology related to a Hall-type electric propulsion device having overheat protection and stable operation that simultaneously solves the problem of waste heat that becomes severe with miniaturization and further the problem of discharge current vibration.

[0003] This Hall-type electric propulsion device first manufactures the magnetic flux line distribution of the ionization / acceleration channel part so that the ion acceleration vector is optimal, arranges a flow path (propellant conduit) of the propellant near the magnetic pole part of the propulsion device, particularly near the acceleration channel part, and then passes the propellant through the flow path, so that the magnetic pole part overheated by the generated plasma can be cooled and at the same time the propellant can be heated. Further, the heated propellant is choked in a throat region (throat part) provided immediately before being introduced into the ionization / acceleration channel part to increase the sound speed of the propellant (neutral particles).

[0004] Japanese Patent Application Laid-Open No. 2008-223655

[0005] However, there is still room for improvement in the technology according to the above-known technology.

[0006] In view of the above circumstances, the present invention aims to provide a novel technology.

[0007] According to one aspect of the present invention, there is provided a Hall thruster including an anode, a vaporization chamber, and a passage forming part. The anode is configured to supply a propellant to a predetermined position in order to generate a propulsive force. The vaporization chamber is configured to vaporize the propellant inside. The passage forming part forms a first passage, a second passage, and a third passage. The first passage is configured to guide the propellant into the vaporization chamber. The second passage is configured to guide a predetermined amount of the propellant guided into the vaporization chamber to the anode. The third passage is configured to guide the propellant other than the predetermined amount of the propellant guided into the vaporization chamber to the outside of the Hall thruster.

[0008] According to this embodiment, unnecessary heat generation in the Hall thruster can be avoided. As a result, a decrease in propulsion efficiency can be prevented and the lifespan of the Hall thruster can be extended.

[0009] This figure shows an example of the overall configuration of the mobile body 1. This figure shows a cross-sectional view illustrating the internal configuration of the thruster 100 and an example of the configuration of the propellant supply unit 2, shown in the direction of the A-A arrow in Figure 1B. This figure shows a cross-sectional view illustrating another example of the internal configuration of the thruster 100 and another example of the configuration of the propellant supply unit 2, shown in the direction of the A-A arrow in Figure 1B. This figure shows a cross-sectional view illustrating another example of the internal configuration of the thruster 100 and another example of the configuration of the propellant supply unit 2, shown in the direction of the A-A arrow in Figure 1B. This figure shows another example of the overall configuration of the mobile body 1. This figure shows a cross-sectional view illustrating another example of the internal configuration of the thruster 100 and an example of the configuration of the propellant supply unit 2 and the heat exchange unit 200, shown in the direction of the B-B arrow in Figure 5B. This figure shows a cross-sectional view illustrating another example of the internal configuration of the thruster 100 and an example of the configuration of the propellant supply unit 2 and the heat exchange unit 200, shown in the direction of the B-B arrow in Figure 5B. Figure 5B shows a cross-sectional view illustrating an alternative internal configuration of the thruster 100, as well as an example of the configuration of the propellant supply unit 2 and the heat exchange unit 200, as shown in the direction of the B-B arrow in Figure 5B.

[0010] Embodiments of the present invention will be described below with reference to the drawings. The various features shown in the embodiments below can be combined with each other.

[0011] (Mobile Body 1) First, the hardware configuration of the mobile body 1 according to one embodiment will be described. Figure 1 is a diagram showing an example of the overall configuration of the mobile body 1. Figure 2 is a diagram showing a cross-sectional view for explaining the internal configuration of the thruster 100 and an example of the configuration of the propellant supply unit 2, shown in the direction of the A-A arrow in Figure 1B. In the following description, the directions of the mobile body 1 and each component constituting the mobile body 1 will be defined based on "up", "down", "left", "right", "front", and "rear" shown in Figures 1 to 2 (and similarly in Figures 3 to 9). Furthermore, in the following description, "up" will also be referred to as "upper side" or "upward", and "down" will also be referred to as "lower side" or "downward". The direction formed by "up" and "down" will be referred to as "up and down" or "up and down direction". The same applies to "down", "left", "right", "front", and "rear".

[0012] The mobile body 1 is, for example, a rocket, artificial satellite, or space probe, and is equipped with various devices depending on its purpose, one of which is a structurally and electrically connected thruster 100. The thruster 100 generates thrust using propellant PR, and is, for example, a Hall thruster 101, an ion thruster, an arcjet thruster, a resistjet thruster, a magnetic nozzle thruster, an electrodeless plasma thruster, or an MPD (Magnet Plasma Dynamic) thruster. In other words, rockets, artificial satellites, space probes, etc., can be equipped with a Hall thruster 101 as the structurally and electrically connected thruster 100. In the following explanation, the case in which a Hall thruster 101 is used as the thruster 100 will be described as an example. The mobile body 1 further includes a propellant supply unit 2 and a control unit 3.

[0013] (Propellant supply unit 2) As shown in Figure 2, the propellant supply unit 2 is a unit that supplies propellant PR to the Hall thruster 101, and has a propellant tank 21, a passage 22, a pump 23, a valve 24, and a fluid resistance 25.

[0014] (Propellant Tank 21) The propellant tank 21 is a tank that can be filled with propellant PR. The propellant tank 21 is filled with an amount of propellant PR appropriate to the purpose of the mobile body 1.

[0015] (Passage 22) Passage 22 is configured to guide the propellant PR to each device. Specifically, passage 22 forms a path through which the propellant PR is guided by connecting the propellant tank 21, pump 23, valve 24 and fluid resistor 25 in a predetermined order.

[0016] The passage 22 shown in Figure 2 comprises passage 22a and passage 22b. By connecting to each device, passage 22a forms a path for guiding the propellant PR from the propellant tank 21 to the Hall thruster 101. Specifically, passage 22a is connected to each device so that the propellant PR is guided to each device in the following order: propellant tank 21, valve 24a (an example of valve 24), pump 23, valve 24b (an example of valve 24), fluid resistor 25a (an example of fluid resistor 25), and Hall thruster 101. Similarly, by connecting to each device, passage 22b forms a path for guiding the propellant PR from the Hall thruster 101 to the propellant tank 21. Specifically, passage 22b is connected to each device so that the propellant PR is guided to each device in the following order: Hall thruster 101, fluid resistor 25b (an example of fluid resistor 25), valve 24c (an example of valve 24), and propellant tank 21.

[0017] (Pump 23) Pump 23 is an electric pump, for example, a positive displacement pump (reciprocating, rotary, etc.), a power pump, etc. Preferably, it is a reciprocating pump with adjustable speed so that the volume change during suction is gradual, and more preferably, it is a diaphragm pump. Specifically, a positive displacement pump (an example of pump 23) is configured so that the volume change per unit time during suction is a predetermined value. In this case, the predetermined value is preferably set so that the local minimum static pressure inside pump 23 exceeds the vapor pressure, and also so that the value obtained by subtracting the maximum dynamic pressure in the passage etc. (pressure determined by the flow velocity determined by the passage area and the diaphragm movement speed) from the total pressure of the suction part of pump 23 exceeds the vapor pressure. By setting the predetermined value in this way, it is possible to adopt specifications for pump 23 and a control method thereof that satisfy the condition that the pump flow rate (or discharge pressure) does not decrease. According to this embodiment, even when the pressure inside the propellant tank 21 and the passage 22b is close to the vapor pressure, it becomes possible to avoid cavitation in the pump 23 and suck in and push out the propellant PR, thereby enabling the transport of the propellant PR. Furthermore, the positive displacement pump (an example of the pump 23) is preferably equipped with a passage that does not undergo abrupt changes in flow area from the propellant PR intake to the diaphragm. According to this embodiment, even when the pressure inside the propellant tank 21 and the passage is close to the vapor pressure, it becomes easier to avoid cavitation in the pump 23 and suck in and push out the propellant PR, thereby enabling the transport of the propellant PR more easily.

[0018] (Valve 24) Valve 24 is a component for controlling the opening and closing of the flow path of the propellant PR. As shown in Figure 2, valve 24 is located in the passage 22 between the propellant tank 21 and the Hall thruster 101. Specifically, valve 24 has valve 24a located between the propellant tank 21 and the pump 23 in passage 22a, valve 24b located between the pump 23 and the fluid resistance 25a, and valve 24c located between the Hall thruster 101 and the fluid resistance 25b in passage 22b.

[0019] Valve 24 may be either a check valve or an electrically controlled solenoid valve. In the case of a solenoid valve, the control unit 3 electrically controls its opening and closing operation to adjust the flow rate and direction of the propellant PR. In the case of a check valve, it automatically opens and closes according to the flow direction of the propellant PR to prevent backflow. In the example shown in Figure 2, valve 24a is a solenoid valve, valve 24b is a check valve, and valve 24c is a solenoid valve. As a result, valve 24 ensures a stable supply of propellant PR by appropriately switching and shutting off the flow paths in the propellant PR supply system and return system. With this configuration, the flow of propellant PR can be stably controlled by either electrical control by the control unit 3 or mechanical control by the check valve mechanism.

[0020] (Fluid Resistance 25) The fluid resistance 25 is a component for adjusting the flow velocity and flow rate of the propellant PR. As shown in Figure 2, the fluid resistance 25 has a fluid resistance 25a located between the valve 24b and the Hall thruster 101 in the passage 22a, and a fluid resistance 25b located between the valve 24c and the Hall thruster 101 in the passage 22b.

[0021] The fluid resistances 25a and 25b are configured to control the flow velocity of the propellant PR and adjust the amount of propellant PR supplied to the Hall thruster 101 within a predetermined range by appropriately setting the size of the flow channel cross-section and the internal shape of each. Specifically, the fluid resistance 25 suppresses abrupt flow rate changes when the propellant PR is supplied to the Hall thruster 101, forming a stable flow, and also acts to mitigate pressure fluctuations when the propellant PR returns from the Hall thruster 101, thereby stabilizing the overall system pressure. With this configuration, the flow and supply amount of propellant PR can be stably adjusted.

[0022] (Control Unit 3) The control unit 3 includes a control unit (not shown), which performs control related to the mobile body 1. The control unit is, for example, a Central Processing Unit (CPU) (not shown). The control unit realizes various functions related to the propellant supply unit 2, the Hall thruster 101, etc., by reading a predetermined program stored in a memory unit (not shown). Specifically, the control unit 3 controls the pump 23 and valve 24 of the propellant supply unit 2 in order to control the amount and timing of the propellant PR supplied to the Hall thruster 101. The control unit 3 also controls the power supplied to the Hall thruster 101. The control unit 3 may be configured to perform only control related to the propellant supply unit 2 and control related to the Hall thruster 101, or it may be configured to perform control related to the propellant supply unit 2 and control related to the Hall thruster 101 as part of the control related to the mobile body 1. Furthermore, when the control unit 3 performs control over the mobile body 1, it may also perform control over communication and safety-related controls for the mobile body 1, in addition to operational control over the propellant supply unit 2 and control over the Hall thruster 101.

[0023] (Hall thruster 101) Figure 2 shows an example of the internal structure of the Hall thruster 101 by showing a cross-section of the Hall thruster 101. As shown in Figure 2, the Hall thruster 101 comprises a cathode 110, an anode 120, a magnetic coil 130, a magnetic circuit 140, a propellant conduit 150, a plenum chamber 160, a channel 170, a vaporization chamber 180, and a passage forming section 190.

[0024] (Cathode 110) The cathode 110 is configured to neutralize ions I and supply electrons E. A power supply 111 is electrically connected to the cathode 110, and the power supply 111 is configured to emit electrons E from the cathode 110 by applying a predetermined potential difference.

[0025] (Anode 120) As shown in Figure 2, the anode 120 is paired with the cathode 110 and configured to form an electric field that electrostatically accelerates ions I in a predetermined direction PD. The anode 120 is configured to supply propellant PR to a predetermined position PP in order to generate thrust.

[0026] (Magnetic coil 130, magnetic circuit 140) The magnetic coil 130 is configured to magnetize the magnetic circuit 140, and the magnetic circuit 140 is cylindrical in shape extending in the front-to-back direction and is configured to form a magnetic field for electromagnetically accelerating ions I.

[0027] (Propellant conduit 150) As shown in Figure 2, the propellant conduit 150 is configured to transfer the propellant PR taken in from the propellant inlet 151 via the fluid resistance 152.

[0028] (Plenum chamber 160) The plenum chamber 160 is configured to choke the flow of preheated propellant PR to increase the speed of sound.

[0029] (Channel 170) Channel 170 is configured to electrostatically or electromagnetically accelerate ions I in the plasma. As shown in Figure 2, channel 170 has a wall portion 171, which forms an annular discharge space 174 for generating thrust. A predetermined position PP, where the propellant PR is supplied by the anode 120, is a predetermined position within the discharge space 174.

[0030] Furthermore, as shown in Figure 2, the wall portion 171 has an inner circumferential wall portion 172 that forms the inner circumference of the discharge space 174 and an outer circumferential wall portion 173 that forms the outer circumference of the discharge space 174. Both the inner circumferential wall portion 172 and the outer circumferential wall portion 173 are cylindrical or annular members having a predetermined thickness, and are arranged coaxially with each other to surround the discharge space 174 in an annular shape.

[0031] Since the inner circumferential wall portion 172 and the outer circumferential wall portion 173 are parts that receive heat from the high-temperature plasma generated by the discharge, it is preferable that they be made of materials with excellent heat resistance and insulation properties. In addition, if necessary, a coating layer that suppresses chemical reactions with the plasma may be formed on the surfaces of the inner circumferential wall portion 172 and the outer circumferential wall portion 173.

[0032] (Vaporization Chamber 180) The vaporization chamber 180 is configured to vaporize the propellant PR inside it. As shown in Figure 2, the vaporization chamber 180 is located in front of the Hall thruster 101 and in contact with the magnetic circuit 140, and is configured to vaporize the propellant PR by transferring heat generated around the channel 170 from rear to front. The inside of the vaporization chamber 180 is formed as, for example, a cylindrical or annular space so that the propellant PR is heated uniformly as it passes through.

[0033] (Passage Forming Section 190) A propellant supply unit 2 is connected to the Hall thruster 101 so that propellant PR can be supplied to it. The passage forming section 190 is located inside or near the Hall thruster 101 and is a member that forms a flow path for the propellant PR. As shown in Figure 2, the passage forming section 190 forms a first passage 191, a second passage 192, a third passage 193, and an introduction passage 194. These passages are interconnected but are configured to separate the flow direction and supply amount of propellant PR. In addition, the introduction passage 194 is connected to the passage 22a of the propellant supply unit 2, and propellant PR is supplied to the Hall thruster 101.

[0034] The propellant PR supplied through the introduction passage 194 is guided to the first passage 191. Part of the first passage 191 is formed by combining a channel 170 and a passage forming section 190, and is configured so that the propellant PR passes near the wall section 171. The propellant PR that has passed near the wall section 171 is guided to the vaporization chamber 180. In other words, the first passage 191 is configured to guide the propellant PR into the vaporization chamber 180. With this configuration, heat transmitted from the channel 170 can be transferred to the propellant PR, and the channel 170 can be cooled by the propellant PR, while the propellant PR can be preheated before being guided to the vaporization chamber 180.

[0035] The vaporization chamber 180 is connected to a second passage 192 and a third passage 193. The second passage 192 connects the vaporization chamber 180 to the propellant conduit 150, and guides propellant PR at a flow rate adjusted by the fluid resistance 152 from the vaporization chamber 180 to the propellant conduit 150. The third passage 193 connects the vaporization chamber 180 to passage 22b, and guides propellant PR at a flow rate adjusted by the fluid resistance 25b from the vaporization chamber 180 to passage 22b. With this configuration, the amount of propellant PR guided to the second passage 192 and the amount of propellant PR guided to the third passage 193 are adjusted to a predetermined relationship. In other words, the second passage 192 is configured to guide a predetermined amount PV of propellant PR from the propellant PR guided to the vaporization chamber 180 to the anode 120. The third passage 193 is configured to guide propellant PR other than a predetermined amount PV from the propellant PR guided to the vaporization chamber 180 to the outside of the Hall thruster 101. With this configuration, unnecessary heat generation in the Hall thruster 101 can be avoided by using the latent heat of vaporization of the propellant PR. As a result, a decrease in propulsion efficiency can be prevented and the lifespan of the Hall thruster 101 can be extended.

[0036] In this case, the predetermined amount PV is preferably 10% or less of the propellant PR introduced into the vaporization chamber 180. Here, the predetermined amount PV refers to the amount of propellant PR supplied to the anode 120 out of the propellant PR introduced into the vaporization chamber 180. In other words, it is preferable that 10% or less of the propellant PR introduced into the vaporization chamber 180 is supplied to the anode 120, and the remaining propellant PR is returned to the propellant tank 21. With this configuration, the amount of propellant PR required to generate thrust in the Hall thruster 101 and the amount of propellant PR required to cool the Hall thruster 101 can be adjusted to a more favorable balance.

[0037] Furthermore, the propellant PR in this case is preferably water. Water has a large latent heat of vaporization when it vaporizes and is chemically stable, making it highly safe and reliable when used as a propellant PR. This embodiment allows for safer acquisition of latent heat of vaporization. Note that the propellant PR is not limited to water; for example, it may be xenon, krypton, or iodine, and a mixture of these gases may be used depending on the application.

[0038] Furthermore, as shown in Figure 2, the first passage 191 is configured such that the propellant PR passes near the wall portion 171. Here, the vicinity of the wall portion 171 refers to the region along at least one of the outer surfaces of the inner circumferential wall portion 172 and the outer circumferential wall portion 173. With this configuration, it is possible to transfer heat from the wall portion 171 of the channel 170 to the propellant PR passing through the first passage 191 via the passage forming portion 190 that forms the first passage 191, or via the passage forming portion 190 that forms the first passage 191 and other members. As a result, in addition to cooling by the latent heat of vaporization of the propellant PR, cooling by the propellant PR passing through the first passage 191 becomes possible. Therefore, in addition to cooling by the latent heat of vaporization of the propellant PR, cooling by the propellant PR passing through the first passage 191 can be performed more efficiently, and overheating of the Hall thruster 101 can be effectively prevented.

[0039] As shown in Figure 2, a portion of the first passage 191 may be formed by combining the passage forming portion 190 and the wall portion 171. In this configuration, the heat from the wall portion 171 of the channel 170 can be directly transferred to the propellant PR passing through the first passage 191. This suppresses localized temperature rise in the channel 170 and makes the heat distribution more uniform. As a result, the channel 170 can be cooled more efficiently.

[0040] As shown in FIG. 2, the first passage 191 may have an inner peripheral passage 191a through which the propellant PR passes in the vicinity of the inner peripheral wall portion 172 and an outer peripheral passage 191b through which the propellant PR passes in the vicinity of the outer peripheral wall portion 173. The inner peripheral passage 191a and the outer peripheral passage 191b are provided substantially concentrically with each other when viewed from the rear in a cross-section defined vertically and horizontally, and are configured to extend toward the vaporization chamber 180. According to such an aspect, it is possible to transfer the heat of the inner peripheral wall portion 172 to the propellant PR in the inner peripheral passage 191a, and further transfer the heat of the outer peripheral wall portion 173 to the propellant PR in the outer peripheral passage 191b. Thereby, heat can be efficiently recovered on both the inner peripheral side and the outer peripheral side of the channel 170, and the overall temperature of the Hall thruster 101 can be effectively controlled. As a result, the channel 170 can be cooled more efficiently, and the overall temperature distribution can be maintained uniformly by performing cooling evenly from the inner peripheral side and the outer peripheral side of the Hall thruster 101.

[0041] The vaporization chamber 180 is located on the distal side of the anode 120 as viewed from the predetermined position PP. According to such an aspect, while ensuring the design freedom of the Hall thruster 101, it is possible to perform cooling using the latent heat of vaporization of the propellant PR. Thereby, by optimizing the arrangement of the vaporization chamber 180, it is possible to achieve both the compactness of the entire structure and the cooling efficiency.

[0042] [Others] The moving body 1 according to one embodiment may be implemented in the following manner.

[0043] FIGS. 3 and 4 are a cross-sectional view for explaining another example of the internal configuration of the thruster 100 and a view showing another example of the configuration of the propellant supply unit 2, shown in the direction of the arrow A-A shown in FIG. 1B.

[0044] In the embodiment shown in FIG. 2, the case where the vaporization chamber 180 is located in front of the Hall thruster 101 has been described as an example, but it is not limited thereto. As shown in FIG. 3, the vaporization chamber 180 may be arranged in the vicinity of the wall portion 171. According to such an aspect, it becomes possible to cool the heat of the wall portion 171 of the channel 170 by the latent heat of vaporization of the propellant PR through the vaporization chamber 180, and as a result, the channel 170 can be cooled efficiently.

[0045] Furthermore, as shown in Figure 3, a portion of the vaporization chamber 180 may be composed of a wall portion 171. In this configuration, the propellant PR can come into direct contact with the wall portion 171 inside the vaporization chamber 180, and the wall portion 171 can be directly cooled by the latent heat of vaporization of the propellant PR. As a result, the channel 170 can be cooled more efficiently.

[0046] Furthermore, as shown in Figure 3, the vaporization chamber 180 may have an inner vaporization chamber 181 located near the inner circumferential wall portion 172 and an outer vaporization chamber 182 located near the outer circumferential wall portion 173. In this configuration, the heat of the inner circumferential wall portion 172 can be cooled by the latent heat of vaporization in the inner vaporization chamber 181, and the heat of the outer circumferential wall portion 173 can be cooled by the latent heat of vaporization in the outer vaporization chamber 182. As a result, the channel 170 can be cooled even more efficiently.

[0047] In the embodiment shown in Figure 2, the first passage 191 is described as being located near the channel 170, but the invention is not limited to this. As shown in Figure 4, the first passage 191 may be located near the vaporization chamber 180. Specifically, the first passage 191 is annular in cross-section defined vertically and horizontally, and is preferably located on the front side of the vaporization chamber 180. This first passage 191 is configured to uniformly distribute the propellant PR, which is introduced from the propellant supply unit 2 via the introduction passage 194, in the circumferential direction of the Hall thruster 101, and then guide it to the vaporization chamber 180. The vaporization chamber 180 is located behind the first passage 191 and is formed as an annular space in cross-section defined vertically and horizontally. The inside of the vaporization chamber 180 is structured so that the propellant PR is heated as it flows in an annular manner, and the heat generated on the outer circumference of the discharge space 174 of the Hall thruster 101 can be efficiently received. In this embodiment, by circulating the propellant PR in an annular manner in the forward region of the Hall thruster 101, heat from the outer circumference of the Hall thruster 101 can be efficiently absorbed, and the vaporization chamber 180 can be heated uniformly. As a result, vaporization efficiency can be increased while simplifying the overall structure with an axially symmetric shape.

[0048] FIG. 5 is a diagram showing another example of the overall configuration of the mobile body 1. FIGS. 6 to 8 are cross-sectional views for explaining another example of the internal configuration of the thruster 100 and diagrams showing an example of the configurations of the propellant supply unit 2 and the heat exchange unit 200, as viewed in the direction of the arrow B-B shown in FIG. 5B.

[0049] In the embodiment shown in FIG. 1, the case where the mobile body 1 includes the propellant supply unit 2, the control unit 3, and the thruster 100 has been described as an example, but the present invention is not limited to this. For example, as shown in FIG. 5, the mobile body 1 may include the propellant supply unit 2, the control unit 3, the thruster 100, and the heat exchange unit 200.

[0050] As shown in FIG. 6, the heat exchange unit 200 is configured to be connectable to the thruster 100, and the heat exchange unit 200 includes a heat exchange section 210 and a passage forming section 220.

[0051] As shown in FIG. 6, in this case, the propellant supply unit 2 further includes a passage 26, a valve 27, a pump 28, and a vaporization chamber 29 in addition to the configuration shown in FIG. 2.

[0052] The passage 26 forms a path for guiding the propellant PR from the propellant tank 21 to the hole thruster 101 by connecting to each device. Specifically, the passage 26 is connected to each device so that the propellant PR is guided to each device in the order of the propellant tank 21, the valve 27, the pump 28, the vaporization chamber 29, and the hole thruster 101 (propellant conduit 150). The valve 27 is provided on the passage 26 and is configured to be able to switch or block the flow path of the propellant PR. The pump 28 is provided on the passage 26 and is configured to pump the propellant PR toward the hole thruster 101 side. The vaporization chamber 29 is configured to vaporize the propellant PR.

[0053] As shown in Figure 6, the heat exchange unit 210 is configured to exchange heat generated at a predetermined location on the mobile body 1 with the propellant PR. In this case, the predetermined location is a predetermined location of a device connected to the mobile body 1 that requires cooling. This device is not particularly limited as long as it is connected to the mobile body 1, and may include, for example, a thruster 100 such as a Hall thruster 101, a control unit 3, a communication device, mission equipment, etc. The following explanation will use the case where the heat exchange unit 210 is connected to the Hall thruster 101 as an example.

[0054] The heat exchange section 210 shown in Figure 6 is positioned in contact with the front of the Hall thruster 101 and is configured to exchange heat with the propellant PR when the Hall thruster 101 is operating. Specifically, the heat exchange section 210 is annular in cross-section defined vertically and horizontally, and is preferably provided on the front side of the magnetic circuit 140. In other words, the predetermined parts in this case are the magnetic circuit 140, the channel 170, etc., and the heat exchange section 210 is configured to exchange heat with the propellant PR when the heat generated in the magnetic circuit 140, the channel 170, etc.

[0055] As shown in Figure 6, the passage forming section 220 forms an anode passage 221 and a heat exchange passage 222. The anode passage 221 is connected to the propellant conduit 150 via a fluid resistance 152 and a propellant inlet 151, and is configured to guide the propellant PR from outside the heat exchange unit 200 to the anode 120.

[0056] Furthermore, the heat exchange passage 222 is provided independently of the anode passage 221 and comprises a heat exchange passage 222a and a heat exchange passage 222b. The heat exchange passage 222a is connected to passage 22a and the heat exchange section 210 and is configured to guide the propellant PR supplied through passage 22a to the heat exchange section 210. In other words, the heat exchange passage 222 is configured to guide the propellant PR from outside the heat exchange unit 200 to the heat exchange section 210. When the heat exchange section 210 is connected to the Hall thruster 101, a portion of the heat exchange passage 222a shown in Figure 6 is annular in cross-section defined vertically and horizontally, and is provided on the front side of the heat exchange section 210. The heat exchange passage 222b is connected to passage 22b and the heat exchange section 210 and is configured to guide the propellant PR discharged from the heat exchange section 210 to passage 22b.

[0057] In this configuration, by using the propellant PR to generate thrust and also using it as a refrigerant for the heat exchange section 210, it is possible to avoid unnecessary heat generation in predetermined parts of the mobile body 1 (for example, the magnetic circuit 140 and channel 170 of the Hall thruster 101). As a result, it is possible to prevent a decrease in thrust efficiency and extend the lifespan of the thruster 100.

[0058] Furthermore, the propellant PR flowing through the heat exchange passage 222 is preferably pumped by a positive displacement pump (an example of pump 23). In other words, the pump 23 of the propellant supply unit 2 is preferably a positive displacement pump. In this case, the positive displacement pump (an example of pump 23) is configured such that the change in volume per unit time during suction is a predetermined value. In this case, the predetermined value is preferably set so that the local minimum static pressure inside the pump 23 exceeds the vapor pressure, and also so that the value obtained by subtracting the maximum dynamic pressure in the passage, etc. (the pressure determined by the flow velocity determined by the passage area and the diaphragm movement speed) from the total pressure of the suction part of the pump 23 exceeds the vapor pressure. By setting the predetermined value in this way, it is possible to adopt specifications for the pump 23 and a control method thereof that satisfy the condition that the pump flow rate (or discharge pressure) does not decrease. With this configuration, even when the pressure inside the propellant tank 21 and the passage 22b, etc. is close to the vapor pressure, it is possible to avoid cavitation in the pump 23 and to suck and push out the propellant PR, thereby enabling the transport of the propellant PR. Furthermore, the positive displacement pump (an example of the pump 23) is preferably equipped with a passage that does not undergo abrupt changes in flow area from the propellant PR intake to the diaphragm. With this configuration, even when the pressure inside the propellant tank 21 and the passage is close to the vapor pressure, it becomes easier to avoid cavitation in the pump 23 and to suck and push out the propellant PR, thereby making it easier to transport the propellant PR. The positive displacement pump is preferably a reciprocating type with adjustable speed so that the volume change during intake is gradual, and preferably a diaphragm type.

[0059] Furthermore, as shown in Figure 7, the heat exchange unit 200 is not limited to the configuration shown in Figure 6, and may include, for example, heat exchange sections 210a and 210b. The heat exchange sections 210a and 210b are annular in cross-section defined by the top and bottom and left and right, and are configured to be arranged in multiple stages along the axial direction of the Hall thruster 101.

[0060] The heat exchange section 210a is located on the outer circumference of the channel 170 and is configured to exchange heat generated in the channel 170 with the propellant PR. The heat exchange section 210b is located on the front side of the Hall thruster 101 and is configured to exchange heat transmitted via the magnetic circuit 140 with the propellant PR. In other words, by providing multiple heat exchange sections 210a and 210b, heat can be efficiently recovered from different heat-generating locations in the front-rear direction of the Hall thruster 101.

[0061] As shown in Figure 7, the passage forming section 220 forms an anode passage 221, a heat exchange passage 222a, a heat exchange passage 222b, and a heat exchange passage 222c. The anode passage 221 is connected to the propellant conduit 150 via a fluid resistance 152 and a propellant inlet 151, and is configured to guide the propellant PR from outside the heat exchange unit 200 to the anode 120.

[0062] The heat exchange passage 222a is connected to passage 22a and the heat exchange section 210a, and is configured to guide the propellant PR supplied through passage 22a to the heat exchange section 210a. The heat exchange passage 222b is connected to the heat exchange section 210a and the heat exchange section 210b, and is configured to guide the propellant PR heated in the heat exchange section 210a to the heat exchange section 210b. The heat exchange passage 222c is connected to the heat exchange section 210b and passage 22b, and is configured to guide the propellant PR that has passed through the heat exchange section 210b to passage 22b.

[0063] In this configuration, the propellant PR is heated in stages as it passes sequentially through the heat exchange sections 210a and 210b, thereby stabilizing the temperature of the propellant PR supplied to the Hall thruster 101. Furthermore, it becomes possible to uniformly distribute and cool the heat generated throughout the Hall thruster 101, thereby further improving propulsion efficiency and extending its lifespan.

[0064] Furthermore, as shown in Figure 8, the heat exchange unit 200 is not limited to the configuration shown in Figure 7, and may be configured by omitting, for example, the heat exchange section 210b and the heat exchange passage 222c. In other words, the heat exchange unit 200 may be configured to have a single heat exchange section 210a. In this case, the heat exchange passage 222b connects the heat exchange section 210a and the passage 22b, and is configured to guide the propellant PR that has passed through the heat exchange section 210a to the passage 22b.

[0065] This configuration allows for cooling of the main heat source, the channel 170, while simplifying the overall structure. Therefore, it is possible to achieve both the heating efficiency of the propellant PR and the cooling performance of the Hall thruster 101 while miniaturizing and reducing the weight of the heat exchange unit 200.

[0066] Figure 9 is a cross-sectional view illustrating an alternative example of the internal configuration of the thruster 100 and an alternative example of the configuration of the propellant supply unit 2, shown in the direction of the B-B arrow in Figure 5B.

[0067] In the embodiment shown in Figure 2, the passage 22a is used as an example to describe a case where the propellant PR is guided to each device in the order of propellant tank 21, valve 24a, pump 23, valve 24b, fluid resistance 25a, and Hall thruster 101, but the invention is not limited to this. As shown in Figure 9, for example, a cooling unit 23a may be provided between the propellant tank 21 and the pump 23. That is, the cooling unit 23a may be configured to cool the propellant PR being drawn into the pump 23. The cooling unit 23a is not particularly limited as long as it is capable of cooling the propellant PR being drawn into the pump 23, and for example, it may be a device that uses a Peltier element as a cooling source.

[0068] Furthermore, as shown in Figures 6 to 8, when the mobile body 1 is equipped with a heat exchange unit 200, it is preferable to provide a cooling section 23a, that is, the cooling section 23a is provided between the time the propellant is drawn from the propellant tank 21 to the pump 23. In other words, it is preferable that the propellant PR flowing through the heat exchange passage 222 be cooled by the cooling section 23a before being drawn in by the pump 23. With this configuration, even when the pressure inside the propellant tank 21 and the passage 22b is close to the vapor pressure, it becomes easier to avoid cavitation in the pump 23 and to suck and push out the propellant PR, making it easier to transport the propellant PR.

[0069] Furthermore, the pump 23 in this case is preferably a positive displacement pump. That is, the propellant PR flowing through the heat exchange passage 222 is cooled by the cooling unit 23a before being drawn in by the positive displacement pump, and then pumped by the positive displacement pump. With this configuration, even when the pressure inside the propellant tank 21 and the passage 22b is close to the vapor pressure, it becomes easier to avoid cavitation in the pump 23 and to suck and push out the propellant PR, making it easier to transport the propellant PR. Note that when the mobile body 1 is equipped with a heat exchange unit 200, the mobile body 1 (propellant supply unit 2) may not have a cooling unit 23a.

[0070] In the above embodiment, a rocket, artificial satellite, space probe, etc., was described as having a Hall thruster 101 as a structurally and electrically connected propulsion system 100. However, the invention is not limited to this, and for example, a rocket, artificial satellite, space probe, etc., may also have an ion engine as a structurally and electrically connected propulsion system 100.

[0071] Furthermore, they may be provided in the following embodiments.

[0072] (1) A Hall thruster comprising an anode, a vaporization chamber, and a passage forming section, wherein the anode is configured to supply propellant to a predetermined position in order to generate thrust, the vaporization chamber is configured to vaporize the propellant inside, the passage forming section forms a first passage, a second passage, and a third passage, the first passage is configured to guide the propellant into the vaporization chamber, the second passage is configured to guide a predetermined amount of the propellant guided into the vaporization chamber to the anode, and the third passage is configured to guide the propellant other than the predetermined amount guided into the vaporization chamber to the outside of the Hall thruster.

[0073] In this configuration, by utilizing the latent heat of vaporization of the propellant, unnecessary heat generation in the Hall thruster can be avoided. As a result, a decrease in propulsion efficiency can be prevented and the lifespan of the Hall thruster can be extended.

[0074] (2) A Hall thruster according to (1) above, further comprising a channel, the channel having a wall portion, the wall portion forming an annular discharge space for generating the thrust, the predetermined position being a predetermined position within the discharge space, and the first passage being configured such that the propellant passes near the wall portion.

[0075] In this embodiment, it is possible to transfer heat from the channel wall to the propellant passing through the first passage via the passage forming section that forms the first passage, or via the passage forming section that forms the first passage and other members. As a result, in addition to cooling by the latent heat of vaporization of the propellant, cooling by the propellant passing through the first passage becomes possible.

[0076] (3) A Hall thruster as described in (2) above, wherein a part of the first passage is formed by combining the passage forming part and the wall part.

[0077] In this configuration, heat from the channel wall can be directly transferred to the propellant passing through the first passage. As a result, the channel can be cooled more efficiently.

[0078] (4) A Hall thruster according to (2) or (3) above, wherein the wall portion has an inner circumferential wall portion that forms the inner circumferential side of the discharge space and an outer circumferential wall portion that forms the outer circumferential side of the discharge space, and the first passage has an inner circumferential passage through which the propellant passes near the inner circumferential wall portion and an outer circumferential passage through which the propellant passes near the outer circumferential wall portion.

[0079] In this configuration, heat from the inner circumferential wall can be transferred to the propellant in the inner circumferential passage, and heat from the outer circumferential wall can be transferred to the propellant in the outer circumferential passage. As a result, the channel can be cooled more efficiently.

[0080] (5) A Hall thruster according to any one of (1) to (4) above, wherein the vaporization chamber is located distal to the anode when viewed from the predetermined position.

[0081] This configuration allows for cooling using the latent heat of vaporization of the propellant while ensuring design flexibility for the Hall thruster.

[0082] (6) A Hall thruster according to any one of (1) to (4) above, further comprising a channel, wherein the channel has a wall portion, the wall portion forms an annular discharge space for generating the thrust, the predetermined position is a predetermined position within the discharge space, and the vaporization chamber is located near the wall portion.

[0083] In this configuration, the heat in the channel wall can be cooled by the latent heat of vaporization of the propellant through the vaporization chamber, and as a result, the channel can be cooled efficiently.

[0084] (7) A Hall thruster as described in (6) above, wherein a part of the vaporization chamber is formed by the wall portion.

[0085] In this configuration, the propellant can come into direct contact with the wall inside the vaporization chamber, and the wall can be directly cooled by the latent heat of vaporization of the propellant. As a result, the channel can be cooled more efficiently.

[0086] (8) A Hall thruster according to (6) or (7) above, wherein the wall portion has an inner circumferential wall portion that forms the inner circumferential side of the discharge space and an outer circumferential wall portion that forms the outer circumferential side of the discharge space, and the vaporization chamber has an inner circumferential vaporization chamber disposed near the inner circumferential wall portion and an outer circumferential vaporization chamber disposed near the outer circumferential wall portion.

[0087] In this configuration, the heat in the inner circumferential wall can be cooled by the latent heat of vaporization in the inner circumferential vaporization chamber, and the heat in the outer circumferential wall can be cooled by the latent heat of vaporization in the outer circumferential vaporization chamber. As a result, the channel can be cooled even more efficiently.

[0088] (9) A Hall thruster according to any one of (1) to (8) above, wherein the predetermined amount is 10% or less of the propellant introduced into the vaporization chamber.

[0089] In this embodiment, the amount of propellant required to generate thrust in the Hall thruster and the amount of propellant required to cool the Hall thruster can be adjusted to a more favorable balance.

[0090] (10) A Hall thruster according to any one of (1) to (9) above, wherein the propellant is water.

[0091] According to this configuration, the latent heat of vaporization can be obtained more safely.

[0092] (11) A heat exchange unit connectable to a thruster, comprising a passage forming section, the passage forming section forming an anode passage and a heat exchange passage, the anode passage being configured to guide propellant from outside the heat exchange unit to the anode, the anode being configured to supply the propellant to a predetermined position in order to generate thrust, and the heat exchange passage being configured independently of the anode passage to guide the propellant from outside the heat exchange unit to the heat exchange section, the heat exchange section being configured to exchange heat with the propellant for heat generated at a predetermined part of the moving body.

[0093] In this configuration, the propellant is used to generate thrust, and furthermore, it is used as a refrigerant in the heat exchange section, thereby preventing unnecessary heat generation in a predetermined part of the moving body. As a result, a decrease in propulsion efficiency can be prevented and the lifespan of the moving body can be extended.

[0094] (12) A heat exchange unit as described in (11) above, wherein the propellant flowing through the heat exchange passage is pumped by a positive displacement pump, wherein the positive displacement pump is configured such that the change in volume per unit time when drawing in is a predetermined value.

[0095] According to this embodiment, the propellant can be transported even when the propellant is at a pressure close to its vapor pressure.

[0096] (13) A rocket comprising a structurally and electrically connected Hall thruster, wherein the Hall thruster is a Hall thruster described in any one of (1) to (10) above.

[0097] According to this embodiment, it is possible to provide technology relating to a rocket equipped with a Hall thruster that can avoid unnecessary heat generation.

[0098] (14) An artificial satellite comprising a structurally and electrically connected Hall thruster, wherein the Hall thruster is a Hall thruster described in any one of (1) to (10) above.

[0099] According to this embodiment, it is possible to provide technology for a satellite equipped with a Hall thruster that can avoid unnecessary heat generation due to the latent heat of vaporization of the propellant.

[0100] (15) A space probe comprising a structurally and electrically connected Hall thruster, wherein the Hall thruster is a Hall thruster described in any one of (1) to (10) above.

[0101] In this embodiment, it is possible to provide technology for a space probe equipped with a Hall thruster that can avoid unnecessary heat generation due to the latent heat of vaporization of the propellant. Of course, this is not limited to this.

[0102] Finally, various embodiments of the present invention have been described, but these are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0103] 1: Mobile body, 2: Propellant supply unit, 21: Propellant tank, 22: Passage, 22a: Passage, 22b: Passage, 23: Pump, 23a: Cooling section, 24: Valve, 24a: Valve, 24b: Valve, 24c: Valve, 25: Fluid resistance, 25a: Fluid resistance, 26: Passage, 27: Valve, 28: Pump, 29: Vaporization chamber, 3: Control unit, 100: Thruster, 101: Hall thruster, 110: Cathode, 111: Power supply, 120: Anode, 130: Magnetic coil, 140: Magnetic circuit, 150: Propellant conduit, 151: Propellant inlet, 152: Fluid resistance, 160: Plenum chamber, 170: Channel, 171: Wall section, 172: Inner circumferential wall portion, 173: Outer circumferential wall portion, 174: Discharge space, 180: Vaporization chamber, 181: Inner circumferential vaporization chamber, 182: Outer circumferential vaporization chamber, 190: Passage forming portion, 191: First passage, 191a: Inner circumferential passage, 191b: Outer circumferential passage, 192: Second passage, 193: Third passage, 194: Introduction passage, 200: Heat exchange unit, 210: Heat exchange portion, 210a: Heat exchange portion, 210b: Heat exchange portion, 220: Passage forming portion, 221: Anode passage, 222: Heat exchange passage, 222a: Heat exchange passage, 222b: Heat exchange passage, 222c: Heat exchange passage, E: Electron, I: Ion, PD: Determined direction, PP: Determined position, PR: Propellant, PV: Determined amount

Claims

1. A Hall thruster comprising an anode, a vaporization chamber, and a passage forming section, wherein the anode is configured to supply propellant to a predetermined position in order to generate thrust, the vaporization chamber is configured to vaporize the propellant inside, the passage forming section forms a first passage, a second passage, and a third passage, the first passage is configured to guide the propellant into the vaporization chamber, the second passage is configured to guide a predetermined amount of the propellant guided into the vaporization chamber to the anode, and the third passage is configured to guide the propellant other than the predetermined amount guided into the vaporization chamber to the outside of the Hall thruster.

2. A Hall thruster according to claim 1, further comprising a channel, the channel having a wall portion, the wall portion forming an annular discharge space for generating the thrust, the predetermined position being a predetermined position within the discharge space, and the first passage being configured such that the propellant passes near the wall portion.

3. A Hall thruster according to claim 2, wherein a part of the first passage is formed by combining the passage forming portion and the wall portion.

4. A Hall thruster according to claim 2 or claim 3, wherein the wall portion has an inner circumferential wall portion that forms the inner circumferential side of the discharge space and an outer circumferential wall portion that forms the outer circumferential side of the discharge space, and the first passage has an inner circumferential passage through which the propellant passes near the inner circumferential wall portion and an outer circumferential passage through which the propellant passes near the outer circumferential wall portion.

5. A Hall thruster according to any one of claims 1 to 4, wherein the vaporization chamber is located distal to the anode when viewed from the predetermined position.

6. A Hall thruster according to any one of claims 1 to 4, further comprising a channel, wherein the channel has a wall portion, the wall portion forms an annular discharge space for generating the thrust, the predetermined position is a predetermined position within the discharge space, and the vaporization chamber is located near the wall portion.

7. A Hall thruster according to claim 6, wherein a part of the vaporization chamber is formed by the wall portion.

8. A Hall thruster according to claim 6 or claim 7, wherein the wall portion has an inner circumferential wall portion that forms the inner circumferential side of the discharge space and an outer circumferential wall portion that forms the outer circumferential side of the discharge space, and the vaporization chamber has an inner circumferential vaporization chamber disposed near the inner circumferential wall portion and an outer circumferential vaporization chamber disposed near the outer circumferential wall portion.

9. A Hall thruster according to any one of claims 1 to 8, wherein the predetermined amount is 10% or less of the propellant introduced into the vaporization chamber.

10. A Hall thruster according to any one of claims 1 to 9, wherein the propellant is water.

11. A heat exchange unit connectable to a thruster, comprising a passage forming section, the passage forming section forming an anode passage and a heat exchange passage, the anode passage configured to guide propellant from outside the heat exchange unit to the anode, the anode configured to supply the propellant to a predetermined position in order to generate thrust, and the heat exchange passage configured to guide the propellant from outside the heat exchange unit to the heat exchange section independently of the anode passage, the heat exchange section configured to exchange heat generated at a predetermined part of a moving body with the propellant.

12. A heat exchange unit according to claim 11, wherein the propellant flowing through the heat exchange passage is pumped by a positive displacement pump, wherein the positive displacement pump is configured such that the change in volume per unit time when drawing in is a predetermined value.

13. A rocket comprising a structurally and electrically connected Hall thruster, wherein the Hall thruster is a Hall thruster according to any one of claims 1 to 10.

14. An artificial satellite comprising a structurally and electrically connected Hall thruster, wherein the Hall thruster is a Hall thruster according to any one of claims 1 to 10.

15. A space probe comprising a structurally and electrically connected Hall thruster, wherein the Hall thruster is a Hall thruster according to any one of claims 1 to 10.

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