JP7085261B2 - Manufacturing method of Hall thruster heater and Hall thruster heater - Google Patents

Description

The present invention is, for example, a Hall thruster heater and a Hall thruster that heat an inserter (thermionic source) of a cathode that emits electrons to a high temperature in a Hall thruster as an electric propulsion machine used for orbit change and attitude control of a small satellite. It relates to a method of manufacturing a heater for a heater.

Conventionally, as a hall-thruster heater similar to the above-mentioned heater, for example, the graphite heater described in Patent Document 1 is known.
The graphite heater includes a cylindrical heater main body and terminal portions extending in the axial direction from a plurality of locations at one end of the heater main body. The cylindrical heater body is provided with slits alternately from one end and the other end, and the portion partitioned by these slits in a zigzag shape functions as a current path (tropical).

Japanese Unexamined Patent Publication No. 2013-220954

A heating element such as the above-mentioned graphite heater can be made compact because the electric resistance can be increased by reducing the cross-sectional area of the current path, for example, by reducing the wall thickness of the heating element.
However, while graphite is resistant to thermal deformation and has excellent corrosion resistance, it has low impact strength and is prone to brittle fracture. Therefore, when graphite heaters are thinned and used for Hall thrusters, they are used during thruster assembly. There is an extremely high possibility that the heater body will be crushed or the terminal portion will be cut off.

Therefore, in the case of a graphite heater, there is no choice but to increase the wall thickness and widen the slit spacing to widen the current path width (shorten the current path length) to increase the size, but the mechanical strength is still high. It is still low and brittle, and the electrical resistance decreases as the size increases.

As a result, when it is used for a Hall thruster, in addition to hindering the miniaturization of the thruster and deteriorating the assembly workability, a large current is required due to the small electric resistance, so that the power supply capacity is increased. As the size increases, the electric wire that supplies the current also becomes thicker, which leads to an increase in the weight of the Hall thruster, and solving these problems has been a conventional problem.

The present invention has been made by paying attention to the above-mentioned conventional problems, and by increasing the impact strength and the material strength, it is possible to contribute to the miniaturization of the Hall thruster and the improvement of the assembly workability, and the current path. Since the cross-sectional area can be reduced and the electrical resistance can be increased, it is an object of the present invention to provide a Hall thruster heater and a Hall thruster heater manufacturing method capable of efficiently heating a cathode inserter.

The first aspect of the present invention is a heater for a hole thruster that heats a cylindrical inserter of a cathode that emits electrons in a hole thruster, which is composed of a C / C composite and is arranged outside the inserter of the cathode. A heater body having a cylindrical shape and having slits in the direction along the axis alternately provided from one end and the other end, and an extension extending in the direction along the axis from a plurality of places at one end of the heater body. The cylindrical heater body and the extending portion are formed by laminating a plurality of carbon fiber blade fabrics having different carbon fiber orientation angles from each other. The flange is formed of carbon fiber preform, the flange is ring-shaped, and a joint portion with the extending portion is formed on the inner peripheral surface thereof, and the flange is centered on the heater. By joining the joining tip of the extending portion to the joining portion while being positioned on the axis of the main body, the structure is integrated with the heater main body .

On the other hand, the invention according to claim 2 of the present invention is a method for manufacturing a heater for a hole thruster that heats a cylindrical inserter of a cathode that emits electrons in a hole thruster, and a carbon fiber blade weaving operation is performed to obtain carbon fibers. Following the formation of a cylindrical material composed of a plurality of layers of reinforcing fiber bands having different orientation angles, the cylindrical material is subjected to pitch impregnation treatment, HIP treatment, and calcined carbonization treatment a plurality of times, and then the cylindrical shape. In the material, slits in the direction along the axis are alternately formed from one end and the other end, and extension portions extending in the direction along the axis are formed from a plurality of places at one end of the cylindrical material to form a heater main body material. After forming the molded base material with the carbon fiber preform, the molded base material is subjected to a pitch impregnation treatment, a HIP treatment and a fired carbonization treatment a plurality of times, respectively, and then the molded base material is ringed. A step of forming a ring-shaped flange material by forming a joint portion with the bonding tip of the extending portion of the heater main body material on the inner peripheral surface of the ring-shaped molded base material. ,
At least one of joining of the joining portion of the flange material to the joining tip of the extending portion of the heater main body material with an adhesive, and joining by pitch impregnation treatment, HIP treatment, and firing carbonization treatment. After being integrated with the above, it is configured to undergo a process of performing a finishing process to obtain a heater for a Hall thruster.

In the hole thruster heater according to the present invention, the cylindrical heater body and the extending portion are formed by laminating a plurality of carbon fiber blade fabrics having different carbon fiber orientation angles from each other, and are formed by pitch impregnation treatment, HIP treatment and firing. Since it is made through carbonization treatment, it can withstand processing to reduce the thickness and width of the current path, and it is possible to increase the electrical resistance while achieving compactness, and as a result, the cathode inserter. Can be heated with a small current.

Further, since the electrode fixed to the flange comes into contact with the heater body, it is not necessary to firmly join the flange and the tip of the extending portion, and the joining with an adhesive, the pitch impregnation treatment, and the HIP treatment are performed. The strength can be ensured by joining at least one of the joining by the calcining carbonization treatment.

On the other hand, since the flange is formed of carbon fiber preform and has undergone pitch impregnation treatment, HIP treatment and calcining carbonization treatment, it has a higher density, higher impact strength and brittleness than the heater body and the extension portion. Destruction is unlikely to occur. Electrodes are fixed to this flange, but since the electrical resistance is small, current flows through this flange and extra power consumption can be suppressed.

Further, when assembling the Hall thruster, there is almost no possibility that the heater main body is crushed or damaged, so that the assembling workability is improved.

The Hall-thruster heater according to the present invention has a very excellent effect that it can contribute to the miniaturization of the Hall-thruster and the improvement of assembly workability, and can heat the cathode inserter with a small current. Brought to you.

Further, the method for manufacturing a Hall thruster heater according to the present invention has a very excellent effect that a heater for Hall thrusters having high impact strength and material strength and high resistance can be manufactured.

It is a perspective explanatory drawing which shows the Hall thruster equipped with the heater for Hall thruster by one Embodiment of this invention. It is sectional drawing which shows the operation principle of the cathode of the heater for Hall thruster in FIG. A perspective explanatory view (a) showing a Hall thruster heater in FIG. 2, an explanatory view (b) in the P direction in FIG. 3 (a), and a cross-sectional explanatory view (c) based on the QQ line position in FIG. 3 (b). ). It is explanatory drawing of the manufacturing process of the heater for Hall thruster in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a main part of a Hall thruster equipped with a Hall thruster heater according to an embodiment of the present invention.

As partially shown in FIG. 1, the Hall thruster 1 has a disc-shaped anode (anode) 2, a cylindrical cathode (cathode) 3 whose axis passes through the center of the anode 2, and the cathode. A cylindrical acceleration channel 4 coaxially arranged around the cathode 3 is provided, and a plurality of propellant injection holes 2a for injecting the propellant F into the space between the cathode 3 and the acceleration channel 4 are arranged in the anode 2. Has been done.

An electric field E is applied in the axial direction of the acceleration channel 4, a magnetic field B is applied in the radial direction, and the electrons e emitted from the cathode 3 and flow into the space between the cathode 3 and the acceleration channel 4 are the electric field E. And the action of the magnetic field B causes a hole motion in the circumferential direction, which induces a hole current.

Then, the electrons e that perform Hall motion in the circumferential direction collide with the neutral particles of the propellant F ejected from the propellant injection hole 2a of the anode 2, and ions (+) are generated, and the generated ions ( +) Is accelerated by the electric field E and emitted in the axial direction, and the thrust of the Hall thruster 1 as a propulsion device is obtained by this reaction.

At this time, the same number of electrons e as the emitted ions (+) are emitted from the cathode 3, so that the electrical neutrality of the Hall thruster 1 is maintained. Further, the electron e moving in the hall in the acceleration channel 4 gradually flows to the anode 2 while consuming the energy acquired by the potential difference for the ionization of the propellant F.

As shown in FIG. 2, a cylindrical inserter 31 made of a chemical substance, for example, LaB6 (lanthanum hexaboride), is arranged inside the tip portion (right end portion in the drawing) of the cathode 3 that emits electrons e. A heater 10 for heating the inserter 31 to a high temperature is arranged outside the tip of the cathode 3. Further, a keeper 32, which is an electrode positively applied to the cathode 3, is arranged at an outlet at the tip of the cathode 3 for emitting electrons e.

In the cathode 3 having such a structure, when the inserter 31 is heated to a high temperature by the heater 10, the heat-excited electrons e are emitted by the inserter 31, and the heat-excited electrons e are supplied from the upstream side (left side in the drawing). It ionizes and collides with the working gas Xe to generate plasma Xe ⁺ . Then, when the plasma Xe ⁺ reaches the keeper 32 positively applied to the cathode 3, the electrons e are drawn out from the plasma Xe ⁺ to the outside of the cathode 3 and emitted.

As shown in FIG. 3, the heater 10 for heating the inserter 31 of the cathode 3 to a high temperature is made of a C / C composite as a whole, and is a cylindrical heater arranged with a space outside the cathode 3. It has a main body 11. The heater main body 11 is provided with slits 11c in the direction along the axis alternately from one end 11a and the other end 11b. Further, the heater 10 includes extending portions 12 extending in a direction along the axis from two positions at one end 11a of the heater main body 11.

At this time, the heater main body 11 and the extending portion 12 are biaxial reinforcing fiber bands having different orientation angles of carbon fibers with respect to the axial direction of the heater main body 11, for example, biaxial reinforcing fibers having an orientation angle of ± 45 °. It is formed by laminating a plurality of biaxial woven fabrics made by weaving a band with a blade. Alternatively, the orientation angle of the heater main body 11 with respect to the axial center direction is, for example, 0 °, which is formed by weaving a total of three reinforcing fiber bands in which a one-axis reinforcing fiber band is added to the above two-axis reinforcing fiber bands. It is formed by laminating a plurality of shaft fabrics.

Further, the heater 10 includes a ring-shaped flange 13 to which the electrode 14 in contact with the heater main body 11 is fixed, and the flange 13 is formed of carbon fiber preform. A connecting portion 13a is formed on the inner peripheral surface of the ring-shaped flange 13, and the flange 13 extends to the connecting portion 13a with its center positioned on the axis of the heater main body 11. By joining the joining tip 12a of the portion 12, it is integrated with the heater main body 11.

As shown in FIG. 4, the Hall thruster heater 10 is manufactured through a step of obtaining a heater main body material, a step of obtaining a flange material, and a step of obtaining a finished product of the heater 10.

In the process of obtaining the heater main body material, first, a carbon fiber blade weaving operation is performed to form a biaxial woven fabric (or triaxial woven fabric) composed of biaxial reinforcing fiber bands having different orientation angles of carbon fibers. A plurality of biaxial woven fabrics (or triaxial woven fabrics) are laminated to form a cylindrical material.

Next, the cylindrical material is sequentially subjected to pitch impregnation treatment, HIP treatment for compressing at high pressure, and calcining carbonization treatment for graphitizing at high temperature, and these treatments are repeated a plurality of times (twice in this embodiment).

After that, slits 11c in the direction along the axis are alternately arranged from one end 11a and the other end 11b in the cylindrical material by machining to form a current path (tropical), and a plurality of places at one end 11a (this implementation). A heater main body material is obtained by forming an extension portion 12 having a joining tip 12a extending in a direction along the axis from two places).

In the process of obtaining the next flange material, first, a molded base material is formed with carbon fiber preform. Following this, the molded substrate is also subjected to pitch impregnation treatment, HIP treatment for compressing at high pressure, and calcining carbonization treatment for graphitizing at high temperature, and these treatments are performed a plurality of times (three times in this embodiment). )repeat.

After that, as in the case of the cylindrical material, a ring-shaped flange material is formed by machining, and the ring-shaped flange material is provided with a joining portion 13a of the extending portion 12 of the heater main body material with the joining tip 12a. Form.

Then, in the process of obtaining the finished product of the heater 10, the adhesive is applied to the tip of the extending portion 12 of the heater main body material with the center of the ring-shaped flange material positioned on the axis of the heater main body material. The heater material is formed by joining and integrating the joint portion 13a of the flange material through the joint portion 13a.

Following this, the integrated heater material is sequentially subjected to pitch impregnation treatment, HIP treatment for compressing at high pressure, and calcining carbonization treatment for graphitizing at high temperature, and these treatments are performed at least once and then finished. Processing is performed to obtain a Hall thruster heater 10.

The joint portion 13a of the flange material is bonded to the tip of the extending portion 12 of the heater main body material with an adhesive, or at least one of a pitch impregnation treatment, a HIP treatment, and a fired carbonization treatment. However, in order to secure the joining strength of the joining portion 13a of the flange material with respect to the tip of the extending portion 12 of the heater main body material, the adhesive and the pitch impregnation treatment, as in this embodiment, It is desirable to integrate by both HIP treatment and calcined carbonization treatment.

In the hole thruster heater 10 thus obtained, the cylindrical heater body 11 and the extending portion 12 are formed of a plurality of layers of biaxial fabric (or triaxial fabric) having different carbon fiber orientation angles from each other. , Pitch impregnation treatment, HIP treatment for compression at high voltage, and calcined carbonization treatment for graphite formation at high temperature, so that it can withstand processing to reduce the thickness and width of the current path, making it compact. As a result, the inserter 31 of the cathode 3 can be heated with a small current.

Further, since the electrode 14 fixed to the flange 13 is in contact with the heater main body 11, the bonding strength is ensured by both bonding with an adhesive and bonding by pitch impregnation treatment, HIP treatment and firing carbonization treatment. You will get it.

On the other hand, since the flange 13 is formed of carbon fiber preform and has undergone pitch impregnation treatment, HIP treatment and calcining carbonization treatment, it has a higher density and higher impact strength than the heater main body 11 and the extension portion 12, and has higher impact strength. , Brittle fracture is unlikely to occur.

At this time, the electrode 14 is fixed to the flange 13, but since the electric resistance is small, the current flows through the flange 13 and the extra power consumed can be suppressed to a small level.

Further, when assembling the Hall thruster 1, there is almost no possibility that the heater main body 11 is crushed or damaged, so that the assembling workability is improved.

Therefore, a cylindrical heater body material obtained by repeating a pitch impregnation treatment, a HIP treatment, and a calcined carbonization treatment three times each, formed by a plurality of layers of three-axis reinforcing fiber bands having different orientation angles of carbon fibers (implementation). Example 1; with C / C shaft yarn (3HIP)), and the carbon fibers are formed of biaxial reinforcing fiber bands having multiple layers with different orientation angles, and the pitch impregnation treatment, the HIP treatment, and the calcined carbonization treatment are performed three times. It is formed of a cylindrical heater body material (Example 2; without C / C shaft thread (3HIP)) obtained by repeating each process and a carbon fiber preform, and is subjected to pitch impregnation treatment, HIP treatment and calcining carbonization treatment four times. The strengths of the flange material (Example 3; C / C (4HIP)) obtained by repeating the process and the heater body made of high-density graphite having a density of about 1.89 g / cm ³ were compared.

Each density (g / cm ³ ), impact absorption energy (kJ / m ² ), bending strength (MPa) of the heater body material of Examples 1 and 2, the flange material of Example 3, and the heater body of the comparative example. And the electrical resistivity (μΩ ・ m) are shown in Table 1.

As can be seen from Table 1, the heater body materials of Examples 1 and 2 are inferior in density to the heater body made of high-density graphite of the comparative example, but all of them are compared in terms of impact absorption energy, bending strength and electrical resistivity. The heater main body of the example is exceeded, and in particular, the heater main body material formed of the three-axis reinforcing fiber band of the first embodiment significantly exceeds the impact absorption energy and the bending strength, and therefore, from this, the present embodiment. It was demonstrated that the heater main body material according to No. 1 has higher impact strength and is less likely to cause brittle fracture than the heater main body of the comparative example.

Further, as can be seen from Table 1, the flange material of Example 3 is, of course, a flange by intentionally increasing the density and lowering the electrical resistivity as compared with the heater main body materials of Examples 1 and 2. The impact absorption energy and bending strength are significantly exceeded while suppressing the consumption of extra current by the material. Therefore, the flange material of the third embodiment has the impact strength and brittleness required for the flange. It was demonstrated that they have both strengths.

In the above-described embodiment, the pitch impregnation treatment, the HIP treatment, and the firing carbonization treatment of the cylindrical material of the heater main body material are repeated twice, and the pitch impregnation treatment, the HIP treatment, and the firing carbonization treatment of the molded substrate of the flange material are repeated three times. However, the number of processes is not limited to this.

Further, in the above-described embodiment, the pitch impregnation treatment, the HIP treatment, and the firing carbonization treatment are performed once on the heater material in which the flange material is integrated with the heater main body material, but the number of treatments is limited to this. is not.

The configuration of the Hall thruster heater and the Hall thruster heater manufacturing method according to the present invention is not limited to the configuration of the above-described embodiment.

1 Hall thruster 3 Cathode
10 Hall thruster heater 11 Heater body 11a One end of the heater body 11b The other end of the heater body 11c Slit 12 Extension 12a Tip for joining the extension 13 Flange 13a Flange joint 14 Electrode 31 Insertor

Claims (2)

A Hall thruster heater that heats the cylindrical inserter of the cathode that emits electrons in the Hall thruster.
Consists of C / C composite
A heater body having a cylindrical shape arranged outside the inserter of the cathode and having slits in the direction along the axis alternately provided from one end and the other end.
Extensions extending in the direction along the axis from multiple locations at one end of the heater body,
It is provided with a flange to which an electrode in contact with the heater body is fixed.
The cylindrical heater body and the extending portion are formed by laminating a plurality of carbon fiber blade fabrics having different carbon fiber orientation angles from each other.
The flange is made of carbon fiber preform and
The flange has a ring shape, and a joint with the extending portion is formed on the inner peripheral surface thereof, and the flange has the joint with its center positioned on the axis of the heater body. A Hall thruster heater integrated into the heater body by joining the joining tip of the extending portion to the portion. A method for manufacturing a heater for a Hall thruster that heats a cylindrical inserter of a cathode that emits electrons in a Hall thruster.
A carbon fiber blade weaving operation is performed to form a cylindrical material composed of multiple layers of reinforcing fiber bands having different carbon fiber orientation angles, and then the cylindrical material is subjected to pitch impregnation treatment, HIP treatment and calcining carbonization treatment. After performing each of a plurality of times, slits in the direction along the axis are alternately formed from one end and the other end of the cylindrical material, and the cylindrical material extends from a plurality of places on one end of the cylindrical material in the direction along the axis. The process of forming the extension and obtaining the heater body material,
Following the formation of the molded base material with the carbon fiber preform, the molded base material is subjected to a pitch impregnation treatment, a HIP treatment, and a calcined carbonization treatment a plurality of times, respectively, and then the molded base material is formed into a ring shape. A step of forming a joint portion of the heater main body material with the bonding tip of the extension portion on the inner peripheral surface of the ring-shaped molded base material to obtain a ring-shaped flange material.
At least one of joining of the joining portion of the flange material to the joining tip of the extending portion of the heater main body material with an adhesive, and joining by pitch impregnation treatment, HIP treatment, and firing carbonization treatment. A method for manufacturing a Hall-thruster heater, which undergoes a process of obtaining a Hall-thruster heater by performing a finishing process after being integrated with the above.

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