JP2597601B2 - Ion thruster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an ion thruster used for controlling the orbit of an artificial satellite.

(Prior Art) An ion thruster used for controlling the orbit of an artificial satellite or the like is usually configured as shown in FIG.
That is, the Xe gas introduced from the gas introduction system into the discharge vessel 2 through the hollow cathode 1 is added to the hollow cathode 1
The electrons accelerated by the anode 3 after being emitted from the ion source collide with each other to generate ionized plasma in the discharge chamber, and the generated Xe ⁺ ions are given kinetic energy by the acceleration electrode 4,
This is neutralized by the electrons emitted from the neutralizer 5 and then released to obtain a thrust. At this time, in order to reduce the loss of the ionized plasma, the magnet 6 forms a cusp magnetic field to confine the ionized plasma, thereby controlling the loss from the wall surface of the discharge vessel 8. In the drawing, reference numeral 7 denotes a thruster case, and reference numeral 8 denotes a baffle plate.

By the way, in such an ion thruster, when the discharge power is increased, the plasma density is increased, and the thrust is increased, the temperatures of the discharge vessel 2 and the acceleration electrode 4 increase. The amount of heat that has flowed into the discharge vessel 2 is transmitted to the thruster case 7 by heat conduction, a part of the heat is released to the satellite main body by heat conduction, and the rest is released to space by heat radiation. On the other hand, most of the heat flowing into the accelerating electrode 4 is released into outer space by thermal radiation.

As shown in FIG. 8, the accelerating electrode 4 is usually constituted by three thin electrode plates 4a, 4b, 4c with a gap of about 1 mm therebetween. Each electrode plate 4a, 4b, 4c has a coaxial electrode hole
Many sets of 9,10,11 are provided. Then, the electrode plate 4a is held at, for example, 1 kV, the electrode plate 4b is held at -800 V, and the electrode plate 4c is held at 0 V, thereby exhibiting an acceleration function. Each electrode plate 4a, 4b, 4c is usually
It is formed of a metal plate having a thickness of about 0.3 mm.
Therefore, heat radiation due to heat conduction is small, and the temperature at the center is several tens of degrees higher than that at the periphery. Therefore, the electrode plate
4a, 4b, 4c are easily thermally deformed. On the other hand, in order to increase the utilization rate of ions, it is necessary to reduce the gap between the electrode plates 4a and 4b to about 1 mm, and to increase the solid angle viewed from the electrode hole 10 through the electrode hole 9. As described above, when the gap between the electrode plates is narrow and the electrode plates are easily deformed by heat, the electrode plates come into contact with each other when the electrode plates are thermally deformed, and the function as an acceleration electrode is lost. Become. Therefore, it is necessary to absorb the thermal deformation of the electrode plate by some means.

Therefore, in the conventional ion thruster, as shown in FIGS. 9 (a) and 9 (b), a cut 13 is provided in the electrode plate support portion 12 so that the electrode plate support portion 12 has a spring property. Has adopted.

However, with such a structure, the notch
When forming 13, the electrode plate support 12 is easily deformed, and it is extremely difficult to manufacture the electrode plate support 12 with high accuracy.

(Problems to be Solved by the Invention) The present invention can surely absorb the thermal expansion of the accelerating electrode without making the production difficult, thereby achieving high thrust,
An object of the present invention is to provide an ion thruster capable of realizing high efficiency.

[Structure of the Invention] (Means for Solving the Problems) The present invention is characterized in that a spring mechanism is provided on an outer peripheral portion of an acceleration electrode plate to absorb thermal expansion of the acceleration electrode plate.

(Operation) Since the spring mechanism is provided on the outer peripheral portion of the thin electrode plate, high-precision processing is easy, and the elastic plate can be easily elasticized and the electrode plate is supported by the rigid electrode plate support portion. The accuracy of the gap between them can be ensured.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an ion thruster according to an embodiment of the present invention, and the same parts as those in FIG. 7 are denoted by the same reference numerals.
Therefore, the description of the overlapping part will be omitted.

The difference of the ion thruster according to this embodiment from the conventional one is the configuration of three electrode plates 4a, 4b, 4c constituting the accelerating electrode 4. That is, in each of the electrode plates 4a, 4b, 4c, a plurality of cuts 21 are provided in the circumferential direction outside the portion where the electrode holes 9 (10, 11) are provided as shown in FIG. . Due to the presence of the notch 21, the electrode plate 4a (4b, 4b
At the periphery of c), the spring pieces 22 are formed in six places in this example.
Are formed. On the electrode plate support portion 23 side, as shown in FIG. 2, a screw 25 is inserted into a hole 24 provided at the free end (tip) of the spring piece 22, and the spring piece is The electrode plates 4a (4b, 4c) are fixed to the electrode plate support 23 to such an extent that the elasticity of the electrode 22 is not lost.

With such a configuration, the radial expansion due to the thermal expansion of the electrode plates 4a (4b, 4c) is absorbed up to the gap of the cut 21, whereby the axial expansion of the electrode plates 4a (4b, 4c) is reduced. It will be kept small. Therefore, the change in the electrode plate gap can be suppressed to a small value, and performance degradation due to thermal deformation of the acceleration electrode 4 can be prevented. Since the thickness of the electrode plates 4a, 4b, 4c is as thin as about 0.3 mm, the processing of the cut 21 is easy, and the deformation of the electrode plates 4a, 4b, 4c during the processing can be prevented. Further, the gap between the respective electrode plates can be easily and accurately set by the electrode plate supporting portion 23 having the rigid structure.

The present invention is not limited to the embodiments described above. That is, as shown in FIG. 4, the notches 21 may be provided in a straight line to facilitate processing. Further, as shown in FIG. 5 and FIG.
A plurality of protrusions 26 are integrally provided on the periphery of 4a (4b, 4c) at a plurality of positions, and the protrusions 26 are connected to the electrode plate as shown in FIG.
The bent portion 27 may be bent in a direction orthogonal to 4a (4b, 4c) so as to exhibit a spring property for absorbing thermal expansion. When the thickness of the electrode plates 4a, 4b, 4c can be increased, each electrode plate may be fixed using a conventional electrode plate support. In this case, the stress in the radial direction increases, so that the cut 21 shown in FIG.
It is more advantageous to provide. Further, when the electrode plate supporting portion is constituted by a plurality of columns or the like, it is advantageous to provide the bent portion 27 shown in FIG. 5 and FIG. Further, the electrodes may be assembled in a state where a tensile stress is applied to each electrode plate. Further, Xe is used as the introduced gas, but is not limited to Xe gas. In addition, although three electrodes are used as the accelerating electrodes 4, the number is not limited to three. Also, the electrode plate need not have a curvature. Further, although an electron impact type of a cusp magnetic field confinement method is used as a discharge type, the present invention is not limited to this discharge type, and for example, a high frequency type can be similarly applied.

[Effects of the Invention] As described above, according to the present invention, it is possible to realize an acceleration electrode that does not have a risk of deteriorating performance even in a large ion thruster, and thus can contribute to the realization of a high thrust and high efficiency ion thruster.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an ion thruster according to an embodiment of the present invention, with a part cut away. FIG. 2 is a longitudinal sectional view showing only an accelerating electrode plate portion of the ion thruster.
FIG. 4 is a plan view of the electrode plate, FIG. 4 is a plan view of a modification of the electrode plate, FIG. 5 is a plan view of another modification of the electrode plate, and FIG. FIG. 7 is a perspective view showing a main part of the conventional ion thruster with a part cut away, FIG. 8 is a sectional view showing the accelerating electrode of the thruster partially taken out, and FIG. It is sectional drawing for demonstrating the mounting structure of an acceleration electrode plate. DESCRIPTION OF SYMBOLS 1 ... hollow cathode, 2 ... discharge vessel, 3 ... anode, 4 ... acceleration electrode, 4a, 4b, 4c ... electrode plate, 5 ... neutralizer, 6 ... magnet, 7 ... thruster case , 9,10,11 ……
Electrode hole, 21 ... cut, 22 ... spring piece, 23 ... electrode plate support, 24 ... hole, 26 ... projecting part, 27 ... bent part.

Claims (4)

(57) [Claims] 1. An ion thruster comprising a plurality of electrode plates for acceleration arranged close to each other, wherein a spring mechanism for absorbing thermal expansion is provided on an outer peripheral portion of each electrode plate for acceleration. . 2. The ion thruster according to claim 1, wherein said spring mechanism is formed by a cut formed in a circumferential direction on an outer peripheral portion of said acceleration electrode plate. 3. The patent according to claim 2, wherein said spring mechanism is constituted by a projecting portion projecting from a peripheral portion of said acceleration electrode plate so as to have elasticity in a direction perpendicular to said acceleration electrode plate. The ion thruster according to claim 1. 4. The ion thruster according to claim 1, wherein said electrode plate for acceleration is assembled by applying a tensile stress during assembly.