JPH06302296A - Space gas analyzer - Google Patents

Abstract

(57) [Abstract] [Purpose] Monitoring device for on-orbit gas to be mounted on an artificial satellite [Constitution] As the artificial satellite advances, gas molecules coming through the opening of the artificial satellite are ionized and do not accelerate. , The energy of the molecule is discriminated by a reflection type energy analyzer. [Function] Since all the molecules entering the artificial satellite have the same artificial satellite velocity, mass spectrometry can be performed by energy analysis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for analyzing gas existing in the orbit space of artificial satellites surrounding the earth. Since the surface material of an artificial satellite is deteriorated by sputtering or chemical reaction of the surface material caused by collision with gas molecules existing in orbit, this is related to the life of the artificial satellite. Therefore, there is a demand for a gas analysis means suitable for mounting on an artificial satellite.

[0002]

2. Description of the Related Art Conventionally, a quadrupole type or magnetic field type mass spectrometer used on the ground has been used for the above-mentioned purpose. However, since the magnetic field type is heavy, it is disadvantageous to mount it on an artificial satellite. The quadrupole type can be made lighter than the magnetic field type, but the power supply circuit is complicated, and it is by no means suitable for mounting on a satellite in terms of reliability and weight. For this reason, there have been proposed methods such as gas analysis by a sputtering phenomenon caused by collision of a gas on the orbit with a target, detection of chemical change of the target, or use of light scattering. If the satellite is not collected, the result will not be known, or the measured value will not appear unless it takes a certain amount of time, so it cannot be said that the on-orbit gas is continuously analyzed immediately after the satellite is launched. Moreover, the conventional device cannot distinguish between the outgas emitted from the artificial satellite itself and the original space gas.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas analysis means for an artificial satellite, which is light in weight, has a simple structure, and can immediately obtain measurement results.

[0004]

[Means for Solving the Problems] A neutral molecular ionization section which is open toward the traveling direction of a satellite, and a reflection electric field type energy analyzer arranged behind the ionization section,
An artificial satellite will be equipped with a device consisting of an ion detector.

[0005]

[Operation] The gas existing in the orbital space of the artificial satellite can be regarded as an extension of the earth's atmosphere to outer space and is a gas sphere stationary with respect to the earth. Therefore, the artificial satellite is advancing at the satellite velocity with respect to the gas in this gas range, and when viewed from the artificial satellite, the gas in the orbit is observed as a molecular flow accelerated to the satellite velocity. Since such gas molecules are taken into the ionization section, according to the present invention, ions accelerated to a constant velocity can be obtained without an ion acceleration means. On the ground, since the ion beam accelerates in the electric field after ionizing neutral molecules, the ion velocity is different depending on the mass, and therefore the mass analysis cannot be performed only by the electric field, but in the case of the present invention, the obtained ion is the ion mass. Since they are all the same regardless of, the kinetic energy of the ion is proportional to the ion mass. Therefore, the ion mass can be discriminated by the energy analyzer. Unlike the energy analyzer that performs energy analysis by focusing incident ions at different positions according to energy, the reflected electric field type energy analyzer does not require the incident ions to be in the shape of a beam, so the direction of the incident ions That is, the ion detection sensitivity does not change even if the orientation of the artificial satellite changes slightly.

[0006]

FIG. 1 shows an embodiment of the present invention. The satellite is moving to the left in the figure, and the device shown in the figure is installed on the satellite. In the figure, the lower part from the chain line AA is the circuit part,
It is constructed on a circuit board and is housed in the body B of the satellite along with other electrical devices. The part above the chain line A-A is the main part of the device of the present invention, which is exposed and attached to the surface of the main body B of the satellite, and no object such as a vessel wall surrounding this part is necessary, but it is convenient for manufacturing. From the above, each part is mounted in the outer cylinder W whose front end is open as shown in the figure, and the outer cylinder is mounted on the outer surface of the artificial satellite body with the cylinder axis oriented in the advancing direction of the artificial satellite. It goes without saying that the entire apparatus shown in the figure may be installed in the artificial satellite with the front open. The outer cylinder is electrically connected to the artificial satellite body B, and in the circuit shown in the figure, the portion connected to the outer cylinder is the grounded portion on the circuit. Since the artificial satellite is traveling to the left in the figure, gas molecules in outer space jump into the outer cylinder from the left in the figure.

In the figure, reference numeral 1 is a neutral molecule ionization section, which ionizes the molecules of the space gas that have jumped in from the left. The ionization part is an electron impact type. The ionized gas molecules pass through the ionization section while maintaining the original velocity at the time of incidence. The ion energy analysis unit 2 is arranged on the right side of the ionization unit and behind the traveling direction of the artificial satellite. The ion energy analysis unit 2 includes a grid electrode 21 and an ion detector 22. The ion detector is an ion trapping electrode plate on which ions are incident, and is formed into a cup shape with a peripheral wall so as to absorb the electric charge of the incident ions and also to collect the two-letter electrons emitted from the electrode plates by the incident ions. is there. That is, the ion detector 22 is a Faraday cup. Since the ion detector 22 outputs one pulse when one ion is incident, this pulse is sent to the data processing device 4 via the amplifier 3 and counted for a certain period of time.

The grid 21 has a positive potential with respect to the satellite body, and this positive potential is variable and controlled by the data processing device 4. Since the grid 21 has a positive potential, ions having a kinetic energy lower than a certain level among the ions coming from the left side according to the potential cannot be passed through the grid 21 because they are reflected by the grid electrode 21. Only energetic ions can pass through the grid 21 and enter the ion detector 22. That is, grid 2
1 is a high-pass filter for the energy of ions, and by changing the voltage applied to the grid 21,
The energy of the transmitted ions can be changed.

The ionization section 1 has an ionization chamber 11 in which a peripheral surface, an entrance surface, and an exit surface are all formed by a grid.
And an electron repeller electrode 12 surrounding this ionization chamber
And a repeller electrode and an electron emission source filament 13 disposed around the ionization chamber between the repeller electrode and the ionization chamber. The front and rear surfaces of the repeller electrode 12 form a grid. The ionization chamber 11 is grounded to the satellite body B. Reference numeral 14 is a filament power source, and 15 is a filament 13 which is connected to the ionization chamber 11
It is a voltage source for maintaining a lower potential, and since the series voltage of these two power supplies is applied to the repeller electrode, the potential is further lower than that of the filament 13. With such a configuration, all the electrons emitted from the filament 11 are accelerated toward the ionization chamber and collide with gas molecules that have entered the ionization chamber from the left side to ionize them.

In the artificial satellite, the center line X of the gas analyzer shown in the figure
It is difficult to accurately orient the satellite in the direction of travel of the satellite. In the above-described embodiment, the cross-sectional area of the passage space for molecules or ions is the same from the opening diameter Di of the incident surface of neutral molecules to the opening diameter Dd of the ion detector, and is relatively large with respect to the apparatus length in the centerline X direction. Since it is large, gas analysis is possible even if the incident direction of molecules is slightly inclined with respect to the center line X.

FIG. 2 shows another embodiment of the present invention. The ion emission surface of the ionization chamber 11 is a spherical surface centered on the center of the chamber, the rear surface of the repeller electrode 12 is also a spherical surface concentric with the ion emission surface of the ionization chamber 11, and the reflection grid electrode 21 is also the ion of the ionization chamber. It is a spherical surface concentric with the emitting surface. The ion detector is composed of a plate-shaped electrode 22 and a grid 23 stretched on the front surface thereof and having a negative potential. With this structure, the range of directions in which gas analysis is possible is wider than that of the structure shown in FIG.

FIG. 3 shows still another embodiment of the present invention, in which the gas cross-sectional direction can be analyzed by expanding the cross-sectional area of the device toward the front in a spherical shape centering on the center of the Faraday cup 22 of the ion detector. It is an expanded range.

Considering the orbit at an altitude of 55 OKm, in this case, the kinetic energy of the orbital space gas with respect to the artificial satellite is
⁴ He is 1.2 eV, ¹⁴ N is 4.2 eV, and ¹⁶ O is 4.8.
When eV ⁴⁰ Ar is 12.0 eV, N ₂ and O ₂ are 8.4 and 9.6 eV, which are twice the N and O, respectively. Therefore, if the potential of the grid electrode 21 is lowered from 12 V or more, it becomes 12 V.
It is Ar that is detected in the vicinity, and when around 9.6 V, a combination of Ar and O ₂ is detected, and a mixture of various ions is detected below. Ions can be discriminated and counted. Space gas molecules are in thermal motion, but their energy is 550 km
Since it is about 0.1 eV in the vicinity, each molecule described above can be sufficiently discriminated.

[0014]

The apparatus of the present invention does not require an ion accelerating means, and does not require a magnetic field type or quadrupole type mass analyzing means, so that the apparatus has a simple structure and a light weight, and an electrical configuration can be made simple and reliable. It is highly suitable for mounting on satellites. In addition, the applicant of the present application has proposed a structure in which the space gas that jumps into the artificial satellite is ionized, and is made into a beam shape with a slit to be deflected by a deflecting means. However, in the present invention, the slit is not used. It is possible to measure even if the direction of is considerably deviated from the tangential direction of the orbit (about 30 °). In addition, since the outgas emitted from the satellite itself has only the energy of thermal kinetic energy, only the space gas can be discriminated and detected.

[Brief description of drawings]

 A side view of an apparatus according to an embodiment of the present invention

FIG. 2 is a side view of a main part of another embodiment.

FIG. 3 is a side view of a main part of still another embodiment.

[Explanation of symbols]

 B Satellite main body W Outer cylinder 1 Neutral molecular ionization part 2 Ion energy analysis part 11 Ionization chamber 12 Repeller electrode 13 Filament 21 Grid electrode 22 Ion detector

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[Procedure amendment]

[Submission date] October 19, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a side view of an apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of a main part of another embodiment.

FIG. 3 is a side view of a main part of still another embodiment.

[Explanation of Codes] B Satellite main body W Outer tube 1 Neutral molecule ionization part 2 Ion energy analysis part 11 Ionization chamber 12 Repeller electrode 13 Filament 21 Grid electrode 22 Ion detector

Claims (1)

[Claims] 1. A neutral molecular ionization section mounted on an artificial satellite and opening toward the advancing direction of the artificial satellite, and a reflection electric field energy analyzer and an ion detector arranged behind the ionization section. Space gas analyzer