JPS6263180A - Rf type ion source - Google Patents

Abstract

PURPOSE:To improve the homogeneity of plasma and improve propulsion effi ciency by providing a spiral induction coil inside the upper cover of a discharge container and arranging a train of magnets in a spiral shape or the like to protect the coil from plasma with magnetic cusps. CONSTITUTION:Electrons accelerated by an induction coil 6 collide against the Hg gas introduced into a discharge container 2, and ionized plasma is gener ated in a discharge chamber 8. Hg<+> ions are applied with kinetic energy by an accelerating electrode consisting of electrodes 3-5 and are neutralized by electrons discharged from a neutralizer then are discharged to become thrust. In this case, a spiral induction coil 10 is provided inside the upper cover to intensify the induction field at the center of the discharge container 2. A train of magnets 9 with different polarity is arranged on both sides of the coil 10. Accordingly, the homogeneity of plasma can be improved and propulsion effi ciency can be improved with simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an RF type ion engine for controlling the attitude of an artificial satellite.

[Technical background of the invention and its problems]

The configuration of a conventional RF (Radiofrequency) type ion engine is shown in FIG. 6, in which electrons accelerated by an induction coil 6 collide with Hg gas introduced into a discharge vessel 2, producing ionized plasma within a discharge chamber 8. The Hg ÷ ions are generated and given operating energy by the accelerating electrodes composed of electrodes 3 and 4.5.

After being neutralized by the electrons emitted from the neutralizer 7,
It is released and becomes the thrust of the ion engine.

In order to obtain efficient thrust, uniformity of the plasma on the surface of the electrode 3 needs to be satisfied. In order to satisfy plasma uniformity, the gas pressure in the discharge chamber 8 must be
10-” Torr or more is required. However, 5
There is a problem in that the gas pressure can only be raised to about 1 G-'Torr, and the ion current density at the center of the electrode is lower than that at the periphery, reducing propulsion efficiency.

[Purpose of the invention]

The present invention was created in view of these circumstances, and provides a high propulsion efficiency without shortening the life of the induction coil on the discharge vessel top cover.

RF with improved plasma uniformity in areas with electrode holes
The purpose is to provide a type ion source.

[Summary of the invention]

The present invention is an RF type characterized in that a spiral induction coil is provided inside the upper lid of the discharge vessel 2, a magnet array is arranged spirally or circularly, and the spiral induction coil is protected from plasma by a magnetic cusp. It is an ion source.

〔Effect of the invention〕

According to the present invention, it is possible to construct an RF type ion source that can improve plasma uniformity and have good propulsion efficiency with a simple configuration without making the life of the induction coil a problem.

[Embodiments of the invention]

Examples of the present invention will be described in detail below. Note that the same reference numerals are given to the parts having the same configuration as those of the conventional device, and the explanation thereof will be omitted. A coil 6 is provided on the inner periphery of the SAS container at the position shown in FIG. 1, and in addition to this, a spiral induction coil 10 is provided inside the upper lid 20 in order to strengthen the induced electric field at the center of the discharge container. As shown in FIGS. 2 and 3, magnet arrays 9 having different polarities are arranged on both sides of the spiral induction coil 10. Since the entire helical induction coil 10 is covered with a magnetic field, direct contact of plasma with the helical induction coil 10 can be prevented. Since the helical induction coil 10 is no longer in contact with plasma, there will be no problem with the lifetime due to sputtering.

FIGS. 4 and 5 show another arrangement example of the magnet array, in which circular magnet arrays are arranged with polarities changed every several turns of the spiral induction coil 1o.

With this magnet array arrangement, the only part of the helical induction coil 10 that is in direct contact with the plasma is the part 11 that crosses the magnet array, and there is no problem with the lifespan due to sputtering in areas other than this part 11. The wall thickness will be determined by the service life, but this part is small and will not result in a large increase in weight.In short, the magnet array 9 should be arranged so that the intersection between the magnet array 9 and the spiral induction coil 10 is reduced. However, the arrangement is not limited to the magnet row arrangement described above, and the induction coil 6 disposed on the side surface of the discharge vessel 1 may be omitted.
Although Hg is used as the introduced gas, it is not limited to Hg gas.

Although the present invention has been described with respect to an RF type ion engine, it can be applied to any device using an RF type discharge chamber. The same applies to type ion sources.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a magnet array arrangement diagram of an embodiment of the present invention, FIG. 3 is a cross-sectional view taken from the A-A' force direction in FIG. The figure shows another arrangement of magnet arrays, FIG. 5 is a sectional view taken along line BB' in FIG. 4, and FIG. 6 is a sectional view of a conventional RF type ion engine. 1... Gas introduction system 2... Discharge vessel 3.4.5.
...Electrode 6...Induction coil 7...
・Neutralizer 8...Discharge chamber 9...Magnet 10...Spiral induction coil ・Agent Patent attorney Yudo Noriyuki Chika Kikuo Takehana Figure 2 Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) In an ion engine consisting of a gas introduction system, a discharge vessel, an electrode, an induction coil installed inside the discharge chamber, a neutralizer, a power supply, etc., a spiral induction coil is installed inside the upper lid of the discharge vessel, An RF type ion engine characterized in that magnets are arranged on the wall of a discharge vessel upper cover so as to form a magnetic cusp ring, and a spiral induction coil is provided between the magnet rows. (2) The RF type ion engine according to claim 1, wherein the discharge vessel upper lid magnet array is arranged in a spiral along a spiral induction coil. (3) The RF type ion engine according to claim 1, wherein the discharge vessel upper lid magnet array is arranged in a circle every plural times of the spiral induction coil.