MAGNETIC CIRCUIT FOR CREATING A MAGNETIC FIELD IN A MAIN ANNULAR IONISATION AND ACCELERATION CHANNEL OF A HALL-EFFECT PLASMA THRUSTER

Abstract

A magnetic circuit for creating a magnetic field in a main annular ionization and acceleration channel of a Hall-effect plasma thruster, having an open top end for emitting ions and a closed bottom end, includes outer magnets comprising a bottom annular outer magnet, and a top annular outer magnet disposed above the bottom outer magnet; inner magnets comprising a bottom inner magnet, of cylindrical form having a bottom part of a diameter less than the diameter of a top part, disposed below the top outer magnet, and a top annular inner magnet disposed above the bottom inner magnet; the outer magnets having a same pole (N, S) on their respective top face and an opposite same pole (S, N) on their bottom face; the inner magnets having an orientation of their poles that is the reverse of that of the outer magnets; and the outer magnets and the inner magnets being disposed above the closed bottom end of the annular channel.

Claims

1. A magnetic circuit for creating a magnetic field in a main annular ionization and acceleration channel of a single-stage Hall-effect plasma thruster, having an open top end for emitting ions and a closed bottom end, comprising: a magnetic base; a first support intended to receive outer magnets disposed outside of the outer wall of the annular channel; a second support intended to receive inner magnets disposed outside of the inner wall of the annular channel; the outer magnets comprising a bottom annular outer magnet, and a top annular outer magnet disposed above the bottom outer magnet; the inner magnets comprising a bottom inner magnet, of cylindrical form having a bottom part of a diameter less than the diameter of a top part, disposed below the top outer magnet, and a top annular inner magnet disposed above the bottom inner magnet; the outer magnets having a same pole (N, S) on their respective top face and an opposite same pole (S, N) on their bottom face; the inner magnets having an orientation of their poles that is the reverse of that of the outer magnets; and the outer magnets and the inner magnets being disposed above the closed bottom end of the annular channel.

2. The magnetic circuit as claimed in claim 1, wherein the bottom outer magnet has of a section two times greater than the section of the top outer magnet.

3. The magnetic circuit as claimed in claim 1, wherein the bottom outer magnet has an average diameter of between 6 mm and 7 mm.

4. The magnetic circuit as claimed in claim 1, wherein the bottom outer magnet has a height twice the height of the top outer magnet.

5. The magnetic circuit as claimed in claim 1, wherein the width of the top outer magnet is equal to the width of the bottom outer magnet.

6. The magnetic circuit as claimed in claim 1, wherein the bottom inner magnet has a height twice the height of the bottom outer magnet.

7. The magnetic circuit as claimed in claim 1, wherein the height of the bottom part of the bottom inner magnet is 1.5 times greater than the height of the top part of the bottom inner magnet.

8. The magnetic circuit as claimed in claim 1, wherein the outer diameter of the top inner magnet is twice the diameter of the top part of the bottom inner magnet.

9. The magnetic circuit as claimed in claim 1, wherein the inner diameter of the top inner magnet is between 1.2 and 1.3 times the diameter of the top part of the bottom inner magnet.

10. The magnetic circuit as claimed in claim 1, wherein the first and second supports are made of copper.

11. The magnetic circuit as claimed in claim 1, comprising an additional annular magnet disposed outside of the outer wall of the annular channel below the bottom outer magnet.

12. The magnetic circuit as claimed in claim 11, comprising a third support intended to receive the additional magnet.

13. The magnetic circuit as claimed in claim 11, wherein the additional magnet has a constant inner diameter and an outer diameter comprising a first, bottom part having a first diameter, a second, medium part having a second diameter greater than the first diameter, and a third, top part having a third diameter between the first and second diameters.

14. A Hall-effect plasma thruster comprising a magnetic circuit according to claim 1.

Description

[0040] The invention will be better understood on studying a few embodiments described as nonlimiting examples and illustrated by the attached drawings in which the figures:

[0041] FIG. 1 schematically illustrates the main components of a Hall-effect thruster, according to the state of the art;

[0042] FIG. 2 schematically illustrates a Hall-effect thruster in which the magnetic circuit comprises coils, according to the state of the art;

[0043] FIG. 3 schematically illustrates the magnetic field lines of a Hall-effect thruster of FIG. 2, according to the state of the art;

[0044] FIG. 4 schematically illustrates a magnetic circuit for creating a magnetic field in a main annular ionization and acceleration channel of a Hall-effect plasma thruster, according to an aspect of the invention;

[0045] FIG. 5 schematically illustrates an exploded view of the magnetic circuit of FIG. 3, according to an aspect of the invention;

[0046] FIG. 6 schematically illustrates magnetic for creating a magnetic field in a main annular ionization and acceleration channel of a Hall-effect plasma thruster, according to another aspect of the invention; and

[0047] FIG. 7 schematically illustrates the magnetic field lines of a Hall-effect thruster, according to an aspect of the invention.

[0048] In all the figures, the elements that have the same references are similar.

[0049] FIGS. 4 and 5 represent a partial cross-section of a magnetic circuit for creating a magnetic field in a main annular ionization and acceleration channel of a Hall-effect plasma thruster, according to an aspect of the invention.

[0050] The magnetic circuit for creating a magnetic field in a main annular ionization and acceleration channel 1 of a Hall-effect plasma thruster, having an open top end for emitting ions.

[0051] The magnetic circuit comprises a magnetic base 2, a first support 3 intended to receive outer magnets disposed outside of the outer wall 1e of the annular channel 1, having an open top end and a closed bottom end, and a second support 4 intended to receive inner magnets disposed outside of the inner wall 1i of the annular channel 1.

[0052] The outer magnets comprise a bottom annular outer magnet 5, and a top annular outer magnet 6 disposed above the bottom outer magnet 5.

[0053] The inner magnets comprising a bottom inner magnet 7, of cylindrical form having a bottom part of a diameter less than the diameter of a top part, disposed below the top outer magnet 6, and a top annular inner magnet 8 disposed above the bottom inner magnet 7.

[0054] The outer magnets 5, 6 have a same pole (for example N, S) on their respective top face and an opposite same pole (in this example S, N) on their bottom face, and the inner magnets 7, 8 have an orientation of their poles that is the reverse of that of the outer magnets 5, 6.

[0055] The outer magnets 5, 6 and the inner magnets 7, 8 are disposed above the closed bottom end of the annular channel 1.

[0056] The permanent magnets prevent the magnetic field lines from crossing with the walls of the discharge channel 1 in the acceleration zone while allowing them to follow the walls towards the anode.

[0057] The bottom outer magnet 5 can have a section two times greater than the section of the top outer magnet 6, and its average diameter can be between 6 mm and 7 mm. The bottom outer magnet 5 has a height twice the height of the top outer magnet.

[0058] The width of the top outer magnet 6 can be equal to the width of the bottom outer magnet 5.

[0059] The bottom inner magnet 7 can have a height twice the height of the bottom outer magnet 5.

[0060] The height of the bottom part of the bottom inner magnet 7 can be 1.5 times greater than the height of the top part of the bottom inner magnet 7.

[0061] The outer diameter of the top inner magnet 8 can be twice the diameter of the top part of the bottom inner magnet 7.

[0062] The inner diameter of the top inner magnet 6 can be between 1.2 and 1.3 times the diameter of the top part of the bottom inner magnet 5.

[0063] The first and second supports 3, 4 can be made of copper.

[0064] As illustrated in FIG. 6, an additional annular magnet 9 can be disposed outside of the outer wall 1e of the annular channel 1 below the bottom outer magnet 5, and a third support 10 can be intended to receive the additional magnet 9.

[0065] The additional magnet 9 can have a constant inner diameter and an outer diameter comprising a first, bottom part having a first diameter, a second, medium part having a second diameter greater than the first diameter, and a third, top part having a third diameter between the first and second diameters.

[0066] FIG. 7 schematically illustrates the magnetic field lines of a Hall-effect thruster, according to an aspect of the invention.

[0067] The present invention therefore makes it possible to have Hall-effect plasma thrusters comprising a magnetic circuit as previously described.