Ion source and arc discharge structure of isotope electromagnetic separator

Abstract

The embodiment of the present invention discloses an ion source of an isotope electromagnetic separator and an arc discharge structure thereof. The arc discharge structure of the ion source of the isotope electromagnetic separator includes an arc discharge chamber and a cathode. The arc discharge chamber has a gas inlet for introducing a gas containing an isotope. The cathode is arranged inside the arc discharge chamber for emitting electrons to ionize the gas in the arc discharge chamber to form plasma. The cathode includes a spiral segment, which extends in a spiral shape from bottom to top. The technical solution of the embodiment of the present application is conducive to improving the ion concentration in the arc discharge chamber.

Description

Technical Field

[0001] The invention relates to the technical field of isotope electromagnetic separation, in particular to an ion source of an isotope electromagnetic separator and an arc discharge structure thereof. Background Art

[0002] Isotope electromagnetic separators use ions with the same energy but different masses to separate isotopes by rotating at different radii in a magnetic field. The ion source is the key device for generating ion beams in isotope electromagnetic separators, and the size of the ion beam current it generates determines the production capacity of the isotope electromagnetic separator. Summary of the invention

[0003] In a first aspect, an embodiment of the present invention provides an arc discharge structure of an ion source of an isotope electromagnetic separator, comprising:

[0004] an arc discharge chamber having a gas introduction port for introducing a gas containing an isotope; and

[0005] A cathode, disposed inside the arc discharge chamber, for emitting electrons to ionize the gas in the arc discharge chamber to form plasma;

[0006] Wherein, the cathode comprises: a spiral segment, and the spiral segment extends from bottom to top in a spiral shape.

[0007] In a second aspect, an embodiment of the present invention provides an ion source of an isotope electromagnetic separator, comprising the arc discharge structure of the first aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Other objects and advantages of the present invention will become apparent from the following description of the present invention with reference to the accompanying drawings, which will help to provide a comprehensive understanding of the present invention.

[0009] Figure 1 is a schematic principle diagram of an arc discharge structure according to an embodiment of the present invention;

[0010] Figure 2 yes Figure 1 A schematic structural diagram of a cathode of the arc discharge structure shown;

[0011] Figure 3 is a schematic diagram of an ion source according to an embodiment of the present invention; and

[0012] Figure 4 yes Figure 3 A side view of the ion source is shown.

[0013] In the attached figure:

[0014] 10. cathode; 11. first lead-out section; 12. spiral section; 13. second lead-out section; 20. arc discharge chamber; 21. beam lead-out slit; 30. steam distribution chamber; 31. steam distribution plate; 311. gas inlet; 40. crucible; 50. insulating part.

[0015] It should be noted that the drawings are not drawn to scale, and for illustrative purposes, elements of similar structure or function are generally represented by similar reference numerals throughout the drawings. It should also be noted that the drawings are only for the convenience of describing the preferred embodiments, not the invention itself. The drawings do not illustrate every aspect of the described embodiments and do not limit the scope of the invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiment is one embodiment of the present invention, not all embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0018] The arc discharge structure provided in the embodiment of the present application is used for the ion source of the isotope electromagnetic separator. The cathode structure of the ion source is used to generate electrons. The electrons generated by the cathode enter the arc discharge chamber to ionize the vaporized elements to turn the elements into plasma, which is then extracted by the extraction electrode to form an ion beam.

[0019] The structure and position of the cathode determine the number of electrons and the degree of ionization. In the related art, the cathode structure is arranged outside the arc discharge chamber, and the electrons enter the arc discharge chamber through an electron window arranged on the arc discharge chamber.

[0020] However, the inventors of the present application have found that, for an arc discharge chamber provided with an electron window, the abundance of the isotopes after separation is slightly lower.

[0021] The inventors further discovered that there are two main reasons why the abundance of isotopes is slightly lower. On the one hand, the presence of the electron window affects the airtightness in the arc discharge chamber, causing the vacuum of the system to deteriorate. On the other hand, the presence of the electron window places very strict requirements on the cathode structure and the installation of the electron window. Assembly errors will cause the electrons emitted by the cathode to not all enter the arc discharge chamber, causing both electron waste and affecting the degree of ionization.

[0022] In addition, electron waste will shorten the life of the cathode, which is not conducive to long-term separation of isotopes.

[0023] Therefore, the present application improves the arc discharge structure of the ion source in the related art.

[0024] Figure 1 : is a schematic diagram of an arc discharge structure according to an embodiment of the present invention. In the figure, the coordinate x-axis represents the lateral direction of the arc discharge chamber 20, the y-axis represents the depth direction of the arc discharge chamber 20, and the z-axis represents the height direction of the arc discharge chamber 20. The "upward" and "downward" mentioned in this application both refer to the height direction of the arc discharge chamber 20.

[0025] See also Figure 1 The arc discharge structure of the embodiment of the present application includes: an arc discharge chamber 20 and a cathode 10.

[0026] The arc discharge chamber 20 has a gas introduction port 311 to introduce a gas containing isotopes.

[0027] The cathode 10 is disposed inside the arc discharge chamber 20 and is used to emit electrons to ionize the gas in the arc discharge chamber 20 to form plasma.

[0028] The embodiment of the present application sets the cathode 10 inside the arc discharge chamber 20. On the one hand, since there is no need to set up an additional electron window, it is beneficial to improve the airtightness of the arc discharge chamber 20, improve the vacuum degree of the system, and thus improve the abundance of separated isotopes; it is also beneficial to reduce the leakage of the arc discharge chamber 20, reduce the ion source ignition, and improve the stability of the ion source. On the other hand, all the electrons generated by the cathode 10 can enter the arc discharge chamber 20, which improves the utilization rate of the electrons, correspondingly increases the life of the cathode 10, and thus increases the single separation time of the separator; and the degree of ionization of the gas is increased, which is beneficial to increase the plasma concentration in the arc discharge chamber 20 and increase the intensity of the extracted ion beam.

[0029] Figure 2 yes Figure 1 The schematic diagram of the structure of the cathode 10 of the arc discharge structure is shown. Figure 2 The cathode 10 includes a spiral segment 12 extending from bottom to top in a spiral shape. In other words, the spiral segment 12 extends in a spiral shape along the height direction of the arc discharge chamber 20 .

[0030] The cathode 10 of the embodiment of the present application has a spiral section 12, which, on the one hand, increases the effective emission area of ​​electrons, increases the number of electrons, and is beneficial to increasing the plasma concentration, increasing the extracted beam intensity, and thereby increasing the separator production capacity; on the other hand, the spiral section 12 extends spirally from bottom to top, reducing the probability of electrons colliding with the cathode 10 itself, which is beneficial to improving the utilization rate of electrons.

[0031] In a further preferred embodiment, the outer diameter of the spiral segment 12 gradually expands from bottom to top. Compared with the spiral segment 12 whose outer diameter gradually decreases from bottom to top, the spiral segment 12 whose outer diameter gradually expands from bottom to top makes more volume of the cathode 10 closer to the edge of the arc discharge chamber 20 (i.e., the top wall of the arc discharge chamber 20), thereby further reducing the shielding of the cathode 10 to the electrons, reducing the probability of the electrons colliding with the cathode 10 itself, and further improving the utilization rate of the electrons.

[0032] See also Figure 2 The cathode 10 further includes: a first lead-out section 11 and a second lead-out section 13 to connect the cathode 10 to an external circuit, thereby providing current and voltage to the cathode 10 .

[0033] The arc discharge chamber 20 may have a top wall, a bottom wall, and a peripheral wall connecting the top wall and the bottom wall. The first lead-out section 11 and the second lead-out section 13 enter the arc discharge chamber 20 from the top wall.

[0034] The first lead-out section 11 extends upward from the upper end of the spiral section 12 to the top wall of the arc discharge chamber 20. The second lead-out section 13 extends upward from the lower end of the spiral section 12 to the top wall of the arc discharge chamber 20.

[0035] The spiral section 12 spirally extends around the second lead-out section 13. In other words, the spiral section 12 spirally extends upward from the lower end of the second lead-out section 13 around the second lead-out section 13. In such an embodiment, the second lead-out section 13 and the axis of the spiral section 12 are colinear, and the electrons emitted outward from the second lead-out section 13 can move more evenly in the directions around the arc discharge chamber 20.

[0036] In addition, since the axes of the second lead-out section 13 and the spiral section 12 are colinear, the distance between the first lead-out section 11 and the second lead-out section 13 can be increased as much as possible, thereby increasing the insulation distance between the first lead-out section 11 and the second lead-out section 13 .

[0037] Insulating parts 50 are respectively provided at the positions where the first lead-out section 11 and the second lead-out section 13 meet the top wall of the arc discharge chamber 20 to prevent the cathode 10 from short-circuiting with the arc discharge chamber 20. The insulating parts 50 may be insulating ceramic rings, for example.

[0038] The insulating portion 50 can not only insulate the cathode 10 from the top wall of the arc discharge chamber 20 , but also seal the top wall of the arc discharge chamber 20 , thereby improving the airtightness of the arc discharge chamber 20 .

[0039] When installing the cathode 10 , it can be installed from bottom to top in the arc discharge chamber 20 , and an insulating ceramic ring is used for insulation at the interface between the cathode 10 and the top wall of the arc discharge chamber 20 .

[0040] The maximum outer diameter of the spiral segment 12 cannot exceed the transverse width of the arc discharge chamber 20. It is easy to understand that the transverse refers to Figure 1The x-axis direction is the direction parallel to the plane where the gas inlet port 311 is located.

[0041] It is easy to understand that the smaller the maximum outer diameter of the spiral segment 12 is, the fewer electrons are emitted by the cathode 10; the larger the maximum outer diameter of the spiral segment 12 is, the easier it is for the electrons emitted by the cathode 10 to directly hit the peripheral wall of the arc discharge chamber 20 without participating in ionizing the gas, resulting in a waste of electrons.

[0042] The embodiment of the present application particularly sets the maximum outer diameter of the spiral segment 12 to be greater than or equal to half of the lateral width of the arc discharge chamber 20 and less than or equal to four fifths of the lateral width of the arc discharge chamber 20, so that the cathode 10 emits a large number of electrons and the electron utilization rate is high.

[0043] The cathode 10 may be made of tungsten wire.

[0044] The diameter of the tungsten wire is uniform, and the diameter can be within the range of 1.6mm-2mm. When manufacturing the cathode 10, the tungsten wire can be folded in half to form a double-segment structure, and then the first segment of the double-segment structure is bent around the second segment (i.e., the second lead-out segment 13 corresponding to the cathode 10). The bending process can be heated with an open flame to prevent the tungsten wire from breaking. The first segment can be bent from the connection between the two segments, and the diameter of the bend increases from small to large, so that the distance between the ends of the two segments gradually increases, and the bending reaches the maximum diameter and extends parallel to the other segment. Thereby, when the cathode 10 passes through the top wall of the arc discharge chamber 20, the distance between the two ends of the cathode 10 reaches the maximum.

[0045] A beam extraction slot 21 is provided on the side wall of the arc discharge chamber 20 opposite to the gas introduction port 311 , for allowing ions in the arc discharge chamber 20 to flow out.

[0046] The present application also provides an ion source for an isotope electromagnetic separator, comprising an arc discharge structure according to any embodiment of the present application.

[0047] Figure 3 is a schematic diagram of an ion source according to an embodiment of the present invention; Figure 4 yes Figure 3 A side view of the ion source is shown. Figure 3 and Figure 4 The ion source further includes a crucible 40. The crucible 40 is used to heat the raw material to generate a gas containing isotopes.

[0048] The ion source further includes a vapor distribution chamber 30. The vapor distribution chamber 30 is communicated with the crucible 40 and the arc discharge chamber 20 respectively, and is used to introduce gas into the arc discharge chamber 20.

[0049] The arc discharge chamber 20 and the steam distribution chamber 30 may be separated by a steam distribution plate 31, and a gas introduction port 311 is provided on the steam distribution plate 31. There may be a plurality of gas introduction ports 311. The gas generated by the raw material being heated in the crucible 40 first passes through the steam distribution plate 31 and then enters the arc discharge chamber 20.

[0050] The steam distribution plate 31 may be a graphite plate with a plurality of small holes. A plurality of gas inlet ports 311 may be provided on the steam distribution plate 31, and the gas inlet ports 311 of two adjacent columns are staggered. Such a configuration ensures that the steam passing through the steam distribution plate 31 does not fluctuate, and the steam is evenly distributed, so as to facilitate collision with the electrons generated by the cathode 10.

[0051] When the ion source is in use, the cathode 10 is heated by an electric current to release hot electrons. The entire arc discharge chamber 20 can be connected to a 30kV high voltage, and the cathode 10 can be connected to a (30kV-300V) high voltage. The 300V voltage difference formed between the cathode 10 and the arc discharge chamber 20 is used to accelerate the electrons generated by the cathode 10 in all directions of the arc discharge chamber 20, so that the electrons fill the entire arc discharge chamber 20, thereby improving the electron utilization rate. The electrons strike the gas in the arc discharge chamber 20 to ionize it, and the ionized gas escapes from the beam extraction slit 21.

[0052] The present application also provides an isotope electromagnetic separator, comprising an ion source according to any embodiment of the present application.

[0053] The isotope electromagnetic separator may also include a magnetic analyzer and an isotope receiver.

[0054] The magnetic analyzer is used to separate ion beams of different masses and focus ion beams of the same mass. The isotope receiver is used to simultaneously receive the separated isotopes.

[0055] The magnetic analyzer and the isotope receiver may both be common structures in the art and will not be described in detail here.

[0056] Regarding the embodiments of the present invention, it should also be noted that, in the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0057] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An arc discharge structure of an ion source of an isotope electromagnetic separator, characterized in that: include: an arc discharge chamber having a gas introduction port for introducing a gas containing an isotope; and A cathode, disposed inside the arc discharge chamber, for emitting electrons to ionize the gas in the arc discharge chamber to form plasma; Wherein, the cathode comprises: a spiral segment, the spiral segment extending from bottom to top in a spiral shape; The outer diameter of the spiral section gradually expands from bottom to top; The cathode further comprises: A first lead-out section extending upward from the upper end of the spiral section to the top wall of the arc discharge chamber; and A second lead-out section extending upward from the lower end of the spiral section to the top wall of the arc discharge chamber; The helical section extends helically around the second lead-out section.

2. The arc discharge structure according to claim 1, characterized in that: Insulating parts are respectively provided at positions where the first lead-out section and the second lead-out section are connected to the top wall of the arc discharge chamber.

3. The arc discharge structure according to claim 1, characterized in that: The maximum outer diameter of the helical segment is greater than half of the transverse width of the arc discharge chamber.

4. The arc discharge structure according to claim 1, characterized in that: The cathode is made of tungsten wire.

5. The arc discharge structure according to claim 1, characterized in that: A beam extraction slot is provided on a side wall of the arc discharge chamber opposite to the gas introduction port, for allowing ions in the arc discharge chamber to flow out.

6. An ion source for an isotope electromagnetic separator, characterized in that: The invention comprises the arc discharge structure according to any one of claims 1 to 5.

7. The ion source according to claim 6, characterized in that Also includes: a crucible for producing a gas containing the isotope; A vapor distribution chamber is communicated with the crucible and the arc discharge chamber respectively, and is used for introducing the gas into the arc discharge chamber.

8. The ion source according to claim 7, characterized in that The arc discharge chamber and the steam distribution chamber are separated by a steam distribution plate. The gas introduction port is disposed on the steam distribution plate.

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