Faraday cylinder for high-energy double-beam measurement of MeV proton beam and electron beam

Abstract

The invention provides a Faraday cup for high-energy double-beam measurement of a MeV proton beam and an electron beam, and belongs to the technical field of charged particle beam measurement. The problem that detection cannot be completed by one Faraday cup during detection due to the fact that particle beams with different particle types carry different energies is solved. The bearing part is of a cavity structure and is used for installing the fixing part, preventing external low-energy charged particles, external electromagnetic environment and the like from interfering measurement and increasing the measurement precision, the fixing part and the bearing part are insulated, and an ion beam is projected to the anti-sputtering part on the fixing part through the injection end on the bearing part, so that the measurement precision is improved. Then the ion beam enters the second cavity through the anti-sputtering part and then is led out through the fixing part, the anti-sputtering part and the second cavity effectively prevent the charged particles from sputtering or back scattering to influence the measurement accuracy, and the first cavity and the second cavity are communicated to prevent breakage and damage caused by pressure difference during vacuumizing.

Description

Technical Field

[0001] The present invention belongs to the technical field of charged particle beam measurement, and particularly relates to a Faraday cup for high-energy dual-beam measurement of MeV proton beams and electron beams. Background Art

[0002] A Faraday cup is one of the basic devices for measuring the intensity of charged particle beams. It intercepts charged ion beams and collects their charges to achieve the measurement of the beam current intensity.

[0003] A ground simulation device for the space environment needs to measure two types of charged particle beams it generates, that is, it cannot damage the vacuum environment and should save the use space of the measurement chamber. The two types of charged particle beams are 1 MeV electron beams and 10 MeV proton beams respectively, and the beam current intensity is less than 1 mA. When using a Faraday cup to measure 1 MeV electron beams and 10 MeV proton beams, Faraday cups with different configurations are generally used for separate measurements. When measuring 10 MeV proton beams, due to their shallow incident depth and the easy occurrence of charged particle sputtering when colliding with conductors, which affects the measurement accuracy, a relatively deep Faraday cup is generally used, and a bias ring is set at the entrance to suppress charged particle sputtering. When 1 MeV electron beams collide with conductors, they have a deeper incident depth and larger track straggling compared with 10 MeV proton beams, and even backscattered electrons will be generated. At the same time, a large number of continuous spectrum γ photons in the 0 - 1 MeV energy region will be generated due to bremsstrahlung. During the escape process of photons, photoelectric effect and Compton scattering occur with conductors to generate secondary electrons. The generation of backscattered electrons and secondary electrons both have a greater impact on the accuracy of 1 MeV electron beam current measurement. Generally, a longer solid Faraday cup is used, and a bias ring is set at the entrance to suppress backscattered electrons. The design scheme of a Faraday cup for high-energy dual-beam measurement of MeV proton beams and electron beams needs to have the above measurement functions and achieve high-precision measurement of the beam current intensity. Summary of the Invention

[0004] In view of this, the present invention aims to provide a Faraday cup for high-energy dual-beam measurement of MeV proton beams and electron beams, and solve the problem that a single Faraday cup cannot complete the measurement when detecting two high-energy particle beams with different energies.

[0005] To achieve the above object, the present invention adopts the following technical solutions. According to one aspect of the present invention, there is provided a Faraday cup for high-energy dual-beam measurement of MeV proton beams and electron beams, including:

[0006] A bearing part, internally insulated with a fixing part, and a first cavity is formed between the two;

[0007] An anti-sputtering part, arranged on the fixing part, and a second cavity is formed between the two, and the first cavity and the second cavity are communicated;

[0008] Among them, an ejection end for guiding the beam current to the anti-sputtering part is provided on the bearing part.

[0009] Furthermore, the first cavity and the second cavity are communicated through a through hole provided on the fixing part.

[0010] Furthermore, the fixing part, the anti-sputtering part and the ejection end are coaxially arranged.

[0011] Furthermore, an insulating support part is provided between the fixing part and the bearing part.

[0012] Furthermore, the bearing part includes an outer cylinder, a beam inlet baffle connected to one end of the outer cylinder, and a fixing baffle connected to the other end of the outer cylinder. The ejection end is a beam inlet hole and is provided on the beam baffle.

[0013] Furthermore, the insulating support part is arranged between the fixing part, the outer cylinder and the fixing baffle.

[0014] Furthermore, the insulating support part, the fixing part, the outer cylinder and the fixing baffle are closely fitted.

[0015] Furthermore, a connecting part for leading out current is provided at the end of the fixing part away from the anti-sputtering part.

[0016] Furthermore, a fastening part is provided on the connecting part for fixing the connecting part.

[0017] Furthermore, the anti-sputtering part is an aluminum foil metal film with a thickness of about 10 microns or an anti-sputtering / backscattering film material.

[0018] Furthermore, the materials of the fixing part and the bearing part are oxygen-free copper.

[0019] Furthermore, the materials of the insulating support part and the insulating gasket are ceramic or other insulating materials such as polytetrafluoroethylene.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The bearing part is a cavity structure for installing the fixing part, preventing external low-energy charged particles and external electromagnetic environment from interfering with the measurement. At the same time, a voltage of 100 - 200V can be applied to the outer cylinder to suppress the secondary electron emission of the fixing part and increase the measurement accuracy, and the fixing part and the bearing part are insulated. The relatively high solid metal part of the fixing part can absorb most of the γ photons, preventing the secondary electrons generated by the photons from affecting the measurement. The particle beam is projected onto the anti-sputtering part on the fixing part through the ejection end on the bearing part, and then the particle beam enters the second cavity through the anti-sputtering part and is then led out through the fixing part. The anti-sputtering part and the second cavity effectively prevent the sputtering or backscattering of charged particles from affecting the measurement accuracy. The communication between the first cavity and the second cavity can prevent rupture and damage due to the pressure difference during vacuum pumping. Brief Description of the Drawings

[0022] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0023] Figure 1 FIG. is a schematic diagram of the overall structure of a high-energy dual-beam measurement Faraday cup for MeV electron beams and proton beams according to the present invention.

[0024] Fixing part 1; anti-sputtering part 2; insulating support part 3; outer cylinder 4; beam inlet baffle 5; fixing baffle 6; through hole 7; insulating gasket 8; fastening part 9; fixed connection part 10; first cavity 11; second cavity 12. Detailed Embodiments

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention may be combined with each other. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0026] It should be noted that the descriptions of directions such as "left", "right", "left side", "right side", "upper part", "lower part", "top", "bottom", etc. in the present invention are all defined based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the structure must be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation to the present invention. In the description of the present invention, the meaning of "a plurality" is more than two, unless otherwise specifically defined.

[0027] In the description of the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0028] Referring to the drawings, this embodiment provides a high-energy dual-beam measurement Faraday cup for MeV electron beams and proton beams, including:

[0029] The bearing part is internally insulated with a fixing part 1, and a first cavity 11 is formed therebetween. The bearing part is a cavity structure for installing the fixing part 1 to prevent external low-energy charged particles and external electromagnetic environment, etc. from interfering with the measurement, increasing the measurement accuracy, and the fixing part 1 and the bearing part are insulated from each other. The bearing part includes an outer cylinder 4, an incoming beam baffle 5 connected to one end of the outer cylinder 4, and a fixing baffle 6 connected to the other end of the outer cylinder 4. The ejection end is an incoming beam hole and is arranged on the incoming beam baffle 5. The outer cylinder 4 is a thin-walled cylinder, and its thickness is determined by the measurement chamber environment and the parameters of the charged particle beam to be measured. The inner diameter of the outer cylinder 4 is determined as needed. The thickness of the outer cylinder 4 is 3 mm, and the inner diameter is 24 mm. Four threaded holes with a depth of 3 mm are provided at the upper and lower ends of the outer cylinder 4. The materials of the outer cylinder 4, the incoming beam baffle 5, and the fixing baffle 6 are oxygen-free copper.

[0030] The anti-sputtering part 2 is arranged on the fixing part 1, and a second cavity 12 is formed therebetween. The first cavity 11 and the second cavity 12 are communicated. The fixing part 1 is an oxygen-free copper cylinder with a length of 55 mm and a diameter of 20 mm. The anti-sputtering part 2 is a micron-level metal film. Since the sputtering rate is less than 0.1% under the beam current energy and intensity in this example, the metal film can be an aluminum foil with a thickness of about 10 microns. Different anti-sputtering / backscattering film materials with different materials and thicknesses can be replaced according to needs and measurement conditions.

[0031] Among them, an ejection end for guiding the beam current to the anti-sputtering part 2 is provided on the bearing part. The particle beam current is projected into the first cavity 11 between the fixing part 1 and the bearing part through the ejection end on the bearing part, and then the particle beam current enters the second cavity 12 through the anti-sputtering part 2 and is then led out through the fixing part 1. The anti-sputtering part 2 and the second cavity 12 effectively prevent the charged particle sputtering or backscattering from affecting the measurement accuracy. The first cavity 11 and the second cavity 12 are communicated through a through hole 7 with a diameter of 1 mm to prevent the anti-sputtering part 2 from being damaged due to the pressure difference during vacuum pumping. The second cavity 12 is a groove with an inner diameter of 15 mm and a depth of 5 mm.

[0032] In this embodiment, the fixing part 1, the anti-sputtering part 2, and the ejection end are coaxially arranged, so that ions can accurately pass through the anti-sputtering part 2 and then penetrate onto the fixing part 1.

[0033] In this embodiment, the insulating support part 3 is arranged between the fixing part 1, the outer cylinder 4, and the fixing baffle 6. The insulating support part 3 is an insulating ceramic support cylinder, and any suitable insulating material can be replaced according to the measurement conditions and measurement needs. The inner diameter of the upper end of the insulating support cylinder is 20.1 mm and is closely fitted with the fixing part 1, the outer diameter is 23.9 mm and is fitted with the outer cylinder 4, the inner diameter of the lower end is 3 mm and is fitted with the connecting part 10, and the outer diameter is 6.9 mm and is fitted with the fixing baffle 6.

[0034] In this embodiment, the bearing part includes an outer cylinder 4, a beam-inlet baffle 5 connected to one end of the outer cylinder 4, and a fixed baffle 6 connected to the other end of the outer cylinder 4. The introduction end is a beam-inlet hole and is arranged on the beam-inlet baffle 5. The beam-inlet baffle 5 is an oxygen-free copper disk with a thickness of 5 mm and a diameter of 30 mm. The center of the oxygen-free copper disk is provided with a beam-inlet hole of 5 mm, 10 mm or 15 mm.

[0035] In this embodiment, the fixed part 1 is provided with a connecting part 10 for conducting current away from the anti-sputtering part 2. The connecting part 10 is fixed by a fastening part 9. The fastening part 9 is a fastening nut. The fastening part 9 moves on the connecting part 10 by rotating the fastening part 9. An insulating gasket 8 is provided between the fastening part 9 and the fixed baffle 6. The material of the insulating gasket 8 is insulating ceramic.

[0036] Working principle:

[0037] The Faraday cage is used in a high vacuum environment. MeV electron beams and proton beams with a current intensity below 1 mA enter the first cavity 11 through the beam entry hole on the beam entry baffle 5, pass through the aluminum foil with a thickness of about 10 microns on the upper surface of the fixed part 1, and then are cast into the second cavity 12. The fixed part 1 collects the charges and transfers them to the connecting part 10 and the detection device connected to the connecting part 10.

[0038] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam, characterized in that: include: The bearing part is insulated and provided with a fixing part (1) inside, and a first cavity (11) is formed therebetween; The anti-sputtering part (2) is arranged on the fixing part (1), and the two form a second cavity (12), and the first cavity (11) and the second cavity (12) are connected; Wherein, the bearing part is provided with an introduction end for directing the beam to the anti-sputtering part (2).

2. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 1, characterized in that: The first cavity (11) and the second cavity (12) are connected via a through hole (7) provided on the fixing part (1).

3. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 2, characterized in that: The fixing portion (1), the anti-sputtering portion (2) and the injection end are coaxially arranged.

4. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 1, 2 or 3, characterized in that: An insulating support portion (3) is provided between the fixing portion (1) and the bearing portion.

5. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 4, characterized in that: The bearing part comprises an outer cylinder (4), a beam-inlet baffle (5) connected to one end of the outer cylinder (4), and a fixed baffle (6) connected to the other end of the outer cylinder (4); the ejection end is a beam-inlet hole and is arranged on the beam baffle (5).

6. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 5, characterized in that: The insulating support portion (3) is arranged between the fixing portion (1), the outer cylinder (4) and the fixing baffle (6); the insulating support portion (3), the fixing portion (1), the outer cylinder (4) and the fixing baffle (6) are tightly matched.

7. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 6, characterized in that: The fixing portion (1) is provided with a connection portion (10) for conducting current at an end away from the anti-sputtering portion (2).

8. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 7, characterized in that: The connecting portion (10) is provided with a fastening portion (9) for fixing the connecting portion (10).

9. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 1, 2, 3, 5, 6, 7 or 8, characterized in that: The anti-sputtering part (2) is an aluminum foil metal film or an anti-sputtering / backscattering film material with a thickness of about 10 micrometers.

10. A Faraday cage for high energy dual beam measurement of MeV proton beam and electron beam according to claim 8, characterized in that: The fixing part (1) and the bearing part are made of oxygen-free copper, and the insulating support part (3) and the insulating gasket (8) are made of ceramics or other insulating materials such as polytetrafluoroethylene.

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