A dual-channel kicker magnet for injection in a circular accelerator

Abstract

The present invention provides a dual-channel kicker magnet for the injection of a circular accelerator, which includes a C-shaped ferrite core, a C-shaped high-conductivity metal block, an aluminum alloy housing, a ceramic vacuum chamber, an internally placed oxygen-free copper shielding pipe, an epoxy fixing plate, and an exciting current plate; the main body of the dual-channel kicker magnet consists of a C-shaped ferrite core and a C-shaped high-conductivity metal block, and two exciting current plates are placed on both sides of the yoke of the C-shaped ferrite core. One of the exciting current plates is fixed to the outside of the C-shaped ferrite core through the epoxy fixing plate, and the other exciting current plate is also fixed to the inside of the C-shaped ferrite core through the epoxy fixing plate. The size of the epoxy fixing plate is slightly larger than that of the exciting current plate, with a hole dug inside, and the exciting current plate is inserted into the middle of the epoxy fixing plate; the dual-channel kicker magnet is placed inside the aluminum alloy housing, and the internally placed oxygen-free copper shielding pipe is located in the ceramic vacuum chamber and is placed on one side close to the C-shaped high-conductivity metal block.

Description

Technical Field

[0001] The present invention belongs to the field of injection of circular accelerators, especially the injection field of low-emittance storage rings, and specifically relates to a dual-channel kicker magnet for the injection of circular accelerators. Background Art

[0002] The bump injection method can realize the injection of beam into the storage ring. In the traditional bump injection method, after the particles are accelerated by the linear accelerator, they enter the bump formed by the kicker magnet through the deflection of the septum magnet. At the same time, the magnetic field generated by the kicker magnet gradually decreases according to a certain time law, so that the bump approaches the equilibrium orbit. After several laps, the incident particles will return to the initial injection point position again. At this time, the shrinkage of the bump is large enough, and the injected particles can avoid the septum plate and be captured by the storage ring, thus realizing the beam injection. The traditional bump injection method has high requirements for the dynamic aperture of the storage ring, generally exceeding 20 mm. However, the dynamic aperture of the fourth-generation diffraction-limited storage ring is very small, and it is no longer applicable to continue using this method to accept the injected beam. The Swiss Light Source proposed an off-axis injection scheme using a reverse septum magnet. In this injection method, 2 kicker magnets and a reverse septum magnet are used to form a local bump. After the injected beam passes through the exit of the septum magnet, it passes through the magnetic shielding channel of the reverse septum magnet. The stored beam does not pass through the magnetic shielding channel. Therefore, when the stored beam passes through the inside of the reverse septum magnet, it is deflected by the magnetic force to form a bump. At this time, the off-axis height of the injected beam is very small and can be captured by the acceptance of the storage ring. Some laboratories internationally have also proposed injection schemes using reverse septum magnets, such as SLS-2, APS-U, etc. Summary of the Invention

[0003] In order to solve the problem of difficult injection caused by the too small dynamic aperture of the diffraction-limited storage ring, the present invention proposes a dual-channel kicker magnet for the injection of circular accelerators. The circular ceramic vacuum chamber design is adopted in the dual-channel kicker magnet, and an oxygen-free copper shielding pipe is built in the circular ceramic vacuum chamber to provide a magnetic shielding channel for the injected beam. The circular ceramic vacuum chamber is easier to process than the racetrack-shaped ceramic vacuum chamber. The built-in oxygen-free copper shielding pipe is lengthened and directly fixed on the two end flanges, which is more stable and has some gaps with the inner wall of the ceramic pipe, which can reserve space for coating the inner wall of the ceramic pipe. At the same time, there are gaps between the ceramic pipe and the excitation magnetic core, which can reserve space to provide air-cooled heat dissipation for the ceramic pipe.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A dual-channel kicker magnet for the injection of circular accelerators includes a C-shaped ferrite magnetic core, a C-shaped high-conductivity metal block, an aluminum alloy shell, a ceramic vacuum chamber, a built-in oxygen-free copper shielding pipe, an epoxy fixing plate, and an excitation current plate;

[0006] The main body of the dual-channel impact magnet consists of a C-shaped ferrite core and a C-shaped high-conductivity metal block. Two exciting current plates are placed on both sides of the yoke of the C-shaped ferrite core. One of the exciting current plates is fixed to the outside of the C-shaped ferrite core through an epoxy fixing plate, and the other exciting current plate is also fixed to the inside of the C-shaped ferrite core through an epoxy fixing plate. The size of the epoxy fixing plate is slightly larger than that of the exciting current plate, with internal holes dug, and the exciting current plate is inserted into the middle of the epoxy fixing plate. The dual-channel impact magnet is placed inside an aluminum alloy housing, and an internally placed oxygen-free copper shielding pipe is located in the ceramic vacuum chamber and is placed on one side close to the C-shaped high-conductivity metal block.

[0007] Further, both ends of the ceramic vacuum chamber are connected and transitioned by flanges and bellows, and the flanges are connected by fixing screws.

[0008] Further, the ceramic vacuum chamber is located exactly in the middle of the inner hole surrounded by the C-shaped ferrite core and the C-shaped high-conductivity metal block, and both sides are connected to the flanges by using kovar through brazing.

[0009] Further, the dual-channel impact magnet generates a magnetic circuit by applying pulsed current to the exciting current plates on both sides of the C-shaped ferrite core, and the magnetic circuit passes through the C-shaped ferrite core to generate magnetic flux in the inner hole of the C-shaped core.

[0010] Further, the oxygen-free copper shielding pipe is internally placed in the ceramic vacuum chamber in the inner hole of the C-shaped core, which can shield most of the magnetic field, so the magnetic field in the internal magnetic shielding channel is almost zero.

[0011] Further, the material of the ceramic vacuum chamber is 95% aluminum oxide and needs to be coated.

[0012] Further, the internally placed oxygen-free copper shielding pipe passes through the C-shaped high-conductivity metal block, is located in the ceramic vacuum chamber, and is fixed to the flanges on both sides respectively at both ends. The internally placed oxygen-free copper shielding pipe is connected to the fixing block by round head screws, and then the fixing block is fixed to the flange through a guide rod, so as to play a role in fixing the internally placed oxygen-free copper shielding pipe.

[0013] Beneficial effects:

[0014] The present invention includes a dual-channel impact magnet that can be used in a circular accelerator, especially for the injection of a low-emittance storage ring. The magnet adopts an asymmetric C-shaped core structure, with the edge of the internally placed oxygen-free copper shielding pipe as the dividing line. The left side of the magnet is made of ferrite material, and the right side is made of high-conductivity metal (such as oxygen-free copper, red copper, etc.), which can make the dipole field of the beam storage channel inside the ceramic tube more flat. The internally placed oxygen-free copper shielding pipe can shield the pulsed magnetic field, and the magnetic shielding channel inside the internally placed oxygen-free copper shielding pipe is the injection beam channel, and the magnetic field is almost zero.

[0015] The magnetic field of the magnet of the present invention is excited by a quasi-sine wave pulse, with an excitation current intensity of 4989 A and a pulse bottom width of 5.6 μs. The magnetic field flatness at the position of the stored beam center point (6 mm to the right of the magnet center) ±0.5 mm is approximately 0.9%, which has little influence on the stored beam. The magnetic field is approximately a dipole field; in the magnetic shielding channel in the built-in oxygen-free copper shielding pipe, the magnetic field is approximately zero. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of a dual-channel impact magnet with a built-in magnetic shielding channel;

[0017] Figure 2 It is the transverse magnetic field distribution of the dual-channel impact magnet;

[0018] Figure 3 It is the longitudinal magnetic field integral field distribution at the center of the magnetic shielding channel of the dual-channel impact magnet;

[0019] Figure 4 It is a three-dimensional model diagram of the dual-channel impact magnet with a ceramic vacuum chamber;

[0020] Figure 5 It is the side view of the dual-channel impact magnet with a ceramic vacuum chamber and the reference numbers of each section;

[0021] Figure 5 (a) is the sectional view A-A of the side view;

[0022] Figure 5 (b) is the sectional view B-B of the side view;

[0023] Figure 5 (c) is the sectional view C-C of the side view;

[0024] Figure 6 It is a schematic diagram of the convex orbit injection layout of the HALF dual-channel impact magnet;

[0025] Figure 7 It is a waveform diagram of the excitation current. Detailed Implementation Modes

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] Such as Figure 1 、 Figure 4 and Figure 5As shown in the figure, the present invention provides a dual-channel kicker magnet for the injection of a circular accelerator, as well as a ceramic vacuum chamber 5 for the dual-channel kicker magnet, which includes an internally placed oxygen-free copper shielding pipe 4. The magnetic shielding channel of the pipe is the channel for the injected beam, and the center of the ceramic vacuum chamber 5 and 6 mm to its right side are the channels for storing the beam. Figure 4 is the three-dimensional model diagram of the dual-channel kicker magnet with a ceramic vacuum chamber;

[0028] The described dual-channel kicker magnet includes a C-shaped ferrite core 1, a C-shaped oxygen-free copper block 2, an aluminum alloy housing 3, an internally placed oxygen-free copper shielding pipe 4, a ceramic vacuum chamber 5, an excitation current plate 6, and an epoxy fixing plate 7.

[0029] See Figure 1 , the main body of the dual-channel kicker magnet is composed of a C-shaped ferrite core 1 and a C-shaped oxygen-free copper block 2. Two excitation current plates 6 are placed on both sides of the yoke of the C-shaped ferrite core 1. One of the excitation current plates 6 is fixed to the outside of the C-shaped ferrite core 1 through an epoxy fixing plate 7, and the other excitation current plate 6 is also fixed to the inside of the C-shaped ferrite core 1 through the epoxy fixing plate 7. The size of the epoxy fixing plate 7 is slightly larger than that of the excitation current plate 6, and there are holes inside, through which the excitation current plate 6 can be inserted into the middle of the epoxy fixing plate 7. Epoxy fixing plates 7 can also be placed on both the inner and outer sides of the C-shaped oxygen-free copper block 2 without the excitation current plate 6 to form a symmetric structure, but they are not placed here. The entire magnet is placed inside the aluminum alloy housing 3. The internally placed oxygen-free copper shielding pipe 4 is located in the ceramic vacuum chamber 5 and is placed on one side close to the C-shaped oxygen-free copper block 2.

[0030] As Figure 4 shown, both ends of the ceramic vacuum chamber 5 are connected and transitioned by CF63 flanges 8 and bellows 9, and the CF63 flanges 8 are connected by fixing screws 10.

[0031] The ceramic vacuum chamber 5 is located exactly in the middle of the inner hole surrounded by the C-shaped ferrite core 1 and the C-shaped oxygen-free copper block 2, and is connected to the CF63 flanges 8 on both sides by using kovar through brazing. The internally placed oxygen-free copper shielding pipe 4 passes through the C-shaped oxygen-free copper block 2, is located in the ceramic vacuum chamber 5, and is placed on one side close to the C-shaped oxygen-free copper block 2. Both ends of the internally placed oxygen-free copper shielding pipe 4 are respectively fixed on the two sides of the CF63 flanges 8. As Figure 5 shown in (b), the internally placed oxygen-free copper shielding pipe 4 is connected to the fixing block 11 through round head screws 13, and then the fixing block 11 is fixed to the CF63 flange 8 through a guide rod 12, thereby playing a role in fixing the internally placed oxygen-free copper shielding pipe 4.

[0032] The dual-channel impact magnet generates a magnetic circuit by applying pulsed current to the excitation current plates 6 on both sides of the C-shaped ferrite core 1. The magnetic circuit passes through the C-shaped ferrite core 1 to generate magnetic flux in the inner hole of the C-shaped core. The magnetic permeability of the C-shaped ferrite core 1 is very high, so almost all of the pulsed magnetic field falls within the inner hole of the C-shaped core. The built-in oxygen-free copper shielding pipe 4 in the ceramic vacuum chamber inside the inner hole of the C-shaped core can shield most of the magnetic field, so the magnetic field in its magnetic shielding channel is almost 0, as Figure 3 shown. This dual-channel impact magnet is used in the injection system of a circular accelerator and needs to be in a vacuum environment during use. Since the material of the ceramic vacuum chamber 5 itself is 95% aluminum oxide and has almost no effect on the magnetic field, the C-shaped ferrite core 1 and the C-shaped oxygen-free copper block 2 can be placed outside the vacuum, as Figure 5 shown in (c), thereby reducing the difficulty of obtaining a vacuum. However, the ceramic vacuum chamber needs to be coated during use, and the thickness and sheet resistance of the film may have a certain impact on the magnetic field, which needs to be determined according to the actual situation of its own application.

[0033] In the experimental stage of the present invention, it is applied to the Hefei Advanced Light Source (HALF) project and is used in the injection system of HALF. The design parameters of the HALF dual-channel impact magnet are shown in Table 1.

[0034] Table 1. Design parameters of HALF non-linear impact magnet

[0035]

[0036] As Figure 6 shown, for beam injection, this figure can simply represent the storage ring injection system, which includes a cutting magnet, a common impact magnet, a dual-channel impact magnet, and several pulsed power supplies. The ceramic vacuum chamber 5 in the present invention is connected to the storage ring vacuum pipeline through the CF63 flanges 8 at both ends and is installed at a certain position in the straight section downstream of the cutting magnet. The injected beam passes through the cutting magnet and deflects into the built-in oxygen-free copper shielding pipe 4 of the dual-channel impact magnet, passing through directly without being affected by the magnetic field. At the same time, the pulsed power supply provides the excitation current, and the stored beam deflects in the dual-channel impact magnet to form a convex orbit. When the injected beam reaches the subsequent common impact magnet, the off-axis height is only a few millimeters and can be successfully captured by the acceptance of the storage ring, thus achieving the purpose of beam injection. Among them, the dual-channel impact magnet and its ceramic vacuum chamber are the parts involved in the present invention and are used to realize the injection of particles and are the key devices of the injection system.

[0037] Figure 1 is the three-dimensional model diagram of the dual-channel impact magnet. The excitation current plates 6 are located on both sides of the ferrite core 1 and are excited by a half-sine wave unidirectional current with a pulse bottom width of 5.6 μs. The current waveform is as Figure 7As shown, different magnetic field peaks can be obtained by changing the magnitude of the excitation current, and the magnitude of the excitation current is related to the pulsed power supply used.

[0038] Figure 2 It is the magnetic field pattern when the peak magnetic field is 1363 Gauss. The left boundary of the built-in oxygen-free copper shielding pipe 4 is at the 7 mm position on the abscissa. The stored beam is deflected by the magnetic field force at around 6 mm. At this time, the main magnetic field inside the magnet is approximately a dipole field, and the magnetic field deviation up and down is only 0.9% at +-0.5 mm near the deflection point (6 mm), which has little impact on the stored beam. Similarly, Figure 2 The magnetic field pattern inside the magnetic shielding channel in the built-in oxygen-free copper shielding pipe is from 8 mm to 16 mm. The longitudinal magnetic field integral at 12 mm inside the magnetic shielding channel is as Figure 3 shown. Its magnetic field is almost zero and will not affect the injected beam in the magnetic shielding channel of the built-in oxygen-free copper shielding pipe 4. The injected beam can directly pass through this magnet and be captured by the acceptance of the storage ring to complete the injection process.

[0039] For other cases with different design requirements, the size and position of the metal shielding tube can be appropriately changed to meet the needs in different situations.

[0040] The above is an implementation manner of the present invention, but the present invention is not limited to the scope of the above specific implementation manners. For those of ordinary skill in the art of this technology, without departing from the measurement principle of the present invention, several improvements and adjustments can still be made, and these improvements and adjustments should also be regarded as the protection scope of the present invention.

Claims

1. A dual-channel kicker magnet for injection in a circular accelerator, characterized in that: It includes a C-shaped ferrite magnetic core, a C-shaped high-conductivity metal block, an aluminum alloy housing, a ceramic vacuum chamber, an internal oxygen-free copper shielding pipe, an epoxy fixing plate, and an exciting current plate; The main body of the double-channel impact magnet adopts an asymmetric C-shaped magnetic core structure, that is, it consists of a C-shaped ferrite magnetic core and a C-shaped high-conductivity metal block. Two exciting current plates are placed on both sides of the yoke of the C-shaped ferrite magnetic core. One of the exciting current plates is fixed to the outside of the C-shaped ferrite magnetic core through an epoxy fixing plate, and the other exciting current plate is also fixed to the inside of the C-shaped ferrite magnetic core through an epoxy fixing plate; taking the edge of the internal oxygen-free copper shielding pipe as the demarcation line, the left side of the double-channel impact magnet is the C-shaped ferrite magnetic core, and the right side is the C-shaped high-conductivity metal block, making the dipole field of the beam current storage channel inside the ceramic tube flatter; the ceramic vacuum chamber is located in the center of the inner hole surrounded by the C-shaped ferrite magnetic core and the C-shaped high-conductivity metal block, and both sides are connected to the flange by kovar through brazing; the size of the epoxy fixing plate is slightly larger than that of the exciting current plate, with a hole dug inside, and the exciting current plate is inserted into the middle of the epoxy fixing plate; the double-channel impact magnet is placed inside the aluminum alloy housing, and the internal oxygen-free copper shielding pipe is located in the ceramic vacuum chamber and is placed on the side close to the C-shaped high-conductivity metal block; the internal oxygen-free copper shielding pipe shields the pulsed magnetic field, and the magnetic shielding channel inside the internal oxygen-free copper shielding pipe is the injection beam current channel, and the magnetic field is almost zero; Both ends of the ceramic vacuum chamber are connected and transitioned by flanges and bellows, and the flanges are connected by fixing screws; The material of the ceramic vacuum chamber is 95% aluminum oxide and needs to be coated inside.

2. The dual-channel kicker magnet for the injection of a circular accelerator according to claim 1, characterized in that: The double-channel impact magnet generates a magnetic circuit by applying pulsed current to the current plates on both sides of the C-shaped ferrite magnetic core, and the magnetic circuit passes through the C-shaped ferrite magnetic core to generate magnetic flux in the inner hole of the C-shaped magnetic core.

3. The dual-channel kicker magnet for injection of a circular accelerator according to claim 2, wherein: The internal oxygen-free copper shielding pipe in the inner hole of the C-shaped magnetic core can shield most of the magnetic field, so the magnetic field in the internal magnetic shielding channel is almost 0.

4. A dual-channel kicker magnet for injection of a circular accelerator according to claim 1, characterized in that: The internal oxygen-free copper shielding pipe passes through the C-shaped high-conductivity metal block, is located in the ceramic vacuum chamber, and is fixed to the two side flanges respectively at both ends. The internal oxygen-free copper shielding pipe is connected to the fixing block by round head screws, and then the fixing block is fixed to the flange through a guide rod, so as to play a role in fixing the internal oxygen-free copper shielding pipe.

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