CN108449859B - Wheel-shaft particle accelerator energy-reducing device and method for reducing energy in vacuum - Google Patents

Abstract

The invention belongs to the technical field of particle accelerators, and relates to a passive energy reducer device for adjusting energy of particles led out by an accelerator, in particular to an energy reducer device of a wheel axle type particle accelerator capable of being used in vacuum and an energy reducing method thereof. The energy degrader comprises: a plurality of energy reducing stop blocks and a set of vacuum system are arranged on a rotary driving mechanism and a rotary disc. The vacuum system enables the rotating disc and the energy-reducing stop block to be in a vacuum environment, and the rotating disc is rotated through the rotating driving mechanism, so that the thickness of the energy-reducing stop block at the beam position is changed to adjust the energy. The invention has compact structure and is beneficial to miniaturization; the magnetic fluid sealing transmission device is adopted, so that the vacuum reliability is high; the wheel shaft type structure is adopted, so that the quick adjustment of different energies can be realized; the energy-reducing stop block is convenient to disassemble and assemble and is beneficial to replacement; the method is a non-superposition energy reduction method and has small influence on beam emittance.

Description

Wheel-shaft particle accelerator energy-reducing device and method for reducing energy in vacuum

technical field

The invention belongs to the technical field of particle accelerators, and relates to a passive energy reducer device for adjusting the energy of particles extracted from an accelerator, in particular to a wheel-shaft particle accelerator energy reducer and its energy reduction method that can be used in vacuum.

Background technique

In the field of particle accelerator technology, especially in the field of cyclotrons and linear accelerators with fixed energy, a passive energy reduction device based on the principle of energy loss due to the interaction between particles and matter is often used. In synchrotrons, since accelerators often have a minimum extraction energy, such passive energy reduction devices are sometimes used.

The core of this energy-reducing device is a material block of different thickness. When a beam of specific energy passes through a material block of different thickness, the energy lost through ionization and scattering is different, so that after passing through the block, different Energy particle beam.

At present, there are mainly three types of energy-reducing devices commonly used: one is based on a one-way plug-in motion mechanism, and an energy-reducing stopper with a stepped thickness is installed at the front end of the motion mechanism to realize the adjustment of different energies; the second is to use double-sided insertion A wedge-shaped stopper is installed at the front end of the movement mechanism, and the thickness of the stopper can be adjusted through the combination of two wedge-shaped stoppers, so as to realize the energy adjustment function; the third is based on a rotating mechanism, and different thicknesses are arranged on a disc. The block, to achieve energy regulation.

Among them, the one-way inserted stepped block-type energy reducer has the advantage of relatively simple structure and easy implementation, as shown in Figure 3. However, in order to achieve multiple energy gears, it is necessary to arrange multiple stoppers with certain sizes and different thicknesses on a linear drive mechanism. The volume occupied in the vertical beam direction is often large, which is not easy to miniaturize, and cannot Realize continuous regulation of energy.

The wedge-shaped energy degrader inserted on both sides uses a pair of completely symmetrical wedges. By controlling the distance between the two wedges in the radial direction, the thickness of the material of the energy degrader that the axial beam passes through can be changed, thereby realizing energy adjustment. , as shown in Figure 4. This kind of energy reducer can realize the continuous adjustment of energy. The disadvantage is that it requires high positioning accuracy; After multiple scattering, the emittance increases greatly and the transmission efficiency is low.

The energy reduction device based on the rotating mechanism has the advantage of being relatively compact, and more stops can be arranged on a rotating disk to realize the adjustment of multiple energy gears. The difficulty is that it involves rotating motion in a vacuum, which is more complicated to implement.

Contents of the invention

The object of the present invention is to provide an energy reducer device that can rapidly change the energy of proton (heavy ion) accelerator particle beams, can be used in vacuum, has a compact structure, and is convenient for replacing energy-reducing blocks. The wheel axle mechanism driven by the motor is used to drive the rotating disk to rotate, and the energy-reducing block is installed on the outside of the rotating disk, and the thickness of the energy-reducing block at the position of the beam is changed by rotation to realize the rapid switching of energy, so that it can be used in physical experiments or radiotherapy. Provide users with particle beams of different energies. To achieve this purpose, it is necessary to install the degrader device in the beam transport line and maintain a high vacuum state on the transport line.

The technical solution of the present invention is to provide a wheel-shaft particle accelerator energy-reduced device for use in vacuum, which is special in that it includes a rotary drive mechanism, a vacuum chamber, and an energy-reduced turntable located inside the vacuum chamber;

The drive shaft of the rotary drive mechanism passes through the vacuum cavity and is connected to the energy-reducing turntable;

The above-mentioned energy-reducing turntable includes a rotating disk and several energy-reducing blocks with different thicknesses located on the rotating disk, and each energy-reducing block is located on the same circumference;

The above-mentioned vacuum chamber is provided with an inlet beam pipe and an outlet beam pipe. The beam enters the vacuum chamber from the inlet beam pipe, vertically passes through the de-energization block on the de-energy turntable, and exits through the outlet beam pipe.

Preferably, the above-mentioned rotary drive mechanism includes a servo motor and a magnetic fluid seal transmission device;

The output shaft of the servo motor is connected to the central shaft of the magnetic fluid seal transmission device through a coupling, and the central shaft of the magnetic fluid seal transmission device passes through the vacuum chamber to connect with the energy-reducing turntable; the magnetic fluid seal transmission device is introduced into the vacuum chamber to rotate movement and achieve a vacuum seal.

Preferably, the rotary drive mechanism further includes a reducer, the input shaft of the reducer is connected to the output shaft of the servo motor, and the output shaft of the reducer is connected to the central shaft of the magnetic fluid seal transmission through a coupling. A central shaft is driven by a servo motor, a reducer and a shaft coupling to provide rotational motion for the vacuum chamber and drive the rotating disk to rotate, so that the energy-reducing blocks of different thicknesses are aligned with the center of the beam pipe.

Preferably, N holes are formed along the same circumference on the rotating disk, and N-1 energy-reducing blocks are respectively fixed in the holes in a detachable manner. According to the subdivision energy requirements, several energy-reducing blocks with different thicknesses are installed on the holes of the rotating disk. According to the energy requirements of the use state, the energy-reducing stopper with a specific thickness is quickly rotated to the center position of the beam pipe that has been calibrated in advance, so as to realize the rapid switching of energy.

Preferably, the energy-reducing block is usually made of a material with a higher density but a lower atomic number, such as graphite, aluminum, etc. First, to ensure that the energy lost by the beam passing through the block per unit thickness is more, thereby reducing the thickness of the block; Second, due to the low atomic number of the material, the scattering effect is small, which is beneficial to control the emittance of the beam; third, because the light elements are not easily activated, it can effectively reduce the induced radioactivity level of the degrader, which is beneficial to the operation and maintenance of the accelerator.

Preferably, the above-mentioned vacuum chamber is provided with a replacement window, an observation window and a vacuuming pipeline, and the replacement window is connected with the flange of the vacuum chamber. The replacement window is used to realize the maintenance and replacement of the beam stopper.

Preferably, the energy reducing device of the present invention further includes a supporting base on which the vacuum chamber is located.

Preferably, the vacuum cavity is a cylindrical cavity with detachable end faces.

Preferably, the material of the rotating disk is stainless steel.

The present invention also provides a method for realizing energy reduction by utilizing the above-mentioned hub-type particle accelerator energy-reduction device for use in vacuum, including the following steps:

Step 1: Use the collimation equipment to calibrate the number of rotations of the servo motor when each energy reduction block moves to the center of the beam pipe, and record it in the control system; and record the corresponding energy reduction of each energy reduction block in the control system ;

Step 2: According to the working state of the accelerator, select the corresponding energy-reducing block, and control the number of rotations of the servo motor, so that the corresponding energy-reducing block is aligned with the center of the beam pipe, and the beam passes through the specific thickness of the energy-reducing block. The energy is reduced to the required energy.

The beneficial effects of the present invention are:

1. The present invention utilizes material blocks of different thicknesses to change the particle beam energy, and has a compact structure, which is beneficial to miniaturization;

2. The present invention uses a magnetic fluid sealing transmission device to introduce rotary motion into the vacuum chamber and realize vacuum sealing, with high vacuum reliability;

3. The invention is easy to operate, adopts the wheel-shaft structure, and can realize rapid and precise adjustment of different energies;

4. The energy-reducing block of the present invention is easy to disassemble and assemble through the observation window and replacement window, which is convenient for maintenance and replacement;

5. The present invention is a non-superimposed energy reduction, which avoids excessive growth of beam emittance while reducing positioning accuracy, and provides a miniaturized solution for particle accelerator energy reduction.

Description of drawings

Fig. 1 is the general structural diagram of the wheel shaft type particle accelerator energy-reducing device used in vacuum in the present invention;

Fig. 2 is a structural diagram of the rotating disk 6 and the energy-reducing block 7 provided by the present invention;

Fig. 3 is a schematic diagram of a stepped block-type energy reducer with one-way insertion in the prior art;

Fig. 4 is a schematic diagram of a wedge-shaped energy reducer inserted on both sides in the prior art;

The reference signs in the figure are: 1-servo motor; 2-reducer; 3-coupling; 4-magnetic fluid seal transmission device; 5-central shaft; Inlet beam pipe; 9-exit beam pipe; 10-vacuumizing pipe; 11-replacement window; 12-observation window; 13-support base; 14-vacuum cavity.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

It can be seen from FIG. 1 that the energy-reducing device of this embodiment mainly includes a rotary drive mechanism, a vacuum chamber 14 and an energy-reducing turntable located inside the vacuum chamber 14;

The rotary drive mechanism includes a servo motor 1, a reducer 2 and a magnetic fluid seal transmission device 4;

The input shaft of the reducer 2 is connected with the output shaft of the servo motor 1, the output shaft of the reducer 2 is connected with the central shaft 5 of the magnetic fluid seal transmission 4 through the coupling 3, and the central shaft 5 of the magnetic fluid seal transmission 4 passes through The vacuum cavity 14 is connected with the energy-reducing turntable; the magnetic fluid sealing transmission device 4 is used to introduce rotary motion into the vacuum chamber and realize vacuum sealing. The servo motor 1 outputs rotary motion, and the speed reducer 2 realizes deceleration and steering, and is connected with the central shaft 5 through the coupling 3, thereby driving the rotating disk 6 to rotate.

The energy-reducing turntable includes a rotating disk 6 and an energy-reducing stopper 7. There are N holes along the same circumference on the rotating disk 6, and N-1 energy-reducing stops 7 are respectively fixed in the holes in a detachable manner;

The vacuum chamber 14 is a cylindrical chamber on which an inlet beam pipe 8 and an outlet beam pipe 9 are arranged. The beam enters the vacuum chamber 14 from the inlet beam pipe 8 and passes vertically through the de-energy barrier on the de-energy turntable. After the block 7, it exits through the exit beam duct 9. The vacuum chamber 14 is fixed on the support base 13, and the vacuum chamber 14 is also provided with a replacement window 11, an observation window 12 and a vacuuming pipe 10. When maintenance or replacement of the energy-reducing block is required, the flange of the replacement window 11 can be opened. , to replace one or more energy-reducing blocks 7 required without disassembling and reinstalling the entire device.

The energy reducing device of this embodiment is used in a proton synchrotron device, and the synchrotron can directly extract proton beams with an energy of 60-230 MeV for irradiation experiments. For energy adjustment below 60 MeV, it is necessary to pass the Energy reducer to achieve.

As shown in Figure 2, there are 24 hole positions on the stainless steel rotating disk 6 in this embodiment, one hole position is not equipped with the energy-reducing stopper 7, and the other hole positions are respectively equipped with 23 detachable graphite stoppers of different thicknesses. The block is used to realize the energy adjustment of protons below 60 MeV, and the corresponding relationship between the thickness of the graphite block and its adjustment energy is shown in the table below, and the calculation is completed using the Monte Carlo program TRIM.

Table 1 Corresponding relationship between the thickness of the graphite energy-reducing block and its adjustment energy

The steps to use the energy-reducing device are as follows:

(1) Before work, use collimation equipment such as a measuring arm to calibrate the number of turns of the servo motor 1 when the energy-reducing stopper 7 of each thickness moves to the center of the beam pipe, and record it in the computer control system. Wherein, there is a position on the rotating disk 6 where the energy-reducing block 7 is not installed, which is marked as position 0.

(2) When the proton beam energy required by the experimental user is above 60 MeV, the accelerator does not need to reduce the energy, and the beam pipe is aligned with the position 0 on the rotating disk 6. At this time, the beam can pass through without being blocked by any object In the vacuum chamber of the energy degrader, the beam energy is kept as the directly extracted energy.

(3) When it is necessary to reduce the energy of the extracted beam to a certain energy point below 60MeV, it is only necessary to input the energy number in the computer control system, and the driving system drives the rotating disk 6 to rotate a specified number of turns in a vacuum environment, so that the The energy-reducing block corresponding to the energy is aligned with the center of the beam pipe, and the beam passes through the energy-reducing block 7 with a specific thickness, and the energy is reduced to the required energy.

(4) When maintenance or replacement of energy-reducing blocks is required, one or more required energy-reducing blocks can be replaced by opening the replacement window 11 flange, without disassembling and reinstalling the entire device.

It is obvious that those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (6)

1. A wheel axle type particle accelerator energy reducing device used in vacuum is characterized in that: comprises a rotary driving mechanism, a vacuum cavity (14) and an energy reducing turntable positioned in the vacuum cavity (14);

a driving shaft of the rotary driving mechanism penetrates through the vacuum cavity (14) to be connected with the energy reducing turntable;

The energy reducing turntable comprises a rotating disk (6) and a plurality of energy reducing stop blocks (7) which are arranged on the rotating disk (6) and have different thicknesses, and the energy reducing stop blocks (7) are arranged on the same circumference;

an inlet beam pipeline (8) and an outlet beam pipeline (9) are arranged on the vacuum cavity (14), and beams enter the vacuum cavity (14) from the inlet beam pipeline (8), vertically pass through an energy reducing stop block (7) on the energy reducing turntable and then are emitted through the outlet beam pipeline (9); the rotary driving mechanism comprises a servo motor (1) and a magnetic fluid sealing transmission device (4);

An output shaft of the servo motor (1) is connected with a central shaft (5) of the magnetic fluid sealing transmission device (4) through a coupler (3), and the central shaft (5) of the magnetic fluid sealing transmission device (4) penetrates through the vacuum cavity (14) to be connected with the energy-reducing turntable; the magnetic fluid seal transmission device (4) guides rotary motion into the vacuum chamber and realizes vacuum seal; the rotary driving mechanism further comprises a speed reducer (2), an input shaft of the speed reducer (2) is connected with an output shaft of the servo motor (1), and the output shaft of the speed reducer (2) is connected with a central shaft (5) of the magnetic fluid sealing transmission device through a coupler (3);

the vacuum cavity (14) is provided with a replacing window (11), an observation window (12) and a vacuum-pumping pipeline (10), and the replacing window (11) is connected with the vacuum cavity (14) through a flange; n hole sites are arranged on the rotating disc (6) along the same circumference, and N-1 energy reducing stop blocks (7) are detachably fixed in the hole sites respectively.

2. The wheel axle type particle accelerator energy-reducing device for vacuum of claim 1, characterized in that: the energy reducing stop block (7) is made of graphite or aluminum.

3. The wheel axle type particle accelerator energy-reducing device for vacuum of claim 2, characterized in that: the vacuum device also comprises a supporting base (13), and the vacuum cavity (14) is positioned on the supporting base (13).

4. a wheel axle type particle accelerator energy-reducing device for vacuum according to any one of claims 1 to 3, characterized in that: the vacuum cavity (14) is a cylindrical cavity, and the end face is detachable.

5. the wheel axle type particle accelerator energy-reducing device for vacuum of claim 4, characterized in that: the material of the rotating disc (6) is stainless steel.

6. A method for reducing energy by using the wheel axle type particle accelerator energy reducing device for vacuum of any one of claims 1 to 5, which is characterized by comprising the following steps:

the method comprises the following steps: calibrating the number of turns of the servo motor when each energy reduction stop block moves to the center of the beam pipeline by using collimation equipment, and recording the number of turns in a control system; recording the corresponding energy reduction amount of each energy reduction stop block in the control system;

step two: according to the working state of the accelerator, selecting a corresponding energy reduction stop block, controlling the rotation number of turns of the servo motor, enabling the corresponding energy reduction stop block to be aligned to the central position of a beam pipeline, and reducing the energy of the beam to the required energy after the beam passes through the energy reduction stop block with the specific thickness.