JPH06204000A - Beam profile monitor for particle accelerator - Google Patents

Abstract

PURPOSE:To detect a fluctuation of beam profile at real time. CONSTITUTION:A screen 20 is arranged on a beam designed orbit 13 in a vacuum chamber 10 in a linear accelerator in such a manner as to be capable of protruding and recessing. The screen 20 is, for example, formed of a fluorescent material or coated with the fluorescent material, and emits a light in a position to which a beam is collided. An observation hole 19 is formed on the side of the screen 20, and a television camera 14 is arranged on the outside thereof to observe the emission on the screen 20. To perform this observation, the screen 20 is arranged slantingly toward the television camera 14 from the beam axis. In the central part of the screen 20, a hole 22 with a diameter B' slightly smaller than a standard beam diameter B is formed with the beam designed orbit 13 as a center.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam profile monitor for observing a profile (size, etc.) of a charged particle beam or SOR light beam passing through a vacuum chamber in a particle accelerator. It is possible to detect in real time.

[0002]

2. Description of the Related Art For example, in a linac (linear accelerator), a beam file monitor is arranged at the beam exit to detect a beam profile, and the magnetic field of a focusing electromagnet is adjusted so as to obtain a predetermined beam profile. .

In a conventional beam monitor, for example, as shown in FIG. 2, a screen 12 is arranged on a beam design track 13 in a vacuum chamber 10 so that the screen 12 can advance and retreat. The screen 12 is made of, for example, a fluorescent substance or coated with a fluorescent substance, and emits light at the position where the beam collides. A viewing window 19 is formed on the side of the screen 12,
The television camera 14 is arranged outside the screen 1
Observe the light emission above 2. In order to make this observation, the screen 12 is arranged so as to be tilted in the direction of the television camera 14 with respect to the beam axis.

The screen 12 is designed so that it does not interfere with the passage of the beam 15 by exiting from the beam design track 13 during operation. At the time of observing the beam profile, the screen 12 advances on the beam design trajectory 13. When the beam 15 enters the vacuum chamber 10 in the advanced state, it collides with any part of the surface of the screen 12 and emits light at that part. By observing this position with the television camera 14, the deviation of the beam 15 from the designed trajectory 13 can be observed, and the trajectory of the beam 15 is corrected by adjusting the amount of excitation of the electromagnet according to this deviation. be able to. When the correction is completed, the screen 12 is moved out of the beam design trajectory 13.

[0005]

In the observation of the beam profile by the conventional screen 12, the beam 15 is observed.
Since it collided with the screen 12 and disappeared, it could not be used during the actual operation of the particle accelerator. For this reason, it was not possible to detect changes in the beam profile over time during operation. The present invention is intended to provide a beam profile monitor of a particle accelerator capable of solving the above-mentioned problems in the conventional technique and detecting the fluctuation of the beam profile in real time.

[0006]

The invention according to claim 1 is
It is placed on the beam design trajectory in the vacuum chamber of the particle accelerator, has a hole slightly smaller than the reference beam diameter around the design trajectory, and looks at this light-emitting member and the light-emitting member that emits light by irradiation of the beam. The observation window is formed in the vacuum chamber as described above, and the observation means for observing the light emitting member through the observation window.

Further, the invention according to claim 2 is arranged so as to be able to enter and leave each of the beam design trajectories in the vacuum chamber of the particle accelerator, and has holes of different diameters centering on the design trajectories, It is provided with a plurality of light emitting members which emit light by irradiation of a beam, a viewing window formed in the vacuum chamber so as to look into these light emitting members, and an observation means for observing the light emitting members through the viewing window. is there.

[0008]

According to the invention described in claim 1, since a hole slightly smaller than the beam diameter is formed in the light emitting member, when the beam diameter is the reference size, the periphery of the hole shines faintly, and the beam is smaller than the reference beam diameter. When it is large, the range of light around the hole is wide, and when it is smaller than the reference beam diameter, almost no light is emitted. Therefore, it is possible to detect whether it matches the reference beam diameter or is larger or smaller than the reference beam.
Since the beam that has passed through the hole can be used as it is, it can be used during actual operation, and the fluctuation of the beam profile during operation can be observed in real time.

According to the second aspect of the present invention, the beam diameter can be measured by the light emitting condition around the hole by alternately inserting and removing the plurality of light emitting members having different beam diameters on the beam orbit. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention described in claim 1 is shown in FIG.
Is shown in a plan sectional view. A screen 20 is provided on the beam design trajectory 13 in the vacuum chamber 10 in the linac or the like.
Are arranged so that they can move in and out. The screen 20 is made of, for example, a fluorescent substance or is coated with a fluorescent substance, and emits light at the position where the beam collides. A viewing window 19 is formed on the side of the screen 20, and a television camera 14 is provided outside the viewing window 19 to observe light emission on the screen 20. In order to make this observation, the screen 20 is tilted in the direction of the television camera 14 with respect to the beam axis.

As shown in the front view of FIG. 1 (b), the screen 20 is supported by a support rod 24 and fixedly arranged in the vacuum chamber 10, or is moved vertically so that the screen 20 can enter and exit. It is set up. A hole 22 having a diameter B ′ slightly smaller than the reference beam diameter B is formed in the center of the screen 20 with the beam design trajectory 13 as the center.

An image observed by the television camera 14 having the configuration shown in FIG. 1 is shown in FIG. (A) is the reference beam diameter,
The periphery of the hole 22 shines faintly. (B) is larger than the reference beam diameter, and the periphery of the hole 22 shines in a wide range.
(C) is a case where the beam diameter is smaller than the reference beam diameter, and there is almost no light around the hole 22. In (d), the beam has a designed trajectory 13
When deviated, it shines in a biased state around the hole 22. Accordingly, it is possible to detect whether these observation images match the reference beam diameter or are larger or smaller than the reference beam. The beam 15 that has passed through the hole 22 can be used as it is,
It can be used during actual operation, and changes in the beam profile during operation can be observed in real time.

[0013]

[Other Embodiments] FIG. 4 is a plan sectional view showing an embodiment of the present invention. On the beam design trajectory 13 in the vacuum chamber 10 in the linac or the like, a plurality of stages of screens 31 to 34 are arranged so that they can individually advance and retreat. The screens 31 to 34 are made of, for example, a fluorescent substance or coated with a fluorescent substance, and emit light at the position where the beam collides. Viewing windows 41 to 44 are formed on the sides of the screens 31 to 34, and the screens 31 to 34 are arranged so as to be inclined with respect to the beam axis in the directions of the viewing windows 41 to 44.

As shown in the front view of FIG. 5, the screens 31 to 34 are supported by support rods 61 to 64, and are arranged so as to be able to enter and leave the vacuum chamber 10 in the vertical direction. In the center of the screens 31-34,
From the diameter B ₁ larger than the reference beam diameter B around the beam design trajectory 13 to the diameter B smaller than the reference beam diameter B
Holes 71 to 74 having different sizes are formed in the hole ₄ .

Half mirrors 51 to 54 (the mirror 51 may be a total reflection mirror) are arranged outside the viewing windows 41 to 44 with their reflection optical axes 55 aligned with each other, and the television camera 14 is placed on the reflection optical axes 55. Is provided. The image taken by the television camera 14 is displayed on the television monitor and is also sent to the image processing and control device 76.

The image processing and control device 76 processes the image of the television camera 14 and observes the light emission status of the screens 31 to 34, drives the screen drive devices 81 to 84, and moves the support rod 61 up and down. , Screen 31-
34 are alternately positioned on the beam design trajectory 13 and the beam diameter is measured in real time during actual operation.

Beam by image processing and controller 76
FIG. 6 shows an example of the screen drive control when measuring the diameter. Is
First, put out the screen 31 with the largest hole on the track 13.
(P1). In this state, does the beam 15 cover the hole 71?
Observe whether or not (P2). If yes, the beam diameter is B₁Yo
It is determined to be slightly larger (P3). If you don't scratch
Raises screen 31 and moves to the next screen 32
Put it on 13 (P4). In this state, the beam 15 has a hole 72
Observe whether or not to remove (P5), and if yes, beam
Diameter is B₂It is determined to be slightly larger than (P6). Kasura
If not, raise screen 32 and move to next screen 3.
3 is put on the orbit 13 (P7). Beam 15 in this state
When observing whether or not the hole 73 is removed (P8)
Has a beam diameter of B₃It is judged to be slightly larger than (P
9). If you don't scratch, raise the screen 33 to the next
The screen 34 is put out on the track 13 (P10). This state
In this state, it is observed whether the beam 15 goes through the hole 74 (P1
1), the beam diameter is B _FourSlightly larger than
The determination is made (P12). If there is no blur, the beam diameter is B
_FourIt is determined to be smaller than (P13). Like this
The beam diameter can be measured in real time during actual operation.
You can If the beam diameter changes, repeat the above operation.
By returning, the beam diameter can be measured each time.
it can.

[0018]

[Modification] The present invention can be used not only for the linac but also for observing the beam profile of the particle beam or the SOR light in the orbiting ring and the SOR light emitting line.

[0019]

As described above, according to the first aspect of the present invention, the light emitting member is formed with a hole slightly smaller than the beam diameter. Therefore, when the beam diameter is the reference size, the circumference of the hole is small. It shines faintly, and when it is larger than the reference beam diameter, the range of the light around the hole is widened, and when it is smaller than the reference beam diameter, it hardly emits light. Therefore, it is possible to detect whether it matches the reference beam diameter or is larger or smaller than the reference beam. Since the beam that has passed through the hole can be used as it is, it can be used during actual operation, and the fluctuation of the beam profile during operation can be observed in real time.

According to the second aspect of the invention, the beam diameter can be measured by the light emitting condition around the hole by alternately inserting and removing a plurality of light emitting members having different beam diameters on the beam orbit. .

[Brief description of drawings]

FIG. 1 is a plan sectional view and a front view of a screen showing an embodiment of the invention described in claim 1.

FIG. 2 is a plan sectional view showing a conventional device.

FIG. 3 is a diagram showing an observed image of a television camera by the apparatus of FIG.

FIG. 4 is a plan sectional view showing an embodiment of the invention described in claim 2.

5 is a front view of each screen of FIG. 4. FIG.

6 is a flowchart showing an example of screen drive control by the image processing and control device of FIG.

[Explanation of symbols]

10 Vacuum Chamber 13 Beam Design Trajectory 14 TV Camera (Observation Means) 15 Particle Beam 19 Viewing Window 20 Screen (Light Emitting Member) 22 Holes 31, 32, 33, 34 Screen (Multiple Light Emitting Members) 71, 72, 73, 74 Different Diameter hole B Reference beam diameter

Claims (2)

[Claims] 1. A light emitting member which is arranged on a beam design trajectory in a vacuum chamber of a particle accelerator, has a hole slightly smaller than a reference beam diameter around the design trajectory, and which emits light by irradiation of the beam. A beam profile monitor for a particle accelerator, comprising: a viewing window formed in the vacuum chamber so as to look into the light emitting member; and an observing means for observing the light emitting member through the viewing window. 2. A plurality of beams which are arranged so as to enter and leave a beam design trajectory in a vacuum chamber of a particle accelerator, have holes of different diameters around the design trajectory, and emit light by irradiation of the beam. A beam profile monitor for a particle accelerator comprising: a light emitting member; a viewing window formed in the vacuum chamber so as to look into the light emitting member; and an observation means for observing the light emitting member through the viewing window.