JPH06290900A - High frequency quadri-polar accelerating device - Google Patents

Abstract

PURPOSE:To provide a high frequency quadripolar electrode accelerating device which is equipped with an adjusting means for keeping the installed position accuracy of each quadripolar electrode to be installed in the casing. CONSTITUTION:An electrode supporting structure is configured so that the installed positions of quadripolar electrode 1-4 to be installed in place within a casing 16 can undergo fine adjustment. The electrode supporting structure is such that a seat face 25 equipped with an opening is furnished on the external wall of the casing 16 and a supporting member 26 fitted with a flange part 28 is inserted through the casing 16 from this opening in the seat face 25 and coupled with metal members 18, 19 supporting the quadripolar electrodes to make possible locating each quadripolar electrode in place within the casing 16. The opening in the seat face 25 is closed with another flange part 27 of the supporting member 26 so that the vacuum structure of the casing 16 is held, and because of adjustability of the position where this flange part 27 and seat face 25 are fastened by bolt, the installed position of each quadripolar electrode can be fine adjusted through adjustment of the supporting member 26 installed position to the casing 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle accelerator using a high frequency quadrupole electrode, and more specifically, for supporting a quadrupole electrode arranged in a housing forming a resonance cavity at a predetermined position. The present invention relates to an electrode support structure for a high frequency quadrupole accelerator.

[0002]

2. Description of the Related Art For example, in order to obtain a high-energy ion beam for performing ion implantation, material analysis, etc., four vane electrodes (quadrupole electrodes) are used as an accelerator utilizing a high frequency electric field. A high-frequency quadrupole accelerator is used in which the vacuum container itself accommodating the electrodes also serves as a resonance cavity. This high frequency quadrupole (RFQ: Radio Frequency Quad)
The configuration of a conventional example of a rupole) accelerator (hereinafter referred to as RFQ) is shown below. In the RFQ 30 shown in FIG. 9, electrodes 1, 2, which form a quadrupole electrode in the central axis direction of the casing 5,
3, 4 are arranged. Each electrode 1, 2, 3,
Reference numeral 4 indicates that the surfaces facing each other are corrugated in an uneven shape, and the electrodes facing each other have the uneven shapes formed in the same phase, and the electrodes adjacent to each other have the uneven shapes formed in the opposite phase. . When high-frequency power of a predetermined frequency is applied to the housing 5 containing the quadrupole electrode formed in this way, the housing 5 operates as a resonant cavity and TE
Resonance frequency of _{21 0} mode is excited. At this time, the same potential is generated at the electrodes facing each other, and the opposite potential is generated at the electrodes adjacent to each other. Therefore, the four electrodes 1, 2,
A quadrupole electric field is generated near the central axis where 3 and 4 face each other. In the TE ₂₁₀ mode, when the electrodes 1 and 3 are positive, the electrodes 2 and 4 are negative, and when the former is negative, the latter is positive. In addition to these conditions, electrode 1,
Since the concavo-convex shapes 2, 3 and 4 are vertically and horizontally shifted by 180 degrees, for example, the electrodes 1 and 3 are positive,
When the electrodes 2 and 4 are negative, an axial electric field is generated on the central axis. When the voltage polarities of the electrodes 1, 2, 3, 4 are reversed, the direction of this electric field is also reversed. Now
When the ions injected into the quadrupole electrode along the central axis have such a velocity and phase that they always receive an accelerating electric field in the left-right direction, they pass through the uneven portions of the electrodes 1, 2, 3, 4. Every time you do, the energy is accelerated and the energy increases monotonously. On the other hand,
Ions that came in at the first phase to undergo deceleration
At the next accelerating electric field, the ions are gradually bunched into subsequent ions, and after that, they are monotonically accelerated. In addition, a strong high-frequency electric field existing in a plane orthogonal to the axis causes a strong focusing force in the vertical and horizontal directions, so that the ions can be accelerated with a very high transmittance.

In the RFQ30, the housing 5 has electrodes 1,
A high-frequency cavity resonator is configured with 2, 3 and 4,
Since the resonance frequency is determined by the geometrical dimensions of the housing 5, in order to construct an accelerator that accelerates heavy ions, a housing having a huge diameter must be used, which is an unrealistic industrial situation. It becomes the target. Therefore, a resonance circuit 12 including a capacitor and an inductor is provided outside, and a high frequency power of a frequency necessary for accelerating an arbitrary ion species is R
It is supplied to the FQ 30 to excite the cavity resonator and generate a high frequency potential in the quadrupole electrode. However, when an external resonance circuit is provided as described above, stray inductance and stray capacitance that cannot be ignored are generated in the cable portion for supplying high-frequency power inside the housing, and the Q value decreases due to loss in the cable portion. However, problems such as susceptibility to external disturbances occur, resulting in an unstable device. Therefore, in order to solve the above problems when a resonance circuit is provided outside, various RFQ configurations in which components of an inductor and a capacitor are formed in a cavity (housing) have been proposed. For example, the RF shown in FIGS.
Q31 is a proposal made by the inventors of the present application, in which flat plate electrodes 61, 62, 64, and 65, which are derived from the opposite side surfaces of the inner wall of the housing 60, are arranged close to each other in parallel with the central axis. By arranging the flat plate electrodes 61, 6 relatively large capacitance can be obtained.
The inductors 2, 64, 65 and the housing 60 constitute an inductor to enable resonance at a low frequency. This configuration realizes a practical size RFQ capable of accelerating heavy ions.

[0004]

However, when the resonance circuit is formed inside the housing as described above, the accuracy of the position of the quadrupole electrode depends on the mechanical processing accuracy of each component. Therefore, there is a problem that a high processing accuracy is required. Further, since the temperature around the quadrupole electrode increases due to power loss, the positional accuracy deteriorates due to thermal strain, but there is also a problem that there is no means for correcting this.
The present invention has been made in view of the above problems, and provides a high-frequency quadrupole electrode accelerator equipped with adjusting means for maintaining the positional accuracy of the arrangement of the quadrupole electrode in the housing. The purpose is to

[0005]

In order to achieve the above object, the means adopted by the present invention is to support a quadrupole electrode with a metal member in the central axis direction inside a cylindrical casing, and In a high-frequency quadrupole accelerator in which the quadrupole electrode is arranged at a predetermined position in the housing by connecting a supporting member attached to the housing and the metal member, the supporting member is attached to the housing. It is configured as a high-frequency quadrupole accelerator characterized in that the mounting position is adjustable. Also,
A thrust bearing may be provided at a bolt tightening position for attaching the support member to the housing.

[0006]

According to the present invention, in the high-frequency quadrupole accelerator, the electrode support structure is provided so that the placement position of the quadrupole electrode, which is required to be accurately placed at a predetermined position in the housing, can be finely adjusted. Is configured. In this electrode support structure, a support member attached to a housing is connected to a metal member that supports the quadrupole electrode, and a mounting position of the support member to the housing is adjustable. Therefore, by finely adjusting the mounting position of the supporting member to the housing, it is possible to finely adjust the disposition position of the metal member connected to the supporting member and by extension, the quadrupole electrode supported by the metal member. it can. Further, by providing the thrust bearing at the bolt tightening position for attaching the support member to the housing, it is possible to prevent the set position from being displaced due to rotational friction when the bolt is tightened. Since the arrangement position of the quadrupole electrode can be finely adjusted by the above configuration, an error in machining accuracy and a power loss that affect the arrangement position accuracy of the quadrupole electrode, which requires high-precision position accuracy. It is possible to correct the decrease in accuracy due to the thermal strain related to. Further, since the arrangement position can be adjusted from the outside of the housing, workability is improved.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. still,
The following example is an example embodying the present invention and does not limit the technical scope of the present invention. Figure 1
Is a side view showing the configuration of the RFQ according to the embodiment of the present invention, and is shown with the half surface of the housing removed to clarify the internal structure. 2 is a sectional view taken along the line AA in FIG. 1, FIG. 3 is a sectional view taken along the line BB in FIG. 1, FIG. 4 is a perspective view for clearly showing the electrode supporting structure, and FIG. 6 is a partial perspective view of the upper surface of the casing showing an example of a seating surface for mounting a support member formed on the outer wall of the seat, FIG. 6 is a sectional view showing a mounting structure of the support member on the seating surface, and FIG. FIG. 8 is a sectional view showing another embodiment of the mounting structure of the supporting member, and FIG. 8 is a sectional view showing another embodiment of the mounting structure of the supporting member on the seating surface. 1, FIG. 2 and FIG. 3, RFQ 15 has quadrupole electrodes 1, 2, 3 and 4 facing each other about a central axis 14 of a cylindrical casing 16 forming a resonance cavity. It is located in. The quadrupole electrodes 1, 2, 3, 4 are supported by first metal members 18 and second metal members 19 which are alternately arranged on the central axis 14. The quadrupole electrodes 1 and 3 are the first metal member 1
8, the quadrupole electrodes 2 and 4 are directly connected to and supported by the second metal member 19, respectively. In addition, the first metal member 18
Two first metal plates 21 and 21 arranged in the central axis direction of the housing 16 are attached to the second metal member 19 and two first metal plates 21 and 21 arranged in the central axis direction of the housing 16 are attached to the second metal member 19. Second
The metal plates 22 and 22 are attached. A third metal plate 23 supported by the second metal member 19 is disposed between the first metal plates 21 and 21, and the first metal plate 22 is disposed between the second metal plates 22 and 22. The fourth metal plate 24 supported by the metal member 18 is arranged. Between the first metal plates 21 and 21 and the third metal plate 23 arranged in this way, and between the second metal plates 22 and 22 and the fourth metal plate 24.
And a first metal plate 21, 21 and a second metal plate 22, which are respectively connected to the housing 16, and a capacitor is formed between
An inductor is formed by 22 and the case 16, and a resonance circuit is formed in the case.

The first metal plate 21 and the second metal plate 22
Is connected to each support pillar 26 mounted on two pairs of seating surfaces 25 formed at the upper and lower positions of the housing 16 in the drawing, and
Attached together with the support pillars 26 and also functions as a support member that supports the metal members 18 and 19 from the housing 16. As shown in FIG. 5, each seating surface 25 formed on the housing 16 has a flat surface portion 25a formed on the outer wall of the cylindrical housing 16 and having a predetermined smooth surface, and the flat surface portion 25a. An opening 27 that penetrates the inside of the housing 16 at the center of the
And are formed. As shown in FIGS. 4 and 6, the seating surface 25 thus formed has the opening 27.
A supporting column 26 having a flange portion 28 capable of covering the above is sufficiently attached. The support pillars 26a mounted on the upper side have the first metal plates 21 and 21, and the support pillars 26b mounted on the lower side have the second metal plates 22 and 2.
2 are fixed by a fitting structure. Therefore, a support member is formed by the support column 26 and the metal plate 21 or 22, and the first metal member 18 or the second metal member 21 or 22, respectively.
The quadrupole electrodes 1, 2, 3 and 4 supported by the metal members 18 and 19 are connected to the metal member 19 of FIG.
The structure supporting from 6 is made. The support pillar 26 is attached to the seating surface 25 by fixing the flange portion 28 to the flat surface portion 25a with bolts 29, 29 as shown in FIG. Since the bolt hole provided in the flange portion 28 has a diameter larger than the diameter of the bolt 29, and the diameter of the support pillar 26 is smaller than the diameter of the opening 27, the diameter of the bolt 29 is smaller than that of the bolt 29. The mounting position of the support column 26 can be adjusted by an amount corresponding to a large margin of the bolt hole diameter. This means for adjusting the mounting position of the support column 26 is, in other words, means for adjusting the position of the quadrupole electrodes 1, 2, 3, 4.

In the high-frequency quadrupole electrode accelerator, the positions of the quadrupole electrodes 1, 2, 3 and 4 must be accurately maintained in order to accelerate the charged particles while efficiently converging them. Although necessary, the processing accuracy of each support member (metal member 18, 19, metal plate 21, 22, support pillar 26) that supports the quadrupole electrodes 1, 2, 3, 4 on the housing 16 is increased. Occurrence of accuracy error is inevitable even after finishing, and it must be said that it is very difficult to ensure accuracy, especially considering that the diameter of the housing 16 is 600 mm or more. Further, even if the accuracy is secured, it is required to correct the deterioration of the accuracy due to the thermal distortion due to the power loss. In the configuration of this embodiment, in order to correct the accuracy error of the machining and the accuracy decrease due to thermal strain, as described above, the quadrupole electrode 1,
A means for adjusting the positions 2, 3, 4 is provided. The means for adjusting the mounting position of the support pillar 26 can be configured as in another embodiment shown in FIG. In this embodiment, a thrust bearing 30 is attached to each bolt 29. With this configuration, when the bolt 29 is tightened, fine positioning is difficult due to rotational movement or parallel movement between the bolt 29 and the washer 31 or between the washer 31 and the flange portion 28, which is affected by the rotational movement or parallel movement that is affected by minute protrusions. Is eliminated.

Further, the means for adjusting the mounting position of the support column 26 can be configured as in another embodiment shown in FIG. In this embodiment, a bellows 32 is provided between the seating surface 25 and the flange portion 28 of the support column 26 so that the vacuum airtight state in the housing 16 can be maintained even when the bolt 29 is loosened. There is. With this configuration, it is possible to adjust the arrangement position of the quadrupole electrodes 1, 2, 3, 4 even when the RFQ 15 is operated. Although not shown in the above drawings, the opening 27 is sealed between the flat surface portion 25a of the seating surface 25 and the inner surface side of the flange portion 28 to more reliably maintain vacuum tightness in the housing 16. The vacuum packing material for is inserted.

[0011]

As described above, according to the present invention, in the high frequency quadrupole accelerator, it is possible to adjustably support the placement position of the quadrupole electrode which requires a high placement position accuracy. Therefore, it is possible to correct an error in the machining accuracy of each supporting member that supports the quadrupole electrode and an accuracy deviation due to thermal strain related to power loss. Therefore, as a result of the arrangement position of the quadrupole electrode being ensured with high accuracy, there is an effect that the configuration of the high-frequency quadrupole accelerating device capable of efficiently accelerating the charged particles while converging them is facilitated.

[Brief description of drawings]

FIG. 1 is a side view showing the configuration of a high frequency quadrupole accelerator according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

3 is a sectional view taken along the line BB in FIG.

FIG. 4 is a perspective view for clearly showing the electrode support structure according to the embodiment.

FIG. 5 is a partial perspective view of the top surface of the housing showing a configuration example of a seating surface according to the embodiment.

FIG. 6 is a cross-sectional view showing an attachment structure of a support column to a seating surface according to the embodiment.

FIG. 7 is a cross-sectional view showing another embodiment of the support pillar mounting structure for the seating surface according to the embodiment.

FIG. 8 is a cross-sectional view showing another embodiment of the structure for attaching the support pillar to the seating surface according to the embodiment.

FIG. 9 is a perspective view showing the configuration of an RFQ according to a conventional example.

FIG. 10 is a diagram showing an R in which a resonance circuit is configured in a housing according to a conventional example.
The side view which shows the structure of FQ.

FIG. 11 is a sectional view taken along the line CC ′ of the above.

FIG. 12 is a partial perspective view showing the internal structure of the housing.

[Explanation of symbols]

 1, 2, 3, 4 ... quadrupole electrode 14 ... central axis 15 ... high-frequency quadrupole accelerator (RFQ) 16 ... housing 18, 19 ... metal member 21, 22 ... metal plate ( Support member 25 ... Seating surface 26 ... Support pillar (support member) 27 ... Opening 28 ... Flange 29 ... Bolt 30 ... Thrust bearing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Inoue 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Co., Ltd. Kobe Research Institute (72) Inventor Takuya Kusaka Nishi-ku, Kobe-shi, Hyogo Prefecture 1-5-5 Takatsukadai, Kobe Steel Research Institute, Kobe Steel, Ltd. (72) Inventor, Yukio Furukawa 1-5-5, Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Kobe Steel, Kobe Steel, Ltd. (72) ) Inventor Toshishi Suzuki 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Works, Ltd. Kobe Research Institute

Claims (2)

[Claims] 1. A quadrupole electrode is supported by a metal member in a central axis direction inside a cylindrical casing, and the supporting member attached to the casing is connected to the metal member to form the quadrupole electrode. A high-frequency quadrupole accelerator in which a quadrupole electrode is arranged at a predetermined position in a housing, wherein the support member is attached to the housing so that the position can be adjusted. 2. The high frequency quadrupole accelerator according to claim 1, wherein a thrust bearing is provided at a bolt tightening position for attaching the support member to the housing.