JPH10142342A - Beam position monitor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability of brazing of a stainless steel flange to a block in a beam position monitor. SOLUTION: Metal plating is applied at least to a part 8 on the surface of a stainless steel flange 3 being brazed to a block 1 in order to retard deposition of M23 C6 in the stainless steel to the brazed surface thus enhancing reliability of brazing. Consequently, a beam position monitor can be manufactured by two times of brazing work, i.e., a brazing work of a pickup electrode to the block 1 and a brazing work of the flange 3 to the block 1 using three kinds of brazing material after brazing the components of the pickup electrode using a eutectic brazing tiller metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam position monitor for monitoring a beam position of a beam accelerator for electrons, positrons and the like.

[0002]

2. Description of the Related Art Conventionally, as a beam position monitor for such an accelerator, TF Design and
Study Report 1995 (ATF DESIGN
AND STUDY REPORT 1995), pp. 99-104.
According to this, 4 for monitoring the beam position.
The pickup electrodes face the inside of a cylindrical block through which a beam passes, are fixed symmetrically to the outer peripheral wall of the block, and the block is fixed to a flange. As the pickup electrode, a stainless steel button electrode is fixed in an aluminum outer cylinder via a ceramic insulating material, and the outer cylinder is inserted into an insertion hole 16 provided in the outer peripheral wall of the aluminum block, so that the electron beam is emitted. Joined by welding. The aluminum block is welded to an aluminum duct for guiding the beam. Electromagnetic waves emitted from the beam are detected by the four pickup electrodes, and the position of the beam is monitored based on the intensity of the detection signal.

[0003] Here, since the electromagnetic wave emitted from the beam is extremely weak, the position accuracy of the pickup electrode of the beam position monitor is required, and the installation accuracy (position accuracy) is required. In the above-mentioned literature, positioning is performed by providing a positioning reference surface on a block and aligning the positioning reference surface with a reference surface of a stainless steel support base.

However, according to the beam position monitor disclosed in the above document, since the pickup electrode is joined to the aluminum block by electron beam welding, the gap between the pickup electrode and the insertion hole 16 of the block must be completely welded. Can not avoid leaving a gap in a part. Such a gap acts as a capacitance when measuring a high-frequency electromagnetic wave, so that there is a problem that an error occurs in beam position detection. Further, since thermal distortion occurs in the aluminum block due to the electron beam welding, an error may occur in the position of the pickup electrode. Furthermore, since the aluminum block has a lower rigidity than the stainless steel support base, the block may be deformed when the block is fixed to the support base, and the positional accuracy of the pickup electrode is reduced. Was.

Therefore, the block is formed of copper, and a stainless steel (for example, SUS316) flange is joined to the copper block with a silver solder, and the flange is fixed to a stainless steel support base using the flange as a reference surface, thereby obtaining a rigid body. It has been proposed to solve the problem of the positional accuracy due to the difference of. In addition, the button electrode, the ceramic insulating material, and the metal outer cylinder that constitute the pickup electrode are joined and assembled with a silver solder, and the pickup electrode is joined to the body block with a silver solder to reduce the gap at the joint. It has been proposed to fill with silver low to reduce the capacitance that hinders the detection of high-frequency electromagnetic waves. According to these methods, for example, 800 ° C.
Since the brazing operation is performed before and after the temperature, the residual strain can be removed similarly to the solution treatment.

[0006]

When brazing copper, stainless steel, or ceramics, a single metal such as gold or silver is used as a brazing material, or a eutectic brazing material (silver 72) having a constant melting temperature is used. %, Copper 28%). Usually, brazing materials using three or more metals and silver and copper brazing materials other than eutectic brazing have two boundary temperatures between a solidus point and a liquidus point. And the liquid phase are mixed. When using a brazing material having such a transition state, the liquefaction after entering the liquid phase is slower than when using a brazing material with a constant melting temperature, and the flat material that maintains a constant at the brazing temperature is used. They tend to take a long time. Therefore, if the brazing of stainless steel, M ₂₃ C ₆ phase stainless steel deposited on the brazing surface,
This hinders the elongation of the brazing material, so that the reliability of brazing is reduced.

[0007] The precipitation of the M ₂₃ C ₆ phase of stainless steel is suppressed, and the components of the pickup electrode are soldered.
As a method of performing three brazing operations of brazing the pickup electrode and the block and brazing the block and the flange, for example, using a silver brazing having a constant melting temperature, the three brazing operations are performed once. It can be done by work. However, since the pickup electrode has many components and is smaller than the flange and the block, it is reasonable to assemble the pickup electrode by individual brazing work. In other words, the metal outer cylinder, insulating ceramics, button electrodes, and the like, which are components of the pickup electrode, are arranged in a desired assembled state using gravity or the like, and supported using a restraining jig that matches the posture thereof.
It is preferable to braze. Therefore, it is not reasonable to perform three brazing operations in one brazing operation using a silver brazing material having a constant melting temperature.

[0008] Further, when the work of brazing the pickup electrode to the block and the work of brazing the block to the flange after the brazing of the components of the pickup electrode are completed, the components of the pickup electrode are joined. The brazing material must not be dissolved. That is, the melting temperature of the brazing material for joining the components of the pickup electrode must be higher than the melting temperature of the brazing material for joining the pickup electrode and the block. For example, it is conceivable to use a single metal such as gold or silver as the brazing material for joining the components of the pickup electrode. However, the brazing operation using a single metal such as gold or silver is not preferable because it is a special operation different from the usual brazing operation for the pickup electrode.

Further, the work of brazing the components of the pick-up electrode and the work of brazing the block and the flange,
By using a silver solder having a constant melting temperature for a relatively short time, the precipitation of the stainless steel M ₂₃ C ₆ phase is suppressed. It is conceivable to perform the brazing operation using lower brazing materials of three metals. However, according to this, since the brazing operation is performed three times, the work efficiency is deteriorated.

An object of the present invention is to improve the reliability of brazing a stainless steel flange and a block in a beam position monitor.

[0011]

In order to solve the above-mentioned problems, the present invention provides a method in which at least a portion of a surface of a flange formed using stainless steel, which is brazed to a block, is subjected to metal plating. Since the precipitation of M ₂₃ C ₆ of stainless steel on the brazing surface can be suppressed, the reliability of brazing can be improved.

Further, since M ₂₃ C ₆ can be prevented from depositing on the brazing surface of the stainless steel flange,
The degree of freedom of the brazing material used for brazing each part of the beam position monitor and the brazing operation procedure is increased. For example, after the brazing of the components of the pickup electrode is performed in advance using a eutectic brazing, the brazing of the pickup electrode to the block and the brazing of the block to the flange are performed using a brazing material of three metals. Thereby, the brazing operation can be performed twice.

Here, as the three kinds of brazing materials, there are generally two kinds of materials, in which indium is added to silver and copper, and in which zinc is added. Since zinc volatilizes in a reduced-pressure atmosphere and adheres to the inner wall of the brazing furnace, it is preferable to use a brazing material to which indium is added. Also, since the beam position monitor measures the beam position with accuracy of several tens of μm, if the entire surface of the stainless steel flange is plated with metal, it is applied to the reference surface that positions the flange by joining it to the support base. Since the thickness of the plated layer may vary, which may cause a problem of installation error, it is preferable that at least the reference plane is not plated with metal.

The metal plating applied to the stainless steel flange is preferably nickel, tin, or the like.

Since the brazing technique has been developed as a joining technique of parts mainly composed of copper or a copper alloy, the present invention cannot be applied to a beam position monitor in which a block is formed of aluminum. When the beam duct joined to the copper block of the present invention is made of aluminum, it is preferable to join the aluminum beam duct and the copper block via a flange and an O-ring.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A beam position monitor according to an embodiment of the present invention will be described below with reference to FIGS. 1 is a front view of the beam position monitor partially cut away, FIG. 2 is a view as seen from the line II-II in FIG. 1, FIG. 3 is a sectional view of the pickup electrode, and FIG. FIG. 5 is a diagram for explaining the relationship between the precipitation start time of M ₂₃ C ₆ of stainless steel and the temperature.

As shown in FIGS. 1 and 2, the beam position monitor comprises a cylindrical block 1 through which a beam of electrons or the like passes or accumulates, and a plurality of blocks inserted from the outer peripheral wall of the block 1 so as to face the inside. Pickup electrode 2 and block 1
, And a support member 4 for positioning and fixing the flange 3. In the present embodiment, the four pickup electrodes 2 are arranged with a phase shift of 90 ° in the circumferential direction of the block 1 and two sets of the two pickup electrodes 2 opposed to each other constitute one set. Is provided. As shown in FIG. 3, each of the pickup electrodes 2 has a ring-shaped insulating tube 12 mounted inside a metal cylindrical outer tube 11, and a metal electrode support member 13 attached to the insulating tube 12. The button electrode 14 as an antenna is supported through the
Are inserted into and joined to an insertion hole 16 provided in the block 1 via a copper electrode flange 15 joined to the outer periphery of the tip of the block. As shown in FIG. 1, the flange 3 has a reference surface 6 for positioning, and the reference surface 6 is fixed by abutting the reference surface 6 on a reference surface 7 formed on a stainless steel support member 4. The position of the pickup electrode 2 is set in a predetermined positional relationship.

The beam duct 5 of the accelerator is used at both ends of the block 1 of the beam position monitor thus constructed in a vacuum-tight manner by welding such as electron beam welding. That is, when the beam 6 accelerated or accumulated in the accelerator is introduced into the block 1, the beam 6
Are detected by the respective pickup electrodes 2 and converted into voltage signals. The voltage signal output from the pickup electrode 2 is correlated with the distance from the pickup electrode 2 to the beam 6, and is input to a signal processing device (not shown). In the signal processing device, the difference between the detection signals of the two pairs of pickup electrodes 2 facing each other is obtained, and the position of the beam 6 is measured based on the difference.

Next, a method of manufacturing the beam position monitor having the above configuration and details of each component will be described. The block 1 is formed by using a hot forging material of copper, and both ends to which the beam duct 5 is joined are formed to have the same diameter and the same thickness as the beam 5, and the central portion has a larger diameter and a greater thickness. Is formed.
Then, the blocks 1 are joined by inserting the small-diameter portions at both ends into the holes formed in the flange 3 and bringing the end surfaces of the large-diameter portions into contact with the flange surfaces of the flanges 3. The flange 3 has rigidity so as not to be deformed when fixed to the support member 4 made of stainless steel, and is formed using non-magnetic SUS 316 in order to eliminate disturbance of high frequency due to magnetism. The flange 3 is formed by machining after a well-known aging (solid solution) treatment in order to remove residual strain.

The outer cylinder 11 of the pick-up electrode 2 is made of a metal such as CuNi or Kovar having a small coefficient of thermal expansion so that tensile strain is not applied to the alumina ceramic of the insulating cylinder 12 due to a temperature change during brazing. It is formed. Here, nonmagnetic CuNi is used. The insulating cylinder 12 is formed of alumina ceramics. The tip of the button electrode 14 is made of stainless steel (for example, S
US 304), the pin-shaped base is made of Kovar or the like. The electrode support member 13 is formed of a metal such as CuNi. Further, the electrode flange 15 is formed of copper. And, between the outer cylinder 11 and the insulating cylinder 12, the insulating cylinder 12
And the electrode support member 13, the electrode support member 13 and the button electrode 14, and the outer cylinder 11 and the electrode flange 15 are assembled by brazing. The brazing operation is performed while holding each component with an auxiliary jig so as not to move. Basically, the components are positioned using gravity and brazed at a temperature of about 800 ° C. using a eutectic brazing.

The pickup electrode 2 soldered in advance as described above is inserted into the insertion hole 1 formed in the wall surface of the block 1.
6 and insert the thin brazing material into it.
A brazing material formed thinly is also sandwiched between the joining surfaces of the flange 3 and the flange 3, and they are set in a predetermined positional relationship, and brazing is performed. The brazing material used here is about 750 using a three-metal brazing material of indium-added silver and copper so that the eutectic brazing of the pickup electrode 2 already brazed is not dissolved.
Braze at a temperature of ° C. By the way, as described above, liquefaction is slow because the mixed state of the liquid phase and the solid phase is present as described above. Usually, the holding time is lengthened to about 10 to 15 minutes. Therefore, between the stainless steel flange 3 and the copper block 1, M ₂₃ C
₆ precipitates, and the joining strength of brazing is significantly reduced. FIG. 5 shows the relationship between the temperature of the SUS316 and the time required for the precipitation of M ₂₃ C ₆ and the solution treatment temperature. As can be seen from the figure, the onset of precipitation is the fastest at around 800 ° C.

In this regard, according to the present embodiment, since the surface of the flange 3 is nickel-plated, the M ₂₃ C
Precipitation of ₆ is suppressed, and brazing can be performed without any trouble. The thickness of the nickel plating is preferably about 5 to 10 μm in consideration of the effect of suppressing precipitation of M ₂₃ C _{6 and} the adverse effect of magnetism. Further, tin may be used as the plating material in addition to nickel.

As described above, according to the present embodiment,
Since the pickup electrode 2 and the block 1 are joined by brazing, the gap between them is filled with the brazing material, so that the formation of an unnecessary gap can be eliminated. Therefore, it is possible to reduce the high-frequency capacitance that causes an error in beam detection.

The copper of the block 1 is made of a hot forged material, the flange 3 is made of an aged stainless steel,
Furthermore, metal plating is applied to the brazing surface of the flange 3 to suppress the precipitation of M ₂₃ C ₆ , which adversely affects the brazing,
Since they are joined by brazing, it is possible to form a beam position monitor having no residual distortion, good dimensional accuracy, and high joining reliability without variation.

When the reference surface 6 of the flange 3 is plated with metal, the relative positional relationship between the reference surface 6 of the flange 3 and the reference surface 7 of the support member 4 varies due to the variation in plating thickness, and the measurement accuracy is affected. In some cases. In such a case, it is preferable that the reference surface 6 is not plated as shown in FIG. In this case, the operation can be easily performed by turning the flange 3 upside down in FIG. 4 and immersing it in the plating solution while leaving the reference surface 6 portion.

[0026]

As described above, according to the present invention,
Of the surface of the flange formed using stainless steel,
Since metal plating is applied to at least the portion to be brazed to the block, it is possible to suppress precipitation of stainless steel M ₂₃ C _{6 on} the brazing surface, thereby improving the reliability of brazing.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a beam position monitor according to an embodiment of the present invention.

FIG. 2 is a view as seen from the line II-II in FIG. 1;

FIG. 3 is a sectional view of a pickup electrode.

FIG. 4 is a front view of a flange.

FIG. 5 is a diagram illustrating the relationship between the time at which M ₂₃ C ₆ precipitation of stainless steel starts and the temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Block 2 Pickup electrode 3 Flange 4 Support member 5 Beam duct 6, 7 Reference plane 11 Outer cylinder 12 Insulation cylinder 13 Electrode support member 14 Button electrode 15 Electrode flange 16 Insertion hole

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[Procedure amendment]

[Submission date] November 11, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Claims (7)

[Claims] 1. A pickup electrode for monitoring a beam position is brazed to an outer peripheral wall of a block facing a part of a cylindrical block that passes or accumulates a beam, and the block supports the block. In the beam position monitor which is brazed to the flange to be formed, the block is formed using copper, the flange is formed using stainless steel, and at least the surface of the flange is brazed to at least the block. A beam position monitor characterized in that a metal part is provided on a portion of the beam position. 2. The beam position monitor according to claim 1, wherein said flange has a positioning reference surface, and is fixed by bringing said reference surface into contact with a reference surface formed on a stainless steel support member. A beam position monitor, wherein the metal plating is applied except for a reference surface of the flange. 3. The beam position monitor according to claim 1, wherein said metal plating is one of nickel and tin. 4. The beam position monitor according to claim 1, wherein the pickup electrode is formed by joining a button electrode to a metal outer cylinder via an insulating ceramic by silver brazing, A beam position monitor, wherein the silver brazing used for the silver brazing has a content of metals other than copper and silver of 0.1% by weight or less. 5. The beam position monitor according to claim 1, wherein the brazing material for joining the block and the flange contains indium in addition to copper and silver. Beam position monitor. 6. The beam position monitor according to claim 1, wherein the copper forming the block is:
A beam position monitor characterized by being a hot forged material. 7. A pick-up electrode for monitoring a beam position is brazed to an outer peripheral wall of the block so as to face the inside of a cylindrical block that passes or accumulates a beam, and the block supports the block. In the method of manufacturing a beam position monitor brazed to a flange to be formed, the step of forming the block using copper, the step of forming the flange using stainless steel, and at least the block of the surface of the flange Applying a metal plating to a part to be brazed to the metal, forming the pickup electrode by brazing the components of the pick-up electrode to silver, and simultaneously setting the pick-up electrode and the block, and the block and the flange to silver. Producing a beam position monitor.