JP3929841B2 - Accelerating tube electrode - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode for an acceleration tube that accelerates charged particles such as electrons and ions in multiple stages.
[0002]
[Prior art]
Conventionally, an acceleration tube for accelerating charged particles such as electrons has been used in an electron microscope. A first electrode member of an acceleration tube electrode provided in the acceleration tube is shown in a front view of FIG. 2 and a sectional view of FIG. 3, and a basic configuration of the acceleration tube is shown in a sectional view of FIG. FIG. 5 shows a cross-sectional view of the first electrode member and the metal member from the central axis direction. 2, 3, 4, and 5, 1 is a first electrode member, 1 a is a notch, 1 b is a through hole, 2 is a metal member, 2 a is a central portion of the metal member 2, and 2 b is a metal member 2. , 3 is a second electrode member, 5 is an insulating ring, 6 is a convex portion, 7 is a groove, and 8 is a projection, and these are mainly the accelerating tube.
[0003]
As shown in FIGS. 2 to 5, the acceleration tube electrode has a substantially annular shape made of a metal such as iron (Fe) -nickel (Ni) -cobalt (Co) alloy, and has a circumferential direction on the entire inner circumferential surface. A first electrode member 1 formed with n grooves (n is an integer of 2 or more) formed at substantially equal intervals, and a groove 7 is formed in the groove 7. It consists of a rod-shaped central portion and both end portions 2b extending from the central portion 2a in opposite directions, and shifted by a predetermined distance to the opposing side walls between the notches 1a of the groove 7 of the first electrode member 1. A metal member 2 made of a metal material such as stainless steel having both ends 2b inserted into the formed through holes 1a and attached by welding or the like, and a substantially cylindrical shape fitted inside the first electrode member 1 N pieces arranged at substantially equal intervals along the circumferential direction of the outer peripheral surface. Stainless steel or permalloy is formed by forming protrusions 8 and inserting the n protrusions 8 from the plurality of notches 1b into the grooves 7, moving in the circumferential direction of the grooves 7, and contacting the metal member 2. And a second electrode member 3 made of a metal such as.
[0004]
The first electrode member 1 includes an insulating ring 5 made of an electrically insulating material such as alumina ceramic and an insulating ring between the first electrode member 1 so that the central axes thereof substantially coincide with each other. 5 is attached via a brazing material such as silver (Ag) -copper (Cu) brazing so that 5 is sandwiched, and the first electrode member 1 located at both ends is attached by welding to a metal such as stainless steel An accelerating tube is arranged in an electron microscope or the like by attaching a flange (not shown).
[0005]
With the above configuration, when an accelerating tube applies a high voltage between the electrodes and causes an electron flow to flow in the internal space, the electrons are greatly accelerated by the electric field formed by the electrodes, thereby functioning as an accelerating tube. .
[0006]
[Problems to be solved by the invention]
However, in the electrode for an acceleration tube as described above, when the first electrode member 1 and the insulating ring 5 are brazed with a brazing material such as Ag—Cu brazing, the first electrode member 1 and the metal member 2 are A large stress is generated in the welded portion (FIG. 5) between the two end portions 2b due to the difference in thermal expansion coefficient between the two, and the stress causes cracks, cracks, etc. in the vicinity of the welded portion of the metal member 2 in the first electrode member 1. Occurs, and the first electrode member 1 cannot hold the second electrode member 3. Further, the end surfaces of both end portions 2b of the metal member 2 become the convex portions 6 (FIG. 5) by welding, and there is a problem that the electric field concentrates on the convex portions 6 and discharge becomes easy.
[0007]
The present invention has been completed in view of the above-mentioned problems in the prior art, and its purpose is to suppress cracks and cracks at the joint between the first electrode member and the metal member, It is to make the joining of metal members strong and to have high reliability. In addition, the concentration of the electric field generated at the projections of both welds is suppressed, discharge is effectively prevented, charged particles such as electrons can be reliably and stably accelerated to a predetermined speed, and reliably in a predetermined direction. It is to be able to generate a beam stably.
[0008]
[Means for Solving the Problems]
The electrode for an acceleration tube of the present invention has a substantially annular shape with a substantially square cross section, and a groove is formed in the circumferential direction on the entire inner circumferential surface, and one side surface of the groove and a side surface facing the groove are formed. A first electrode member having n notches penetrating therethrough (n is an integer of 2 or more) formed at substantially equal intervals, a substantially rod-shaped central portion, and extending from the central portion in a bowl shape in opposite directions to each other The both end portions are formed in a through-hole that passes through one side surface of the groove and the side surface facing the groove, each formed by shifting a predetermined distance to the opposite side surface of the groove located between the notches. Inserted and brazed metal member, and a substantially cylindrical shape fitted inside the first electrode member, and n projections are formed at substantially equal intervals along the circumferential direction of the outer peripheral surface, The n protrusions are respectively inserted into the grooves from the notches. A second electrode member positioned by moving in the circumferential direction in the groove and abutting against the metal member, and the metal member includes end surfaces of the both end portions and the first electrode member. The side surfaces of the metal plate and the surface of the brazing material between them are substantially flush with each other.
[0009]
In the acceleration tube electrode according to the present invention, the metal member has the first electrode member because the end surfaces of both ends, the side surfaces of the first electrode member, and the surface of the brazing material therebetween are substantially flush. Even if a large stress due to the difference in thermal expansion coefficient occurs between the metal and the metal member, it can be mitigated by the brazing material, and it is effective that cracks and cracks occur at the joint between the two due to the stress Can be suppressed. Therefore, the first electrode member and the metal member can be firmly joined to obtain a highly reliable acceleration tube.
[0010]
Also, by brazing both, the gap between the through hole on the side surface of the groove of the first electrode member and both ends of the metal member can be filled, and the end surface of both ends of the metal member and the first electrode member Since the side surfaces and the surface of the brazing material between them are substantially flush, the electric field is less likely to concentrate at the joint between the first electrode member and the metal member, and it is difficult to develop a large discharge. For this reason, charged particles such as electrons can be reliably and stably accelerated to a predetermined speed, and the beam and the beam can be generated reliably and stably in a predetermined direction.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The acceleration tube electrode of the present invention will be described in detail below. FIG. 1 shows a cross-sectional view of the joint portion between the first electrode member and the metal member of the acceleration tube electrode as seen from the central axis direction of the first electrode member. 2 is a front view of the first electrode member, FIG. 3 is a cross-sectional view of the first electrode member, and FIG. 4 is a cross-sectional view showing a basic configuration of the acceleration tube. In these drawings, 1 is a first electrode member, 1a is a notch, 1b is a through hole, 2 is a metal member, 2a is a central portion of the metal member 2, 2b is both ends of the metal member 2, and 3 is a second. , 4 is a brazing material, 5 is an insulating ring, 7 is a groove, and 8 is a projection, and these mainly constitute an acceleration tube electrode. 1 to 4, the same parts as those in FIG. 5 are denoted by the same reference numerals.
[0012]
The electrode for an acceleration tube of the present invention has a substantially annular shape with a substantially quadrangular cross-sectional shape, and a groove 7 is formed in the circumferential direction on the entire inner circumferential surface, and one side surface of the groove 7 and a side surface facing it. The first electrode member 1 in which notches 1a penetrating through the first electrode member 1 are formed at substantially equal intervals (n is an integer of 2 or more), and the rod-shaped central portion 2a and the central portion 2a are formed in a bowl shape in opposite directions. One side surface of the groove 7 and the first electrode member 1 opposite to the one side surface of the groove 7, which are formed by extending both ends 2 b and are respectively shifted by a predetermined distance from the opposite side surface of the groove 7 positioned between the notches 1 a. A metal member 2 having both end portions 2b inserted and brazed into a through-hole 1b penetrating the side surface, and a substantially cylindrical shape fitted inside the first electrode member 1, and in the circumferential direction of the outer peripheral surface N protrusions are formed at approximately equal intervals, and the n protrusions are cut. And a second electrode member 3 positioned by being inserted into the groove 7 from the groove 1a, moved in the circumferential direction in the groove 7 and brought into contact with the metal member 2, and the metal member 2 has both end portions 2b. These end faces, the side face of the first electrode member 1, and the surface of the brazing material 4 between them are substantially flush.
[0013]
As shown in FIG. 4, the first electrode member 1 includes an insulating ring 5 made of an electrically insulating material such as alumina ceramic, and the center electrode thereof substantially coincides with the first electrode member 1. 1 is attached via a brazing material such as an Ag-Cu brazing so that the insulating ring 5 is sandwiched between them, and is attached to the first electrode member 1 located at both ends by welding with a metal such as stainless steel. An accelerating tube is arranged in an electron microscope or the like by attaching a flange (not shown). The insulating ring 5 functions to electrically insulate each acceleration tube electrode.
[0014]
The first electrode member 1 forms an electric field for accelerating electrons in its internal space when a high voltage is applied to each of the first electrode members 1. The first electrode member 1 is either a vacuum container or provided in a vacuum device. It is done. The first electrode member 1 is made of a metal such as an Fe—Ni—Co alloy. For example, an ingot (lumb) such as an Fe—Ni—Co alloy is conventionally known as a metal processing method such as a rolling method or a punching method. Is manufactured by processing into a predetermined annular shape.
[0015]
The first electrode member 1 has a substantially annular shape with a substantially square cross-sectional shape, and a groove 7 is formed in the circumferential direction on the entire inner circumferential surface, and one side surface of the groove 7 is opposed to the side surface. N notches 1a penetrating the side surfaces of the groove 7 are formed at substantially equal intervals (n is an integer of 2 or more). From the notches 1a penetrating one side surface of the groove 7, the second electrode member 3 The n protrusions 8 formed at substantially equal intervals along the circumferential direction of the outer peripheral surface are inserted into the grooves 7 and moved in the circumferential direction in the grooves 7.
[0016]
The number of the cutouts 1a is preferably 5 or less. If the number of cutouts 1a exceeds 5, it becomes difficult to fit the second electrode member 3 at the positions of the cutouts 1a at the same time.
[0017]
The first electrode member 1 has a substantially annular shape with a substantially square cross-section, but has a circular through-hole formed in the center of the disk, and the cross-sectional shape of the ring portion is It is a substantially square shape.
[0018]
And the through-hole which penetrates the side surface of the groove | channel 7 and the side surface of the 1st electrode member 1 which opposes it formed in the side surface which the groove | channel 7 located between the notches 1a of the groove | channel 7 opposes by predetermined distance, respectively. Both end portions 2b of the metal member 2 are inserted into 1b and joined through a brazing material 4 such as an Ag-Cu brazing material. In this case, the gap between the two is filled with the brazing material 4.
[0019]
By brazing the first electrode member 1 and the metal member 2 with a brazing material 4 such as Ag—Cu brazing, it is possible to absorb and relax the stress caused by the difference in thermal expansion coefficient between them. Moreover, since the gap between the two can be filled with the brazing filler metal 4, it is possible to join more firmly than the conventional welding.
[0020]
The metal member 2 is composed of a substantially rod-shaped central portion 2a and both end portions 2b extending from the central portion 2a in opposite directions in the opposite directions, and the metal member 2 has a circumferential surface around the outer peripheral surface of the second electrode member 3. The position of the second electrode member 3 is determined by the n projections 8 formed in the direction being arranged at substantially equal intervals in contact with each other. Further, the metal member 2 is made of spring stainless steel (JIS G 4314) or the like in order to absorb a shock when the protrusion 8 on the outer peripheral surface of the second electrode member 3 contacts and is fixed.
[0021]
Both end portions 2b of the metal member 2 are inserted into the through holes 1b of the grooves 7 of the first electrode member 1 and joined through the brazing material 4, but the end surfaces of the both end portions 2b of the metal member 2 and the end surfaces thereof. By grinding and polishing the excess brazing material 4 around the metal by machining using a lathe or the like, the end surfaces of both ends 2b and the side surfaces of the first electrode member 1 are finished to be substantially flush with each other. ing. As a result, the end surfaces of both end portions 2b of the metal member 2 and the surface of the brazing material 4 do not protrude, so that the electric field is less likely to concentrate at the joint between the two, and it is difficult to develop a large discharge. The beam can be reliably and stably accelerated in a predetermined direction and the beam can be generated reliably and stably in a predetermined direction.
[0022]
The metal member 2 has a rod-like (cylindrical) shape with a cross-sectional diameter of about 0.7 mm and a length of about 16 mm, and the length of both end portions 2b is about 30% of the whole. Therefore, the distance between the two through holes 1b formed on the opposite side surfaces of the groove 7 is about 11.2 mm. Further, as shown in FIG. 1, approximately half of the central portion 2a of the metal member 2 is slightly inclined toward the end portion 2b with respect to the circumferential direction of the groove 7 (about 15 to 25 °). The second electrode member 3 is positioned by fixing the projection 8 between the inner surface and the inner surface.
[0023]
The second electrode member 3 is for accelerating electrons and the like in the axial direction of the internal space, and makes it difficult for the electron beam to be deflected by an alternating magnetic field generated by a high voltage generation circuit outside the accelerator tube. Yes. That is, it is made of a metal material such as permalloy (JIS C 2351) effective for magnetic field shielding in order to prevent deflection due to an alternating magnetic field.
[0024]
Thus, according to the accelerating tube electrode of the present invention, the stress caused by the difference in thermal expansion coefficient between the first electrode member 1 and the metal member 2 is absorbed and relaxed by filling and brazing the gap between the joint portions of the first electrode member 1 and the metal member 2. And both can be firmly joined. In addition, since the end surfaces of both end portions 2b of the metal member 2 and the brazing material 4 around the end surfaces are substantially flush with the side surface of the first electrode member 1, the first electrode member 1 and the metal member The electric field is less likely to be concentrated at the junction with 2 and it is difficult to develop a large discharge. Therefore, when a predetermined high voltage is applied to each accelerating tube electrode to form a predetermined electric field inside the accelerating tube and an electron flow is generated in the internal space of the accelerating tube, the electron flow is generated in a predetermined direction and a predetermined speed by the electric field. To be stably accelerated.
[0025]
Note that the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the scope of the present invention.
[0026]
【The invention's effect】
The electrode for an acceleration tube of the present invention has a substantially annular shape with a substantially square cross-section, and a groove is formed in the circumferential direction on the entire inner circumferential surface and penetrates one side surface of the groove and a side surface facing the groove. A first electrode member in which n notches are formed at substantially equal intervals (n is an integer of 2 or more), and a substantially rod-shaped central portion and both end portions extending in a hook shape in opposite directions from the central portion Both end portions are formed in a through-hole penetrating one side surface of the groove and the side surface of the first electrode member facing the groove, each formed by shifting a predetermined distance on the opposite side surface of the groove located between the notches. The inserted and brazed metal member and the substantially cylindrical shape that is fitted inside the first electrode member, and n protrusions are formed at substantially equal intervals along the circumferential direction of the outer peripheral surface. Each protrusion is inserted into the groove from the notch and moved in the groove in the circumferential direction. And a second electrode member that is positioned by being brought into contact with the metal member. The metal member has an end face at both ends, a side face of the first electrode member, and a surface of the brazing material between them. By being flush with each other, even if a large stress due to the difference in thermal expansion coefficient occurs between the first electrode member and the metal member, this can be relaxed by the brazing material, It is possible to effectively suppress the occurrence of cracks and cracks at the joints. Therefore, the first electrode member and the metal member can be firmly joined to obtain a highly reliable acceleration tube.
[0027]
Also, by brazing both, the gap between the through hole on the side surface of the groove of the first electrode member and both ends of the metal member can be filled, and the end surface of both ends of the metal member and the first electrode member Since the side surfaces and the surface of the brazing material between them are substantially flush, the electric field is less likely to concentrate at the joint between the first electrode member and the metal member, and it is difficult to develop a large discharge. Therefore, charged particles such as electrons can be reliably and stably accelerated to a predetermined speed, and a beam can be generated reliably and stably in a predetermined direction.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of an acceleration tube electrode according to the present invention and showing a joining structure of a first electrode member and a metal member.
FIG. 2 is a front view of a first electrode member in an acceleration tube electrode according to the present invention.
3 is a cross-sectional view of the first electrode member of FIG.
FIG. 4 is a cross-sectional view showing a basic configuration of an acceleration tube.
FIG. 5 is a cross-sectional view showing a connection structure between a first electrode member and a metal member in a conventional acceleration tube electrode.
[Explanation of symbols]
1: First electrode member 1a: Notch 2: Metal member 3: Second electrode member 4: Brazing material 7: Groove 8: Projection

Claims (1)

Sectional shape is a substantially annular substantially rectangular cutout through a side surface you one side and opposed thereto of the groove with the groove in the circumferential direction over the entire circumference on the inner peripheral surface is formed outs shown A first electrode member formed at equal intervals (n is an integer of 2 or more), a substantially rod-shaped central portion, and both end portions extending in a hook shape in opposite directions from the central portion, are respectively formed on opposite sides of the groove located between notches shifted a predetermined distance, one side and the both ends are inserted brazed into a through hole passing through the side faces you opposed to that of said groove The metal member and the substantially cylindrical shape that is fitted inside the first electrode member, and n protrusions are formed at substantially equal intervals along the circumferential direction of the outer peripheral surface. Protrusions are inserted into the grooves from the notches and moved in the circumferential direction in the grooves. A second electrode member that is positioned by contacting the metal member, and the metal member includes end surfaces of the both ends, a side surface of the first electrode member, and a brace between them. An electrode for an acceleration tube, characterized by being substantially flush with the surface of the material.

Images