JP3405487B2 - Accelerator tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration tube for accelerating a charged particle flow. 2. Description of the Related Art Conventionally, electron microscopes use an accelerating tube for accelerating charged particles such as electrons. As shown in FIG. 2, such an acceleration tube generally includes a plurality of ring-shaped electrodes 11 made of a metal material such as an iron-nickel-cobalt alloy and an insulating ring 12 made of an electrically insulating material such as alumina ceramics. An accelerating tube main body which is attached through a brazing material such as silver brazing such that the central axes thereof substantially coincide with each other and an insulating ring 12 is sandwiched between the ring-shaped electrodes 11. 10 and a mounting flange 13 made of a metal such as SUS which is welded to the ring electrodes 11 located at both ends of the accelerator tube main body 10, and a high voltage is applied between the ring electrodes 11. When the electron current is applied and passes through the internal space of the acceleration tube main body 10, the electron current is greatly accelerated by the electric field formed by the ring-shaped electrode 11, thereby functioning as an acceleration tube. That. [0004] The mounting flange 13 of the accelerating tube is
The accelerating tube is fixed to the inside of the electron microscope or the like.
The accelerating tube is arranged in the electron microscope or the like by attaching and fixing. The ring-shaped electrodes 11 at both ends of the accelerating tube main body 10 are provided with upright wall portions 11a in advance, and the mounting flanges 13 are welded to the end surfaces of the upright wall portions 11a to form the accelerating tube main body 10a. The mounting flanges 13 are joined to the ring-shaped electrodes 11 located at both ends of the mounting. [0006] However, in this conventional accelerating tube, the thickness of the ring-shaped electrode is usually 0.1 mm.
It is as thin as about 5 mm, low in rigidity, and the upright wall provided on the ring-shaped electrode is provided slightly apart from the insulating ring. Therefore, it is easily elastically deformed when external force such as vibration is applied. ing. Therefore, when an external force such as vibration is applied to the accelerator tube, the ring-shaped electrode is elastically deformed, and this is greatly amplified by the co-operation of the mounting flange joined to the ring-shaped electrode, causing resonance vibration in the accelerator tube body. As a result, the electric field inside the accelerating tube main body has a variation, which has a disadvantage that the flow of the accelerated electron flow is disturbed. SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of the conventional accelerating tube, and has as its object to accelerate the accelerating tube accurately without disturbing the electron flow. Is to provide. According to the present invention, there is provided an accelerating tube comprising: a plurality of ring-shaped electrodes and an insulating ring such that their central axes substantially coincide with each other; An accelerating tube main body attached so that an insulating ring is sandwiched between the accelerating tube main body, and a mounting flange joined to end surfaces of a pair of upright wall portions formed on ring-shaped electrodes located at both ends of the accelerating tube main body And between the accelerating tube body and the mounting flange, brazed to a portion between the pair of standing walls of the ring-shaped electrode , and a joint between the mounting flange and the pair of standing walls.
Bolts inserted from outside into the bolt holes formed in the area between
Electrical insulation screwed to the mounting flange with a bolt
And a reinforcing ring made of a material. According to the acceleration tube of the present invention, the portion between the pair of standing walls of the ring-shaped electrodes located at both ends of the acceleration tube main body is brazed between the acceleration tube main body and the mounting flange. , Formed at a portion between the joining portion of the mounting flange and the pair of standing wall portions.
Mounting bolts with bolts inserted from outside into the bolt holes
Since a reinforcing ring made of an electrically insulating material screwed to the flange is provided, no elastic deformation occurs even when an external force is applied to the ring-shaped electrode, thereby applying an external force such as vibration to the acceleration tube. Even when this occurs, no resonance vibration occurs due to the elastic deformation of the ring-shaped electrode in the accelerator tube body. As a result, the electric field inside the accelerator tube body becomes constant, and the acceleration of the electron flow can be made constant and accurate. it can. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an accelerating tube according to the present invention. FIG. 1 shows an embodiment of an acceleration tube according to the present invention, wherein 1 is an acceleration tube main body, and 2 is a mounting flange. The joint of the acceleration tube main body 1 and the mounting flange 2 constitutes an acceleration tube. [0011] The acceleration tube body 1, an iron - nickel - is composed of cobalt plurality of ring-shaped electrode made of a metal alloy such as 3 and Ru electrically insulating material or RaNaru alumina ceramics or the like insulating ring 4 which, the ring Electrode 3 and insulating ring 4
Are manufactured by joining a brazing material such as silver brazing such that the insulating ring 4 is interposed between the ring-shaped electrodes 3 and has a substantially cylindrical shape as a whole. The accelerator tube main body 1 has a function of accelerating the electron flow by flowing an electron flow into its internal space, and the electron flow generated from an electron source (not shown) is provided in the internal space of the accelerator tube main body 1. About 10 kV between each ring-shaped electrode 3
When a high voltage of about 50 kV is applied, the electron flow is accelerated by an electric field formed inside the acceleration tube main body 1 by the voltage. An insulating ring 4 constituting the acceleration tube main body 1
Acts to electrically insulate each ring-shaped electrode 3,
It is formed from an electrically insulating material such as alumina ceramics. When the insulating ring 4 is made of, for example, alumina ceramics, alumina, silica, calcia,
A raw material powder such as magnesia is filled in a mold having a predetermined shape and pressed at a constant pressure to form a cylindrical product, and then the product is fired at a high temperature of about 1600 ° C. Be produced. The ring-shaped electrodes 3 constituting the accelerating tube main body 1 function to form an electric field for accelerating the electron flow in the internal space of the accelerating tube main body 1 when a high voltage is applied between them. And made of a metal material such as an iron-nickel-cobalt alloy or titanium. [0016] The ring-shaped electrode 3, for example, iron - nickel <br/> Le - cobalt alloy rolling method and punching method ingot (mass) such as such, a predetermined disk shape by a conventionally known metal processing method It is manufactured by processing. Further, the insulating ring 4 and the ring-shaped electrode 3 are joined via a brazing material such as silver brazing, and both ends of each insulating ring 4 are made of a refractory metal powder such as tungsten, molybdenum, manganese or the like. The metallized metal layer is previously deposited, and the metallized metal layer and the ring-shaped electrode 3 are
Are brought into contact with each other with a brazing material such as silver brazing sandwiched therebetween, and the silver brazing material is heated and melted to be joined. Note that metallizing is applied to both end faces of the insulating ring 4.
In order to apply a metallized metal layer, for example, a method of printing and applying a metal paste to be a metallized metal layer to both end surfaces of the insulating ring 4 by a conventionally known screen printing method and baking it at a temperature of about 1500 ° C. is adopted. Is done. When the metal paste to be the metallized metal layer is made of, for example, molybdenum-manganese, it is manufactured by adding an organic binder, a solvent, and the like to molybdenum powder and manganese powder. Further, among the ring-shaped electrodes 3, the ring-shaped electrodes 3 located at both ends of the accelerating tube main body 1 are provided with upright wall portions 3.
The mounting flange 2 is fixed to the end face of the standing wall 3a by welding. The mounting flange 2 is provided with a plurality of mounting bolt holes 2a on the outer periphery.
Then, the acceleration tube main body 1 is arranged in the electron microscope or the like by bolting the mounting bolt hole 2a to a mounting member provided in the electron microscope or the like. The mounting flange 2 is made of, for example, SU
The mounting bolt hole 2a is formed in a predetermined shape at a predetermined position of the mounting flange 2 by subjecting the mounting flange 2 to a metal drilling process such as a conventionally known drilling process. A reinforcing ring 5 brazed to the ring-shaped electrode 3 and screwed to the mounting flange 2 is provided between both ends of the accelerator tube main body 1 and the mounting flange 2. The reinforcing ring 5 is brazed to the ring-shaped electrodes 3 located at both ends of the accelerating tube body 1 and screwed to the mounting flange 2 to effectively prevent the ring-shaped electrode 3 from being elastically deformed. As a result, even if an external force such as vibration is applied to the ring-shaped electrode 3, no elastic deformation occurs in the ring-shaped electrode 3.
The resonance vibration of the acceleration tube main body 1 is also effectively prevented due to the elastic deformation of, and the electric field inside the acceleration tube main body 1 is always constant,
Acceleration of the electron flow can be made constant and accurate. The reinforcing ring 5 is made of an electrically insulating material such as alumina ceramics having a thermal expansion coefficient substantially the same as the thermal expansion coefficient of the insulating ring 4. For example, when it is made of alumina ceramics, alumina, silica, calcia, magnesia The raw material powder is filled into a mold having a predetermined shape and pressed at a constant pressure to form a cylindrical product, and then the product is fired at a high temperature of about 1600 ° C. Is done. The brazing of the reinforcing ring 5 and the ring-shaped electrode 3 is carried out by using tungsten,
This is performed by depositing a metallized metal layer made of a high melting point metal powder such as molybdenum and manganese, and brazing the metallized metal layer to the ring-shaped electrode 3 via a brazing material such as silver brazing. Further, the reinforcing ring 5 and the mounting flange 2
A metal bush 6 with a female thread is embedded in the end face of the reinforcing ring 5 in advance, and a bolt hole 2b is formed in the mounting flange 2 so that the bolt 7
Is inserted through the bolt hole 2 b from the outside of the mounting flange 2, and its tip is screwed into the metal bush 6. When the metal bush 6 is embedded in the reinforcing ring 5, a concave portion 5a for accommodating the metal bush 6 is formed in the reinforcing ring 5 in advance.
a. A metallized metal layer made of a refractory metal powder such as tungsten, molybdenum, manganese or the like is previously applied to the inner wall, and then the metallized metal layer and the metal bush 6 are brazed with a brazing material such as silver brazing. Done by The metallized metal layer is applied to the inner wall of the concave portion 5a of the reinforcing ring 5 in the same manner as the metalized metal layer is applied to the end surface of the reinforcing ring 5 described above. According to the accelerating tube of the present invention, the mounting flange is attached and fixed to a mounting member provided in the electron microscope or the like, and is arranged in the electron microscope or the like.
When a high voltage of about 10 kV to 50 kV is applied between the ring-shaped electrodes 3 to form a predetermined electric field inside the accelerator tube main body 1 and the electron flow passes through the internal space of the accelerator tube main body 1, the electron flow becomes The electric field accelerates in a predetermined direction and a predetermined speed, thereby functioning as an acceleration tube. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. According to the accelerating tube of the present invention, between the accelerating tube main body and the mounting flange, a portion between the pair of upright wall portions of the ring-shaped electrode located at both ends of the accelerating tube main body. Attached
At the part between the joint of the mounting flange and the pair of standing walls,
With bolts inserted from outside into the formed bolt holes.
Since the reinforcing ring made of an electrically insulating material that is screwed to the attachment flange is disposed, even if an external force is applied to the ring-shaped electrode , the ring-shaped electrode does not undergo elastic deformation, and thus the acceleration tube Even if external force such as vibration is applied to the accelerating tube body, resonance vibration due to the elastic deformation of the ring-shaped electrode does not occur,
As a result, the electric field inside the accelerating tube main body becomes constant, and the acceleration of the electron flow can be made constant and accurate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing one embodiment of an acceleration tube of the present invention. FIG. 2 is a cross-sectional view of a conventional acceleration tube. [Description of Signs] 1 ... Accelerator tube body 2 ... Flange for mounting 3 ... Ring-shaped electrode 4 ... Insulating ring 5 ... .Reinforcing ring 7 bolts

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-176621 (JP, A) JP-A-3-101040 (JP, A) JP-A-53-90599 (JP, A) 3700 (JP, U) JP-A 4-115800 (JP, U) JP-A 64-12369 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 37/04 H05H 5 / 00-5/08

Claims (1)

(57) Claims 1. A plurality of ring-shaped electrodes and an insulating ring are arranged so that their central axes substantially coincide with each other, and an insulating ring is provided between the ring-shaped electrodes. , A mounting flange joined to end faces of a pair of standing wall portions formed on ring-shaped electrodes located at both ends of the acceleration tube main body, and the acceleration tube Between the main body and the mounting flange, between the pair of standing wall portions of the ring-shaped electrode.
And the pair of mounting flanges
Is it outside the bolt hole formed at the part between the joint with the wall
In that it consists of a reinforcing ring made of electrically insulating material which is screwed to the mounting flange by Luo inserted through was a bolt
Accelerator tube characterized .