JP3440455B2 - 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
A function of fixing the accelerating tube in an electron microscope or the like is performed, and a mounting flange 1 is mounted on a mounting member provided in the electron microscope or the like.
By mounting and fixing 3, the accelerating tube is arranged in an electron microscope or the like. 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 body formed by attaching as insulating ring is sandwiched between and bonded to the end surfaces of the pair of vertical wall portions which are formed on the annular electrodes located at both ends of the acceleration tube body, this vertical wall parts are joining member made of <br/> metal to be welded to the vertical wall portion is disposed at a position facing is bonded to the flange body structure
A mounting flange that have been made, is disposed between said acceleration tube and the mounting flange, the site and the connecting member between the pair of vertical wall portions of the ring-shaped electrodes located at both ends of the acceleration tube body And a reinforcing ring made of an electrically insulating material which is joined by brazing to both of the portions between the joining portions with the pair of standing wall portions. According to the acceleration tube of [0009] the present invention, as well as provided with reinforcing ring made of electrically insulating material between the acceleration tube and the mounting flange, the ring electrodes located at both ends of the acceleration tube body Are joined to a portion between the pair of standing wall portions and the mounting flange, and end faces of the pair of standing wall portions of the ring-shaped electrode are joined.
The reinforcing ring has elastic deformation of the ring-shaped electrode because it is joined to both portions of the joining member disposed at the position where the upright wall portion is opposed to the joining portion between the pair of upright wall portions.
By effectively preventing the ring-shaped electrode from being elastically deformed even when an external force is applied to the ring-shaped electrode, even if an external force such as vibration is applied to the accelerating tube, the ring-shaped electrode is not affected by the external force. No resonance vibration is generated due to the elastic deformation of the ring-shaped electrode. As a result, the electric field inside the acceleration 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 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. The accelerating tube main body 1 is composed of a plurality of ring-shaped electrodes 3 made of a metal such as iron-nickel-cobalt alloy and an insulating ring 4 made of an electrically insulating material such as alumina ceramics. 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. The ring-shaped electrode 3 is formed by processing an ingot (lumps) of, for example, an iron-nickel-cobalt alloy into a predetermined disc shape by a conventionally known metal working method such as a rolling method or a punching method. Be produced. 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 therebetween, and the silver brazing material is heated and melted to be brazed and 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 disposed at a position where the flange body 6 having a plurality of mounting bolt holes 6a formed on the outer periphery thereof and the standing wall 3a of the ring-shaped electrode 3 face each other. Joined joining members 7
The welding member 7 is welded to the standing wall 3a of the ring-shaped electrode 3 so that the mounting flange 2 is positioned at both ends of the acceleration tube main body 1.
Bolt holes 6 provided in the flange body 6
The acceleration tube main body 1 is arranged in an electron microscope or the like by bolting a to a mounting member provided in the electron microscope or the like. [0022] Incidentally, the flange body 6 of the mounting flange 2, for example, made of SUS, also connecting member 7 iron -
It is formed of a nickel - cobalt alloy or the like. Further, a reinforcing ring 5 is further provided between the ring-shaped electrodes 3 located at both ends of the accelerating tube main body 1 and the mounting flange 2, and the ring-shaped electrodes 3 and Both the attachment flange 7 and the joining member 7 are joined. The reinforcing ring 5 functions to effectively prevent elastic deformation of the ring-shaped electrode 3 by being joined to both the ring-shaped electrode 3 and the mounting flange 2 located at both ends of the acceleration tube main body 1. 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, and the resonance vibration of the acceleration tube main body 1 is also caused by the elastic deformation of the ring-shaped electrode 3. The electric field inside the accelerating tube body 1 is always kept constant, and the 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 reinforcing ring 5 is joined to the ring-shaped electrode 3 and the mounting flange 2 by joining the reinforcing ring 5 to the joining member 7 for connecting the ring-shaped electrode 3 and the mounting flange 2 with a brazing material such as silver solder. This is done by brazing. When the reinforcing ring 5 is brazed to the ring-shaped electrode 3, a metallized metal layer made of a refractory metal powder such as tungsten, molybdenum, manganese or the like is previously applied to the end surface of the reinforcing ring 5. Every
This is performed by joining the metallized metal layer to the ring-shaped electrode 3 via a brazing material such as silver brazing. The metallized metal layer is applied to the end face of the reinforcing ring 5 in the same manner as the method used when the metallized metal layer is applied to the end face of the insulating ring 4, that is, the reinforcing ring 5 is formed. A method of printing and applying a metal paste to be a metallized metal layer on an end face by a conventionally well-known screen printing method and baking it at a temperature of about 1500 ° C. is adopted. The metal paste to be a metallized metal layer is, for example, molybdenum-manganese. In the case of comprising, a molybdenum powder and a manganese powder are manufactured by adding and mixing an organic binder, a solvent and the like. According to the accelerating tube of the present invention, the mounting flange is attached to 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 embodiment.
In the rather, various modifications as long as it does not depart from the gist of the present invention are possible. According to the acceleration tube of the present invention, as well as provided with reinforcing ring made of electrically insulating material between the acceleration tube and the mounting flange, ring located at both ends of the acceleration tube body The portion between the pair of standing walls of the ring-shaped electrode and the mounting flange are joined, and the end faces of the pair of standing walls of the ring-shaped electrode are
The reinforcing ring is joined to both the portions between the joints between the pair of upright walls and the pair of upright walls of the joining member to be joined.
By effectively preventing the shape , the ring-shaped electrode does not undergo elastic deformation even when an external force is applied to the ring-shaped electrode , and thus, even when external force such as vibration is applied to the acceleration tube, No resonance vibration is generated in the main body due to the elastic deformation of the ring-shaped electrode. 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 ...・ Reinforcement ring

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-176621 (JP, A) JP-A-53-90599 (JP, A) JP-A 4-115800 (JP, U) JP-A 64-64 12369 (JP, U) (58) Fields studied (Int. Cl. ⁷ , DB name) H01J 37/04 H01J 37/06-37/07 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. And a pair of upright wall portions formed on ring-shaped electrodes located at both ends of the acceleration tube main body.
They are joined, standing the vertical wall portion is disposed at a position facing
The joining member made of metal welded to the wall is a flange
A mounting flange that is configured to be joined to the body, arranged between said acceleration tube and the mounting flange, the site between the pair of vertical wall portions of the ring-shaped electrodes located at both ends of the acceleration tube body And a reinforcing ring made of an electrically insulating material, which is joined by brazing to both portions of the joining member between the joining portions with the pair of upright walls.