JP4921248B2 - Electron tube - Google Patents

Description

  The present invention relates to an electron tube for multiplying an incident electron current by dynodes stacked in multiple stages.

Conventionally, with respect to an electron tube having a laminated structure of dynodes, in order to laminate them at a predetermined interval while ensuring insulation between a plurality of dynodes, an apparatus or a channel in which glass balls are arranged between dynode support materials or channels are used. There are known devices in which conductive layers in which holes to be formed are formed and line-shaped separator layers are alternately arranged, devices having a spherical separating member fixed with glass enamel between adjacent dynodes, etc. References 1-3). In these devices, a spherical member or a line-shaped member is used as a member for arranging each dynode in a state in which it is insulated from adjacent dynodes. Furthermore, in the apparatus described in Patent Document 1, a hole for holding the glass sphere is provided on the dynode support material side, and the glass sphere is held with respect to the dynode support by the hole.
U.S. Pat. No. 3,229,143 JP-A-48-74167 Japanese Examined Patent Publication No. 62-41378

  Here, in order to stably guide the incident electrons to the output side in the channel for electron multiplication formed in the dynode composed of a plurality of stages, in order to stabilize the channel structure, between the channel component members during assembly. It is required to reduce the displacement of the position. In the conventional apparatus described above, when adjacent dynodes are stacked with a spherical member or a line-shaped member interposed therebetween, a positional deviation in a direction perpendicular to the stacking direction tends to occur. In addition, when the glass sphere is held in the hole provided on the dynode side, the positioning accuracy between adjacent dynodes is improved, but the discharge is likely to occur between the dynodes along the surface of the glass sphere. In some cases, noise was generated in the detection signal due to light emission.

  Therefore, the present invention has been made in view of such problems, and an object of the present invention is to provide an electron tube capable of stabilizing detection sensitivity while reducing noise in a detection signal.

To solve the above problems, an electron tube of the present invention is laminated in a plurality of stages, an electronic tube with a dynode having an electron multiplying holes multiplying incident electrons, between adjacent dynodes, more on the surface The adjacent dynodes have first and second protrusions formed on the respective surfaces on the front side and the rear side, respectively. Insulating member in a state where each of the first protrusion of the dynode and the second protrusion of the preceding dynode is fitted in a hole formed at a position facing the first and second protrusions Are stacked.

  According to such an electron tube, the two dynodes adjacent in the stacking direction are stacked via the insulating member in a state where the first and second protrusions are fitted in the holes of the insulating member. Thus, the dynodes are reliably aligned in the direction perpendicular to the direction, and the detection sensitivity can be stabilized. In addition, since the protruding portion of the dynode is housed in the hole of the insulating member, even if a discharge occurs between adjacent dynodes, light emission due to the discharge is prevented from leaking into the electron tube, and noise generation in the detection signal is reduced. be able to.

  It is preferable that a protruding portion is formed at the peripheral edge portion of the hole portion of the insulating member, and adjacent dynodes are stacked on each other while being in contact with the protruding portion. In this case, in a state where the dynodes are stacked, the dynodes are in contact with the raised portions formed at the peripheral edge of the hole portion of the insulating member. The extended distance along the surface can be increased, and the withstand voltage between dynodes can be increased.

  It is also preferable that a flat surface is formed at the center of the first and second protrusions. With such a configuration, the distance between the protruding portion of the dynode and the adjacent dynode on the protruding portion side is increased, and discharge between adjacent dynodes can be suppressed.

  In addition, a recess is formed at a position opposite to the second protrusion on the front surface of the dynode and a position opposite to the first protrusion on the rear surface of the dynode. It is also preferable that it is provided. In this way, the distance between the surface of the dynode opposite to the surface on which the protrusion is formed and the adjacent dynode is increased, so that the withstand voltage between the dynodes can be increased.

  Further, at least two holes are formed in the insulating member, and the adjacent dynodes are such that the first protrusions of the subsequent dynodes are fitted into one hole of the insulating member, and the dynodes in the previous stage It is preferable that the second protrusions are stacked via an insulating member in a state where the second protrusions are fitted in the other hole. In this case, since the first protrusion and the second protrusion of the two adjacent dynodes are accommodated in different holes of one insulating member, the first protrusion and the second protrusion face each other. This prevents the distance between dynodes from being shortened. Accordingly, the adjacent dynodes can be reliably positioned via the insulating member, and the withstand voltage between the dynodes can be further increased.

  Furthermore, it is preferable that the insulating member has a frame shape surrounding the region where the electron multiplying hole of the dynode is formed. By adopting such a configuration, it is possible to improve the positioning accuracy between dynodes, and more reliably prevent light emission due to discharge flowing along the insulating member between adjacent dynodes from leaking to the outer space of the stacked dynodes. can do.

  According to the present invention, it is possible to provide an electron tube capable of stabilizing detection sensitivity while reducing noise in a detection signal.

  Hereinafter, preferred embodiments of an electron tube according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is an end view along a tube axis direction of a photomultiplier tube 1 which is an electron tube according to a preferred embodiment of the present invention. The photomultiplier tube 1 sandwiches a circular light-receiving surface plate 2 that receives incident light, a cylindrical metal side tube 3 attached to the outer edge of the light-receiving surface plate 2, and the metal side tube 3. The vacuum vessel 5 is constituted by a circular stem 4 disposed so as to face the light receiving face plate 2, and the focusing electrode 6, the electron multiplier 7, and the anode 8 arranged in the vacuum vessel 5. ing. The size of the photomultiplier tube 1 is not limited to a specific size. For example, the length of the vacuum vessel 5 in the tube axis Z direction is 12 mm, and the width in the direction perpendicular to the tube axis Z is 15 mm.

  A photocathode 2a is provided on the inner surface of the light-receiving face plate 2. Between the photocathode 2a and the electron multiplying unit 7, the photocathode 2a is substantially perpendicular to the tube axis Z direction (X-axis direction in FIG. 1). Linear focusing electrodes 6 are provided so as to be arranged at equal intervals. The converging electrode 6 causes electrons emitted from the photocathode 2a into the vacuum vessel 5 as light enters the light-receiving face plate 2 from the outside to enter the electron multiplier 7 by converging the trajectory.

  The electron multiplying unit 7 includes a plurality of dynodes 10 having a plurality of electron multiplying holes 9 stacked in the tube axis Z direction. A substantially rectangular anode 8 is disposed facing the electron multiplying hole 9 of the dynode 10. In addition, the stem 4 is provided with a stem pin 11 that is connected to an external voltage terminal and applies a predetermined voltage to the photocathode 2 a, the focusing electrode 6, each dynode 10, and the anode 8. The number of stages of the dynodes 10 and the voltage applied to the stem pin 11 can be set variously. For example, the dynodes 10 are stacked in eight stages, and the voltages applied to the photocathode 2a, the focusing electrode 6, each dynode 10 and the anode 8 are stacked. Are set to 0 V, 0 V, 160 to 720 V (80 V interval), and 800 V, respectively, so as to increase from the photocathode 2 a toward the anode 8. As a result, the incident electron current is multiplied from upstream to downstream in the electron multiplication path, specifically, from the first stage dynode 10 to the last stage dynode 10, and is externally detected as a detection signal at the anode 8. It is taken out.

  Each dynode 10 is formed of a substantially rectangular plate made of metal such as stainless steel or aluminum, with a slit-shaped electron increase in parallel with each other along a direction perpendicular to the tube axis Z direction (Y axis direction in FIG. 1). A plurality of double holes 9 are formed. The plurality of dynodes 10 are stacked at predetermined intervals with a frame-shaped insulating member 12 interposed therebetween. At this time, the two adjacent dynodes 10 are stacked via the insulating member 12, thereby being aligned with each other in a direction along a plane (XY plane) perpendicular to the tube axis Z. Thereby, the electron multiplying hole 9 formed in the dynode 10 has an opening 9a on the front stage side (focusing electrode 6 side) thereof and an opening 9b on the rear stage side (anode 8 side) of the electron multiplying hole 9 of the preceding dynode 10. Zigzag-shaped electron multiplying channels are formed in parallel along the tube axis Z direction.

  As the dynode 10 having such a structure, for example, a plate obtained by laminating electron multiplying holes 9 at intervals of 1 mm on a stainless steel plate 9 mm square and 0.1 mm thick is used at a pitch of 0.8 mm.

  Next, with reference to FIGS. 2-4, the laminated structure of the electron multiplying part 7 will be described in detail. 2 is a plan view of the electron multiplier section 7 of FIG. 1, FIG. 3 is an end view taken along line III-III of the electron multiplier section 7 of FIG. 2, and FIG. FIG. 4 is an exploded perspective view showing a part of a multiplication unit 7.

  Two protrusions 13a and 13b are formed at two diagonal corners of the four corners of the front surface 10a of the dynode 10, and two corners positioned on another diagonal of the surface 10a have two Indentations 14c and 14d are formed. In addition, depressions 14a and 14b having substantially the same size as the protrusions 13a and 13b are formed at positions opposite to the protrusions 13a and 13b on the surface 10b on the rear stage side of the same dynode 10, respectively. In the surface 10b, projections 13c and 13d having substantially the same size as the depressions 14c and 14d are formed at positions opposite to the depressions 14c and 14d, respectively. That is, no protrusions or depressions are formed on both the surface 10a and the surface 10b at a predetermined position of the dynode 10. These protrusions 13a, 13b, 13c, and 13d protrude in a substantially circular shape, and a flat surface 15 is formed at the center thereof. Similarly, the recessed portions 14a, 14b, 14c, and 14d have shapes that are recessed in a substantially circular shape, and a flat surface 16 is formed at the center thereof.

  The insulating member 12 is a member formed in a frame shape from an insulating material such as ceramic so as to have substantially the same edge shape as that of the dynode 10. The insulating member 12 is sufficient to surround the region A so as not to cover the region A (see FIG. 1) of the electron multiplying hole 9 of the electron multiplying unit 7 when it is disposed between the two dynodes 10. The center is cut out in a rectangular shape with a large size. Further, the insulating member 12 includes a front surface 12a to a rear surface 12b at four corner positions facing the protrusions 13a, 13b, 13c, and 13d when arranged between the two dynodes 10. A through hole 17 is formed. In addition, circular raised portions 18 are formed on the peripheral portions of the holes 17 on the surfaces 12a and 12b side, respectively.

  When the two dynodes 10 having the above-described shape are stacked via the insulating member 12, the protrusions 13 c and 13 d of the preceding dynode 10 are fitted into the two hole portions 17 on the diagonal line of the insulating member 12. The protrusions 13a and 13b of the subsequent dynode 10 are stacked on each other by being fitted into the two holes 17 on another diagonal line of the insulating member 12 (FIG. 4). In this case, the adjacent two-stage dynodes 10 are fixed to each other with their surfaces 10 a and 10 b abutting against the ridges 18 at the peripheral edge of the hole 17. Here, since the inner diameter of the hole 17 has substantially the same diameter as the outer diameter of the protrusions 13a, 13b, 13c, and 13d, the two adjacent dynodes are aligned in a direction perpendicular to the tube axis Z. Made. In this way, the first stage dynode 10 to the last stage dynode 10 are stacked via the insulating member 12.

  According to the photomultiplier tube 1 described above, the two dynodes 10 adjacent to each other in the stacking direction have the insulating members 12 in a state where the protrusions 13a, 13b, 13c, and 13d are fitted in the holes 17 of the insulating member 12. Therefore, the dynodes 10 are reliably aligned in the direction along the XY plane perpendicular to the tube axis Z direction. As a result, the assembly accuracy of the electron multiplication channel is improved, so that the detection sensitivity can be stabilized. Further, since the protrusions 13a, 13b, 13c, and 13d of the dynode 10 are accommodated in the hole 17 of the insulating member 12, even if discharge along the inner wall of the hole 17 occurs between the adjacent dynodes 10, the discharge is caused. Light emission is easily confined in the hole 17 and is prevented from leaking to the photocathode 2 a side in the vacuum vessel 5. Therefore, the generation of noise in the detection signal output via the stem pin 11 can be reduced.

  In particular, the insulating member 12 has four through-holes 17 formed at four corners, and the adjacent two-stage dynodes 10 have protrusions 13a and 13b of the subsequent dynode 10 on the diagonal line of the insulating member 12. The projections 13c and 13d of the preceding dynode 10 are fitted into the holes 17 on another diagonal line. Therefore, since the protrusions 13a and 13b and the protrusions 13c and 13d of the two adjacent dynodes 10 are accommodated in the separate holes 17 of the single insulating member 12, the distance between the dynodes is increased by the protrusions facing each other. It will not be shortened. Accordingly, the adjacent dynodes 10 can be reliably positioned via the insulating member 12, and the withstand voltage between the dynodes 10 can be further increased.

  Further, since the dynodes 10 are stacked on each other in contact with the ridges 18 formed at the peripheral edge of the hole 17 of the insulating member 12, the dynodes 10 are in contact with the holes 17 of the insulating member between the adjacent dynodes 10. Thus, the extended distance along the outer side surface 20 (see FIG. 5) is increased, and the withstand voltage between the dynodes 10 can be increased.

  Moreover, since the flat surfaces 15 and 16 are formed in the center of the protrusions 13a, 13b, 13c, and 13d and the recesses 14a, 14b, 14c, and 14d, the protrusions 13a and 13a of the adjacent two-stage dynodes 10 are formed. The distance between 13b, 13c, 13d and the depressions 14a, 14b, 14c, 14d is increased, and the discharge between adjacent dynodes 10 can be further suppressed.

  Further, in the surfaces 10a and 10b of each dynode 10, the protrusions 13a, 13b, 13c, and 13d are formed on the opposite sides of the respective positions of the recesses 14a, 14b, 14c, and 14d, and therefore adjacent two steps. The distance between the dynodes 10 is increased, and the withstand voltage between the dynodes can be further increased.

  Further, since the insulating member 12 has a frame shape surrounding the region A where the electron multiplying holes 9 of the dynodes 10 are formed, the insulating members 12 are aligned at two corners with respect to the dynodes 10 facing each dynode 10. By doing so, the positioning accuracy between the dynodes 10 can be improved. Furthermore, it is possible to more reliably prevent light emission due to the discharge flowing along the insulating member 12 between the adjacent dynodes 10 from leaking to the outer space of the electron multiplier 7 where the dynodes 10 are stacked. Noise can be further reduced.

  In addition, this invention is not limited to embodiment mentioned above. For example, as the shape of the insulating member disposed between the dynodes, a U-shaped shape in which one side of the insulating member 12 is removed as shown in FIG. 6A, or as shown in FIG. 6B. Various shapes such as an L-shaped shape in which two sides of the insulating member 12 are removed, and an I-shaped shape in which two sides of the insulating member 12 are removed as shown in FIG. Shape can be adopted. However, from the viewpoint of improving positioning accuracy and reducing the number of parts, the number of holes 17 per member of the insulating member is preferably 3 or more, and insulation is particularly ensured while ensuring a withstand voltage between dynodes. It is more preferable that the number of the holes 17 is four in that the positioning accuracy can be improved by fitting at two points on both sides of the member. Further, the shape of the dynode 10 is not limited to a substantially rectangular shape, and may be a substantially circular shape, for example. In this case, it is preferable that the protrusion and the depression are formed on a diagonal line passing through the center of the circle.

  Moreover, the hole 17 formed on the surfaces 12 a and 12 b of the insulating member 12 may have a recess formed on both surfaces of the insulating member 12 so as not to penetrate the opposite surface. Also, the edge portions of the holes 17, the protrusions 13a, 13b, 13c, and 13d formed on the dynode 10 and the recesses 14a, 14b, 14c, and 14d are not limited to circles, and may be rectangular, elliptical, or the like. It may have other shapes. However, a circular shape is more preferable from the viewpoint of ease of processing by pressing or the like, and since there is no square end and it is difficult to discharge.

  Further, the raised portion 18 provided on the periphery of the hole portion 17 is not limited to a circular shape, and may be formed in a plurality of arc shapes or dot shapes. However, it is preferable that the raised portion 18 is formed in a circular shape over the entire periphery of the peripheral edge portion of the hole portion 17 from the viewpoint of preventing leakage of light emission due to discharge in the hole portion 17.

  In the embodiment described above, a photomultiplier tube is shown as an electron tube having an electron multiplier. However, an electron multiplier having no other photocathode, an image for amplifying the luminance of an input light image. An electron tube having an electron multiplier such as a multiplier may be used.

1 is an end view along a tube axis direction of a photomultiplier tube according to a preferred embodiment of the present invention. It is a top view of the electron multiplication part of FIG. FIG. 3 is an end view of the electron multiplier section of FIG. It is a disassembled perspective view which shows a part of electron multiplication part of FIG. FIG. 4 is an end view showing an enlarged part of the electron multiplier section of FIG. 3. It is a top view of the insulating member concerning the modification of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Photomultiplier tube, 9 ... Electron multiplication hole, 10 ... Dynode, 10a ... Front side surface, 10b ... Rear side surface, 12 ... Insulation member, 12a, 12b ... Surface, 13a, 13b, 13c, 13d ... Projection part, 14a, 14b, 14c, 14d ... depression, 15, 16 ... flat surface, 17 ... hole, 18 ... raised portion, A ... electron multiplying hole region.

Claims (6)

An electron tube including a dynode having electron multiplier holes stacked in a plurality of stages and multiplying incident electrons,
Between the adjacent dynodes, an insulating member having a plurality of holes formed on the surface is provided,
The adjacent dynodes have first and second protrusions formed on respective surfaces on the front side and the rear side, respectively, and the first protrusions of the dynode on the rear stage and the front dynodes Each of the second protrusions of the dynode is stacked via the insulating member in a state of being fitted in the hole formed at a position facing the first and second protrusions .
An electron tube characterized by that. A protuberance is formed on the peripheral edge of the hole of the insulating member,
The adjacent dynodes are stacked on each other in contact with the raised portion,
The electron tube according to claim 1, wherein: A flat surface is formed at the center of the first and second protrusions.
The electron tube according to claim 1 or 2, wherein There is a depression at a position opposite to the second protrusion on the front surface of the dynode and a position opposite to the first protrusion on the rear surface of the dynode. Part is provided,
The electron tube according to claim 1, wherein: The insulating member has at least two holes formed therein,
In the adjacent dynodes, the first protrusion of the subsequent dynode is fitted in one of the holes of the insulating member, and the second protrusion of the preceding dynode is the other of the holes. In a state of being fitted to the part, it is stacked via the insulating member,
The electron tube according to any one of claims 1 to 4, wherein: The insulating member has a frame shape surrounding the region where the electron multiplier hole of the dynode is formed.
The electron tube according to any one of claims 1 to 5, wherein:

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