JP2008293918A - Electron tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron tube with sensitivity efficiently enhanced even in the case downsizing of a device is required. <P>SOLUTION: A photomultiplier tube 1 is provided with dynodes 10 having photomultiplier holes 9 of a plurality of channels for multiplying incident electrons laminated in a plurality of steps. The photomultiplier holes 9 have adjacent channels in the dynodes 10 of the same steps partitioned by a partitioning member 12, which 12 is formed so that a cross section along a tube axis Z direction is extended aslant toward the tube axis Z direction, and that, a protruded part 13 along an opening 9a of the front-step dynode 10 side is formed at the upstream side side face 12a of the front-step dynode 10 side, and a tip face 12c at the front-step dynode 10 side is slanted to a face vertical to the tube axis Z direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

Conventionally, as this type of electron tube, a photomultiplier tube described in Patent Document 1 below is known. This photomultiplier tube has a plurality of dynodes provided along the main axis direction. In each dynode, a plurality of thin plates inclined with respect to the main axis are arranged at a specific pitch in a direction perpendicular to the main axis. Has been. When electrons enter along the main axis between adjacent thin plates of such dynodes, the electrons are sequentially multiplied while colliding with the thin plates and collected by the collector.
Japanese Patent Publication No.59-23609 JP-A-62-160652 JP-T-2001-508917 Patent No. 3078905

  However, in the dynode having the above-described shape, it is necessary to increase the size of the thin plate to some extent in order to achieve high sensitivity. Since it becomes stronger, the electron multiplication factor tends to decrease. Such a tendency is remarkable when downsizing of the electron tube is required.

  Therefore, the present invention has been made in view of such problems, and an object thereof is to provide an electron tube capable of efficiently increasing sensitivity even when downsizing of the apparatus is required. .

  In order to solve the above-described problems, an electron tube of the present invention is an electron tube including a dynode having a plurality of channel electron multiplying holes stacked in a plurality of stages and multiplying incident electrons. Adjacent channels in a single stage dynode are partitioned by a partition member, and the partition member is formed such that a cross section along the stacking direction of the dynode extends inclining with respect to the stacking direction, and upstream of the previous dynode side A protrusion is formed on the side surface along the end portion on the dynode side of the previous stage, and the tip surface on the dynode side of the previous stage is inclined with respect to a plane perpendicular to the stacking direction.

  According to such an electron tube, the dynodes stacked in a plurality of stages are configured with electron multiplying holes that are partitioned by a partition member that is inclined between adjacent channels with respect to the stacking direction. A protrusion along the opening end of the electron multiplier hole is provided on the side surface on the front dynode side, and the front end surface on the front dynode side of the partition member is inclined with respect to a surface perpendicular to the stacking direction of the dynodes. ing. By such a shape of the partition member, the penetration of the electric field due to the voltage applied to the preceding dynode is blocked by the protrusion, so that the potential in the electron multiplier hole is prevented from being lowered and the electron multiplier hole The potential in the vicinity of the side surface on the dynode side in the subsequent stage is raised. In addition, since the front end surface on the dynode side in the previous stage is inclined, the electric field is likely to penetrate from the front end surface toward the inside of the electron multiplier hole of the previous dynode. By such a synergistic effect of the protrusion and the tip surface shape, the electron multiplication efficiency in the dynode is improved, and the detection sensitivity can be effectively increased.

  The projection of the partition member is preferably formed with a dent at the tip along the end on the dynode side of the previous stage. In this case, the desired detection sensitivity can be maintained without degrading the withstand voltage characteristic between the protruding portion of the partition member and the preceding dynode.

  Moreover, it is also preferable that a recess along the end portion on the dynode side of the previous stage is formed on the downstream side surface on the dynode side of the rear stage of the partition member. With such a configuration, the volume of the electron multiplying hole can be secured, so that the electron collection efficiency for each channel can be improved even when the dynode is multi-channeled.

  Moreover, it is also preferable that the hollow part of a partition member is formed in the position of the downstream side surface on the opposite side with respect to the formation position of the projection part of an upstream side surface. In this way, it is easy to reduce the thickness of the partition member, and the electron multiplier holes can be easily multi-channeled in a limited size dynode.

  Or it is preferable that the protrusion part is further formed in the downstream side surface by the side of the back | latter stage dynode of a partition member along the edge part by the side of the front | former stage dynode. Providing such a protrusion makes it easier to generate an electric field that leads secondary electrons to the subsequent stage on the dynode side subsequent to the electron multiplier hole, so that the detection sensitivity can be further increased.

  Further, the protrusion on the upstream side surface is a midpoint between the first surface including the opening on the dynode side upstream of the electron multiplier hole and the second surface including the opening on the dynode side in the subsequent stage. It is also preferable that it is arranged closer to the first surface than the including surface. In this case, the penetration of the electric field into the electron multiplier hole due to the voltage applied to the preceding dynode is further prevented, and the electron multiplication factor can be further increased.

  Furthermore, it is also preferable that the upstream side surface of the partition member is formed so as to bend toward the dynode side in the previous stage from the protrusion to the tip surface. In such a shape, the distance from the side surface of the partition member to the preceding dynode is increased, so that discharge between the dynodes can be prevented and the electric field easily penetrates from the tip of the partition member into the preceding electron multiplier hole. Therefore, the multiplication factor of electrons can be further improved.

  Furthermore, it is also preferable that the upstream side surface of the partition member is formed so as to bend toward the front dynode side from the protrusion to the front end portion on the rear dynode side. In the case of such a shape, since the distance from the front end portion of the partition member to the subsequent dynode is increased, the discharge between the dynodes can be sufficiently prevented.

  According to the present invention, it is possible to provide an electron tube capable of efficiently increasing sensitivity even when downsizing of the apparatus is required.

  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, and the photocathode 2a is linearly arranged between the photocathode 2a and the electron multiplier 7 in a direction perpendicular to the tube axis Z direction. The focusing electrode 6 is provided. 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 so as to increase from 0V, 0V, 160 to 720V (80V interval), 800V, respectively, from the photocathode 2a toward the anode 8, so that the incident electron current flows from upstream in the electron multiplication path. As it goes downstream, specifically, it is multiplied from the first stage dynode 10 toward the last stage dynode 10, and taken out as a detection signal at the anode 8.

  Next, the configuration of the electron multiplier section 7 will be described in detail with reference to FIGS. 2 is an end view showing a part of the electron multiplying unit 7 in FIG. 1 in an enlarged manner, FIG. 3 is an end view showing the partition member in FIG. 2 in an enlarged manner, and FIG. 4 shows the dynode 10 in FIG. It is the top view seen from the pipe-axis Z direction.

  Each dynode 10 has a plurality of slit-like electron multiplying holes 9 formed in parallel to each other along a direction perpendicular to the tube axis Z direction on a substantially rectangular plate electrode made of metal such as stainless steel or aluminum. Become. The plurality of electron multiplier holes 9 have an opening 9a on the front stage side (focusing electrode 6 side) extending from the opening 9b on the rear stage side (anode 8 side) of the electron multiplier hole 9 of the dynode 10 in the front stage. A plurality of zigzag electron multiplying channels along the tube axis Z direction are formed by being positioned on the line.

  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.

  The characteristics of the electron multiplying hole 9 will be described in more detail. The two electron multiplying holes 9 constituting the adjacent electron multiplying channel are formed by a partition member 12 formed by, for example, pressing a plate electrode. It is partitioned. The partition member 12 is formed such that a cross section along the XZ plane when the arrangement direction of the slit-like electron multiplying holes 9 is the X axis extends in an inclined manner with respect to the tube axis Z. (Figure 3).

  On the upstream side surface 12a of the upstream side of the partition member 12 on the dynode 10 side, a protrusion is formed along the front side end of the partition member 12 forming the opening 9a of the electron multiplying hole 9 (along the Y-axis direction). A portion 13 is formed. The protrusion 13 is formed so as to be positioned closer to the surface S1 than the surface S3 including the midpoint between the surface S1 including the opening 9a of the electron multiplying hole 9 and the surface S2 including the opening 9b. Yes. In addition, a recess 13a is formed in the center of the protrusion 13 along the longitudinal direction of the protrusion 13, that is, along the opening 9a. The upstream side surface 12a forms a curved surface from the protrusion 13 to the front end surface 12c and the rear end surface 12d so as to curve toward the front dynode 10 side.

  On the downstream side surface 12b on the dynode 10 side at the rear stage of the partition member 12, a recess 14 is formed linearly along the direction in which the protrusion 13 is formed, that is, along the opening 9a (see FIG. 3 and FIG. 3). FIG. 4). The recess 14 is formed at the position of the downstream side surface 12b opposite to the formation position of the protrusion 13 of the upstream side surface 12a. Further, the downstream side surface 12b forms a curved surface so as to bend toward the front dynode 10 from the recess 14 to the front end surface 12c and the rear end surface 12d.

  Further, the front end surface 12c of the partition member 12 is inclined with respect to the surface S1 perpendicular to the tube axis Z direction so that the opening 9a protrudes into the electron multiplying hole 9 on the upstream side of the same channel. Is formed. Similarly, the front end surface 12d of the partition member 12 is also formed to be inclined with respect to the surface S2 perpendicular to the tube axis Z direction.

  The electron multiplying function in the electron multiplying unit 7 having such a configuration will be described with reference to FIGS.

  The electrons that have passed through the focusing electrode 6 and entered the electron multiplier hole 9 of the first stage dynode 10 are accelerated by the voltage applied to the dynode 10, and are then anodes on the upstream side surface 12 a of the electron multiplier hole 9. It collides with the lower part on the 8 side, where secondary electrons are emitted and the incident electron current E is multiplied. The multiplied incident electron stream E enters the electron multiplying hole 9 of the next dynode 10 of the same channel, collides with the upstream side surface 12a while being accelerated by the voltage applied to the dynode 10, and increases again. Doubled. In this way, the electron flow E emitted from the electron multiplier hole 9 of the final stage dynode 10 is taken out as an electrical signal from the anode 8 through the stem pin 11.

  According to the photomultiplier tube 1 described above, the dynodes 10 stacked in a plurality of stages are configured with the electron multiplier holes 9 partitioned between the adjacent channels by the partition member 12 inclined with respect to the tube axis Z direction. The partition member 12 is provided with a protrusion 13 along the opening 9a of the electron multiplying hole 9 on the side surface 12a on the front dynode 10 side, and on the front dynode side of the partition member 12. The tip surface 12c is inclined with respect to the surface S1 perpendicular to the tube axis Z direction. With such a shape of the partition member 12, penetration of the electric field F <b> 1 into the electron multiplier hole 9 due to the voltage applied to the dynode 10 in the previous stage is blocked by the protrusion 13, so that the potential in the electron multiplier hole 9 is reduced. Is prevented, and the potential in the vicinity of the side surface 12a on the dynode 10 side at the rear stage of the electron multiplier hole 9 is raised (FIG. 5). In addition, since the front end surface 12c on the front dynode 10 side is inclined, the electric field F2 is likely to penetrate from the front end surface 12c toward the inside of the electron multiplier hole 9 of the front dynode 10. Due to the synergistic effect of the shape of the protruding portion 13 and the tip surface 12c, an electric field distribution is formed that facilitates introduction of the multiplied incident electron current E from the upstream side surface 12a to the subsequent electron multiplying hole 9. Electron multiplication efficiency in the dynode 10 is improved, and detection sensitivity can be effectively increased. Further, since the partition member 12 has almost no part parallel to the surface S1 perpendicular to the tube axis Z direction, it is possible to suppress foreign matters that may cause noise or the like from being placed on the partition member 12. .

  In particular, the protrusion 13 is disposed closer to the surface S1 than the surface S3 including the midpoint between the surface S1 including the opening 9a of the electron multiplying hole 9 and the surface S2 including the opening 9b. Further, the penetration of the electric field into the electron multiplier hole 9 due to the voltage applied to the preceding dynode 10 is further prevented, and the electron multiplication factor can be further increased.

  Moreover, since the protrusion 13 of the partition member 12 has a recess 13a formed along the opening 9a at the tip thereof, the withstand voltage characteristic between the protrusion 13 of the partition member 12 and the dynode 10 in the previous stage is improved. A desired detection sensitivity can be maintained without being lowered.

  Moreover, since the volume of the electron multiplying hole 9 can be secured by forming the recess 14 along the opening 9a on the downstream side surface 12b of the partition member 12, the dynode 10 can be multi-channeled. Even in this case, the electron collection efficiency for each channel can be improved. Furthermore, since the recessed part 14 of the partition member 12 is formed in the position of the downstream side surface 12b on the opposite side with respect to the formation position of the projection part 13 of the upstream side surface 12a, the thickness of the partition member 12 is made thin. Therefore, the electron multiplier holes 9 can be easily multi-channeled in the dynodes 10 of a limited size.

  Further, since the upstream side surface 12a of the partition member 12 is formed to bend toward the front dynode 10 from the protrusion 13 to the tip surface 12c, the distance from the side surface 12a of the partition member 12 to the front dynode 10 Can be prevented from being discharged between the dynodes 10, and an electric field can easily penetrate from the opening 9 a of the partition member 12 into the electron multiplier hole 9 in the previous stage, so that the electron multiplication factor can be further improved. it can.

  Furthermore, since the upstream side surface 12a of the partition member 12 is formed so as to bend toward the front dynode 10 from the protrusion 13 to the tip surface 12d, from the opening 9b of the partition member 12 to the rear dynode 10 The distance between the dynodes can be sufficiently prevented.

  In addition, this invention is not limited to embodiment mentioned above. For example, the shape of the dynode 10 can take various modifications. For example, FIG. 6 shows an end view along the tube axis direction similar to FIG. 1 of a dynode 110 which is a modification of the present invention. The dynode 110 has a partition member 112 that partitions adjacent electron multiplying holes 109, and linearly extends along the opening 109 a of the electron multiplying hole 109 on the upstream side surface 112 a of the partition member 112. A protrusion 113 having a sharp shape is formed. A protrusion 114 that linearly protrudes toward the subsequent dynode 110 is formed at a position opposite to the protrusion 113 on the downstream side surface 112b of the partition member. In the case of such a shape, since the electron multiplying hole 109 is configured to become narrower toward the subsequent dynode 110 side, an electric field that guides secondary electrons to the subsequent stage is likely to be generated. The multiplication factor can be further increased, and the detection sensitivity can be further increased.

  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 an end elevation which shows the principal part of the electron multiplication part of FIG. It is an end view which expands and shows the partition member of FIG. It is the top view which looked at the dynode of FIG. 1 from the pipe-axis direction. It is a figure which shows the track | orbit of the incident electron in the electron multiplier hole of FIG. It is an end elevation along the pipe axis direction of the dynode concerning the modification of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Photomultiplier tube, 9, 109 ... Electron multiplication hole, 9a, 109a ... Opening part (end part), 9b ... Opening part, 10, 110 ... Dynode, 12, 112 ... Partition member, 12a, 112a ... Upstream Side surface, 12b, 112b ... downstream side surface, 12c ... tip surface, 13, 113, 114 ... projection, 13a ... depression, 14 ... depression, Z ... tube axis (stacking direction).

Claims (8)

An electron tube comprising a dynode having a multi-channel electron multiplier hole stacked in a plurality of stages and multiplying incident electrons,
In the electron multiplier hole, adjacent channels in the dynode in the same stage are partitioned by a partition member,
The partition member is
A section along the stacking direction of the dynode is formed so as to extend inclined with respect to the stacking direction, and an upstream side surface on the dynode side of the previous stage is along an end portion on the dynode side of the previous stage A protrusion is formed, and the front end surface on the dynode side in the previous stage is inclined with respect to a plane perpendicular to the stacking direction.
An electron tube characterized by that. In the projection of the partition member, a depression is formed along an end on the dynode side of the previous stage.
The electron tube according to claim 1, wherein: On the downstream side surface on the dynode side in the rear stage of the partition member, a recess is formed along the end part on the dynode side in the front stage.
The electron tube according to claim 1 or 2, wherein The recessed portion of the partition member is formed at the position of the downstream side surface opposite to the formation position of the protruding portion of the upstream side surface.
The electron tube according to claim 3, wherein: On the downstream side surface on the dynode side of the rear stage of the partition member, a protrusion is further formed along the end part on the dynode side of the front stage.
The electron tube according to claim 1 or 2, wherein The protrusion on the upstream side surface is between a first surface including an opening on the dynode side upstream of the electron multiplier hole and a second surface including an opening on the dynode side in the subsequent stage. It is arranged closer to the first surface than the surface including the midpoint,
The electron tube according to any one of claims 1 to 5, wherein: The upstream side surface of the partition member is formed so as to curve toward the dynode side in the previous stage from the protrusion to the tip surface.
The electron tube according to any one of claims 1 to 4, wherein: The upstream side surface of the partition member is formed so as to bend toward the dynode side in the front stage from the protrusion to the tip part on the dynode side in the rear stage.
The electron tube according to any one of claims 1 to 4, wherein:

Images