JP6570972B2 - Fusion neutron generator and fusion neutron generation method - Google Patents

Description

  Embodiments of the present invention relate to a fusion neutron generator and a fusion neutron generation method.

  An apparatus using inertial electrostatic confinement fusion is known as a fusion neutron generator. An apparatus using an inertial electrostatic confinement fusion reaction has a structure in which, for example, a lattice-shaped cathode is arranged in a concentric sphere at the center of a spherical vacuum vessel that also serves as an anode.

  In this type of apparatus, fuel gas such as deuterium is filled in a vacuum vessel and a high voltage of about several kV to 100 kV is applied between the anode and the cathode, so that deuterium ions and the like are generated by discharge. . The generated ions are accelerated and converged toward the center by the electric field between the electrodes. Since the cathode has a lattice shape, most of the ions do not collide with the cathode, reach the inside of the cathode, jump out from the inside of the cathode, and are accelerated and converged toward the center again by the electric field.

  Ions that become dense at the center of the sphere collide with each other, collide with fuel gas, or collide with fuel gas particles embedded in the cathode or anode, causing a fusion reaction to generate neutrons or charges. Particles are generated. Moreover, the structure of the fusion neutron generator using the inertial electrostatic confinement fusion reaction may be, for example, a structure in which an anode and a cathode are formed in a cylindrical shape and arranged coaxially. This type of fusion neutron generator is configured to apply a high voltage to the cathode via a high voltage introduction section.

Japanese Patent No. 3867972 Japanese Patent No. 3700496 JP 2004-311152 A JP 2008-202942 A

  Neutrons and charged particles obtained by fusion neutron generators are expected to be applied to nuclear material detection, explosives detection, and nondestructive inspection. For this reason, for example, downsizing of the apparatus is demanded so as to enhance the convenience of use in the field such as outdoors.

  On the other hand, since the amount of neutron generation increases with the voltage applied to the cathode, it is effective to apply a higher voltage to the cathode in order to obtain high-power neutron generation. However, when a high voltage is applied to the cathode via the high voltage introduction part, creeping discharge may occur depending on the positional relationship between the anode such as the grounding part of the vacuum vessel and the high voltage introduction part.

  Therefore, the conventional fusion neutron generator is provided with an insulator structure extending in a direction along the axial direction of the cathode high-voltage introduction section, thereby providing a high-voltage introduction section for the anode and the cathode, The creepage distance and insulation distance of However, if the insulator structure is provided so as to increase the creeping distance and the insulation distance in the direction along the axial direction of the high voltage introduction portion, the size of the high voltage introduction portion is increased. For this reason, the apparatus has become larger and more complicated, and its use in the field such as outdoors has been restricted.

  The present invention has been made to solve the above-described problem, and a fusion neutron generator and a fusion neutron capable of suppressing creeping discharge between the anode and the high voltage introduction portion while reducing the size of the high voltage introduction portion. The purpose is to provide a generation method.

  A fusion neutron generator according to an embodiment of the present invention is a fusion neutron generator for accelerating ionized fuel gas to cause a fusion reaction in order to solve the above-described problems, and includes a vacuum vessel, A cathode, a high voltage introduction part, and an insulator structure are provided. The vacuum vessel has an anode and is maintained at a pressure lower than atmospheric pressure. The cathode is electrically insulated from the vacuum vessel and is provided inside the vacuum vessel. The high voltage introduction unit is electrically insulated from the vacuum vessel and applies a power supplied from the voltage application means to the cathode so as to accelerate the fuel gas ionized by the electric field between the anode and the cathode, thereby applying a negative potential to the cathode. Cause it to occur. The insulator structure is an insulator structure that constitutes at least a part of the inner surface of the vacuum vessel, and the creeping distance between the triple point on the high voltage introduction portion side and the triple point on the anode side is longer than the spatial distance. It has the shielding object provided in the inner surface side of the vacuum vessel so that it may have a distance.

The lineblock diagram showing an example of the fusion neutron generator concerning a 1st embodiment of the present invention. The block diagram which shows the other example of the fusion neutron generator which concerns on 1st Embodiment of this invention. The block diagram which shows an example of the conventional fusion neutron generator. Explanatory drawing which shows an example of the relationship between an insulation distance and a creeping discharge voltage. Explanatory drawing which shows an example of a mode that the insulator structure and shield which concern on 1st Embodiment were seen from the inside of a vacuum vessel. (A) is explanatory drawing which shows an example of the creeping distance of the cathode side triple point TJc and anode side triple point TJa when there is no conventional shield, (b) is the shield which concerns on 1st Embodiment. Explanatory drawing which shows an example of the creeping distance of the cathode side triple point TJc at the time of providing, and the anode side triple point TJa. (A) is explanatory drawing which shows the 1st modification of the shielding object which concerns on 1st Embodiment, (b) is explanatory drawing which shows the 2nd modification of the shielding object which concerns on 1st Embodiment. The block diagram which shows an example of the fusion neutron generator which concerns on 2nd Embodiment of this invention. The block diagram which shows the other example of the fusion neutron generator which concerns on 2nd Embodiment of this invention. The block diagram which shows the modification of the fusion neutron generator which concerns on 2nd Embodiment of this invention. The block diagram which shows an example of the fusion neutron generator which concerns on 3rd Embodiment of this invention. Explanatory drawing which shows an example of a mode that the progress of the secondary electron avalanche which generate | occur | produced on the creeping surface by the inclination which the shielding which concerns on 3rd Embodiment has occurred is suppressed. (A) is explanatory drawing which shows the modification of the shield which concerns on 3rd Embodiment, (b) is description which shows the example which calculates | requires inclination-angle (theta) of the shield which concerns on 3rd Embodiment from contact angle (phi). Figure. The block diagram which shows an example of the fusion neutron generator which concerns on 4th Embodiment of this invention. The block diagram which shows an example of the fusion neutron generator which concerns on 5th Embodiment of this invention. (A) is explanatory drawing which shows the 1st example of the charge release means which concerns on 5th Embodiment, (b) is explanatory drawing which shows the 2nd example of charge release means, (c) is the 3rd example of charge release means. FIG. The block diagram which shows an example of the fusion neutron generator which concerns on 6th Embodiment of this invention. (A) is explanatory drawing which shows an example when the shape of a vacuum vessel is a truncated cone, (b) is explanatory drawing which shows an example when it is a hexagonal truncated cone, (c) is a high voltage introduction part side as a bottom. (D) is an explanatory view showing an example when the shape of the vacuum vessel is a cylinder and the inner surface of the vacuum vessel formed by the insulator structure is a curved surface. e) Explanatory drawing showing an example of a vacuum vessel having a spherical shape, (f) is a cone whose shape is a cone with the high voltage introduction part at the top, and the side surface of the vacuum vessel is constituted by an insulator structure. Explanatory drawing which shows an example in the case of.

  Embodiments of a fusion neutron generator and a fusion neutron generation method according to the present invention will be described with reference to the accompanying drawings.

  A fusion neutron generator according to an embodiment of the present invention is an insulator structure that constitutes at least a part of the inner surface of a vacuum vessel, and is provided with three shields on the cathode side by a shield provided on the insulator structure. By making the creepage distance between the emphasis and the triple point on the anode side longer than the spatial distance, the creepage with the high-voltage introduction part without providing an insulator structure extending in the direction along the axial direction of the high-voltage introduction part It suppresses discharge.

(First embodiment)
FIG. 1 is a configuration diagram showing an example of a fusion neutron generator 10 according to the first embodiment of the present invention. FIG. 2 is a block diagram showing another example of the fusion neutron generator 10 according to the first embodiment of the present invention. FIGS. 1 and 2 schematically show an example of a cross-sectional view of the vacuum vessel 11 taken along a plane parallel to the axis of the cylinder when the vacuum vessel 11 has a cylindrical shape.

  As shown in FIG. 1, the fusion neutron generator 10 includes a vacuum vessel 11 that also serves as an anode, a cathode 12 that is arranged inside the vacuum vessel 11, and a high voltage introduction for applying a predetermined high voltage to the cathode 12. And an insulator structure 15 that constitutes at least a part of the inner surface of the vacuum vessel 11 and also serves as a flange of the vacuum vessel 11.

  The vacuum vessel 11 is maintained at a pressure lower than the atmospheric pressure, and a fuel gas composed of deuterium, deuterium, or a mixed gas thereof is introduced therein. As the shape of the vacuum vessel 11, an arbitrary shape such as a spherical shape, a cylindrical shape, or a hexahedron can be selected. The vacuum vessel 11 may be made of a conductive material such as aluminum or stainless steel such as SUS304, or titanium, or may be made of an insulating material such as glass.

  The anode is provided between the inner wall of the vacuum vessel 11 and the cathode 12 and is made of a conductive material. The shape of the anode can be arbitrarily selected according to the shape of the cathode 12. When the inner wall of the vacuum vessel 11 is a conductive substance such as aluminum, stainless steel, or stainless steel, the vacuum vessel 11 can also serve as an anode.

  In the following description, an example is shown in which the vacuum vessel 11 has a cylindrical shape, the inner wall of the vacuum vessel 11 is made of a conductive material such as SUS304, and the inner wall of the vacuum vessel 11 also serves as an anode.

  The cathode 12 is a cage-like electrode that is provided inside the anode so as to be electrically insulated from the vacuum vessel 11 that also serves as the anode, and is made of a conductive material. The geometric transmittance of the cage cathode 12 is preferably 90% or more. The shape of the cathode 12 can be a cylindrical shape, a spherical shape, a ring shape, or the like. As the material of the cathode 12, various materials can be used as long as they are conductive and have a high melting point such as titanium and tantalum. In the following description, an example in which the cathode 12 is made of pure tungsten and has a cylindrical shape with a geometric transmittance of 95% will be described. That is, in the following, a cylindrical vacuum vessel 11 that also serves as an anode and a cylindrical cathode 12 are provided concentrically, and when a voltage is applied, the electric field distribution is symmetrical in the circumferential direction. An example will be described.

  An intermediate electrode, which is a cage electrode made of a conductive material, may be provided between the anode and the cathode 12. In this case, the geometric transmittance of the cage-shaped intermediate electrode is preferably 90% or more. Further, the shape of the intermediate electrode can be a cylindrical shape, a spherical shape, a ring shape, or the like. At least one intermediate electrode can be arranged in the space between the anode and the cathode 12.

  The high voltage introducing portion 13 is made of a conductive material and supports the cathode 12. The high voltage introduction unit 13 is electrically insulated from the vacuum vessel 11 serving also as an anode, and supplies the cathode 12 with power supplied from the high voltage applying means 14 outside the vacuum vessel 11 via the cable 14a. A negative potential is generated at the cathode 12. As shown in the cross-sectional view of FIG. 1, the high voltage introducing portion 13 is surrounded by an insulator structure 15, and the vacuum vessel 11 and the cathode 12 are electrically insulated by the insulator structure 15. ing. The high voltage introduction unit 13 also seals the outside (atmospheric pressure side) and the inside (vacuum side) of the vacuum vessel 11 with respect to vacuum. Further, as shown in FIG. 2, the high voltage introducing portion 13 may be surrounded by an insulating material such as alumina.

  The high voltage applying unit 14 is a power source for applying a negative high voltage to the cathode 12 through the high voltage introducing unit 13.

  Here, the flow of fusion reaction generation in the fusion neutron generator 10 will be briefly described. First, a high voltage applying means 14 applies a negative voltage between the vacuum vessel 11 that also serves as an anode and the cathode 12. The vacuum vessel 11 is grounded. A negative voltage between the cathode 12 and the vacuum vessel 11 serving also as an anode generates an electric field inward in the radial direction of the cylindrical vacuum vessel 11. By this electric field, glow discharge is generated between the vacuum vessel 11 serving also as the anode and the cathode 12, and fuel gas ions are generated. Ions generated in the space between the cathode 12 and the vacuum vessel 11 are accelerated toward the cathode 12. The accelerated ions pass through the gap between the basket-like cathodes 12 and are converged inside the cathode 12. A fusion reaction occurs due to collision between accelerated and converged ions, collision between ions and fuel gas, or the like. For example, when deuterium is used as the fuel gas, neutrons and protons are generated by the fusion reaction.

  The insulator structure 15 is made of an insulating material. The insulator structure 15 is provided on a surface where the vacuum vessel 11 and the high voltage introducing portion 13 intersect with each other, and constitutes at least a part of the inner surface of the vacuum vessel 11. The shape of the insulator structure 15 can be arbitrarily selected according to the shape of the vacuum vessel 11. For example, when the vacuum vessel 11 has a cylindrical shape, the insulator structure 15 has a columnar shape as shown in FIG. The insulator structure 15 may also serve as the flange of the vacuum vessel 11. Of course, it is also possible to use a combination of a flange of an arbitrary material and the insulator structure 15 separately.

  The position where the insulator structure 15 and the high voltage introducing portion 13 are in contact forms a triple junction with the vacuum atmosphere. The position where the insulator structure 15 and the vacuum vessel 11 serving as the anode come into contact also forms a triple junction with the vacuum atmosphere. In the following description, the triple point on the high voltage introduction portion 13 side formed at the junction between the insulator structure 15 and the high voltage introduction portion 13 is referred to as the cathode side triple point TJc, and the insulator structure 15 and the anode are referred to as the triple point TJc. The triple point at the junction with the vacuum vessel 11 that also serves as the anode side triple point TJa. In the example shown in FIG. 1, the cathode-side triple point TJc and the anode-side triple point TJa each have a circular shape centering on the cylinder axis of the vacuum vessel 11.

  On the inner surface side of the vacuum container 11 of the insulator structure 15, a shield 16 is provided so that the creeping distance between the cathode side triple point TJc and the anode side triple point TJa is longer than the spatial distance. . On the other hand, an arbitrary shape can be selected for the outer surface side of the vacuum vessel 11 of the insulator structure 15, that is, the surface on the atmospheric pressure side. The insulator structure 15 and the shield 16 may be formed of the same insulating material, for example, may be integrally formed, or may be formed of different insulating materials.

  Further, the insulator structure 15 having the shield 16 is perpendicular to a straight line (for example, a cylindrical shape) connecting the center of the high voltage introducing portion 13 and the vacuum vessel 11 so as to make the electric field distribution in the vacuum vessel 11 uniform. It is further provided on the inner surface of the vacuum vessel 11 facing the insulator structure 15 so as to be symmetric with the insulator structure 15 with respect to a plane passing through the center of the vacuum vessel 11 and perpendicular to the axis of the vacuum vessel 11. (See the lower side of FIG. 2).

  Next, an example of operation | movement of the fusion neutron generator 10 and the fusion neutron generation method which concern on this embodiment is demonstrated.

  Insulator creeping discharge in a vacuum is generated starting from electron emission from a conductor called a triple junction (triple junction), an insulator structure, and a three-part junction of vacuum. In triple junction, the electric field strength is high and electrons are field-emitted. The secondary electrons emitted from the triple junction collide with the surface of the insulator structure and generate secondary electrons. The secondary electrons cause a secondary electron avalanche on the surface of the insulator structure and cause creeping discharge (dielectric breakdown).

  FIG. 3 is a configuration diagram showing an example of a conventional fusion neutron generator 100. FIG. 4 is an explanatory diagram showing an example of the relationship between the insulation distance and the creeping discharge voltage.

  As shown in FIG. 4, it is known that the creeping discharge voltage increases as the insulation distance, that is, the creeping distance between the ground portion and the high voltage portion increases. For this reason, the conventional fusion neutron generator 100 increases the creepage distance between the high voltage introduction unit 103 for applying a voltage from the high voltage applying means 104 to the cathode 102 and the vacuum vessel 101 that also serves as the anode. An insulator structure 105 extending in the direction along the axial direction of the high voltage introducing portion 103 for the cathode 102 is provided in the high voltage introducing portion 103.

  However, if the insulator structure 105 is provided so as to increase the creeping distance and the insulation distance in the direction along the axial direction of the high-voltage introduction portion 103, the insulator structure 105 protrudes greatly from the vacuum vessel 101, and thus the fusion neutron The generator 100 will be enlarged.

  Therefore, the fusion neutron generator 10 according to the present embodiment is provided with the insulator structure 15 between the cathode 12 and the high voltage introduction unit 13 which are high potential portions and the vacuum vessel 11 which is a ground potential, A shield 16 is provided on the inner surface side of the vacuum vessel 11 of the insulator structure 15.

  FIG. 5 is an explanatory diagram illustrating an example of a state in which the insulator structure 15 and the shield 16 according to the first embodiment are viewed from the inside of the vacuum vessel 11. FIG. 5 shows an example in which the shield 16 is an annular pleat protruding from the inner surface of the vacuum vessel 11 so as to surround the cathode side triple point TJc. As shown in FIG. 5, the cathode-side triple point TJc and the anode-side triple point TJa each have a circular shape centering on the axis of the cylinder of the vacuum vessel 11.

  FIG. 6A is an explanatory view showing an example of a creeping distance 20 between the cathode side triple point TJc and the anode side triple point TJa when there is no conventional shield 16, and FIG. 6B shows the first embodiment. It is explanatory drawing which shows an example of the creeping distance 20 of the cathode side triple point TJc at the time of providing the shielding body 16 which concerns on, and the anode side triple point TJa.

  By providing a shield 16 on the inner surface side of the vacuum vessel 11 of the insulator structure 15 so that the creeping distance 20 between the cathode side triple point TJc and the anode side triple point TJa is longer than the spatial distance (see FIG. 6 (b)), the effective creepage distance 20 can be made longer compared to the case where the shield 16 is not provided (see FIG. 6 (a)), and the insulation voltage can be improved.

  Fig.7 (a) is explanatory drawing which shows the 1st modification of the shielding object 16 which concerns on 1st Embodiment, (b) is explanatory drawing which shows the 2nd modification of the shielding object 16 which concerns on 1st Embodiment. is there.

  The shield 16 according to the first embodiment may be provided so that the creeping distance 20 between the cathode side triple point TJc and the anode side triple point TJa is longer than the spatial distance. Insulator so as to surround a plurality of circular islands (see FIG. 7A), a circular groove, a plurality of elliptical islands (see FIG. 7B), an elliptical groove, or the cathode-side triple point TJc. Various shapes and arrangement positions such as an annular groove in which the inner surface of the structure 15 is recessed can be adopted.

  In the fusion neutron generator 10 according to the first embodiment, an insulator structure 15 is provided between a high-voltage introducing portion 13 and a vacuum vessel 11 that also serves as an anode, and the vacuum vessel 11 of the insulator structure 15 is provided. The shield 16 is provided on the inner surface side so that the creeping distance 20 between the cathode-side triple point TJc and the anode-side triple point TJa is longer than the spatial distance. For this reason, without providing the insulator structure 15 so as to increase the creeping distance and the insulation distance in the direction along the axial direction of the high-voltage introducing portion 13, the cathode-side triple point TJc and the anode-side triple point TJa are not provided. Creeping discharge can be suppressed. Therefore, according to the fusion neutron generator 10 according to the present embodiment, the insulator structure provided in the direction along the axial direction of the high voltage introducing portion 13 is eliminated, and the high voltage introducing portion 13 is reduced to, for example, about several cm. Creeping discharge between the anode and the high voltage introducing portion 13 can be suppressed while downsizing.

(Second Embodiment)
Next, a second embodiment of the fusion neutron generator and fusion neutron generation method according to the present invention will be described.

  FIG. 8 is a block diagram showing an example of a fusion neutron generator 10 according to the second embodiment of the present invention. Moreover, FIG. 9 is a block diagram which shows the other example of the fusion neutron generator 10 which concerns on 2nd Embodiment of this invention.

  The fusion neutron generator 10 according to the second embodiment is different from the fusion neutron generator 10 according to the first embodiment in that the electric field in the vicinity of a triple junction having a high electric field strength is relaxed. Since other configurations and operations are not substantially different from those of the fusion neutron generator 10 according to the first embodiment shown in FIG. 1, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 8, the fusion neutron generator 10 according to the second embodiment has a pleated shape, for example, at least one of the vicinity of the cathode-side triple point TJc and the vicinity of the anode-side triple point TJa. It is shielded by the shield 16. By arranging the shield 16 having a pleated shape so as to shield the triple point, the electric field strength at the triple point can be relaxed and the oozing of the electric lines of force from the cathode side triple point TJc can be suppressed. be able to.

  Further, as shown in FIG. 9, the fusion neutron generator 10 according to the second embodiment has an inner surface of the insulator structure 15 around the high-voltage introduction part 13 recessed to form an annular shape as the shield 16. By providing this groove 31, the cathode-side triple point TJc may be included in the annular groove 31. In this case, the cathode side triple point TJc is shielded by the annular groove 31. An arbitrary value can be selected for the depth of the recess.

  The annular groove 31 can also shield the cathode-side triple point TJc, reduce the electric field intensity at the cathode-side triple point TJc, and suppress the seepage of electric field lines from the cathode-side triple point TJc. can do.

  FIG. 10 is a configuration diagram showing a modification of the fusion neutron generator 10 according to the second embodiment of the present invention.

  As shown in FIG. 10, the conductive material has an outer diameter L1 that surrounds the high-voltage introducing portion 13, has one end in contact with the cathode 12 and the other end in contact with the insulator structure 15, and is smaller than the outer diameter L2 of the cathode 12. A material 32 may be provided. This conductive material 32 functions as the pseudo cathode 12 and can reduce the electric field strength of the cathode side triple point TJc.

  The shield 16 according to the first embodiment such as the pleated shield 16 shown in FIG. 5, the shield 16 shown in FIGS. 7A and 7B, and the pleated shield 16 near the triple point. The groove 31 and the conductive material 32 can be used in appropriate combination.

  The fusion neutron generator 10 according to the second embodiment has the same effects as the fusion neutron generator 10 according to the first embodiment. In addition, the fusion neutron generator 10 according to the second embodiment can suppress the emission of electrons from the triple point that triggers the creeping discharge by relaxing the electric field strength at the triple point. Further, by suppressing the oozing of the lines of electric force from the cathode side triple point TJc, it is possible to suppress the occurrence of local air discharge between the ground portion and the high voltage portion. For this reason, according to the fusion neutron generator 10 which concerns on 2nd Embodiment, the creeping discharge in the inside of the vacuum vessel 11 and local air discharge generation | occurrence | production can be suppressed.

(Third embodiment)
Next, a third embodiment of the fusion neutron generation apparatus and fusion neutron generation method according to the present invention will be described.

  FIG. 11 is a configuration diagram showing an example of a fusion neutron generator 10 according to the third embodiment of the present invention.

  The fusion neutron generator 10 according to the third embodiment is the second embodiment in that the pleated surface is inclined so as to reduce secondary electron amplification along the pleated surface of the insulator structure 15. This is different from the fusion neutron generator 10 according to FIG. Since other configurations and operations are not substantially different from those of the fusion neutron generator 10 according to the second embodiment shown in FIG. 8-10, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 11, in the fusion neutron generator 10 according to the third embodiment, the creeping surface on the side facing the cathode triple point TJc of the pleated shield 16 is, for example, a vacuum vessel in the example shown in FIG. The angle θ with respect to a plane parallel to the axis of 11 cylinders has an inclination of −90 degrees or more and 45 degrees or less. Here, the angle θ is the lower side of FIG. 11 along the surface of the pleated shield 16 facing the cathode side triple point TJc from the surface perpendicular to the inner surface of the vacuum vessel 11 formed by the insulator structure 15. The direction in which the (center side of the vacuum vessel 11) approaches the anode side triple point TJa is defined as a positive direction.

  FIG. 12 is an explanatory diagram illustrating an example of how the secondary electron avalanche generated on the creeping surface is suppressed due to the inclination of the shield 16 according to the third embodiment. As shown in FIG. 12, the angle θ formed by the creeping surface of the pleated shield 16 and the insulator structure 15 is set to 45 ° or less so that the shield 16 has electrons generated from the cathode triple point TJc. It is possible to suppress the progress of secondary electron avalanches generated along the surface of the insulator structure 15.

  FIG. 13A is an explanatory view showing a modified example of the shielding object 16 according to the third embodiment, and FIG. 13B obtains the inclination angle θ of the shielding object 16 according to the third embodiment from the contact angle φ. It is explanatory drawing which shows an example. As shown in FIG. 13A, the shape of the creeping surface on the side facing the cathode-side triple point TJc of the shield 16 according to the third embodiment may be a concave shape. Further, as shown in FIG. 13B, when the creeping surface is not planar, an angle obtained by subtracting the contact angle φ of the shield 16 on the cathode side triple point TJc side from 90 degrees may be θ.

  The shield 16 according to the first embodiment, the pleated shield 16 near the triple point according to the second embodiment, the groove 31, the conductive material 32, and the inclined shield 16 according to the third embodiment. Can be used in appropriate combinations.

  The fusion neutron generator 10 according to the third embodiment has the same effects as the fusion neutron generator 10 according to the first embodiment. Further, the fusion neutron generator 10 according to the third embodiment can use the pleated shield 16, the groove 31, the conductive material 32 or a combination thereof near the triple point according to the second embodiment, In this case, the same effects as the fusion neutron generator 10 according to the second embodiment are obtained.

  Further, the fusion neutron generator 10 according to the third embodiment tilts the creeping side of the pleated shield 16 on the cathode side triple point TJc side, so that the shield 16 has electrons generated from the cathode side triple point TJc. Can be stopped, and the progress of secondary electron avalanches occurring along the creeping surface of the insulator structure 15 can be suppressed.

(Fourth embodiment)
Next, a fourth embodiment of a fusion neutron generator and a fusion neutron generation method according to the present invention will be described.

  FIG. 14 is a configuration diagram showing an example of a fusion neutron generator 10 according to the fourth embodiment of the present invention.

  The fusion neutron generator 10 according to the fourth embodiment is illustrated in that a charged particle collecting conductor 41 is provided on the insulator structure 15 in order to suppress charge-up of the surface of the insulator structure 15. 11 differs from the fusion neutron generator 10 according to the third embodiment shown in FIG. Since other configurations and operations are not substantially different from those of the fusion neutron generator 10 according to the third embodiment shown in FIG. 11, the same components are denoted by the same reference numerals and description thereof is omitted.

  As the charged particle collection conductor 41, for example, a conductive metal such as titanium or tantalum can be used. Note that the shape of the charged particle collection conductor 41 can be an arbitrary shape corresponding to the shape of the shielding object 16 or the vacuum vessel 11 such as a spherical shape or a ring shape. In the present embodiment, as shown in FIG. 14, the fusion neutron generator 10 according to the third embodiment is charged on a creeping surface of the pleated shield 16 facing the cathode-side triple point TJc. A particle collecting conductor 41 is provided. As the pleated shield 16 is provided so as to surround the cathode side triple point TJc, the charged particle collection conductor 41 has a cylindrical shape surrounding the cathode side triple point TJc.

  The inner side surface of the cylindrical charged particle collection conductor 41 faces the cathode side triple point TJc, and the conductor is exposed. On the other hand, the outer surface of the cylindrical charged particle collecting conductor 41 faces the cathode side triple point TJc, and is embedded and fixed in the creeping surface of the pleated shield 16 of the insulator structure 15. It is arranged so that the surface is not exposed. Any number of cylindrical charged particle collection conductors 41 can be arranged according to the number of pleated shields 16 of the insulator structure 15. The charged particle collection conductors 41 are electrically insulated from each other, and are also electrically insulated from the anode and the cathode 12.

  The insulator structure 15 has its surface charged up when electrons generated at the triple point flow in, flow out due to secondary electron generation, or flow in from plasma generated in the vacuum vessel 11. End up. If the surface of the insulator structure 15 is charged up, the creeping discharge generation voltage is lowered.

  In the fusion neutron generator 10 according to the fourth embodiment, by providing the charged particle collecting conductor 41, the movement of electrons along the surface of the shield 16 is facilitated, and the charge-up of the surface of the insulator structure 15 is suppressed. can do. In the fusion neutron generator 10 according to the fourth embodiment, the conductor surface of the charged particle collection conductor 41 is disposed only on the side facing the cathode side triple point TJc, and the conductor is disposed on the side facing the anode side triple point TJa. Do not place faces. For this reason, the electrons flowing from the cathode side triple point TJc can be collected by the charged particle collection conductor 41, and the electron amplification to the anode side triple point TJa can be suppressed. Further, by not providing a conductor surface at the anode side triple point TJa, secondary electron avalanche amplification generated when ions generated in the vacuum vessel 11 collide with the charged particle collecting conductor 41 or the insulator structure 15 is prevented. Can be reduced.

  Therefore, according to the fusion neutron generator 10 according to the fourth embodiment, it is possible to facilitate the movement of electrons along the creeping surface of the insulator structure 15 and suppress the charge-up. Generation of air discharge can be reduced.

  Further, the fusion neutron generator 10 according to the fourth embodiment includes a shield 16 according to the first embodiment, a pleated shield 16 near the triple point according to the second embodiment, a groove 31, and a conductive material. 32 and the inclined shielding object 16 according to the third embodiment can be used in appropriate combination, and the same effects as the fusion neutron generator 10 according to the first to third embodiments can be obtained.

(Fifth embodiment)
Next, a fifth embodiment of the fusion neutron generator and fusion neutron generation method according to the present invention will be described.

  FIG. 15: is a block diagram which shows an example of the fusion neutron generator 10 which concerns on 5th Embodiment of this invention.

  The fusion neutron generator 10 according to the fifth embodiment includes a charge escaping means 42 that removes the electric charge of the charged particle collection conductor 41 to the outside of the vacuum vessel 11 in that the fusion neutron according to the fourth embodiment shown in FIG. Different from the generator 10. Since other configurations and operations are not substantially different from those of the fusion neutron generator 10 according to the fourth embodiment shown in FIG. 14, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 15, the fusion neutron generator 10 according to the fifth embodiment includes a charge release means 42 that releases the charge of the charged particle collection conductor 41 to the outside of the vacuum vessel 11.

  FIG. 16A is an explanatory view showing a first example of the charge releasing means 42 according to the fifth embodiment, FIG. 16B is an explanatory view showing a second example of the charge releasing means 42, and FIG. It is explanatory drawing which shows the 3rd example of the electric charge escape means.

  The charge release means 42 may be provided independently for each of the charged particle collection conductors 41 by combining the power sources V1-V3 and the resistors R1-R3 (see FIG. 16A). Further, the charge release means 42 may be constituted by a resistor and electrically connect the charged particle collection conductors 41 via the resistance (see FIG. 16B), or may be connected between the charged particle collection conductors 41, etc. You may connect to an electric potential (refer FIG.16 (c)). As described above, any means such as a resistor or a high voltage power supply can be selected as the charge release means 42. For example, using a high voltage power supply, voltage is applied to a plurality of resistors, and the divided particles are collected. A voltage may be applied to.

  Further, the charge release means 42 has a potential applied to the charged particle collection conductor 41 so as to generate an equal electric field between the charged particle collection conductors 41 when there are a plurality of charged particle collection conductors 41 and between the cathode 12 and the vacuum vessel 11. It is good to adjust.

  For example, in this embodiment, since the cathode 12 is a negative potential and the vacuum vessel 11 is a ground potential, a negative potential having a smaller absolute value than the potential applied to the cathode 12 may be applied to each charged particle collection conductor 41. In this case, the direction of the generated electric field is the direction from the vacuum vessel 11 toward the cathode 12.

  In the charged particle collection conductor 41 according to the fourth embodiment, the potential becomes a floating potential, and cannot be set to an arbitrary value. For this reason, a local electric field may be generated between the charged particle collection conductors 41 and between the cathode 12 and the vacuum vessel 11. When a local electric field is generated, an electronic avalanche occurs, which may cause creeping discharge and local air discharge.

  On the other hand, the fusion neutron generator 10 according to the fifth embodiment can set the potential of each charged particle collection conductor 41 to an arbitrary value using the charge release means 42. For this reason, local electric field generation can be suppressed, and an equal electric field can be generated between the charged particle collection conductors 41, and between the cathode 12 and the vacuum vessel 11. Therefore, according to the fusion neutron generator 10 according to the fifth embodiment, the generation of a local electric field can be suppressed, and the creeping discharge and the local air discharge due to the occurrence of an electron avalanche can be reduced. .

  Further, the fusion neutron generator 10 according to the fifth embodiment includes a shield 16 according to the first embodiment, a pleated shield 16 near the triple point according to the second embodiment, a groove 31, and a conductive material. 32 and the inclined shielding object 16 according to the third embodiment can be used in appropriate combination, and the same operational effects as the fusion neutron generator 10 according to the first to fourth embodiments can be obtained.

(Sixth embodiment)
Next, a sixth embodiment of the fusion neutron generator and fusion neutron generation method according to the present invention will be described.

  FIG. 17: is a block diagram which shows an example of the fusion neutron generator 10 which concerns on 6th Embodiment of this invention.

  The fusion neutron generator 10 according to the sixth embodiment is provided with an insulating material 51 that covers the high-voltage introduction part 13 outside the vacuum vessel 11, and the fusion neutron generator 10 according to the fifth embodiment shown in FIG. And different. Since other configurations and operations are not substantially different from those of the fusion neutron generator 10 according to the fifth embodiment shown in FIG. 15, the same components are denoted by the same reference numerals and description thereof is omitted.

  The fusion neutron generator 10 according to the sixth embodiment includes a portion exposed to the outside of the vacuum vessel 11 in the high voltage introduction unit 13 and a high voltage introduction unit, as shown by a circle A surrounded by a broken line in FIG. 13 and the high voltage applying means 14 and the insulating material 51.

  In the example shown in FIG. 17, the joint portion between the high voltage introducing portion 13 and the high voltage applying means 14 indicates a connection portion between the cable 14 a and the metal terminal as the high voltage introducing portion 13. As the insulating substance 51, for example, an arbitrary material such as ceramic such as alumina, insulating oil, or insulating resin can be used. The insulating material 51 preferably has an appropriate thickness so that the material selected for the applied voltage does not cause solid breakdown. For example, when the high potential portion is molded using an insulating resin as the insulating material 51 and the applied voltage is minus 100 kV, the insulating material 51 may have a thickness of about several centimeters. Little impact on miniaturization.

  The fusion neutron generator 10 according to the sixth embodiment can be appropriately combined with the fusion neutron generator 10 according to the first to fifth embodiments, and the fusion neutron generator according to the first to fifth embodiments. 10 has the same effect.

  Moreover, the fusion neutron generator 10 according to the sixth embodiment can cover the high potential portion outside the vacuum vessel 11 with the insulating material 51 so that the high potential portion is not exposed. For this reason, it is possible to prevent the occurrence of atmospheric pressure creeping discharge or discharge during the period between the high potential portion and the outer surface of the vacuum vessel 11. The fusion neutron generator 10 according to the sixth embodiment only needs to perform an insulation design considering only the dielectric breakdown voltage of the insulating material 51, and has an insulation structure for preventing creeping discharge and air discharge, which are conventionally required. It becomes unnecessary. For this reason, the size of the high voltage introduction part 13 on the atmospheric pressure side can be reduced.

  According to at least one embodiment described above, the insulator structure 15 is provided between the high voltage introducing portion 13 and the vacuum container 11 serving also as an anode, and the inside of the vacuum container 11 of the insulator structure 15 On the side surface side, the shield 16 is provided such that the creeping distance 20 between the cathode side triple point TJc and the anode side triple point TJa is longer than the spatial distance. For this reason, without providing the insulator structure 15 so as to increase the creeping distance and the insulation distance in the direction along the axial direction of the high-voltage introducing portion 13, the cathode-side triple point TJc and the anode-side triple point TJa are not provided. Creeping discharge can be suppressed. Therefore, it is possible to suppress creeping discharge between the anode and the high voltage introduction part 13 while eliminating the insulator structure provided in the direction along the axial direction of the high voltage introduction part 13 and reducing the size of the high voltage introduction part 13. it can.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, although the example in the case where the vacuum vessel 11 has a cylindrical shape is shown in the above description, the shape of the vacuum vessel 11 is not limited to this.

  FIG. 18A is an explanatory view showing an example when the shape of the vacuum vessel 11 is a truncated cone, FIG. 18B is an explanatory view showing an example when it is a hexagonal truncated cone, and FIG. It is explanatory drawing which shows an example in the case of the cone which makes the voltage introduction part 13 side the bottom.

  The insulator structure 15 may be provided on the surface where the vacuum vessel 11 and the high-voltage introducing portion 13 intersect and constitute at least a part of the inner surface of the vacuum vessel 11. Further, for example, the pleated shield 16 has an inner surface of the vacuum vessel 11 of the insulator structure 15 such that the creeping distance 20 between the cathode side triple point TJc and the anode side triple point TJa is longer than the spatial distance. What is necessary is just to be provided in the side. As long as this is the case, the vacuum vessel 11 can take various shapes (see, for example, FIGS. 18A to 18C).

  Further, even when the shape of the vacuum vessel 11 is a cylinder as described above, the insulator structure 15 is not limited to a plane as described above, and the inside of the vacuum vessel 11 formed by the insulator structure 15 is not limited. The side surface may be a curved surface (see FIG. 18D).

  The vacuum vessel 11 may be spherical. When the vacuum vessel 11 is spherical, the shape of the cathode 12 is also preferably spherical. Also in this case, the insulator structure 15 may be provided on the surface where the vacuum vessel 11 and the high voltage introducing portion 13 intersect, and at least part of the inner surface of the vacuum vessel 11 may be configured (FIG. 18E). reference). Further, even if the side surface of the vacuum vessel 11 is constituted by the insulator structure 15 and the insulator structure 15 serves as both the surface where the vacuum vessel 11 and the high voltage introducing portion 13 intersect and the side surface of the vacuum vessel 11. Good (see FIG. 18 (f)).

  DESCRIPTION OF SYMBOLS 10 ... Fusion neutron generator, 11 ... Vacuum container, 12 ... Cathode, 13 ... High voltage introduction part, 14 ... High voltage application means, 15 ... Insulator structure, 16 ... Shielding object, 20 ... Creeping distance, 31 ... Groove, 41 ... conductor, 41 ... charged particle collection conductor, 42 ... means, 51 ... insulating material, TJa ... anode side triple point, TJc ... cathode side triple point.

Claims (12)

A fusion neutron generator that accelerates ionized fuel gas to cause a fusion reaction,
A vacuum vessel having an anode and maintained at a pressure lower than atmospheric pressure;
A cathode electrically insulated from the vacuum vessel and provided inside the vacuum vessel;
A negative potential is applied to the cathode by applying power supplied from voltage applying means to the cathode so as to accelerate the ionized fuel gas by an electric field between the anode and the cathode, which is electrically insulated from the vacuum vessel. A high voltage introduction part to be generated;
An insulator structure constituting at least a part of the inner surface of the vacuum vessel, wherein a creeping distance between the triple point on the high voltage introduction portion side and the triple point on the anode side is longer than a spatial distance. An insulator structure having a shield provided on the inner surface side of the vacuum vessel,
Fusion neutron generator equipped with. The insulator structure is
The shield has at least one annular pleat projecting from the inner surface of the vacuum vessel formed by the insulator structure so as to surround the triple point on the high voltage introduction part side,
The fusion neutron generator according to claim 1. At least one of the pleats is
The creeping surface on the side opposite to the triple point on the high voltage introduction part side is a surface perpendicular to the inner surface of the vacuum vessel formed by the insulator structure, and the triple point on the anode side is the center side of the creeping vacuum vessel With a direction approaching to a plus, with a slope of minus 90 degrees or more plus 45 degrees or less from a plane perpendicular to the inner surface of the vacuum vessel,
The fusion neutron generator according to claim 2. At least one of the pleats is
Having a charged particle collection conductor for collecting charged particles;
The fusion neutron generator according to claim 2 or 3. The charged particle collection conductor is:
The annular pleat is fixed to a creeping surface on the side facing the triple point on the high voltage introduction part side, and has a cylindrical shape surrounding the triple point on the high voltage introduction part side,
The fusion neutron generator according to claim 4. Charge escape means for removing the charge collected by the charged particle collection conductor to the outside;
The fusion neutron generator according to claim 4 or 5, further comprising: The charge releasing means is
Adjusting the potential applied to the charged particle collection conductor so that the electric field between the cathode, the charged particle collection conductor and the vacuum vessel is a uniform electric field;
The fusion neutron generator according to claim 6. The insulator structure is
The shield has at least one annular groove in which the inner surface of the vacuum vessel formed by the insulator structure is recessed so as to surround a triple point on the high voltage introduction part side,
The fusion neutron generator according to any one of claims 1 to 7. At least one of the grooves is
Provided to enclose the triple point on the high voltage introduction part side,
The fusion neutron generator according to claim 8. An insulating material that covers a portion of the high voltage introduction portion exposed to the outside of the vacuum vessel, and a junction between the high voltage introduction portion and the voltage application means;
The fusion neutron generator according to any one of claims 1 to 9 , further comprising: The vacuum formed by the insulator structure so as to be symmetrical to the insulator structure with respect to a plane perpendicular to a straight line connecting the high-voltage introduction portion and the center of the vacuum vessel and passing through the center of the vacuum vessel. The insulator structure having the shield on the inner surface of the vacuum container facing a part of the inner surface of the container;
The fusion neutron generator according to any one of claims 1 to 10 , further comprising: A vacuum vessel that has an anode and is maintained at a pressure lower than atmospheric pressure; a cathode provided inside the vacuum vessel; and an electrically insulated and ionized fuel gas that is electrically insulated from the vacuum vessel. A high voltage introduction section for generating a negative potential at the cathode by applying electric power supplied from a voltage application means to the cathode so as to accelerate the electric field between the anode and the cathode, and accelerate the ionized fuel gas A fusion neutron generation method of a fusion neutron generator for causing a fusion reaction,
Providing an insulator structure to constitute at least part of the inner surface of the vacuum vessel;
Providing a shield on the inner surface side of the vacuum vessel so that the creepage distance between the triple point on the high voltage introduction portion side and the triple point on the anode side is longer than the spatial distance;
A method for generating fusion neutrons.

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