Closed system neutron generator tube

Claim 2

A neutron generator comprising, in combination: a. a closed vacuum housing for maintaining a discharge gas of at least one Of the heavy hydrogen isotopes under a low pressure; b. ion generating means including a hollow cylindrical anode electrode enclosing a discharge space and a planar cathode electrode arranged at one of the open frontal faces of said anode electrode completely covering said frontal face of said anode electrode so as to limit said discharge space in the axial direction and the other frontal face of said anode electrode remaining completely open so as to form an emission opening; c. a first magnetic pole surface of a first polarity disposed in parallel with and at a small distance from the side of said cathode electrode facing away from said discharge space, said first magnetic pole surface covering the cross-sectional area of said anode electrode and being connected therewith, a second annular magnetic pole surface of a second polarity arranged at the edge of said emission opening of said anode electrode, both of said magnetic pole surfaces being connected by said anode electrode; d. magnetic field means for establishing a magnetic field emanating from said first magnetic pole surface and substantially laterally penetrating said cathode electrode and passing through said discharge space in the direction of the axis of said anode electrode substantially parallel to said anode electrode and being increasingly laterally deflected in the vicinity of said emission opening in the direction toward said second annular magnetic pole surface arranged at the edge of said anode electrode and ending at said second annular magnetic pole surface, said magnetic field means including a current carrying magnetic coil for generating said magnetic field passing through said discharge space, said magnetic coil surrounding the outer surface of said anode electrode, and a magnetic yoke surrounding the outer surface of said magnetic coil and connecting said magnetic pole surfaces together; e. an acceleration electrode disposed at a short distance from the edge of said emission opening and said second annular magnetic pole surface, said acceleration electrode having an opening corresponding in its width to said emission opening and covering the same and being laterally widened in its portion facing away from said emission opening; f. a target electrode arranged at the side of said acceleration electrode facing away from said emission opening, said target electrode being connected with said acceleration electrode and having a lateral cross section corresponding to the cross section of an impinging ion stream, said target electrode being provided at its surface facing said ion generating means with an active target layer which contains at least one of the heavy hydrogen isotopes in absorbed form; g. a current source connected with said magnetic coil, a first high voltage source connected with said cathode electrode and a second high voltage source operatively connected with both said acceleration electrode and said target electrode, the established acceleration potential which is negative with respect to the potential of said anode electrode being substantially higher than the high voltage potential of said cathode electrode which is negative with respect to said anode electrode so that a high voltage low pressure discharge is maintained in said discharge space with the aid of said magnetic field for producing positive ions of the discharge gas which leave said discharge space through said emission opening and are accelerated toward said target electrode by the electric field maintained between said emission opening and said acceleration electrode, thereby causing neutrons to be released from the heavy hydrogen isotopes absorbed in said target layer on said target electrode; and h. gas pressure control means for storing said discharge gas and for supplying said discharge gas containing at least one of the heavy isotopes of hydrogen to said discharge space so as to regulate the gas pressure within said housing and to replenish the spent gas.

Claim 3

A neutron generator as defined in claim 1 wherein said anode electrode, said magnetic pole surfaces connected therewith, and portions of said magnetic yoke constitute the covering of said closed vacuum housing.

Claim 4

A neutron generator comprising, in combination: a. a closed vacuum housing for maintaining a discharge gas containing at least one of the heavy hydrogen isotopes under a low pressure; b. an annular ion generating means including two annular disc-shaped anode electrodes arranged around a common axis and enclosing a discharge chamber and a coaxial annular cathode electrode arranged between said annular anodes so as to surround the outer periphery of said discharge chamber and said discharge chamber having an inner periphery opening towards the axis at a distance therefrom so as to form an annular emission opening, the distance of said emission opening from the axis corresponding to the spacing of said annular anodes from the axis; c. a first annular magnetic pole surface of a first polarity arranged at the outer periphery of said ion generating means at a slight axial distance from the side of said cathode electrode facing away from said discharge chamber, said first magnetic pole surface being connected with both said anode electrodes, the axial width of said first magnetic pole surface corresponding to the spacing between said anode electrodes, and two second annular magnetic pole surfaces of a second polarity arranged at the inner periphery of said ion generating means and connected with said anode electrodes at the edge of said emission opening, the axial spacing between said second magnetic pole surfaces corresponding to the axial spacing between said anode electrode; d. magnetic field means for establishing a magnetic field emanating from said first magnetic annular pole surface passing through said cathode electrode, flowing through said annular discharge chamber radially from the outside toward the inside in parallel with said anode electrodes and axially deflected in the area of said emission opening in the direction toward said two second magnetic pole surfaces and toward the inner edges of said anode electrodes, said magnetic field means including two current conducting magnetic coils for generating said magnetic field radially flowing through said annular discharge chamber, said coils being disposed outside of said anode electrodes on the sides facing away from said annular discharge chamber and conduct currents of the same magnitude but directed in opposite directions and two magnetic yokes each enclosing one of said magnetic coils from the outside and connecting said first magnetic pole surface at the outer periphery of said ion generating means with a respective one of said two second magnetic pole surfaces at the edge of said emission opening; e. two cup-shaped acceleration electrodes coaxially arranged around the axis of said ion generating means in the vicinity of the edges of said emission opening, the axial distance between said acceleration electrodes in the area adjacent to said emission opening corresponding to the width of said emission opening and the space between said acceleration electrodes forming an annular acceleration opening having an axial distance increasing with decreasing radius from the axis; f. a target electrode having a substantially tubular form and being coaxially arranged about the axis of said ion generating means, said target electrode being disposed between said acceleration electrodes and connected therewith, the axial length of said target electrode corresponding to the axial width of a radially impinging ion stream and said target electrode being provided with an active target layer at the surface facing said ion generating means, said target layer containing in absorbed form at least one of the heavy hydrogen isotopes; g. a current source connected with said two magnetic coils, a first voltage source connected with said cathode electrode and a second high voltage source operatively connected with both said acceleration electrodes and said target electrode, the potential of said acceleration electrodes which is negative with respect to the potential of said anode electrodes being substantially higher than the high voltage potential of said cathode electrode which is negative with respect to the potential of said anode electrodes, so that a high voltage low pressure discharge is maintained within said annular discharge chamber with the aid of said magnetic field for producing positive ions of the discharge gas which leave said annular discharge chamber through said emission opening and are radially inwardly accelerated toward said tubular target electrode by the electric field maintained between said emission opening and said acceleration electrodes so as to cause neutrons to be released from the heavy hydrogen isotopes absorbed by said target layer; and h. a gas pressure control means for storing said discharge gas and for supplying said discharge gas containing at least one of the heavy isotopes of hydrogen to said discharge chamber so as to regulate the gas pressure within said housing and to replenish the spent gas.

Claim 5

A neutron generator comprising, in combination: a. a closed vacuum housing for maintaining a discharge gas containing at least one of the heavy hydrogen isotopes under a low pressure; b. an annular ion generating means including two annular disc-shaped anode electrodes arranged around a common axis and enclosing a discharge chamber and a coaxial annular cathode electrode arranged between said annular anodes so as to surround the outer periphery of said discharge chamber and said discharge chamber having an inner periphery opening towards the axis at a distance therefrom so as to form an annular emission opening, the distance of said emission opening from the axis corresponding to the spacing of said annular anodes from the axis; c. a first annular magnetic pole surface of a first polarity arranged at the outer periphery of said ion generating means at a slight axial distance from the side of said cathode electrode facing away from said discharge chamber, said first magnetic pole surface being connected with both said anode electrodes, the axial width of said first magnetic pole surface corresponding to the spacing between said anode electrodes, and two second annular magnetic pole surfaces of a second polarity arranged at the inner periphery of said ion generating means and connected with said anode electrodes at the edge of said emission opening, the axial spacing between said second magnetic pole surfaces corresponding to the axial spacing between said anode electrode; d. magnetic field means for establishing a magnetic field emanating from said first magnetic annular pole surface passing through said cathode electrode, flowing through said annular discharge chamber radially from the outside toward the inside in parallel with said anode electrodes and axially deflected in the area of said emission opening in the direction toward said two second magnetic pole surfaces and toward the inner edges of said anode electrodes, said magnetic field means including two current conducting magnetic coils for generating said magnetic field radially flowing through said annular discharge chamber, said coils being disposed outside of said anode electrodes on the sides facing away from said annular discharge chamber and conduct currents of the same magnitude but directed in opposite directions and two magnetic yokes each enclosing one of said magnetic coils from the outside and connecting said first magnetic pole surface at the outer periphery of said ion generating means with a respective one of said two second magnetic pole surfaces at the edge of said emission opening; e. two cup-shaped acceleration electrodes coaxially arranged around the axis of said ion generating means in the vicinity of the edges of said emission opening, the axial distance between said acceleration electrodes in the area adjacent to said emission opening corresponding to the width of said emission opening and the space between said acceleration electrodes forming an annular acceleration opening having an axial distance increasing with decreasing radius from the axis; f. a target electrode having a substantially tubular form and being coaxially arranged about the axis of said ion generating means, said target electrode being disposed between said acceleration electrodes and connected therewith, the axial length of said target electrode corresponding to the axial width of a radially impinging ion stream and said target electrode being provided with an active target layer at the surface facing said ion generating means, said target layer containing in absorbed form at least one of the heavy hydrogen isotopes; g. a current source connected with said two magnetic coils, a first voltage source connected with said cathode electrode and a second high voltage source operatively connected with both said acceleration electrodes and said target electrode, the potential of said acceleration electrodes which is negative with respect to the potential of said anode electrodes being substantially higher than the high voltage potential of said cathode electrode which is negative with respect to the potential of said anode electrodes, so that a high voltage low pressure discharge is maintained within said annular discharge chamber with the aid of said magnetic field for producing positive ions of the discharge gas which leave said annular discharge chamber through said emission opening and are radially inwardly accelerated toward said tubular target electrode by the electric field maintained between said emission opening and said acceleration electrodes so as to cause neutrons to be released from the heavy hydrogen isotopes absorbed by said target layer; and h. a gas pressure control means for storing said discharge gas and for supplying said discharge gas containing at least one of the heavy isotopes of hydrogen to said discharge chamber so as to regulate the gas pressure within said housing and to replenish the spent gas.

Claim 6

A neutron generator as defined in claim 3 wherein said anode electrode, said magnetic pole surfaces connected therewith, and portions of said magnetic yoke constitute the covering of said closed vacuum housing.

Claim 7

Neutron generator as defined in claim 3, further comprising cooling channels for the passage of a coolant.

Claim 8

Neutron generator as defined in claim 3, wherein said magnet coils are enclosed in a watertight shell of corrosion resistant material and are enclosed by said magnet yoke and said anode electrodes so as to form a cooling channel for the passage of a coolant for cooling the coils on the vacuum housing.

Claim 9

Neutron generator as defined in claim 3, wherein said cathode electrode is a ring of metal tubes whose windings are welded or soldered to each other.

Claim 10

Neutron generator as defined in claim 3, wherein said target electrode is a metal tube supporting structure with a metal tube wound upon said support tube in a bifilar arrangement in the region of the ion current providing a coolant conduit for transfer of a coolant, the windings of said coolant conduit being welded to each other.

Claim 11

Neutron generator as defined in claim 3, further comprising a guide tube for guiding an irradiation specimen into the area of said target electrode and being connected with a rabbit system, said guide tube being installed coaxially with the axis of said ion generating means and equipped with penetrations at this end.

Claim 12

Neutron generator as defined in claim 3, further comprising a high voltage insulator connected to one side of said ion generating means in the axial direction so as that it is vacuum tight and a support tube passing through the center of said annular ion generating means and said insulator and being attached to its outer front so as to be vacuum tight, and said support tube being extended beyond the point of connection with said insulator and provided with a connection device for the introduction of gas into an internal annular channel.

Claim 13

Neutron generator as defined in claim 3, further comprising a guide tube for carrying an irradiation sample into the center of said target electrode and two insulators for attaching said guide tube so as to be vacuum tight on both sides of said target electrode in the axial direction.

Claim 14

Neutron generator as defined in claim 3, further comprising a capsule for accommodation of a sample to be irradiated with neutrons, a guide tube for supplying said capsule to the area of said target electrode, means for dispensing said capsule into said guide tube, positioning means for fixing said capsule in a part of said guide tube enclosed by said target electrode for a predetermined period of time for irradiation with neutrons.

Claim 15

Neutron generator as defined in claim 3, wherein said tubular target electrode is closed on one end and is designed as a slightly conical frustrUm at its closed end and which conical frustrum is part of a cone whose tip is outside said vacuum housing.

Claim 16

Neutron generator as defined in claim 3, further comprising collimation means for collimating the neutrons flux emitted from said target layer connected to said vacuum housing on the side provided for the emission of neutrons.

Claim 17

Neutron generator as defined in claim 14, wherein said collimation means consist essentially of a collimation cone of a conical frustrum constituted by said target electrode, and a block with a conical or cylindrical bore therein forming a collimation channel, and said collimation cone extends into the inlet section of said collimation channel.