RU2703449C1 - Neutron emitter unit - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the neutron emitter unit. Device contains the following elements in a metal sealed housing filled with a liquid dielectric: neutron tube, accelerating voltage generation circuit including multiplication circuit with high-voltage transformer at input, temperature compensator. All elements are made in form of rotation bodies, and multilayer insulation is arranged between high-voltage structural elements and housing of neutron radiator unit. Electrical circuit of voltage multiplication is placed on insulating flexible tape and is located along helical line around hollow cylinder with metal bottom, made of ceramic material with high electric resistance, equal to resistance of voltage divider, connected between metal bottom and housing of unit. Inside hollow cylinder neutron tube is coaxially located, target of which is connected to output of multiplication circuit and metal bottom, and between the housing end and the metal bottom there is a heat conducting insulator with annular grooves, having thermal contact with the housing. Parts of layers of interlayer insulation are bent into grooves of heat-conducting insulator. Temperature compensator includes a rubber U-shaped collar arranged in the compensator housing and dividing the compensator into two cavities, one of which is connected to the liquid dielectric, and the other one is filled with gas under pressure.

EFFECT: improving reliability, reducing labor intensity of manufacturing, reducing dimensions and weight of a neutron generator.

1 cl, 1 dwg

Description

The invention relates to the field of physical instrumentation, in particular to sources of neutron radiation, and is intended for use in the development of neutron and x-ray generators.

Known borehole pulsed neutron generator containing a vacuum neutron tube and a power circuit of a vacuum neutron tube, consisting of two high-voltage transformers, a storage capacitor, an accelerating pulse formation circuit, a capacitor of a neutron tube power source and a charging choke, placed in a sealed enclosure in which all elements The power circuit of the vacuum neutron tube is made in the form of bodies of revolution with central holes, interconnected th mechanically and electrically by means of electrical contacts with the threaded central holes, and the vacuum neutron tube - through the threaded cup-like sleeve with central and lateral holes are installed on the target and the anode by vacuum neutron tube. Patent of the Russian Federation No. 2368024, IPC G21G 4/02, 09/20/2009.

A disadvantage of the known generator is the sequential and coaxial arrangement of the neutron tube and its power circuit, which significantly increases the block size (length). The connection of all elements of the power circuit of the neutron tube using threaded electrical contacts welded to the target and anode electrodes of the neutron tube requires additional time in the assembly and disassembly of the neutron generator.

In the known generator, the temperature compensator is made on a metal bellows, which serves to compensate for the variable volume of the liquid dielectric when the temperature changes. To ensure thermal compensation in a wide range of operating temperatures, the length of the bellows varies widely and reaches the third part of the length of the entire generator, which leads to a significant increase in the dimensions and mass of the generator.

A known block of a neutron emitter containing a neutron tube, a power circuit of a neutron tube with a high-voltage transformer at the input, and all elements are made in the form of bodies of revolution, the power circuit consists of a voltage multiplier made in cascade, each cascade is a separate module connected in series with each other and connected to a neutron tube, the temperature compensator is made piston and placed in a separate housing, rigidly and hermetically installed in the housing of the neutron emitter block s filled with a liquid dielectric. Patent of the Russian Federation No. 2399977, IPC G21G 4/02, July 9, 2009. This technical solution was made as a prototype.

A disadvantage of the known generator is the sequential and coaxial arrangement of the neutron tube and its power circuit. This significantly increases the block size. In addition, the compensator is a complex device requiring high precision assembly. The operation of the compensator at low temperatures is unreliable. To ensure reliability, an additional device is required, for example, a spring that provides constant overpressure in the emitter unit.

To stabilize the parameters of the neutron tube, information is used in the feedback circuit on the magnitude of the high voltage and neutron output. To do this, the prototype uses a voltage divider in the form of a separate unit with a set of series-connected high-voltage resistors in series for the full operating voltage. This is an independent structural unit with large dimensions, for the placement of which and its installation requires time and place.

The objective of the invention is to increase reliability, reducing the complexity of manufacturing, reducing the size and mass of the neutron generator.

The technical result of the invention is to increase reliability, reduce the complexity of manufacturing, reduce the size and mass of the neutron generator.

The technical result is achieved by the fact that in a neutron emitter block containing in a metal sealed enclosure filled with a liquid dielectric, a neutron tube, an accelerating voltage generation circuit, including a multiplication circuit with a high-voltage transformer at the input, a temperature compensator, and all elements are made in the form of bodies of revolution, and between the high-voltage structural elements and the case of the neutron emitter block there is a multilayer insulation, the voltage multiplication circuit is placed on and flexible flexible tape and is located along a helix around a hollow cylinder with a metal bottom made of ceramic material with high electrical resistance equal to the resistance of the voltage divider included between the metal bottom and the block body; inside the hollow cylinder, a neutron tube is coaxially located, the target of which is connected to the output of the multiplication circuit and a metal bottom, and a heat-conducting insulator with annular grooves is installed between the housing end and the metal bottom; parts of the interlayer insulation layers are bent into the grooves of the heat-conducting insulator; the temperature compensator includes a rubber U-shaped cuff placed in the compensator body and separating the compensator into two cavities, one of which is connected to a liquid dielectric and the other is filled with gas under pressure.

The invention is illustrated in the drawing, where:

1 - metal block body;

2 - neutron tube;

3 - voltage multiplier;

4 - pulse high-voltage transformer;

5 - hollow ceramic cylinder;

6 - metal bottom;

7 - target electrode of a neutron tube;

8 - heat-conducting insulator with annular grooves;

9 - multilayer insulation;

10 - U-shaped rubber cuff;

11 - compensator housing;

12 - a cavity filled with a liquid dielectric;

13 - passage hole;

14 - a cavity filled with gas under pressure;

15 - valve;

16 - liquid dielectric;

17 - high-voltage bushing.

The neutron generator is made according to the scheme of switching on a neutron tube with a grounded cathode. The neutron generator includes a housing 1, a neutron tube 2, a high-voltage part of its power circuit, including a voltage multiplier 3 with a high-voltage transformer 4. The electrical elements of the voltage multiplier 3 are placed on an insulating flexible tape, which is arranged along a helical line around a hollow ceramic cylinder 5 along its width . The end face of the ceramic cylinder 5 is closed by a metal bottom 6, and has good electrical and thermal contact with it. Inside the hollow ceramic cylinder 5 and voltage multiplier 3, a neutron tube 2 is coaxially located, the target 7 of which is closely adjacent to the bottom 6 and also has electrical and thermal contact with it. On the other side of the metal bottom, a heat-conducting insulator with annular grooves 8 is arranged coaxially with it, having thermal contact with the housing 1. As a material of the heat-conducting insulator 8, ceramics with high electrical and heat-conducting properties can be selected: electrical strength more than 30 kV / mm and thermal conductivity more 100 W / ° C ・ m, for example aluminum nitride or beryllium oxide, or other thermally conductive insulation materials. The electric elements of the multiplier circuit are located on an insulating flexible tape, which is wound along a helical line with multilayer insulation 9 onto a hollow cylinder 5 made of ceramic material with high electrical resistance equal to the resistance of the voltage divider connected between the metal bottom and the body. This arrangement of the elements of the multiplication scheme around the neutron tube allows you to evenly distribute the high voltage along the neutron tube, provide reliable isolation of the target 7, which is under a full voltage of 100-120 kV, and also remove heat generated on the target during operation. The hollow cylinder can be made of ceramic material with the necessary resistance in various ways, for example, from semiconductor ceramics or by applying a resistive layer.

The end part of the layers of the interlayer insulation 9, after winding it together with the elements of the multiplication circuit, is layer-wise layer-wound from the target side into the annular grooves of the heat-conducting insulator. This implementation of the bends forms a barrier electrical insulation of the metal bottom 6, which is under a full output voltage of 100-120 kV from the generator housing.

To ensure electrical strength and improve heat transfer from internal energy sources to the external environment, the block is flooded with a liquid dielectric 16.

To compensate for temperature changes in the volume of the liquid dielectric, a compensator is installed, which includes a rubber U-shaped sleeve 10 located in the body of the compensator 11. The sleeve 10 divides the volume of the housing 11 into two sealed cavities, one of which 12 is connected to the liquid dielectric through the passage opening 13, and the other 14 is filled with gas under pressure through valve 15. The pressure in the cavity 14 at minimum operating temperatures and a decrease in liquid volume is at least 0.5 ati, at maximum temperatures the pressure in the generator torus reaches not more than 6 atm. External power and triggering pulses are supplied through ceramic bushing insulators 17. Transformer oil TKp having good dielectric properties is used as a liquid dielectric 16 in the block.

External power and start pulses are fed through ceramic bushing insulators 17.

When the emitter unit is operating, the target electrode is heated to a temperature of more than 100 ° C.

Part of the heat is removed from the target through the metal bottom 6 and the heat-conducting insulator 8 to the generator housing 1. In addition, natural circulation of oil occurs around the tube, and heat from the tube 2 is transferred by convective exchange to the housing 1.

The advantage of the proposed design of the emitter unit is that the placement of the voltage multiplication circuit on the insulating flexible tape along the helix of the coaxial neutron tube ensures uniform distribution of high voltage from the multiplication circuit along the neutron tube to the housing, which reduces the overall dimensions of the unit by about 50% while providing the necessary electrical strength and reliability. The hollow ceramic cylinder performs the functions of the resistance of the voltage divider, which eliminates the resistance of the voltage divider as an independent structural element, thereby reducing the overall dimensions of the unit, the complexity of manufacturing, and increasing its reliability.

Replacing the piston thermal compensator with a rubber U-shaped sleeve located in the compensator housing and separating the compensator into two cavities, one of which is connected to a liquid dielectric and the other is filled with gas under pressure, provides a constant oil pressure in the block, thereby increasing its electric strength .

Installing a heat-conducting insulator with annular grooves between the end face of the casing and the metal bottom provides the necessary electric strength of the insulation of the target of the neutron tube, which is under high voltage, and to remove part of the heat generated on it. The other part is diverted by a liquid dielectric by convective exchange to the housing.

Claims (2)

1. The neutron emitter unit, containing in a metal sealed enclosure filled with a liquid dielectric, a neutron tube, an accelerating voltage pulse generating circuit, including a multiplication circuit with a high-voltage transformer at the input, a temperature compensator, and all elements are made in the form of bodies of revolution, and between the high-voltage elements multilayer insulation is located in the design and body of the block of the neutron emitter, characterized in that the voltage multiplication circuit is placed on an insulating g the ribbon and is located together with multilayer insulation along a helical line around a hollow cylinder with a metal bottom made of ceramic material with high electrical resistance equal to the resistance of the voltage divider included between the metal bottom and the block body; a neutron tube is coaxially located inside the hollow cylinder, the target of which connected to the output of the multiplication circuit and a metal bottom, and between the end of the housing and the metal bottom there is a heat-conducting insulator with ring wires dots having thermal contact with it, parts of the interlayer insulation layers are folded in the bore thermally conductive insulator. 2. The neutron emitter block according to claim 1, characterized in that the temperature compensator includes a rubber U-shaped cuff placed in the compensator body and separating the compensator into two cavities, one of which is connected to a liquid dielectric and the other is filled with gas under pressure .

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