High-yield compact deuterium-deuterium neutron generator

Abstract

The invention relates to a high-yield compact deuterium-deuterium neutron generator, which belongs to the technical field of accelerator neutron sources, and mainly comprises an ion source part, a cavity part, a target body part, and a vacuum-pumping system, a high-voltage feed-in system, a radio frequency system, a cooling system and a gas supply system which are matched with the ion source part, the cavity part and the target body part, the gas supply system introduces reaction gas into the ion source, the ion source ionizes the gas through the radio frequency system to generate ion beams, the target body part leads out the ion beams through the high-voltage system, accelerates the ion beams and then bombards the ion beams onto the target, deuterium-deuterium fusion reaction is carried out, and neutrons are generated. According to the device, an inductively coupled plasma source serves as a single ion source, a high-voltage feed-in line is soaked in a flowing insulating medium, a titanium adsorption target with a copper substrate is adopted, the neutron yield can reach # imgabs0 # or above, and the device has the advantages of being low in energy consumption, high in neutron yield, compact in structure and the like.

Description

Technical Field

[0001] The invention relates to the field of accelerator neutron sources, in particular to a high-yield compact deuterium-deuterium neutron generator. Background Art

[0002] Neutron technology is widely used in all walks of life, especially in the medical field, where neutron technology is often used to treat tumors, neutron therapy systems, boron neutron capture therapy, and fast neutron radiation therapy. The application of neutron therapy represents one of the highest technologies for treating tumors, providing hope for the treatment of tumors. Among them, the deuterium-deuterium neutron generator is one of the most promising and miniaturized accelerator neutron sources. In order to be more widely used in various scenarios in industry, such as neutron photography and neutron activation analysis, the accelerator neutron source needs to be able to provide a higher neutron yield.

[0003] Generally speaking, the neutron yield of a deuterium-deuterium neutron generator increases linearly with the increase of the deuterium ion flux. Therefore, the neutron yield can be increased by increasing the flux. Summary of the invention

[0004] The present invention provides a high-yield compact deuterium-deuterium neutron generator, which uses an inductively coupled plasma source as a single ion source and a copper-based titanium adsorption target. The overall device is compact, simple in structure, and easy to process parts. The deuterium ion beam current can reach 165keV and 30mA, while meeting the neutron yield of above.

[0005] The technical solution adopted by the present invention to solve its technical problem is: A high-yield compact deuterium-deuterium neutron generator comprises an ion source part, a chamber part and a target part arranged in sequence from top to bottom; The ion source part includes an air inlet pipe, a flow meter, an ion source upper cover plate, a support column, an ion source chamber, a coil, a cavity upper cover plate and a plasma electrode. The ion source chamber is arranged between the ion source upper cover plate and the cavity upper cover plate. The ion source upper cover plate and the cavity upper cover plate are connected and fixed by the support column. The upper end of the ion source chamber is connected to the air inlet pipe, and the air inlet pipe is provided with a flow meter. The coil is spirally wound and arranged on the outer diameter of the ion source chamber. The plasma electrode is arranged in the cavity upper cover plate and connected to the coil. The chamber part includes a chamber body, a molecular pump, a chamber upper flange and a chamber lower flange. The chamber body is provided with a vacuum port around the chamber body, and is sealedly connected to the molecular pump through the vacuum port. The chamber body is connected to the ion source part and the target part respectively through the chamber upper flange and the chamber lower flange arranged at the upper and lower ends. The target body part includes a lead-out tube, a target and a high-voltage base. A sinking groove is formed on the high-voltage base. The lead-out tube and the target are arranged in the sinking groove. The lower end of the lead-out tube is connected and fixed to the target. Magnets are fixed and symmetrically distributed on both sides of the lead-out tube. A high-voltage channel and a coolant channel are arranged in the high-voltage base.

[0006] In the above technical solution, the air inlet pipe is connected to a gas storage container storing deuterium gas, which is a hydrogen isotope gas.

[0007] In the above technical solution, the coil is connected to a matching device.

[0008] In the above technical solution, cooling water channels are provided in the ion source upper cover plate and the cavity upper cover plate.

[0009] In the above technical solution, the chamber body is provided with functional ports around it, and the functional ports include observation ports or measurement ports.

[0010] In the above technical solution, the material of the chamber body is quartz glass or boron nitride.

[0011] In the above technical solution, the target surface is plated with a coating, and the coating is a titanium film or a lithium film.

[0012] In the above technical solution, an ion beam extraction hole is arranged in the middle of the upper cover plate of the chamber, and the hole diameter is smaller than the extraction circular hole at the upper end of the extraction tube. A sealing groove is formed around the ion beam extraction hole for placing a sealing ring, which forms a vacuum seal with the ion source chamber after being compressed. A cooling water channel is formed inside the ion beam extraction hole.

[0013] In the above technical solution, a metal shell is arranged outside the target body.

[0014] In the above technical scheme, the lead-out tube is divided into three parts: upper, middle and lower, including an upper lead-out tube, a middle lead-out tube and a lower lead-out tube. The lower lead-out tube is a shielding tube, which is concentric with the target. The middle lead-out tube is a transition ring. By adjusting the height of the transition ring, the distance from the upper cover plate of the cavity is adjusted. The upper lead-out tube is an lead-out electrode. A lead-out circular hole is arranged on the upper end face. There is a distance between the lead-out tube and the upper cover plate of the chamber. After high voltage is passed through the lead-out tube, it is used to lead the ion beam to the target.

[0015] In the above technical solution, the target is in the shape of a round cake.

[0016] In the above technical solution, the magnet is made of neodymium iron boron or samarium cobalt, and the core can provide a magnetic field of 1.1 T. The side facing the inside of the lead-out tube is the magnetized surface.

[0017] The beneficial effects of the present invention are: 1. This device uses an inductively coupled plasma source as a single ion source and a copper-based titanium adsorption target. This ensures that the overall device is compact, simple in structure, and easy to process parts. It can make the deuterium ion beam current reach 165keV and 30mA, while meeting the neutron yield of above.

[0018] 2. This device immerses the high-voltage feed line in a circulating insulating medium, which can effectively avoid the sparking problem during high-voltage feed-in, so as to ensure the long-term stable operation of the entire device.

[0019] 3. The whole device adopts common sealing methods, convenient plug-in connectors, and convenient threaded connections, which can be easily assembled and replaced with later parts, reducing production and use costs and facilitating commercialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a high-yield compact deuterium-deuterium neutron generator of the present invention; Figure 2 It is a schematic diagram of the cross-sectional structure of the ion source; Figure 3 It is a schematic diagram of the three-dimensional structure of the ion source; Figure 4 It is a schematic diagram of the structure of the chamber; Figure 5 Schematic diagram of the target structure.

[0021] In the figure: 1-ion source part; 101-inlet pipe; 102-flow meter; 103-ion source upper cover plate; 104-support column; 105-ion source chamber; 106-coil; 107-chamber upper cover plate; 108-plasma electrode; 2-chamber part; 201-chamber upper flange; 202-molecular pump; 203-chamber body; 204-chamber lower flange; 3-target part; 301-upper lead tube; 302-middle lead Cylinder; 303-lower lead-out cylinder; 304-metal shell; 305-high voltage base; 306-high voltage plug; 307-high voltage feed-in line; 308-high voltage terminal; 309-target; 310-magnet; 311-magnet shell; 312-insulating medium water outlet; 313-insulating medium water inlet; 314-high voltage channel; 315-insulating medium; 316-cooling liquid water inlet; 317-cooling liquid water outlet; 318-matching device. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with the embodiments shown in the accompanying drawings: like Figure 1As shown, the present invention provides a high-yield compact deuterium-deuterium neutron generator, which is mainly divided into an ion source part 1, a chamber part 2, a target part 3, and its supporting vacuum system, high-voltage feeding system, radio frequency system, cooling system and gas supply system from top to bottom; its working principle is: first, the gas supply system introduces reaction gas into the ion source, and then the ion source ionizes the gas through the radio frequency system to generate an ion beam flow, and finally the target part accelerates and constrains the ion beam with the help of the high voltage on the target, and then bombards the target, so that a deuterium-deuterium fusion reaction occurs and neutrons are generated.

[0023] like Figure 4 As shown, the main body of the neutron generator is a cylindrical chamber body 203, and the two sides of the chamber body 203 are respectively connected to the chamber upper flange 201 and the chamber lower flange 204 by bolts and vacuum sealed by a sealing ring. The chamber body 203 is provided with an air extraction port around it, and the air extraction port is connected to the molecular pump 202 by bolts in a copper ring sealing manner.

[0024] See also Figure 1 , Figure 2 and Figure 3 The upper end of the ion source chamber 105 is a cylinder with a through hole, and the lower end is a cylinder with a through hole with an inward-retracted annular edging, and a coil 106 is wound around the outside. The gas is fed in by the gas supply system with the help of an air inlet pipe 101, and a flow meter 102 is connected to the air inlet pipe 101, and the air intake volume is controlled by the flow meter 102. The two ends of the ion source chamber 105 are squeezed by the ion source upper cover plate 103 and the cavity upper cover plate 107, and the squeezing force comes from the support column 104 fixed on the cavity upper cover plate 107, and the contact between the ion source upper cover plate 103, the cavity upper cover plate 107 and the ion source chamber 105 is sealed with a sealing ring. A cooling water channel is provided inside the ion source upper cover plate 103 for cooling the sealing ring installed on the cover plate to prevent problems such as ablation and deflation. The coolant quick connector is threadedly fixed at the coolant inlet and outlet to facilitate the plugging and unplugging of the coolant pipe from the load-bearing cooling system. At the same time, a cooling water channel is also provided inside the cavity upper cover plate 107, and the cooling water channel is formed by welding the cavity upper cover plate 107 and the plasma electrode 108, so that the cooling medium is directly in contact with the plasma electrode 108 and the cavity upper cover plate 107, which can increase the cooling capacity, remove more heat, and avoid the occurrence of problems such as thermal deformation and degassing of the plasma electrode 108 and ablation and degassing of the vacuum sealing ring near the plasma electrode 108, thereby increasing the stable operation time of the discharge device. It is used to excite the gas inside the ion source chamber 105 after the coil 106 is connected to the radio frequency system.

[0025] See also Figure 1 , Figure 5The target body part 3 is composed of an extraction tube, a target 309, a high-voltage base 305 and a metal shell 304. The extraction tube is fixed to the target 309 by fixing bolts at the bottom, and symmetrically distributed magnets 310 are fixed on both sides of the extraction tube. The surface of the target 309 is coated, and a stepped heat sink type coolant channel is provided inside, which provides heat removal for the target 309 after the coolant flows. The target 309 is surrounded by threaded through holes distributed in a circle. The target 309 is fixed by bolts to the target 309, the extraction tube and the magnet 310 in the sunken circular groove of the high-voltage base 305. A coolant channel is provided in the high-voltage base 305 (with coolant inlet 316 and coolant outlet 317 at both ends), and a coolant quick connector is threadedly fixed at the coolant channel mouth, which is convenient for plugging and unplugging the coolant pipeline from the load-carrying cooling machine pump. A high-pressure channel 314 is also opened inside the high-pressure base, which is convenient for the high-pressure system to feed high voltage to the target 309 through the high-pressure feed line 307. In addition, an insulating medium channel (with insulating medium outlet 312 and insulating medium inlet 313 at both ends) is provided inside the high-voltage base 305. One end of the insulating medium channel is connected to the high-voltage channel 314, and the other end is equipped with an insulating medium quick connector. The high-voltage feed line 307 is immersed in the insulating medium 315 to avoid arcing and ignition problems that are easy to occur on the atmospheric side when feeding into the vacuum. At the same time, the flowing insulating medium 315 can avoid the ignition problem caused by the accumulation of free charges inside the high-voltage channel 314, and can also cool the high-voltage feed line 307. The high-voltage base 305 is in the shape of a rectangular parallelepiped, and the metal shell 304 is used to wrap the part of the high-voltage base 305 exposed outside the vacuum.

[0026] Preferably, the chamber body 203 is made of metal with certain strength and good processing performance, such as SUS304 / SUS316 / aluminum, and the chamber body 203 can withstand The pressure change is less than The chamber body 203 is provided with exhaust ports, observation ports, and measurement ports as required. The functional ports provided around the body and the flanges at both ends are in accordance with GB / T 6070-2007 and GB / T 6071-2003. The diameter of the chamber body 203 can be changed according to the target diameter and the installation environment. In this example, the diameter is 220 mm and the length is 265 mm.

[0027] Preferably, the vacuum system is composed of two molecular pumps 202 and a chamber body 203 , and the air in the chamber body 203 is pumped out by the molecular pump 202 , thereby achieving a vacuum environment.

[0028] Preferably, the chamber upper flange 201 is made of the same material as the chamber body 203, and is a flange with a hole in the middle as a whole, and the flange specifications refer to GB / T 6070-2007.

[0029] Preferably, the ion source chamber 105 is made of non-metallic materials, such as quartz glass and boron nitride. The inner diameter of the ion source chamber 105 is 40 mm, and the wall thickness should not be too thick under the conditions of meeting the pressure bearing and sealing properties. In this example, the wall thickness is 5 mm.

[0030] Preferably, the cross-sectional diameter of the coil 106 is 3 mm, and it is wound around the outer diameter of the ion source chamber 105 with 6 turns, and the turn spacing is 2-3 mm. The coil diameter, number of turns, and turn spacing affect the electron density of the excited plasma, and can be adjusted according to the required ion beam performance and the diameter of the chamber body 203. The coil 106 should be made of a material with excellent thermal conductivity and high electrical conductivity.

[0031] Preferably, the RF system is connected to the coil 106 by a matcher, and the RF power is adjusted by a RF power supply.

[0032] Preferably, in the gas supply system, the gas introduced into the gas inlet pipe 101 is deuterium gas, which is stored in a gas storage bottle and flows into the ion source chamber 105 through the gas inlet pipe 101 .

[0033] Preferably, the flow meter 102 is installed on the air inlet pipe 101 to control the flow rate of the hydrogen isotope gas released into the ion source chamber 105 , and the flow rate in this example is 10 SCCM.

[0034] Preferably, the upper cover plate 107 of the chamber is made of a metal material with good thermal conductivity, and SU304 is used in the example, and the outer shape is a flange shape. A 69mm through hole is drilled in the middle of the upper cover plate for welding and fixing with the plasma electrode 108, so that the coolant can directly contact the plasma electrode 108 to improve the cooling effect. The plasma electrode 108 adopts a sinking type, and a conical ion beam extraction hole is drilled in the middle. The upper aperture should be smaller than the extraction hole of the upper extraction tube 301. In this example, the upper aperture of the plasma electrode 108 is 6mm, and the aperture of the upper extraction tube 301 is 12mm.

[0035] Preferably, the plasma electrode 108 is made of oxygen-free copper, a material with low resistance and good processing performance, to achieve good electrical conductivity.

[0036] Preferably, the lead-out tube (including the upper lead-out tube 301, the middle lead-out tube 302 and the lower lead-out tube 303) is made of a material with good machining performance and good electrical conductivity, and is a thin-walled cylinder as a whole, fixed to the target 309 by bolts at the bottom. The lead-out tube is divided into three parts: upper, middle and lower. The lower lead-out tube 303 is a shielding tube, which is concentric with the target 309. The middle lead-out tube 302 is a transition ring, and the distance from the upper cover plate 107 of the cavity is adjusted by adjusting the height of the transition ring. The upper lead-out tube 301 is an extraction electrode, and a lead-out circular hole is drilled on the end face, which has a certain distance from the upper cover plate 107 of the cavity. The lead-out tube is used to extract the ion beam to the target 309 after passing high voltage.

[0037] Preferably, two symmetrical magnets 310 are installed on the side of the lower half of the extraction tube to generate a magnetic field in the extraction tube, which can suppress secondary electrons. In this example, the magnetic field of the magnet 310 is 1.1T, and the magnetic field at the center of the target 309 is 40Gs.

[0038] Preferably, the magnet 310 is made of neodymium iron boron or samarium cobalt, is arc-shaped as a whole, has a magnetized surface inside, and the core magnetic field can reach 1.1T.

[0039] Preferably, the target 309 is in the shape of a round cake as a whole, can withstand the bombardment of high-energy ion beams and can adsorb deuterium ions for subsequent deuterium-deuterium reactions to produce neutrons. The target 309 uses oxygen-free copper as a water-cooled substrate and is coated on the surface. The coating is a titanium film / lithium film, and the plated area and thickness can be set according to the ion beam and neutron parameters. A stepped heat sink type water channel is provided inside the target body 309 to increase the heat exchange area and reduce the flow resistance to improve the cooling capacity. A threaded hole is provided at the bottom of the target 309 for installing a high-voltage terminal 308, and the high voltage is fed to the target 309 through the high-voltage terminal 308.

[0040] Preferably, the high-voltage base 305 is made of insulating material, and has a channel for coolant inlet and outlet, a high-voltage channel 314, and an insulating medium channel drilled inside. One end of the coolant channel is concentric with the water inlet and outlet at the bottom of the target 309, and the other end is equipped with a coolant quick connector. A high-voltage feed line 307 is inserted into the high-voltage channel 314 to feed the high voltage generated by the high-voltage system to the target 309. One end of the insulating medium channel is connected to the high-voltage channel 314, and the other end is equipped with an insulating medium quick connector. The high-voltage feed line 307 is immersed in the insulating medium 315 to avoid arcing and ignition problems that are prone to occur on the atmospheric side when feeding into the vacuum. At the same time, the flowing insulating medium 315 can avoid the occurrence of ignition problems caused by the accumulation of free charges inside the high-voltage channel 314, and can also cool the high-voltage feed line 307. The high-voltage base 305 is in the shape of a rectangular parallelepiped, and a metal shell 304 is used to wrap the part of the high-voltage base 305 that is exposed outside the vacuum.

[0041] Furthermore, the metal shell 304 is made of a material with good machining performance and good electrical conductivity, and is a thin-walled rectangular solid as a whole. The metal shell 304 and the chamber body 203 are connected by copper wire, so that the entire chamber body 203 and the high-voltage base 305 are maintained at the same potential and play a role in voltage equalization.

[0042] Preferably, the high-voltage plug 306 is a stepped shaft type, one end of which is inserted into the high-voltage channel 314 of the high-voltage base 305, and the high-voltage feed-in line 307 is connected to the end of the high-voltage plug 306 inserted into the high-voltage channel 314, and the high voltage is fed to the target 309. The sealing ring around it is tightened by bolts to perform vacuum sealing and fixed on the high-voltage base 305, and the other end has a conical groove for inserting a high-voltage coaxial cable.

[0043] Preferably, the high-voltage terminal 308 is made of a material with good machining performance and good electrical conductivity. It is a cylinder as a whole. An M3 thread is machined on the upper part of the cylinder, which cooperates with the threaded hole at the bottom of the target 309 to feed high voltage. A circular groove is opened on the lower end surface for the high-voltage feed-in line 307 to be inserted into the circular hole and connected by soldering.

[0044] Preferably, the resistivity of the coolant should be greater than or equal to 16 , ensuring that the surface temperature of the target 309 is less than 200° C. and the overall temperature of the coil 106 is less than 50° C. The coolant is pumped into the cooling part through the cooler, and the coolant pressure, flow rate and temperature can be set by the cooler.

[0045] Preferably, the sealing ring is made of fluororubber and has a circular or rectangular cross section. It is placed in the sealing groove and fills the sealing groove to form a vacuum seal after being squeezed by pressure.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A high-yield compact deuterium-deuterium neutron generator, characterized in that: It includes an ion source part, a chamber part and a target part which are arranged in sequence from top to bottom; The ion source part includes an air inlet pipe, a flow meter, an ion source upper cover plate, a support column, an ion source chamber, a coil, a cavity upper cover plate and a plasma electrode. The ion source chamber is arranged between the ion source upper cover plate and the cavity upper cover plate. The ion source upper cover plate and the cavity upper cover plate are connected and fixed by the support column. The upper end of the ion source chamber is connected to the air inlet pipe, and the air inlet pipe is provided with a flow meter. The coil is spirally wound and arranged on the outer diameter of the ion source chamber. The plasma electrode is arranged in the cavity upper cover plate and connected to the coil. The chamber part includes a chamber body, a molecular pump, a chamber upper flange and a chamber lower flange. The chamber body is provided with a vacuum port around the chamber body, and is sealedly connected to the molecular pump through the vacuum port. The chamber body is connected to the ion source part and the target part respectively through the chamber upper flange and the chamber lower flange arranged at the upper and lower ends. The target body part includes a lead-out tube, a target and a high-voltage base. A sinking groove is formed on the high-voltage base. The lead-out tube and the target are arranged in the sinking groove. The lower end of the lead-out tube is connected and fixed to the target. Magnets are fixed and symmetrically distributed on both sides of the lead-out tube. A high-voltage channel and a coolant channel are arranged in the high-voltage base.

2. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: The air inlet pipe is communicated with a gas storage container storing deuterium gas which is a hydrogen isotope gas.

3. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: The coil is connected to a matching device.

4. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: Cooling water channels are arranged in the ion source upper cover plate and the cavity upper cover plate.

5. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: The chamber body is provided with observation ports or measurement ports around its periphery.

6. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: The target surface is plated with a coating, which is a titanium film or a lithium film.

7. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: An ion beam extraction hole is arranged in the middle of the upper cover plate of the cavity, and the hole diameter is smaller than the extraction circular hole at the upper end of the extraction tube. A sealing groove is arranged around the ion beam extraction hole for placing a sealing ring.

8. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: A metal shell is arranged outside the target body.

9. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: The lead-out tube is divided into three parts: upper, middle and lower, including an upper lead-out tube, a middle lead-out tube and a lower lead-out tube. The lower lead-out tube is a shielding tube, which is concentric with the target. The middle lead-out tube is a transition ring. The distance from the upper cover plate of the cavity is adjusted by adjusting the height of the transition ring. The upper lead-out tube is an lead-out electrode. A lead-out circular hole is arranged on the upper end surface. There is a distance between the lead-out tube and the upper cover plate of the chamber. The lead-out tube is used to lead the ion beam to the target after high voltage is passed through it.

10. A high-yield compact deuterium-deuterium neutron generator according to claim 1, characterized in that: The magnet is made of neodymium iron boron or samarium cobalt, the core provides a 1.1T magnetic field, and the side facing the inside of the lead-out tube is the magnetized surface.

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