A compact neutron source based active water-cooled solid deuterium target with easy disassembly

Abstract

This invention discloses a conveniently detachable, actively water-cooled solid-state deuterium target based on a compact neutron source, comprising a micron-sized solid titanium film, a titanium film carrier, and a water-cooled substrate. Deuterium is deposited in the solid titanium film by bombarding it with a deuterium ion beam, and neutrons are generated by collisions with the subsequent deuterium ion beam. Oxygen-free copper, with its high thermal conductivity, is used as the carrier for the titanium film. The threaded structure on the side of the titanium film carrier allows for convenient installation and removal from the water-cooled substrate. The oxygen-free copper substrate, with multiple annular water-cooling structures inside, enables rapid and effective removal of heat flux from the target, preventing deuterium particles deposited in the solid titanium film from desorbing due to excessive temperature, thus avoiding impact on neutron yield. This invention provides a conveniently detachable, actively water-cooled solid-state deuterium target suitable for compact deuterium-deuterium neutron generators, providing a sound technical foundation for the widespread application of compact accelerator neutron source systems in production and daily life.

Description

Technical Field

[0001] This invention relates to the technical field of neutron measurement and irradiation based on compact accelerator neutron sources, and particularly to a conveniently detachable active water-cooled solid deuterium target based on a compact neutron source. Background Technology

[0002] Neutrons, as an important research tool, have been widely applied in many fields such as metallurgy, chemistry, biochemistry, neutron therapy, food, neutron photography, oil exploration, geology, and mineral exploration, yielding many significant results. Neutron sources are generally classified into three types according to their neutron production methods: radioactive isotope neutron sources, reactor neutron sources, and accelerator neutron sources. Accelerator neutron sources utilize accelerators to generate and accelerate charged particles, which then bombard certain target materials to produce neutrons. Compared to isotope neutron sources, low-energy charged ion accelerator neutron sources have higher neutron yields, better monochromaticity, and generally no strong radioactivity when not in operation. Compared to electron accelerator white light neutron sources and reactor neutron sources, low-energy charged ion accelerator neutron sources are less expensive, can produce monoenergetic neutrons, and can be miniaturized, showing broad application prospects in neutron technology. Therefore, deuterium-deuterium neutron generators are among the most promising miniaturized accelerator neutron sources.

[0003] In a compact deuterium-deuterium neutron generator, the deuterium target is one of its core key components, and its performance directly determines the neutron yield and lifetime of the neutron generator. A deuterium target generally consists of two parts: a target substrate and a deuterium-absorbing film. The target substrate is typically made of copper or molybdenum, materials with good thermal conductivity. The most commonly used and ideal metal for the deuterium-absorbing film is titanium. Titanium exhibits extremely strong adsorption capacity for H, D, and T elements at high temperatures, and titanium hydrides have the highest hydrogen density to date, more than twice the density of liquid hydrogen. The targets in compact neutron generators typically use solid-state target structures. Especially for titanium-substrate deuterium-titanium targets, the temperature of the target sheet needs to be strictly controlled below 200℃ to prevent the desorption of deuterium particles deposited in the titanium substrate, which would affect the neutron yield of the deuterium-deuterium reaction and the system stability. Currently, there are two main types of titanium substrates used for deuterium adsorption: one is the titanium-deuterium adsorption target, where deuterium is naturally adsorbed under high temperature conditions after the titanium film is prepared, forming titanium deuteride in the titanium film; the other is to deposit or weld pure titanium sheets onto the target substrate, and then use active deuterium ion beam bombardment to continuously deposit deuterium particles in the titanium film, forming a deuterium target. Therefore, designing a deuterium target that is easy to disassemble and has strong thermal removal capabilities is of great significance for the application of compact deuterium-deuterium neutron sources. Summary of the Invention

[0004] The purpose of this invention is to provide a deuterium target that can stably and continuously generate neutrons over a long period of time, enabling convenient installation and disassembly of the target, while also meeting the requirements for neutron yield, removal of high heat load from the target, and continuous safe and stable operation of the system.

[0005] This invention is achieved through the following technical solution:

[0006] A conveniently detachable, actively water-cooled solid-state deuterium target based on a compact neutron source includes a micron-sized solid titanium film, a conveniently detachable titanium film carrier, and a water-cooled substrate. The micron-sized solid titanium film is disposed on the conveniently detachable titanium film carrier; the conveniently detachable titanium film carrier is integrally connected to the bottom water-cooled substrate via a threaded connection; the top of the water-cooled substrate has a groove matching the conveniently detachable titanium film carrier, and a vent is provided at the edge of the groove; multiple annular water-cooling structures are formed inside the water-cooled substrate; and a cooling water inlet and a cooling water outlet are provided at the bottom of the water-cooled substrate.

[0007] Furthermore, the multi-channel annular water-cooling structure is interconnected.

[0008] Furthermore, both the cooling water inlet and the cooling water outlet are connected to the annular water-cooling structure.

[0009] Furthermore, both the cooling water inlet and outlet are connected to low-activation steel water pipes.

[0010] Furthermore, the easily disassembled titanium film carrier is a circular oxygen-free copper block with a threaded structure.

[0011] Preferably, the multi-channel annular water-cooling structure is a multi-channel annular water tank structure.

[0012] Furthermore, the micron-sized solid titanium film is deposited onto a easily removable titanium film carrier using magnetron sputtering. High-purity titanium target material with a purity >99.99% is used in the preparation of the micron-sized solid titanium film. This invention primarily addresses deuterium ion beam parameters of 200 keV, 1.5 mA, and a neutron yield greater than 1 × 10⁻⁶. 8 Therefore, the titanium film is set to a circle with a diameter of Φ40mm and a thickness of 2μm.

[0013] Furthermore, the easily detachable titanium film carrier is a round block made of oxygen-free copper. To match the size of the solid titanium film, the oxygen-free copper block is Φ40mm in diameter and 3mm in thickness. To facilitate quick target replacement during later operation of the neutron source, a single-threaded fine-pitch external thread with a pitch of 0.5mm is provided on the sidewall of the easily detachable titanium film carrier for connection with the grooved thread of the water-cooled substrate. Two Φ3.2mm through holes are also symmetrically located on the edge of the oxygen-free copper carrier to facilitate installation and removal of the target using custom tools.

[0014] Furthermore, the water-cooled substrate is a circular block made of oxygen-free copper. To meet the requirement of heat removal generated by the stable bombardment of the deuterium target by a 200keV, 1.5mA deuterium ion beam, the oxygen-free copper water-cooled substrate designed in this invention has dimensions of Φ100mm × 14mm, and consists of an upper cover plate and a lower cover plate. A circular groove with a diameter of Φ40mm and a depth of 3mm is drilled at the center of the top of the upper cover plate, and an internal thread with a pitch of 0.5mm is formed on the inner wall of the groove for threaded connection with the easily disassembled titanium film carrier. At the same time, a cavity with a diameter of Φ1mm and a depth of 3mm is formed at the edge of the groove to avoid leaving a narrow closed space inside the thread after the easily disassembled titanium film carrier is threadedly connected to the water-cooled substrate, which would affect the achievement of ultra-high vacuum in the accelerator system. To achieve effective removal of steady-state heat flux from the deuterium ion beam, multiple annular water groove structures are formed on the upper cover plate of the water-cooled substrate to ensure sufficient contact between the cooling water and the substrate to remove heat. A first annular water trough with an outer diameter of 85mm, an inner diameter of 73mm, and a depth of 4mm is formed 7mm from the bottom edge of the water-cooled base cover plate, serving as the cooling water inlet. A second annular water trough with an outer diameter of 65mm, an inner diameter of 53mm, and a depth of 4mm is formed 4mm from the inner wall of the first trough. A third annular water trough with an outer diameter of 45mm, an inner diameter of 33mm, and a depth of 4mm is formed 4mm from the inner wall of the second annular water trough. Finally, an annular water trough with an outer diameter of 25mm, an inner diameter of 13mm, and a depth of 4mm is formed 4mm from the inner wall of the third annular water trough, serving as the cooling water outlet. An inlet with an inner diameter of 8mm and a depth of 4mm is formed at a radius of 41mm; an outlet with an inner diameter of 8mm and a depth of 4mm is formed at a radius of 8mm. A cooling water inlet is made at the center of the interval between the first and second water tanks (75.5mm from the center of the inlet), at the center of the interval between the second and third water tanks (16.5mm from the center of the inlet), and at the center of the interval between the third and fourth water tanks (55.5mm from the center of the inlet). This allows cooling water from the first water tank to flow into the second, third, and fourth water tanks, and finally out through the outlet, forming a closed-loop cooling water flow circuit. A through hole with an inner diameter of 9mm is made at radii of 41mm and 8mm on the cover plate under the water-cooled base, respectively, for vacuum brazing connection to the low-activation steel pipe.

[0015] Furthermore, for the 200keV, 1.5mA compact deuterium-deuterium neutron source system and the Φ40mm×2μm solid titanium film and water-cooled substrate, in order to ensure the thermodynamic stability of the deuterium target during the deuterium ion beam bombardment of the solid titanium film to generate neutrons, the room temperature water flow pressure at the inlet of the oxygen-free copper water-cooled substrate is not less than 0.5MPa and the flow rate is not less than 0.5kg / s.

[0016] The advantages of this invention are: it can effectively solve the thermodynamic instability problem during target operation while meeting the neutron yield requirement, ensuring the continuous, safe and stable operation of the neutron source system; at the same time, it allows for convenient disassembly and replacement of the target during the later maintenance work of the accelerator. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall cross-sectional structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the cooling water trough structure opened in the cover plate of the water-cooled substrate.

[0019] In the diagram, 1-micron-level solid titanium membrane; 2-easily disassembled titanium membrane carrier; 3-vent hole; 4-water-cooled substrate upper cover plate; 5-water-cooled substrate lower cover plate; 6-first water tank; 7-second water tank; 8-third water tank; 9-fourth water tank; 10-inlet; 11-outlet; 12-water inlet a; 13-water inlet b; 14-water inlet c; 15-low-activation steel water pipe a; 16-low-activation steel water pipe b. Detailed Implementation

[0020] like Figure 1-2 As shown, a conveniently detachable active water-cooled solid deuterium target based on a compact neutron source includes a micron-sized solid titanium film 1, a conveniently detachable titanium film carrier 2, a water-cooled substrate upper cover plate 4, and a water-cooled substrate lower cover plate 5. The micron-sized solid titanium film 1 is deposited on the conveniently detachable titanium film carrier 2 by magnetron sputtering. The conveniently detachable titanium film carrier 2 is connected to the water-cooled substrate upper cover plate 4 by a threaded connection. The water-cooled substrate includes two parts: the water-cooled substrate upper cover plate 4 and the water-cooled substrate lower cover plate 5. A threaded groove is formed at the center of the top of the water-cooled substrate upper cover plate 4 to achieve a threaded connection with the conveniently detachable titanium film carrier 2. A vent hole 3 is formed at the edge of the groove. Multiple annular water-cooling structures are formed at the bottom of the water-cooled substrate upper cover plate 4. A water inlet 10 and a water outlet 11 are formed in the water-cooled substrate lower cover plate 5. The water-cooled substrate upper cover plate 4 and the water-cooled substrate lower cover plate 5 are connected by vacuum brazing. The water-cooled substrate under cover plate 5 is connected to the low-activation steel water pipe a15 by vacuum brazing. The water-cooled substrate under cover plate 5 is connected to the low-activation steel water pipe b16 by vacuum brazing.

[0021] The micron-sized solid titanium film 1 is deposited onto a easily removable titanium film carrier 2 using magnetron sputtering. A high-purity titanium target with a purity >99.99% is used when preparing the micron-sized solid titanium film. This invention primarily addresses deuterium ion beam parameters of 200 keV, 1.5 mA, and a neutron yield greater than 1 × 10⁻⁶. 8 Therefore, the solid titanium film 1 is set to a circle with a diameter of Φ40mm and a thickness of 2μm.

[0022] The titanium film carrier 2 is a round block made of oxygen-free copper. To match the micron-sized solid titanium film 1, the dimensions of the easily disassembled titanium film carrier 2 are set at Φ40mm and the thickness at 3mm. To facilitate quick target replacement during later operation of the neutron source, a single-threaded fine-pitch external thread with a pitch of 0.5mm is provided on the side wall of the easily disassembled titanium film carrier 2 for connection with the grooved thread of the water-cooled substrate cover plate 4. Two Φ3.2mm through holes are also symmetrically located at the edge of the easily disassembled titanium film carrier 2 to facilitate the installation and removal of the target using custom tools.

[0023] The water-cooled substrate is a circular block made of oxygen-free copper. To meet the heat removal requirements generated by the stable bombardment of the target by a 200keV, 1.5mA deuterium ion beam, the water-cooled substrate designed in this invention has dimensions of Φ100mm × 14mm. The water-cooled substrate includes an upper cover plate 4 and a lower cover plate 5. A circular groove with a diameter of 40mm and a depth of 3mm is formed at the center of the top of the upper cover plate 4. An internal thread with a pitch of 0.5mm is formed on the inner wall of the circular groove for threaded connection with the easily disassembled titanium film carrier 2. At the same time, a vent hole 3 with a diameter of 1mm and a depth of 3mm is formed at the edge of the groove to avoid leaving a narrow, closed dead space inside the thread after the titanium film carrier 2 is connected to the upper cover plate 4, which would affect the achievement of ultra-high vacuum in the accelerator system. To achieve effective removal of the steady-state heat flux of the deuterium ion beam, multiple annular cooling water loops are designed inside the upper cover plate 4 to ensure full contact between the cooling water and the substrate, thereby removing heat. A first annular water trough (i.e., the first water trough 6) with an outer diameter of 85 mm, an inner diameter of 73 mm, and a depth of 4 mm is opened 7 mm from the edge of the top cover plate 4 of the water-cooled base, serving as the cooling water inlet trough; a second annular water trough (i.e., the second water trough 7) with an outer diameter of 65 mm, an inner diameter of 53 mm, and a depth of 4 mm is opened 4 mm from the inner wall of the first annular water trough; a third annular water trough (i.e., the third water trough 8) with an outer diameter of 45 mm, an inner diameter of 33 mm, and a depth of 4 mm is opened 4 mm from the inner wall of the second annular water trough; and a fourth annular water trough (i.e., the fourth water trough 9) with an outer diameter of 25 mm, an inner diameter of 13 mm, and a depth of 4 mm is opened 4 mm from the inner wall of the third annular water trough, serving as the cooling water outlet trough. A water inlet 10 with an inner diameter of 8 mm and a depth of 4 mm is opened at a bottom radius of 41 mm on the cover plate 4 of the water-cooled base; a water outlet 11 with an inner diameter of 8 mm and a depth of 4 mm is opened at a radius of 8 mm on the cover plate of the water-cooled base. A water inlet a12 is opened at the center of the first water tank 6 and the second water tank 7, located 75.5 mm from the center of the water inlet. A water inlet b13 is opened at the center of the second water tank 7 and the third water tank 8, located 16.5 mm from the center of the water inlet. A water inlet c14 is opened at the center of the third water tank 8 and the fourth water tank 9, located 55.5 mm from the center of the water inlet.

[0024] Water inlets a12, b13, and c14 are all cooling water inlets, used to direct the cooling water from the first water tank 6 to the second, third, and fourth water tanks 7 and 8, and finally out through outlet 11, forming a closed-loop cooling water circuit. A 9mm inner diameter through-hole (i.e., inlet 10) is formed at a radius of 41mm on the lower cover plate 5 of the water-cooled base. This through-hole is used for vacuum brazing connection to the low-activation steel water pipe a15. A 9mm inner diameter through-hole (i.e., outlet 11) is formed at a radius of 8mm on the lower cover plate 5 of the water-cooled base. This through-hole is used for vacuum brazing connection to the low-activation steel water pipe b16.

[0025] This invention first connects the low-activation steel water pipes a15 and b16 at the bottom of the water-cooled substrate to the cooling water circuit on the compact accelerator. The water circuit parameters are adjusted to achieve a water flow rate of 0.5 kg / s and a water pressure of 0.5 MPa at the inlet 10 and outlet 11, ensuring continuous water supply. Then, under the protection of inert argon gas, the prepared 2.0-micron titanium film carrier 2 is threadedly connected to the cover plate 4 on the water-cooled substrate. Afterward, the accelerator system is vacuum-sealed, and the vacuum pump unit is activated to evacuate the vacuum chamber to a vacuum level of 1.0 × 10⁻⁶. -4 Pa is sufficient. The compact accelerator then begins operation, introducing a 200 keV, 1.5 mA deuterium ion beam into a 2.0-micron titanium film. Deuterium particles deposit into the titanium film and collide with subsequent bombardment, producing neutrons. During the compact accelerator's operation, an infrared camera monitors the temperature of the titanium film on the solid deuterium target surface. By adjusting the cooling water parameters, the temperature is strictly controlled below 200°C. If the deuterium target needs replacement, the water in the water-cooled substrate's internal cooling tank is first drained, and then the titanium film support is removed under the protection of inert argon gas, and a new target is installed.

[0026] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. A conveniently detachable, actively water-cooled solid-state deuterium target based on a compact neutron source, characterized in that: The system includes a micron-sized solid titanium film, a removable titanium film carrier, and a water-cooled substrate. The micron-sized solid titanium film is mounted on the removable titanium film carrier. The removable titanium film carrier is connected to the bottom water-cooled substrate by a threaded connection. The top of the water-cooled substrate has a groove matching the removable titanium film carrier, and a vent is provided at the edge of the groove. Multiple annular water-cooling structures are formed inside the water-cooled substrate. A cooling water inlet and outlet are provided at the bottom of the water-cooled substrate. Multiple annular water groove structures are formed on the top cover of the water-cooled substrate. These annular water groove structures include: a first annular water groove with an outer diameter of 85 mm, an inner diameter of 73 mm, and a depth of 4 mm, located 7 mm from the bottom edge of the top cover of the water-cooled substrate, serving as a cooling water inlet; a second annular water groove with an outer diameter of 65 mm, an inner diameter of 53 mm, and a depth of 4 mm, located 4 mm from the inner wall of the first water groove; and a third annular water groove with an outer diameter of 45 mm, an inner diameter of 33 mm, and a depth of 4 mm, located 4 mm from the inner wall of the second annular water groove. A third annular water trough with an outer diameter of 25 mm, an inner diameter of 13 mm, and a depth of 4 mm is formed on the inner side of the third annular water trough, 4 mm from the inner wall, serving as the outlet for cooling water; an inlet with an inner diameter of 8 mm and a depth of 4 mm is formed at a radius of 41 mm on the cover plate of the water-cooled base; an outlet with an inner diameter of 8 mm and a depth of 4 mm is formed at a radius of 8 mm at the bottom of the water-cooled base; and locations are: the center of the first and second annular water troughs at a distance of 75.5 mm from the center of the inlet; the center of the second and third annular water troughs at a distance of 16.5 mm from the center of the inlet; and the center of the third annular water trough at a distance of 55.5 mm from the center of the inlet. At the center of the interval between the third and fourth annular water tanks at a distance of mm, a cooling water inlet is respectively opened to allow cooling water from the first annular water tank to flow into the second, third, and fourth annular water tanks, and finally out through the outlet, forming a closed-loop cooling water flow circuit. To address the need for heat removal from the stable bombardment of the target by a 200keV, 1.5 mA deuterium ion beam, an infrared camera is used to monitor the temperature of the titanium film on the solid deuterium target surface during the operation of the compact accelerator. By adjusting the cooling water parameters, the temperature is strictly controlled below 200℃. A high-purity titanium target with a purity >99.99% is used when preparing the micron-sized solid titanium film. The micron-sized solid titanium film is a Φ40 mm circle with a thickness of 2 μm. The easily disassembled titanium film carrier is a circular oxygen-free copper block with an external thread structure on the side. The circular oxygen-free copper block has a size of Φ40 mm and a thickness of 3 mm. The pitch of the external thread is 0.5 mm, and two Φ3 threads are symmetrically located on the edge of the circular oxygen-free copper block.A 2 mm through-hole; the water-cooled substrate is divided into an upper cover plate and a lower cover plate; a circular groove is provided at the center of the top of the upper cover plate, with internal threads on the inner wall of the groove, and holes are provided at the edge of the groove.

2. The easily detachable, actively water-cooled solid-state deuterium target based on a compact neutron source according to claim 1, characterized in that: The inlet and outlet of the cooling water are welded to low-activation steel water pipes, respectively.

3. The easily detachable, actively water-cooled solid-state deuterium target based on a compact neutron source according to claim 1, characterized in that: The micron-scale solid titanium film is prepared on a easily removable titanium film carrier by magnetron sputtering.

4. The easily detachable, actively water-cooled solid-state deuterium target based on a compact neutron source according to claim 1, characterized in that: The water-cooled substrate is a circular block made of oxygen-free copper material; the dimensions of the water-cooled substrate are: Φ100 mm × 14 mm; a circular groove with a diameter of Φ40 mm and a depth of 3 mm is provided at the center of the top of the cover plate of the water-cooled substrate, and an internal thread with a pitch of 0.5 mm is provided on the inner wall of the groove, while a hole with a diameter of Φ1 mm and a depth of 3 mm is provided at the edge of the groove.

5. A conveniently detachable, actively water-cooled solid-state deuterium target based on a compact neutron source according to claim 1, characterized in that: A through hole with an inner diameter of 9 mm is opened at a radius of 41 mm and 8 mm on the cover plate under the water-cooled substrate, respectively, for vacuum brazing connection with the low-activation steel pipe.

Images