Compact high-stability ECR (electron cyclotron resonance) deuterium-deuterium neutron source device

Abstract

The invention discloses a compact high-stability ECR (electron cyclotron resonance) deuterium-deuterium neutron source device, and belongs to the technical field of accelerator neutron sources, the device is composed of an ECR ion source, a vacuum chamber and a target body system, and a vacuum pumping system, a high-voltage feed-in system, a microwave feed-in system, a circulating cooling system, a gas supply system and other multifunctional systems are integrated for cooperative work; the ECR ion source adopts three sets of permanent magnet structures to synergistically generate a uniform 875GS magnetic field, and meanwhile, the newly designed microwave window adopts a micro water channel structure and a tungsten target, so that heat deposited in the microwave window can be greatly reduced on the premise of not influencing microwave feed-in, and the service time of the microwave window is doubled; the target and extraction electrode integrated design is adopted, damage of electrons to peek and other insulating materials is reduced, the service life is prolonged, meanwhile, pure zirconium metal is used as the target material, and the deuterium adsorption capacity under the high-temperature condition is greatly improved. The device has the advantages of small size, long-time stable operation and the like.

Description

Technical Field

[0001] This invention belongs to the field of compact accelerator neutron sources, and particularly relates to a compact, highly stable ECR deuterium-deuterium neutron source device. Background Technology

[0002] Neutron sources, as core devices for basic scientific research and industrial applications, play an irreplaceable role in fields such as nuclear physics research, materials analysis, cancer treatment, and nuclear energy development. Traditional neutron sources mainly rely on high-pressure accelerators or inertial confinement fusion devices to produce neutrons by accelerating deuterium ions to bombard tritium (T) or deuterium (D) targets. However, these devices generally suffer from problems such as large size, high energy consumption, and complex maintenance, making it difficult to meet the needs of on-site detection or portable applications. Electron cyclotron resonance (ECR) technology, with its high-density, high-ionization steady-state plasma characteristics, is considered an ideal approach to achieve efficient deuterium-deuterium fusion reactions.

[0003] Therefore, the improved compactness and high stability of neutron sources will lead to their wider application in industrial equipment. Summary of the Invention

[0004] To improve the usability of neutron sources and expand their application scenarios, this invention provides a compact, highly stable ECR deuterium-deuterium neutron source device. This device has advantages such as small size and long-term stable operation, and is suitable for fields such as neutron imaging, activation analysis, and nuclear instrument calibration.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A compact and highly stable ECR deuterium-deuterium neutron source device includes a vertically integrated ECR ion source section, a vacuum chamber and a target system, which are cascaded from top to bottom through a sealing flange;

[0007] The ECR ion source consists of a microwave feed device and a plasma chamber system, including: a waveguide connected to a 2.45 GHz microwave source, with its bottom connected to an electrically driven triple pin; the electrically driven triple pin is located between the waveguide and the plasma chamber; the plasma chamber is a through-type T-shaped cylinder, which forms a vacuum seal through a T-shaped ceramic window and plasma electrodes; the plasma chamber is externally wrapped with three sets of permanent magnets to form an 875 Gs magnetic field to couple the 2.45 GHz microwave to excite the plasma;

[0008] The vacuum chamber is made of stainless steel, with a molecular pump, observation window and vacuum gauge tube connected to the side wall. The upper and lower ends of the chamber are vacuum sealed to the ion source module and target system through flanges.

[0009] The target system includes a PEek base, a pure zirconium target, a deflection magnet, and an extraction electrode. The PEek base has a high-voltage feed hole and a water-cooling inlet and outlet. The pure zirconium target is located on the PEek base and is isolated by a sealing ring. The zirconium target is welded with a threaded cylindrical barrel to connect to the extraction electrode. The deflection magnet is installed inside the extraction electrode and is in close contact with the zirconium target to suppress secondary electrons.

[0010] Furthermore, the T-shaped ceramic window is fixed by a cover flange and has two layers of sealing rings inside. The bottom ring isolates the vacuum, and the upper and lower rings form a sealed space as a water cooling channel.

[0011] Furthermore, the T-shaped plasma chamber is equipped with a fully covered water-cooled pipe on the side facing the plasma.

[0012] Furthermore, the plasma electrode is made of aluminum, is horizontal on the plasma side, and has a concave shape on the lead-out electrode side.

[0013] Furthermore, the permanent magnet is made of N42 material, and a non-magnetic alloy isolation ring is provided between the magnets.

[0014] Furthermore, the side wall of the vacuum chamber is provided with two observation windows, which are respectively aligned with the lead-out electrode port and the zirconium target position.

[0015] Furthermore, the upper part of the peek base is recessed, and the pure zirconium target is embedded in the recessed part.

[0016] Furthermore, the pure zirconium target has a finned heat dissipation structure on its back side and two cylinders on its target surface. The inner cylinder blocks secondary electrons, and the outer cylinder has external threads for assembling lead-out electrodes.

[0017] Furthermore, the lead-out electrode is cylindrical with a tapered, concave top to form a beam focusing structure.

[0018] Furthermore, a tungsten target is welded to the bottom of the T-shaped ceramic window to block reverse electron bombardment. Beneficial effects:

[0019] 1. This invention provides a compact and highly stable ECR deuterium-deuterium neutron source device, which adopts a three-section strong magnet design to form a uniform 875GS magnetic field inside the ion source. The minimum illumination power is 50W, and the ion source can extract 19mA of beam current under 90kV conditions.

[0020] 2. This device adopts a new ceramic window design and a ring-shaped water-cooling structure, which does not affect the microwave transmission and can greatly reduce the heat accumulation inside the ceramic window. At the same time, the tungsten target welded to the top of the ceramic window can directly block the reverse bombardment of electrons, thus increasing the lifespan of the microwave window many times over.

[0021] 3. This device uses pure zirconium target material, avoiding the problems of short lifespan and film peeling of traditional coating targets. It adopts an integrated design, forming a semi-enclosed space with the lead-out electrode, reducing the impact of sputtering. It has achieved a good state of three ignitions in 100 hours. At the same time, after 100 hours of testing, the system did not have any problems, and all components were in good condition, making it a stable commercial product. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a compact, highly stable ECR deuterium-deuterium neutron source device according to the present invention.

[0023] Figure 2 This is a schematic diagram of the overall ECR deuterium-deuterium ion source.

[0024] Figure 3 This is a schematic diagram of the cross-section of the ECR deuterium-deuterium ion source.

[0025] Figure 4 This is a schematic diagram of the cross-section of the target system.

[0026] In the figure, the reference numerals are as follows: 1 is the ECR ion source; 2 is the vacuum chamber; 2-1 is the molecular pump; 2-2 is the vacuum gauge tube; 2-3 is the observation window; 2-4 is the stainless steel cylindrical chamber; 3 is the target base; 4 is the waveguide; 5 is the water-cooled flange; 6 is the three-pin; 7 is the ECR ion source; 8 is the T-shaped ceramic window; 9 is the cover flange; 10 is the T-shaped ion source chamber; 11 is the magnetic isolation ring; 12 is the ring magnet; 13 is the plasma electrode; 14 is the magnetic gasket; 15 is the tungsten target; 16 is the gas inlet pipe; 17-1 is the upper sealing ring; 17-2 is the lower sealing ring; 18 is the lead-out electrode; 19 is the deflection magnet; 20 is the pure zirconium target; 21 is the PEEK base; 22 is the water-cooled pipe; 23 is the pressure-resistant isolation ring; 24 is the magnet support. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Example

[0029] like Figure 1 As shown, an embodiment of the present invention provides a compact, highly stable ECR deuterium-deuterium neutron source device, comprising an ECR ion source section 1, a vacuum chamber section 2, a target base section 3, and external supporting (not shown) water cooling system, microwave system, high-voltage system, and gas supply system.

[0030] like Figure 2 and Figure 3 As shown, the ECR ion source consists of a waveguide 4, three pins 6, a T-shaped ion source chamber 10, a T-shaped ceramic window 8, a ring magnet 12, and a plasma electrode 13. The waveguide 4, three pins 6, and ion source chamber 10 are fixed with screws from top to bottom. The waveguide 4 is connected to an external microwave source, and microwaves are fed into the ion source chamber through a microwave transmission line. The three pins 6 adopt a ring-shaped water-cooling structure, which greatly removes the heat during microwave conduction and can match microwaves and plasma to minimize reflection. The T-shaped ion source chamber 10 is in a vacuum state. At the head of the T-shaped ion source chamber 10, there is a rubber ring sealing groove. The T-shaped ceramic window 8 is squeezed by the cover flange 9, so that the ceramic window fits tightly with the upper sealing ring 17-1. At the same time, the lower sealing ring 17-2 forms a sealed space between the two sealing rings due to the compression of the ceramic window. A water-cooling pipe is installed in this space to cool the ceramic window. The lower sealing ring 17-2 plays the role of isolating the vacuum inside the ion source. At the bottom of the T-shaped ceramic window is a protrusion from which microwaves can be transmitted. On the top of the protrusion, a cylindrical tungsten target 15 is welded. The tungsten target is open on one side and sealed on the other. The open side is directly welded to the inside of the ceramic window and works in conjunction with the internal micro water channels. The tungsten target 15 is used to block the bombardment of reverse electrons and increase the service life of the equipment.

[0031] A ring magnet 12 is fitted around the outside of the T-shaped ion source chamber 10. The magnet consists of three sets of N42 ring permanent magnets. The interlayer is separated by two non-magnetic magnet isolation rings 11. The purpose is to create a uniform magnetic field of 875 Gs inside the T-shaped ion source chamber 10. A water-cooling structure is provided inside the T-shaped ion source chamber 10 near the plasma. The plasma location is completely covered by a hollowed-out internal structure. This can reduce the temperature of the ion source chamber wall and prevent the permanent magnets from demagnetizing due to excessive temperature.

[0032] The plasma electrode 13 is made of aluminum, which can increase the excitation rate of electrons. At the same time, there are sealing ring rubber grooves on both the upper and lower surfaces of the plasma electrode. The upper part is sealed by a PEEK screw to press the T-shaped ion source chamber and the plasma electrode together to form a sealed space, and the lower part is sealed by a stainless steel screw to press the plasma electrode and the vacuum chamber together to form a sealed space.

[0033] like Figure 1As shown, the vacuum chamber part 2 is a cylindrical body (see stainless steel cylindrical chamber 2-4 in the figure). There is an observation window 2-3 and a molecular pump 2-1 on the side of the body. The upper flange part has two symmetrical holes for installing the observation window 2-3 and the vacuum gauge tube 2-2. The observation window 2-3 is used to observe the position of the ion source beam extraction and the intersection of the target and the PEK. It is sealed with a copper ring. At the flange connection between the molecular pump 2-1 and the side wall of the chamber, a polyethylene isolation flange is used to physically isolate the potential between the molecular pump and the chamber. The flange is mainly sealed by a sealing rubber ring.

[0034] like Figure 4 As shown, the target base 3 consists of a pure zirconium target 20, a deflecting magnet 19, an extraction electrode 18, and a PEek base 21. The extraction electrode 18 is made of 304 stainless steel, and its outlet is a concave spherical tube, which can form a good extraction magnetic field. The lower end of the extraction electrode has an internal thread, which can be directly fitted with the zirconium target. When the external high-voltage line is connected to the zirconium target, the zirconium target and the extraction electrode are at the same high voltage potential. During the operation of the system, a large number of secondary electrons will be generated on the target. The secondary electrons will bombard the T-shaped ceramic window 8 in the opposite direction, causing the ceramic window to break. Therefore, a deflecting magnet 19 is set inside the extraction electrode and installed on the magnet bracket 24. The zirconium target is internally cooled by water. Two water cooling pipes 22 and a high-voltage feed channel are opened on the PEek base. The outer side of the water cooling pipe is directly connected to the water chiller, and the inner side is formed by the zirconium target and the PEek base squeezing the rubber ring to form a sealed circuit inside the target.

[0035] Preferably, the lower part of the T-shaped ceramic window 8 inside the ion source has a cylindrical diameter of 20mm and a length of 12mm, which can maximize the feeding of microwaves and reduce microwave loss. At the same time, the tungsten target 15 has a diameter of 5mm, and its main function is to resist reverse electron bombardment and prevent the ceramic window from cracking.

[0036] Preferably, the distance between the plasma electrode and the extraction electrode is 25 mm. Simulation verification shows that this distance achieves optimal beam extraction.

[0037] Preferably, a pressure-resistant isolation ring 23 with a height of 20 mm is machined around the zirconium target. At this time, the closest distance between the innermost side of the peek ring and the zirconium target is 15 mm, which greatly increases the pressure resistance of the peek base.

[0038] Preferably, the water chiller uses fluorinated liquid as coolant, and its resistivity during operation can reach up to 19 MΩ / cm. Under the premise of ensuring the cooling effect of the zirconium target, it can withstand high voltage of more than 150KV.

[0039] 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 compact, highly stable ECR deuterium-deuterium neutron source device, characterized in that: It includes a vertically integrated ECR ion source, a vacuum chamber, and a target system, which are cascaded from top to bottom via a sealing flange; The ECR ion source consists of a microwave feed device and a plasma chamber system, including: a waveguide connected to a 2.45 GHz microwave source, with its bottom connected to an electrically driven triple pin; the electrically driven triple pin is located between the waveguide and the plasma chamber; the plasma chamber is a through-type T-shaped cylinder, which forms a vacuum seal through a T-shaped ceramic window and plasma electrodes; the plasma chamber is externally wrapped with three sets of permanent magnets to form an 875 Gs magnetic field to couple the 2.45 GHz microwave to excite the plasma; The vacuum chamber is made of stainless steel, with a molecular pump, observation window and vacuum gauge tube connected to the side wall. The upper and lower ends of the chamber are vacuum sealed to the ion source module and target system through flanges. The target system includes a PEEK base, a pure zirconium target, a deflection magnet, and an extraction electrode. The PEEK base has a high-voltage feed hole and a water-cooling inlet and outlet. The pure zirconium target is located on the PEEK base and is isolated by a sealing ring. The zirconium target is welded with a threaded cylindrical barrel to connect to the extraction electrode. The deflection magnet is installed inside the extraction electrode and is in close contact with the zirconium target to suppress secondary electrons.

2. The compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The T-shaped ceramic window is fixed by a cover plate flange and has two layers of sealing rings inside. The bottom ring isolates the vacuum, and the upper and lower rings form a sealed space as a water cooling channel.

3. The compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The T-shaped plasma chamber is equipped with a fully covered water-cooled pipe on the side facing the plasma.

4. The compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The plasma electrode is made of aluminum, with a horizontal shape facing the plasma side and a concave shape facing the lead-out electrode side.

5. A compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The permanent magnets are made of N42 material, and non-magnetic alloy isolation rings are provided between the magnets.

6. A compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The vacuum chamber has two observation windows on its side wall, which are respectively aligned with the lead-out electrode port and the zirconium target position.

7. A compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The upper part of the PEek base is recessed, and the pure zirconium target is embedded in the recessed part.

8. A compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The pure zirconium target has a finned heat dissipation structure on the back and two cylinders on the target surface. The inner cylinder blocks secondary electrons, and the outer cylinder has external threads to assemble the lead-out electrodes.

9. A compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The lead-out electrode is cylindrical, with a tapered inward top to form a beam focusing structure.

10. A compact, highly stable ECR deuterium-deuterium neutron source device according to claim 1, characterized in that, The bottom of the T-shaped ceramic window has a tungsten target welded on it to block reverse electron bombardment.

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