A neutral beam injection negative ion source high-energy exit electron protection device

Abstract

The application discloses a high-energy outgoing electron protection device for a neutral beam injection negative ion source, belongs to the field of the neutral beam injection negative ion source of magnetic confinement nuclear fusion, and mainly comprises a protection plate, a supporting base, a thermocouple and an infrared thermal imager. The protection plate is used for intercepting high-energy outgoing electrons. The supporting base is used for mounting and positioning the protection plate in a beam line vacuum chamber. The thermocouple is used for realizing real-time monitoring of the local temperature of the protection plate. The infrared thermal imager is used for observing a large-area heat source of the protection plate and determining the heat deposition position distribution of the high-energy outgoing electrons. The application realizes protection of heat load sensitive components such as a cryogenic pump by intercepting the high-energy outgoing electron beam and monitoring the deposition position of the high-energy outgoing electron beam, promotes the performance improvement and scheme perfection of an electron suppression means, is favorable for long-pulse stable operation of the negative ion source, and can effectively protect the high-energy outgoing electron in the neutral beam injection negative ion source.

Description

Technical Field

[0001] This invention belongs to the field of neutral beam injection negative ion sources for magnetic confinement nuclear fusion, and specifically relates to a high-energy electron emission protection device for neutral beam injection negative ion sources. Background Technology

[0002] Neutral beam injection (NBI) is a crucial method for injecting high-energy neutral particle beams into magnetic confinement fusion devices to heat plasma and drive plasma current. When the beam energy exceeds 100 keV, a negative ion source-based NBI system is necessary to achieve high neutralization efficiency and ensure sufficiently high neutral beam injection power. In the negative ion source, negative ions undergo stripping reactions with the background gas during acceleration, generating stray electrons, and collide with electrodes to generate secondary electrons. These electrons are further accelerated, reducing the electrical efficiency of the acceleration system and causing severe particle bombardment and thermal load on the acceleration system and its upstream and downstream components. This increases the risk of electrode arcing and thermal deformation, ultimately leading to a decrease in acceleration voltage and beam current, a shortened beam pulse width, and even safety accidents such as component damage. Installing magnets inside the accelerator can effectively reduce the number of stray electrons, but some electrons are still accelerated and emitted from the accelerator. These high-energy electrons can damage components within the beamline vacuum chamber, especially heat-sensitive cryogenic pumps, severely affecting the stable operation of the system. Therefore, it is necessary to protect this part of the high-energy emitted electrons to avoid damage to downstream components. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a high-energy emitted electron protection device for a neutral beam injected negative ion source. This device can intercept high-energy emitted electrons from the neutral beam injected negative ion source and measure the distribution of high-energy emitted electron deposition locations. It mainly consists of a protective plate, a support base, thermocouples, and an infrared thermal imager. The protective plate intercepts the high-energy emitted electrons; the support base is used for the installation and positioning of the protective plate within the beamline vacuum chamber; the thermocouples are used for real-time monitoring of the local temperature of the protective plate; and the infrared thermal imager is used for large-area heat source observation of the protective plate, clearly identifying the thermal deposition location distribution of high-energy emitted electrons. This invention, by intercepting the high-energy emitted electron beam and monitoring its deposition location, protects heat-sensitive components such as cryogenic pumps, promotes the improvement and refinement of electron suppression methods, facilitates the stable operation of long-pulse negative ion sources, and effectively protects high-energy emitted electrons in neutral beam injected negative ion sources.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A high-energy electron protection device for a neutral beam injected negative ion source includes a protective plate, a support base, thermocouples, and an infrared thermal imager. The protective plate is used to intercept high-energy electrons emitted from the accelerator. The support base is connected to the protective plate and is used to install and position the protective plate in the beamline vacuum chamber. The thermocouples are arranged on the protective plate to monitor the local temperature of the protective plate. The infrared thermal imager is aimed at the protective plate to observe the large-area heat source distribution on the surface of the protective plate.

[0006] Preferably, the protective plate is made of oxygen-free copper material and has an internal water-cooling channel embedded in the protective plate and connected to an external cooling water circulation system.

[0007] Preferably, the back of the protective plate is coated with a ceramic coating by plasma spraying, so that the surface emissivity is close to 1.

[0008] Preferably, the support base is made of 301 stainless steel and is connected to the protective plate by nuts.

[0009] Preferably, the support base includes two H-shaped steel columns, with reinforcing ribs between the two H-shaped steel columns, and the bottom of the support base is fixedly connected to the inner wall base of the wire harness vacuum chamber.

[0010] Preferably, the thermocouples are armored thermocouples, which are evenly arranged in the thermocouple mounting holes on the back of the protective plate, and the thermocouple measuring ends are attached to the surface of the protective plate by a combination of welding and bonding.

[0011] Preferably, the flexible wire of the thermocouple is integrated into the cooling water header of the protective plate.

[0012] Preferably, the infrared thermal imager has a thermal sensitivity of less than 50 mK and a temperature measurement range of -20 ℃ to 500 ℃.

[0013] Preferably, the temperature measurement parameters of the infrared thermal imager include an emissivity value corresponding to the ceramic coating on the back of the protective plate.

[0014] Preferably, the water cooling channel adopts a bottom-in, top-out cooling water flow structure, and the cooling medium is deoxygenated and deionized high-purity water.

[0015] Preferably, the thermocouples are armored thermocouples of different sizes, evenly distributed on the back of the protective plate, for real-time monitoring of surface temperature rise.

[0016] Beneficial effects:

[0017] This invention intercepts high-energy emitted electrons using a protective plate, and utilizes flowing water cooled in the water-cooling channels within the protective plate to remove the deposited heat, effectively protecting heat-sensitive components downstream of the accelerator (such as cryogenic pumps). Monitoring with thermocouples and infrared thermal imagers clarifies the deposition location and heat distribution of high-energy emitted electrons, promoting the improvement of electron suppression methods and solutions, and providing a reference for optimizing the heat exchange of the protective plate. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a high-energy emitted electron protection device for a neutral beam injected negative ion source according to the present invention.

[0019] Figure 2 This is a schematic diagram of the plasma-sprayed ceramic coating on the back of the protective plate of the present invention.

[0020] The attached diagram is labeled as follows: 1. Protective plate; 2. Support base; 3. Thermocouple; 4. Infrared thermal imager. Detailed Implementation

[0021] 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.

[0022] like Figure 1 As shown, the present invention provides a high-energy emitted electron protection device for a neutral beam injected negative ion source, used to intercept high-energy electrons emitted from an accelerator and to provide the thermal deposition distribution of high-energy emitted electrons, including a protective plate 1, a support base 2, a thermocouple 3, and an infrared thermal imager 4.

[0023] The protective plate 1 consists of an oxygen-free copper plate. The oxygen-free copper plate employs a steady-state water-cooled single-tube structure, with the single tube embedded within it. During beam extraction experiments using the negative ion source, the protective plate 1 is filled with deoxygenated and deionized high-purity water. This deoxygenated and deionized high-purity water circulates, absorbing electron energy and carrying away heat, resulting in excellent and uniform heat dissipation, and durability. The cooling water uses a bottom-in, top-out method. Using a water flow thermometry method, the power deposition of high-energy emitted electrons on the protective plate is measured based on the mass flow rate, duration, and temperature rise of the cooling water.

[0024] Preferably, the back of the protective plate 1 is treated with plasma spraying to blacken its surface, making its surface emissivity close to 1, which facilitates measurement by an infrared thermal imager. A schematic diagram of the ceramic coating sprayed on the surface is shown below. Figure 2 As shown.

[0025] The protective plate 1 and the support base 2 are connected by nuts. The two columns of the support base 2 are made of H-beams with excellent resistance to welding deformation. To ensure structural stability, a set of reinforcing ribs are provided between the H-beam columns. The bottom surface of the support base 2 is directly connected to the base on the inner wall of the wire harness vacuum chamber to realize the installation and positioning of the protective plate 1 in the vacuum chamber. The protective plate 1 is provided with several thermocouple mounting holes, and several thermocouples 3 are evenly distributed in the thermocouple mounting holes.

[0026] Thermocouple 3 employs a high-precision armored thermocouple, characterized by its wide measurement range, fast response speed, and strong stability, meeting the temperature monitoring requirements of the protective plate under complex operating conditions. Through a combination of welding and bonding, the measuring end of thermocouple 3 is tightly bonded to the surface of the oxygen-free copper plate, ensuring lossless heat transfer. The thermocouple wire is integrated into the cooling water header. This integration not only effectively protects the wire using the header's pipe structure, reducing interference from external factors, but also utilizes the cooling water flowing within the header to cool the wire, preventing aging and failure due to prolonged exposure to high temperatures. Thermocouples enable continuous and accurate monitoring of the localized temperature rise of the protective plate, providing data support for the safe and stable operation of the equipment.

[0027] The infrared thermal imager 4 is selected for its high resolution, high temperature measurement accuracy, and wide temperature measurement range. The emissivity of the coating material on the surface of the protective plate 1 to be observed is 0.95. Corresponding emissivity parameters are set in the imager to improve the accuracy of temperature measurement. By adjusting parameters such as focal length, contrast, and brightness of the infrared thermal imager 4, the thermal imaging image is made clear and layered. Furthermore, the infrared thermal imager 4 has real-time recording and data storage functions, facilitating subsequent data review and analysis, enabling large-area heat source observation of the protective plate, and clearly identifying the location distribution of high-energy emitted electron thermal deposition.

[0028] The above description of specific illustrative embodiments of the present invention is provided to enable those skilled in the art to understand the present invention. The present invention is not limited to the scope of the specific embodiments. For those skilled in the art, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-energy emitted electron protection device for a neutral beam injected negative ion source, characterized in that, It includes a protective plate, a support base, thermocouples, and an infrared thermal imager; the protective plate is used to intercept high-energy electrons emitted from the accelerator, the support base is connected to the protective plate and is used to install and position the protective plate in the beamline vacuum chamber, the thermocouples are arranged on the protective plate to monitor the local temperature of the protective plate, and the infrared thermal imager is aimed at the protective plate to observe the large-area heat source distribution on the surface of the protective plate.

2. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 1, characterized in that, The protective plate is made of oxygen-free copper and has an internal water-cooling channel that is embedded in the protective plate and connected to an external cooling water circulation system.

3. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 2, characterized in that, The back of the protective plate is coated with a ceramic coating using a plasma spraying process.

4. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 1, characterized in that, The support base is made of 301 stainless steel and is connected to the protective plate by nuts.

5. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 4, characterized in that, The support base includes two H-shaped steel columns, with reinforcing ribs between the two H-shaped steel columns. The bottom of the support base is fixedly connected to the inner wall base of the wire harness vacuum chamber.

6. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 1, characterized in that, The thermocouples are armored thermocouples, which are evenly arranged in the thermocouple mounting holes on the back of the protective plate. The thermocouple measuring ends are attached to the surface of the protective plate by a combination of welding and bonding.

7. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 6, characterized in that, The thermocouple's flexible wire is integrated into the cooling water header of the protective plate.

8. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 1, characterized in that, The infrared thermal imager has a thermal sensitivity of less than 50 mK and a temperature measurement range of -20 ℃ to 500 ℃.

9. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 3, characterized in that, The infrared thermal imager has an emissivity value set in its temperature measurement parameters that corresponds to the ceramic coating on the back of the protective plate.

10. The high-energy emitted electron protection device for a neutral beam injected negative ion source according to claim 2, characterized in that, The water cooling channel adopts a bottom-in, top-out cooling water flow structure, and the cooling medium is deoxygenated and deionized high-purity water.

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