A combined gas injection method and system for divertor target plate heat load and impurity control

Abstract

The application discloses a combined gas injection method and system for controlling the heat load and impurities of a divertor target plate. ‑2 The combined gas injection method can effectively control the heat load peak value of the divertor target plate to be lower than 10 MWm ‑2 , i.e., the heat load peak value of the divertor target plate is effectively controlled to be below the engineering limit, so that the long-term stable operation of the divertor can be ensured; in addition, compared with the prior impurity control, the new impurities are easy to be introduced, and the effective control of the impurities cannot be achieved, the combined gas injection method can effectively control the edge effective charge peak value and the edge impurity particle density, the impurities at the edge are controlled to be at a lower level, and the adverse effects caused by the previous impurity injection are greatly reduced.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic confinement nuclear fusion, and in particular to a combined gas injection method and system for controlling thermal load and impurities in a divertor target plate. Background Art

[0002] Nuclear fusion is the process of light nuclei colliding and combining to form heavier nuclei, releasing energy. The conditions for achieving nuclear fusion reactions are extremely demanding, requiring a sufficiently high plasma density, high plasma temperature, and sufficient energy confinement time. In other words, the triple product of the fusion reaction must reach a sufficiently high level to ensure the continued occurrence of the nuclear fusion reaction and the subsequent release of large amounts of energy.

[0003] Taking the deuterium-tritium reaction as an example, the power triple product required for the fusion reaction is about 10 21 keV −3 To achieve this parameter requirement, all three factors must be maintained at relatively high levels. However, during the actual operation of a tokamak, once the plasma and heat flows diffuse from the core region, they bombard the device's materials. This can cause impurity particles to be sputtered from the wall material due to the particle and heat bombardment. These impurity particles collide and react with electrons and ions in the magnetic field confinement region, ionizing them into different valence states. These collisions deplete the energy of plasma ions and electrons, significantly detrimental to increasing the plasma temperature in the fusion triple product. Furthermore, impurities in the fusion reaction center produce radiation effects, which also deplete the energy of the central plasma, making it difficult to maintain the plasma temperature. Furthermore, the particle pressure in the core region of a tokamak is subject to a quantitative limit. Therefore, if excess impurities are transported to the core region along the magnetic field lines, they will encroach on the plasma pressure in the core region, making it difficult to maintain or further increase the plasma density. For this reason, tokamaks require that the impurity concentration within the device be maintained at a relatively low level.

[0004] The divertor, a key component in a tokamak, directs the particle and energy fluxes transported from the core to the edge region into regions away from the central plasma. This helps direct excess particles and heat away from the core, while also preventing impurities from flowing back into the core. However, as fusion device operating power levels increase, some impurities, both for reactor-level fusion devices and those operating at standard power levels, will still be transported to the core region and may even be unable to be effectively directed into the divertor region. This is extremely detrimental to maintaining low impurity levels in the device. In addition to impurities generated by the bombardment of materials with particle and heat fluxes, external impurity injection is often required to effectively mitigate the heat load deposited on the divertor target plate surface during high-power operation. This inevitably introduces impurities from outside, and impurities that effectively mitigate the heat flux in the divertor region are typically high-atomic-number impurities, such as nitrogen, neon, and argon. These externally introduced impurities are ionized into impurity ions of varying valences after radiation collisions. Some impurity ions are also transported along the magnetic field lines to areas closer to the core, or even directly into the core where the fusion reaction occurs. Therefore, impurity control in tokamaks, especially for fusion devices operating under high-power conditions, is a major scientific issue that needs to be addressed urgently.

[0005] Research has found that the adverse effects of impurities in tokamak devices are mainly manifested in the following aspects: (1) Excessive impurities will affect the plasma pressure and dilute the plasma in the core and base regions, affecting the plasma quality. The larger the impurity principle number, the deeper the fuel dilution in the base region. (2) The energy confinement factor, which represents the confinement level of the fusion device, is inversely proportional to the effective charge (which is one of the important parameters used to describe the edge impurity level). In other words, when the impurity level in the tokamak device is too high, it will directly affect the confinement performance of the plasma in the core, which is fatal for improving the discharge parameters of the device. In addition, the linear radiation effect generated by excessive impurities will affect the energy confinement in the core region, making it extremely difficult for the plasma to maintain a high temperature state. (3) The radiation inhomogeneity of impurity ions will lead to local temperature inhomogeneity of the plasma or reduced thermodynamic stability. (4) Excessive impurity injection may affect the current distribution and magnetic field structure in the plasma. (5) Impurities will cause erosion of the wall material, which will damage the inner wall of the device and affect the operation of the tokamak device. (6) Because impurities come from many sources and are subject to complex electromagnetic and hydrodynamic forces in plasma, excessive impurities make it more difficult to accurately locate the source of impurities and effectively control them, affecting the operation and maintenance of the tokamak device. (7) Impurity ions present in the tokamak device can seriously interfere with the signals of the diagnostic system, reducing the accuracy of measurements.

[0006] To address the above adverse effects, a variety of impurity control means have been developed, mainly including: (1) In the early tokamak device, a physical limiter is used to protect the inner wall of the device and reduce the impurities into the plasma. The limiter is usually made of graphite or other low-Z materials, which can absorb the impurities generated by the interaction of plasma and wall. Since the divertor configuration was proposed, impurity control can rely on divertor configuration technology, which is also a major progress in tokamak device impurity control. The presence of the divertor magnetic field topology introduces the plasma and all charged particles including impurity ions in the edge region of the device into the region far from the core, thereby reducing the impurities into the core region of the plasma, i.e. the region where fusion reactions occur. This special magnetic field structure design effectively reduces the impurities sputtered by the plasma particle flow and heat flow bombardment of the first wall. Further, for the divertor magnetic field topology, the way of optimizing the magnetic field configuration can reduce the deposition of impurity ions. (2) During the actual operation of the device, a series of inner wall condition optimization methods can be used to maintain the cleanliness and low impurity characteristics of the wall surface, or hydrogen or helium gas can be used for discharge cleaning and cleaning to remove impurities on the surface of the first wall material. This technology is mainly used before the start of the tokamak discharge, and the impurity level during the plasma discharge is reduced by this technology. In addition, RF heating can be used to reduce the impurities in the device, which can inject high-frequency electromagnetic waves into the plasma. This way will transfer energy to particles, especially low-energy electrons. These particles that obtain energy will move along the magnetic field lines and collide with impurities. This high-temperature ionization state makes it easier for impurities to be guided out by the divertor, thereby reducing the impurity concentration in the plasma. (3) By using high-quality materials, such as tungsten and beryllium-coated walls, these materials have a high melting point and low sputtering rate, so they can reduce impurity generation in high-temperature and high-radiation environments.

[0007] However, the above impurity control methods have certain limitations and uncontrollability, which are mainly manifested in the following aspects: (1) Although the emergence of the divertor magnetic field topology has achieved optimization in helping to achieve impurity diversion. However, with the increase in fusion power, this method is no longer sufficient to effectively control impurities at higher operating powers, especially for the case of external impurity injection. (2) Radio frequency heating and electron cyclotron resonance heating technologies rely on the energy coupling between electromagnetic waves and particles in the plasma (such as electrons). However, under certain plasma conditions, the energy of electromagnetic waves may not be effectively coupled into the plasma, resulting in reduced heating efficiency. This low coupling efficiency may lead to unsatisfactory expected impurity removal effects; in addition, radio frequency heating and electron cyclotron resonance heating are usually concentrated in a specific spatial region (such as the edge of the plasma or a local area). If the energy distribution is uneven, it may cause some areas in the plasma to be overheated, while other areas are not sufficiently cleared of impurities, affecting the overall plasma performance. Moreover, during the radio frequency heating process, high-frequency electromagnetic waves may interact with the inner wall material of the tokamak device, causing the wall material to sputter, thereby generating new impurities. This phenomenon may offset the effect of partially removing impurities or even introduce new types of impurities. RF heating and electron cyclotron resonance heating can overheat materials at the plasma edge, generating new impurities. For example, overheated carbon divertor material may release more carbon impurities, increasing the impurity concentration in the plasma. Intense RF heating and electron cyclotron resonance heating can lead to plasma instabilities, especially at high power levels. Excessive local heating can trigger unstable modes or plasma turbulence, affecting the overall confinement and stability of the plasma. In summary, current impurity control technologies introduce new impurities at high power levels, making effective impurity control difficult. Summary of the Invention

[0008] In order to solve the problem that existing impurity control technologies introduce new impurities and are difficult to achieve effective impurity control at high power operating levels, the present application provides a combined gas injection method and system for divertor target plate thermal load and impurity control. The present application adopts a combined gas injection method that can effectively control the impurity level in the edge area and reduce the adverse effects of impurity injection. At the same time, it can effectively control the peak thermal load of the divertor target plate below the engineering limit, thereby promoting the off-target operation of the divertor.

[0009] This application is implemented through the following technical solutions:

[0010] A combined gas injection method for controlling heat load and impurities in a divertor target plate, the combined gas injection method comprising:

[0011] Two gas injection ports are provided on the divertor, and impurities and deuterium gas are respectively injected through the two gas injection ports; the injected impurities are nitrogen, neon or argon.

[0012] In some embodiments, the two gas injection ports are each supplied with gas through a gas injection valve, and joint gas injection control of the two gas injection ports is achieved by controlling the opening and closing of the gas injection valve.

[0013] In some embodiments, the injection flow rates of the impurities and deuterium gas are (2.0-3.0)×10 20 s -1 and 1.0×10 20 s -1 .

[0014] In some embodiments, the combined gas injection method can effectively control the heat load of the divertor target plate to less than 10 MWm -2 level.

[0015] On the other hand, the present application also proposes a combined gas injection system for controlling the heat load and impurities of a divertor target plate. The combined gas injection system is used to implement the above-mentioned combined gas injection method. The combined gas injection system includes:

[0016] Two gas injection ports are provided on the divertor, namely a first gas injection port and a second gas injection port;

[0017] The first gas injection port is arranged on the outer baffle of the divertor near the exhaust port, and the second gas injection port is arranged at the divertor throat. The divertor throat is the entrance for transporting gas from the core to the edge area and further into the divertor area.

[0018] In some embodiments, each of the two gas injection ports is provided with a gas injection valve.

[0019] In some embodiments, the gas injection valve is a PEV-1 valve.

[0020] In some embodiments, the center position coordinates of the gas injection valve of the first gas injection port in the plane coordinate system are (3340.51, -3766.53), and the center position coordinates of the gas injection valve of the second gas injection port in the plane coordinate system are (3510.38, -2882.81), and the unit is mm.

[0021] In some embodiments, the gas injection direction of the first gas injection port is 300-330 degrees counterclockwise or 30-60 degrees clockwise relative to the positive direction of the X-axis in the plane rectangular coordinate system; the gas injection direction of the second gas injection port is 195-225 degrees counterclockwise or 135-165 degrees clockwise relative to the positive direction of the X-axis in the plane rectangular coordinate system.

[0022] In some embodiments, the two gas injection ports are sized to 1 / 4 the diameter of a bottom hole of a pipe thread.

[0023] Compared with the existing divertor geometry, the peak heat load can be controlled at 25 MWm -2 The present application proposes a combined gas injection method and system for controlling the thermal load and impurities of the divertor target plate. The combined gas injection method can effectively control the peak thermal load of the divertor target plate to less than 10MWm -2 level, that is, effectively controlling the thermal load peak of the divertor target plate below the engineering limit, preventing the divertor target plate material from exceeding the tolerable engineering limit level (thermal load level) during actual application of the device, thereby ensuring the long-term stable operation of the divertor; in addition, compared with the existing impurity control, which is easy to introduce new impurities and cannot achieve effective control of impurities, the present application adopts a combined gas injection method, which can effectively control the edge effective charge peak and the edge impurity particle density, and control the edge impurities at a lower level, greatly reducing the adverse effects of the previous impurity injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation of the embodiments of the present application. In the drawings:

[0025] Figure 1 Schematic diagram of the combined gas injection system proposed in an embodiment of the present application;

[0026] Figure 2 The heat load profile near the outer target plate of the divertor; (a) is the heat load profile before combined gas injection; (b) is the heat load profile after combined gas injection;

[0027] Figure 3 is the edge effective charge distribution diagram; among them, (a) is the edge effective charge distribution diagram when only impurity argon is injected from the first gas injection port; (b) is the edge effective charge distribution diagram when impurity argon and deuterium are jointly injected;

[0028] Figure 4 is the edge impurity particle density distribution diagram; among them, (a) is the edge impurity particle density distribution diagram when only impurity argon is injected from the first gas injection port; (b) is the edge impurity particle density distribution diagram when impurity argon and deuterium are jointly injected;

[0029] Reference numerals and corresponding component names:

[0030] 1-first gas injection port, 2-second gas injection port, 3-divertor inner target plate, 4-divertor outer target plate, 5-divertor inner baffle, 6-divertor outer baffle. DETAILED DESCRIPTION

[0031] Hereinafter, the terms "include" or "may include" as used in various embodiments of the present application indicate the presence of an invented function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. In addition, as used in various embodiments of the present application, the terms "include," "have," and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components, or combinations of the foregoing, and should not be understood as excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing or the possibility of adding one or more features, numbers, steps, operations, elements, components, or combinations of the foregoing.

[0032] In various embodiments of the present application, the expression "or" or "at least one of A or / and B" includes any or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0033] The expressions (such as "first", "second", etc.) used in the various embodiments of the present application may modify the various constituent elements in the various embodiments, but may not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used to distinguish one element from other elements. For example, a first user device and a second user device indicate different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of the present application, a first element may be referred to as a second element, and similarly, a second element may also be referred to as a first element.

[0034] It should be noted that when a component is described as being “connected” to another component, the first component may be directly connected to the second component, and a third component may be “connected” between the first and second components. Conversely, when a component is described as being “directly connected” to another component, it can be understood that there is no third component between the first and second components.

[0035] The terms used in the various embodiments of the application are only used to describe the purpose of specific embodiments and are not intended to limit the various embodiments of the application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meaning generally understood by those of ordinary skill in the art of the application. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having idealized meaning or too formal meaning, unless clearly defined in the various embodiments of the application.

[0036] In order to make the objectives, technical solutions and advantages of this application more clear, the present application is further described in detail below in conjunction with examples and drawings. The schematic implementation methods of this application and their descriptions are only used to explain this application and are not intended to limit this application.

[0037] Example 1

[0038] Existing impurity control technologies in tokamaks have certain limitations and uncontrollability. For example, optimizing the divertor configuration is difficult to achieve and may cause other parameters related to the plasma shape to fail to meet parameter requirements. New impurities introduced by radio frequency and electromagnetic wave injection, as well as excessive local heating, may trigger unstable modes or plasma turbulence, affecting the overall confinement and stability of the plasma. Furthermore, existing technologies rarely achieve off-target operation of the divertor while controlling impurity levels, thereby ensuring the long-pulse stable operation of the device. To address the above issues, this embodiment proposes a combined gas injection method for controlling the thermal load and impurity control of the divertor target plate. The combined gas injection method proposed in this embodiment uses two gas injection ports to inject impurities and deuterium respectively, and combines this with automatic control of the gas injection valve to achieve the required gas injection control. It should be noted that this embodiment can inject impurities such as nitrogen, neon, and argon. Argon has a better energy radiation effect based on its atomic and molecular properties, so this embodiment preferably injects the impurity argon.

[0039] Furthermore, the two gas injection ports were respectively supplied with PEV-1 valves, and the injection flow rates of impurities and deuterium gas were (2.0-3.0)×10 20 s -1 and 1.0×10 20 s -1 Preferably, the injection flow rate of impurity argon is 2.0×10 20 s -1The PEV-1 valve drive requirements are: voltage 0~100V DC, current <10μA‌, operating temperature range: +10°C~+60°C‌, electrical connection: using a standard BNC connector1, and response time: 2 microseconds.

[0040] Furthermore, the opening and closing of the gas injection valve (such as the PEV-1 valve) is automatically controlled by the automatic control system, thereby achieving corresponding joint gas injection control.

[0041] In order to realize the above-mentioned combined gas injection method, this embodiment also proposes a combined gas injection system for controlling the heat load and impurities of the divertor target plate, such as Figure 1 As shown, the combined gas injection system proposed in this embodiment includes two gas injection ports, namely a first gas injection port 1 and a second gas injection port 2, disposed on the divertor. The divertor primarily comprises an inner divertor target plate 3, an outer divertor target plate 4, an inner divertor baffle 5, and an outer divertor baffle 6. The first gas injection port 1 is located near the exhaust port of the outer divertor baffle 6 and injects impurities. The second gas injection port 2 is located at the divertor throat, defined as the inlet from the core to the edge region and further into the divertor region. The second gas injection port 2 injects deuterium. Furthermore, in a rectangular coordinate system, the coordinates of the PEV valve center position at the first gas injection port 1 are (3340.51, -3766.53), and the coordinates of the PEV valve center position at the second gas injection port 2 are (3510.38, -2882.81), both in mm.

[0042] Furthermore, the injection direction is calibrated according to a plane rectangular coordinate system, with the center of the two injection ports as the coordinate origin, the positive direction of the X-axis of the conventional rectangular coordinate system as 0 degrees, and other angles consistent with the conventional rectangular coordinate system. The injection direction of the first injection port 1 is 300-330 degrees counterclockwise or 30-60 degrees clockwise from the positive direction of the X-axis, and the injection direction of the second injection port 2 is 195-225 degrees counterclockwise or 135-165 degrees clockwise from the positive direction of the X-axis.

[0043] In this embodiment, the two gas injection ports, combined with the injection direction (angle), can achieve thermal load and impurity control for the fusion device under high-power operating conditions. In actual operation, the PEV valve can be made of rubber, and the valve's injection direction can be manually or automatically controlled.

[0044] Furthermore, the size (diameter) of the two gas injection ports is preferably 1 / 4 the diameter of the bottom hole of the pipe thread, which is approximately 11.46 mm.

[0045] Example 2

[0046] This embodiment uses an edge plasma simulation program (such as SOLPS) to simulate and evaluate the method and device proposed in the above embodiment. This embodiment takes the injection of impurity argon and deuterium as an example, and obtains Figure 2-Figure 4 The evaluation results are shown.

[0047] in, Figure 2 The figure shows the heat load cross section of the divertor outer target plate 4 (i.e., the heat load along the radial position of the divertor outer target plate 4, where the radial position of the outer target plate refers to the position on the left and right sides of the outer target plate with the impact point as the reference point or origin). Figure 2 In the figure, (a) is the heat load profile near the outer target plate 4 of the divertor before combined gas injection, and (b) is the heat load profile near the outer target plate 4 of the divertor after combined gas injection. Figure 2 It can be seen that the heat load near the divertor outer target plate 4 is reduced from the original maximum heat load of about 25MWm -2 Reduced to a maximum heat load of approximately 2.5 MWm -2 As can be seen, the combined gas injection method significantly reduces the heat load near the outer divertor target plate 4, effectively controlling the heat load of the divertor target plate in the fusion reactor, thereby promoting off-target operation of the divertor. It should be noted that the heat load near the outer divertor target plate is higher than the heat load near the inner divertor target plate. Therefore, this embodiment uses the heat load of the outer divertor target plate as an example for explanation. That is, if the heat load of the outer divertor target plate is effectively controlled, the heat load of the inner divertor target plate is also effectively controlled.

[0048] Figure 3 shows the edge effective charge distribution diagram, Figure 3 In the figure, (a) is the edge effective charge distribution diagram when only impurity argon is injected from the first gas injection port 1, and (b) is the edge effective charge distribution diagram when impurity argon and deuterium are jointly injected. Figure 3 It can be seen that when only impurities are injected, the peak value of the edge effective charge reaches 5.5; using the combined gas injection method, the peak value of the edge effective charge can be reduced to 4.0. In other words, the combined gas injection method can significantly reduce the edge effective charge.

[0049] Figure 4 shows the edge impurity particle density distribution diagram, Figure 4 In the figure, (a) is the edge impurity particle density distribution diagram when only impurity argon is injected from the first gas injection port 1, and (b) is the edge impurity particle density distribution diagram when impurity argon and deuterium are jointly injected. Figure 4 It can be seen that when only impurities are injected, the density of impurity particles at the edge is as high as 1E18m -3 ,like Figure 4 As shown in the black circle in (a), by using the combined gas injection method, the peak density of edge impurity particles can be reduced to 5E17 m-3 ,like Figure 4 As shown in the black circle in (b), the combined gas injection method can significantly reduce the density of edge impurity particles.

[0050] It can be seen from this that, under the same conditions, the combined gas injection method can significantly control edge impurities to a lower level, thereby effectively reducing the adverse effects of previous impurity injections. Furthermore, external injection of argon impurities is more likely to cause excessively high edge impurity levels, and backflow into the fusion core region is more likely to cause discharge flameout. Therefore, this embodiment uses argon impurities as an example, and the combined gas injection method can control edge impurities to a lower impurity level through the combined gas injection method, demonstrating the effectiveness of the combined gas injection method proposed in this embodiment of the present invention and its applicability to the effective control of other impurities.

[0051] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of this application. It should be understood that the above description is only the specific implementation methods of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A combined gas injection system for controlling heat load and impurities in a divertor target plate, characterized in that: The combined gas injection system comprises: Two gas injection ports are provided on the divertor, namely a first gas injection port and a second gas injection port; The first gas injection port is provided on the outer baffle of the divertor near the exhaust port, and the second gas injection port is provided at the divertor throat. The divertor throat is the entrance for gas transported from the core to the edge region and then further into the divertor region. The injection direction of the first gas injection port is 300-330 degrees counterclockwise or 30-60 degrees clockwise relative to the positive direction of the X-axis in the plane rectangular coordinate system; the injection direction of the second gas injection port is 195-225 degrees counterclockwise or 135-165 degrees clockwise relative to the positive direction of the X-axis in the plane rectangular coordinate system.

2. A combined gas injection system for controlling heat load and impurities in a divertor target plate according to claim 1, characterized in that: The two gas injection ports are respectively provided with a gas injection valve.

3. A combined gas injection system for controlling heat load and impurities in a divertor target plate according to claim 2, characterized in that: The gas injection valve is a PEV-1 valve.

4. The combined gas injection system for controlling heat load and impurities in a divertor target plate according to claim 1, characterized in that: The center position coordinates of the gas injection valve of the first gas injection port in the plane coordinate system are (3340.51, -3766.53), and the center position coordinates of the gas injection valve of the second gas injection port in the plane coordinate system are (3510.38, -2882.81), and the unit is mm.

5. A combined gas injection system for controlling heat load and impurities in a divertor target plate according to any one of claims 1 to 4, characterized in that: The size of the two gas injection ports is 1 / 4 of the diameter of the bottom hole of the pipe thread.

6. A combined gas injection method for controlling heat load and impurities in a divertor target plate, the combined gas injection method being implemented based on the combined gas injection system according to any one of claims 1 to 5, characterized in that: The combined gas injection method comprises: Two gas injection ports are provided on the divertor, and impurities and deuterium gas are respectively injected through the two gas injection ports; the injected impurities are nitrogen, neon or argon.

7. A combined gas injection method for controlling heat load and impurities in a divertor target plate according to claim 6, characterized in that: The two gas injection ports are respectively supplied with gas through a gas injection valve, and joint gas injection control of the two gas injection ports is achieved by controlling the opening and closing of the gas injection valve.

8. A combined gas injection method for controlling heat load and impurities in a divertor target plate according to claim 6, characterized in that: The injection flow rates of the impurities and deuterium gas are (2.0~3.0)×10 20 s -1 and 1.0×10 20 s -1 .

9. A combined gas injection method for controlling heat load and impurities in a divertor target plate according to any one of claims 6 to 8, characterized in that: The combined gas injection method can effectively control the heat load of the divertor target plate to less than 10MWm -2 level.

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