Combined gas injection method and system for controlling thermal load and impurities of divertor target plate

Abstract

The invention discloses a divertor target plate thermal load and impurity control combined gas injection method and system, and the method comprises the steps: arranging two gas injection ports in a divertor, and respectively injecting impurities argon and deuterium gas through the two gas injection ports. The combined gas injection method is adopted, the thermal load peak value of the divertor target plate can be effectively controlled to be lower than 10 MWm <-2 >, in other words, the thermal load peak value of the divertor target plate is effectively controlled to be lower than the engineering limit, and therefore it is ensured that the divertor can stably run for a long time; besides, compared with existing impurity control which is easy to introduce new impurities and cannot realize effective control of the impurities, a combined gas injection mode is adopted, the peak value of the effective charge quantity at the edge and the particle density of the impurity at the edge can be effectively controlled, and the impurity at the edge is controlled at a lower level; and adverse effects caused by impurity injection in the prior art 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 of a divertor target plate. Background Art

[0002] Nuclear fusion is the principle of using light nuclei to collide and combine into heavier nuclei and release energy. The conditions for achieving nuclear fusion reactions are very harsh, requiring a sufficiently large plasma density, a sufficiently high plasma temperature, and a sufficiently long energy confinement time. That is, the triple product of the fusion reaction must reach a high enough level to ensure that the nuclear fusion reaction continues to occur and release a large amount of energy.

[0003] Taking the deuterium-tritium reaction as an example, the power triple product required for fusion reaction is about 10 21 VxF -3 To achieve this parameter requirement, the three factors must be maintained at a relatively high level as much as possible. However, in the actual operation of the tokamak device, once the plasma flow and heat flow diffuse out from the core area, they will bombard the material of the device to a certain extent. This will cause the wall material to sputter out impurity particles due to the bombardment of particles and heat flow. The impurity particles will collide and react with electrons and ions in the magnetic field confinement area and ionize into different valence states. On the one hand, this collision will lose the energy of plasma ions and electrons, which is extremely unfavorable for increasing the plasma temperature in the fusion triple product. In addition, since the impurities in the fusion reaction center will produce radiation effects, this radiation effect will also consume the energy of the central plasma, making it difficult to maintain the plasma temperature. On the other hand, the particle pressure in the core area of ​​the tokamak device has a quantitative limit. Therefore, if the excess impurities are transported to the core area along the magnetic field lines, they will occupy the plasma pressure in the core area of ​​the device, making it difficult to maintain or further increase the plasma density of the device. Based on this, in the tokamak device, the impurity concentration in the device is required to be maintained at a relatively low level.

[0004] As a key component in the tokamak device, the divertor has the main function of introducing the particle flow and energy flow transported from the core to the edge area into the area away from the central plasma, thereby helping to introduce excess particles and heat into the area away from the core, while ensuring that impurities are not easy to flow back to the core area. However, with the increase in the operating power level of the fusion device, for the operation of the reactor-level fusion device and the device at the general power level, some impurities will still be transported to the core area, and even cannot be effectively introduced into the divertor area. This is extremely unfavorable for maintaining the low impurity level of the device. In addition to the impurities generated by the bombardment of the material by the particle flow and the heat flow. Usually, in order to effectively reduce the heat load deposited on the surface of the divertor target plate during high-power operation, it is also necessary to use the external impurity injection method to enhance the radiation power level of the divertor area, so that impurities will inevitably be introduced from the outside, and in order to effectively reduce the impurities of the heat flow in the divertor area, the atomic number is usually relatively high, such as nitrogen, neon and argon. The impurities introduced from the outside will be ionized into impurity ions of different valence states after radiation collision. Among them, some impurity ions will also be transported along the magnetic field lines to areas closer to the core area, or even directly enter the core area where the fusion reaction occurs. Therefore, impurity control in the tokamak device, especially for fusion devices under high-power operating conditions, is a major scientific problem that needs to be solved urgently.

[0005] Research has found that the adverse effects of impurities in the tokamak device are mainly manifested in the following aspects: (1) Excessive impurities will affect the plasma pressure and dilute the plasma in the core and base areas, affecting the plasma quality. The larger the impurity principle number, the deeper the fuel dilution in the base area. (2) The energy confinement factor representing 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 the device to improve the discharge parameters. In addition, the linear radiation effect generated by excessive impurities will affect the energy confinement of the core area, making it extremely difficult for the plasma to maintain a high temperature state. (3) The radiation inhomogeneity of impurity ions will lead to uneven local temperature 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 wall material erosion, which will damage the inner wall of the device and affect the operation of the tokamak device. (6) Since there are many sources of impurities and impurities are subject to complex electromagnetic forces and fluid dynamics 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) The impurity ions present in the tokamak device will seriously interfere with the signal of the diagnostic system and reduce the accuracy of the measurement.

[0006] In response to the above-mentioned adverse effects, a variety of impurity control methods have been developed, mainly including: (1) In early tokamaks, physical limiters were used to protect the inner wall of the device and reduce the entry of impurities into the plasma. The limiter is usually made of graphite or other low-Z materials, which can absorb impurities generated by the interaction between the plasma and the wall. However, since the divertor configuration was proposed, impurity control can rely on the divertor configuration technology, which is also a major advancement in impurity control in tokamaks. The existence of the divertor magnetic field topology introduces the plasma in the edge area of ​​the device, including all charged particles such as impurity ions, into the area far away from the core, thereby reducing the entry of impurities into the core area of ​​the plasma, that is, the area where fusion reactions occur. This special magnetic field structure design effectively reduces the impurities generated by sputtering of the first wall of the device due to the bombardment of plasma particle flow and heat flow. Furthermore, with respect to the divertor magnetic field topology, the magnetic field configuration can be optimized to 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 gases can be used for discharge cleaning and washing to remove impurities on the surface of the first wall material. This technology is mainly used before the discharge of the tokamak device begins. This technology can reduce the impurity level during the plasma discharge. In addition, radio frequency heating can be used to inject high-frequency electromagnetic waves into the plasma to reduce impurities in the device. This method transfers energy to particles, especially low-energy electrons. These particles that gain energy will move along the magnetic lines and collide with impurities. This high-temperature ionization state makes it easier for impurities to be guided and removed by the divertor, thereby reducing the impurity concentration in the plasma. (3) Through the use of high-quality materials, such as tungsten and beryllium-plated wall surfaces, these materials have a higher 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) RF heating and electron cyclotron resonance heating technologies rely on the energy coupling between electromagnetic waves and particles (such as electrons) in the plasma. 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, RF 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 RF heating process, high-frequency electromagnetic waves may interact with the inner wall material of the tokamak device, resulting in sputtering of the wall material and the generation of 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 may cause the material in the edge region of the plasma to be overheated, generating new impurities. For example, overheated carbon divertor material may release more carbon impurities, which in turn increases the impurity concentration in the plasma. Intense RF heating and electron cyclotron resonance heating may cause plasma instability, especially under high-power conditions. Excessive local heating may induce unstable modes or plasma turbulence, affecting the overall confinement and stability of the plasma. In summary, current impurity control technology will introduce new impurities at high-power operating levels, making it difficult to achieve effective impurity control. Summary of the invention

[0008] In order to solve the problem that existing impurity control technologies will introduce new impurities and find it difficult to achieve effective control of impurities under high-power operation 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 value of the divertor target plate thermal load 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 arranged 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 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.

[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 being used to implement the combined gas injection method, and the combined gas injection system comprising:

[0016] Two gas injection ports are provided on the divertor, namely, gas injection port A and gas injection port B;

[0017] The gas injection port A is arranged on the outer baffle of the divertor near the exhaust port, and the gas injection port B is arranged at the throat of the divertor. The throat of the divertor is the entrance for transporting gas from the core to the edge area and further entering 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 gas injection port A in the plane coordinate system are (3340.51, -3766.53), and the center position coordinates of the gas injection valve of the gas injection port B 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 gas injection port A is 300-330 degrees counterclockwise or 30-60 degrees clockwise from the positive direction of the X-axis in the plane rectangular coordinate system; the gas injection direction of the gas injection port B is 195-225 degrees counterclockwise or 135-165 degrees clockwise from the positive direction of the X-axis in the plane rectangular coordinate system.

[0022] In some embodiments, the size of the two gas injection ports is 1 / 4 of the diameter of the bottom hole of the pipe thread.

[0023] Compared with the existing divertor geometry, the peak heat load can be controlled at 25MWm -2 The present application proposes a combined gas injection method and system for controlling the heat load and impurities of a divertor target plate. The combined gas injection method can effectively control the peak heat load of the divertor target plate to less than 10MWm -2 level, that is, to effectively control the thermal load peak of the divertor target plate below the engineering limit, so as to avoid the divertor target plate material exceeding the tolerable engineering limit level (thermal load level) during the actual application of the device, thereby ensuring the long-term and stable operation of the divertor; in addition, compared with the existing impurity control, it is easy to introduce new impurities and it is impossible to 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 impurities at the edge to a lower level, which greatly reduces the adverse effects of 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 on the embodiments of the present application. In the drawings:

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

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

[0027] Figure 3 is the edge effective charge distribution diagram; wherein (a) is the edge effective charge distribution diagram when only impure argon is injected from the gas injection port A; (b) is the edge effective charge distribution diagram when impure argon and deuterium are jointly injected;

[0028] Figure 4 : is the edge impurity particle density distribution diagram; wherein (a) is the edge impurity particle density distribution diagram when only impurity argon is injected from the gas injection port A; (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-gas injection port A, 2-gas injection port B, 3-divertor inner target plate, 4-divertor outer target plate, 5-divertor inner baffle, 6-divertor outer baffle. DETAILED DESCRIPTION

[0031] Hereinafter, the term "include" or "may include" used in various embodiments of the present application indicates the presence of the invented function, operation or element, and does 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 a combination of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items.

[0032] In various embodiments of the present application, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the words listed at the same time. 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 for the purpose of distinguishing one element from other elements. For example, the first user device and the 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, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

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

[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 meanings commonly understood by ordinary technicians in the field of the various embodiments 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 an idealized meaning or an overly formal meaning, unless clearly defined in the various embodiments of the application.

[0036] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with examples and drawings. The illustrative implementation scheme of the present application and its description are only used to explain the present application and are not intended to limit the present application.

[0037] Example 1

[0038] In the tokamak device, the existing impurity control technology has certain limitations and uncontrollability. For example, the optimization of the divertor configuration is not easy to achieve, and it may also cause other parameters related to the plasma shape to fail to meet the parameter requirements; new impurities brought by the injection of radio frequency waves and electromagnetic waves, and excessive local heating may cause unstable modes or plasma turbulence, affecting the overall confinement and stability of the plasma; in addition, the existing technology rarely can realize the off-target operation mode of the divertor while controlling the impurity level, and provide guarantees for maintaining the long-pulse stable operation of the device. In response to the above problems, this embodiment proposes a combined gas injection method for the thermal load and impurity control of the divertor target plate. The combined gas injection method proposed in this embodiment performs combined gas injection through two gas injection ports, injecting impurities and deuterium gas respectively, and combines the automatic control of the gas injection valve to achieve the corresponding gas injection control. It should be noted that this embodiment can inject impurities such as nitrogen, neon, and argon. Among them, according to the atomic and molecular properties, argon has a better energy radiation effect. Therefore, this embodiment preferably injects 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 -1Among them, the PEV-1 valve drive requirements are: voltage 0~100V DC, current <10μA, operating temperature range: +10℃~+60℃, electrical connection: standard BNC connector 1, 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 realizing the corresponding combined 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 arranged on the divertor, namely, gas injection port A1 and gas injection port B2, wherein the divertor mainly includes the divertor inner target plate 3, the divertor outer target plate 4, the divertor inner baffle 5 and the divertor outer baffle 6, etc. The gas injection port A1 is arranged at the position of the outer divertor baffle 6 close to the exhaust port, and the gas injection port A1 injects impurities. The gas injection port B2 is arranged at the divertor throat position, and the so-called divertor throat is defined as the entrance from the core to the edge area and further into the divertor area. The gas injection port B2 injects deuterium. Further, in the plane rectangular coordinate system, the PEV valve center position coordinates of the gas injection port A1 are (3340.51, -3766.53), and the PEV valve center position coordinates of the gas injection port B2 are (3510.38, -2882.81), both in mm.

[0042] Furthermore, the gas injection direction is calibrated according to a plane rectangular coordinate system, with the centers of the two gas injection ports as the coordinate origin, the positive direction of the X-axis of the conventional rectangular coordinate system as the 0 degree direction, and other angles are consistent with the conventional rectangular coordinate system. The gas injection direction of the gas injection port A1 is 300-330 degrees counterclockwise or 30-60 degrees clockwise from the positive direction of the X-axis, and the gas injection direction of the gas injection port B2 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 are provided as above, and combined gas injection is performed according to the gas injection direction (angle) to achieve the heat load and impurity control of the fusion device under high power operation conditions. In actual operation, the PEV valve can be made of rubber material, and the valve jet direction can be controlled manually or automatically.

[0044] Furthermore, the size (diameter) of the two gas injection ports is preferably 1 / 4 of 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 cross-sectional view of the heat load of the outer target plate 4 of the divertor is shown (i.e., the heat load along the radial position of the outer target plate 4 of the divertor, 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 striking 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 outer target plate 4 of the divertor is reduced from the original maximum heat load of about 25MWm -2 Reduced to a maximum heat load of about 2.5MWm -2 It can be seen that the combined gas injection method greatly reduces the heat load near the divertor outer target plate 4, and realizes the effective control of the heat load of the divertor target plate of the fusion reactor device involved, thereby promoting the off-target operation of the divertor. It should be noted that the heat load near the divertor outer target plate is higher than the heat load near the divertor inner target plate. Therefore, this embodiment takes the heat load of the divertor outer target plate as an example for explanation, that is, the heat load of the divertor outer target plate is effectively controlled, and the heat load of the divertor inner target plate is also effectively controlled accordingly.

[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 gas injection port A1, 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. That is, 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 gas injection port A1, 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 edge impurity particles 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 that, under the same other conditions, the combined gas injection method can significantly control edge impurities at a lower level, thereby effectively reducing the adverse effects of previous impurity injections. In addition, external injection of impurity argon will more easily lead to excessively high levels of edge impurities, and reflux to the fusion core area will more easily cause discharge flameout. Therefore, this embodiment takes argon impurities as an example, and the combined gas injection method can control edge impurities at a lower impurity level, indicating the effectiveness of the combined gas injection method proposed in the embodiment of the present invention, and can be applied to the effective control of other impurities.

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

Claims

1. A combined gas injection method for controlling heat load and impurities in a divertor target plate, characterized in that: The combined gas injection method comprises: Two gas injection ports are arranged 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.

2. A combined gas injection method 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 supplied with gas through a gas injection valve, and the joint gas injection control of the two gas injection ports is achieved by controlling the opening and closing of the gas injection valve.

3. A combined gas injection method for controlling heat load and impurities in a divertor target plate according to claim 1, 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 .

4. A combined gas injection method for controlling heat load and impurities in a divertor target plate according to any one of claims 1 to 3, 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.

5. A combined gas injection system for divertor target plate heat load and impurity control, characterized in that: The combined gas injection system is used to implement the combined gas injection method according to any one of claims 1 to 4, and the combined gas injection system comprises: Two gas injection ports are provided on the divertor, namely, gas injection port A and gas injection port B; The gas injection port A is arranged on the outer baffle of the divertor near the exhaust port, and the gas injection port B is arranged at the throat of the divertor. The throat of the divertor is the entrance for transporting gas from the core to the edge area and further entering the divertor area.

6. A combined gas injection system for controlling heat load and impurities in a divertor target plate according to claim 5, characterized in that: The two gas injection ports are respectively provided with a gas injection valve.

7. A combined gas injection system for controlling heat load and impurities in a divertor target plate according to claim 6, characterized in that: The gas injection valve adopts a PEV-1 valve.

8. A combined gas injection system for controlling heat load and impurities in a divertor target plate according to claim 5, characterized in that: The center position coordinates of the gas injection valve of the gas injection port A in the plane coordinate system are (3340.51, -3766.53), and the center position coordinates of the gas injection valve of the gas injection port B in the plane coordinate system are (3510.38, -2882.81), and the unit is mm.

9. A combined gas injection system for controlling heat load and impurities in a divertor target plate according to claim 5, characterized in that: The injection direction of the injection port A is 300-330 degrees counterclockwise or 30-60 degrees clockwise from the positive direction of the X-axis in the plane rectangular coordinate system; the injection direction of the injection port B is 195-225 degrees counterclockwise or 135-165 degrees clockwise from the positive direction of the X-axis in the plane rectangular coordinate system.

10. A combined gas injection system for controlling heat load and impurities in a divertor target plate according to any one of claims 5 to 9, 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.

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