Method for measuring reverse positive ion current of high-power negative ion source

Abstract

The invention discloses a high-power negative ion source reverse positive ion flow measurement method, and relates to the field of high-current ion source diagnosis, and the method comprises the steps: obtaining the cooling water flow and the cooling water temperature of each component of a high-power negative ion source; a specific backboard is designed and manufactured for reverse positive ion flow profile measurement; the real-time temperature rising value and flow of cooling water on the ion source component are measured, and heat deposition on each component is obtained through analysis; the temperature rise value and the flow of cooling water on each component under the beam extraction condition are measured, heat deposition on each component is analyzed, the power deposition change on the component bombarded by the reverse positive ion current when the beam extraction condition exists or not is compared and analyzed, and the reverse positive ion current power under the operation parameters is obtained; the negative ion source operation parameters are singly changed, the experiment is repeated, and the influence rule of the parameters on the reverse positive ion flow is obtained. According to the invention, a basis is provided for design optimization of the ion source expansion chamber back plate and the Faraday shield back plate and safe and stable operation of the high-power negative ion source.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of strong current negative ion source, in particular to a method for measuring the reverse positive ion current of a high-power negative ion source, which is used for accurately measuring the energy deposition distribution of the reverse positive ion current generated in the acceleration process of the high-energy negative ion beam, and providing technical support for the heat dissipation design optimization of the ion source and the safe operation of the fusion device. BACKGROUND

[0002] The neutral beam negative ion source includes a plasma generator and an accelerator, and the electrostatic acceleration system adopted accelerates the negative ions (H - / D - ) and the positive ions (H + / D + ) generated due to the collision of high-energy ions with background gas and stripping loss in the acceleration zone and returns them into the expansion chamber and the driver at the same time. The heavy heat burden of the high-energy positive ion flow on the back plate of the expansion chamber and the back plate of the Faraday shield poses a great challenge to the design and processing of the ion source. Meanwhile, the back plate of the expansion chamber and the back plate of the Faraday shield are bombarded by the reverse positive ion flow, which will splash some impurities, affecting the yield of negative hydrogen ions; the high-energy positive ion flow will also enter the expansion chamber, which will affect the yield of negative hydrogen ions by interacting with the electrons, positive and negative ions in the plasma of the expansion chamber, and on the other hand, the high-energy reverse positive ion flow will bombard the back plate of the expansion chamber, causing the cesium deposited thereon to evaporate again and enter the cesium cycle, causing a sudden change in the cesium atomic density, thereby causing a change in the extraction electron / negative ion ratio.

[0003] Therefore, during the extraction process of the long-pulse beam, the reverse positive ion flow has become a problem that cannot be ignored, and a suitable measurement method for the reverse positive ion flow of the strong current negative ion source is urgently needed. The existing measurement system can only obtain the average result of the energy deposition in the ion source components, cannot obtain the spatial distribution of the power density, is difficult to guide the local heat dissipation optimization, and cannot distinguish the energy deposition in different areas, resulting in design redundancy or local overheating risk. Profiling analysis of the reverse ion flow is a necessary condition for heat exchange improvement of the area components bombarded by the reverse ion flow of the high-power negative ion source. SUMMARY

[0004] In order to solve the problem that the traditional measurement system cannot distinguish the power density distribution on a single component, the present application provides a method for measuring the reverse positive ion current of a high-power negative ion source, which supports the profiling measurement of the reverse ion current on the back plate of the expansion chamber and the back plate of the Faraday cylinder, and provides a reliable measurement method for the energy deposition proportion analysis of the reverse positive ion current and the spatial distribution analysis in the components.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0006] A method for measuring reverse positive ion current of a high-power negative ion source, comprising:

[0007] An independent cooling inlet and return water path is designed according to measurement requirements;

[0008] The radio frequency power, air pressure, extraction voltage and filtering magnetic field current are fixed, the component energy deposition data of the high-power negative ion source in the beam extraction state are obtained under different acceleration voltages, the component energy deposition data obtained under the condition of no beam extraction are subtracted from the component energy deposition data as reference data, and the energy deposition data caused by the reverse positive ion current is obtained;

[0009] The air pressure, radio frequency power, acceleration voltage and filtering magnetic field current are fixed, the extraction voltage is changed alone, the reference data is subtracted, and the power deposition and power density distribution of the reverse positive ion current on the ion source component are measured;

[0010] The radio frequency power, extraction voltage, acceleration voltage and filtering magnetic field current are fixed, the air pressure is changed alone, the reference data is subtracted, and the power deposition and power density distribution of the reverse positive ion current on the ion source component are measured;

[0011] The air pressure, extraction voltage, acceleration voltage and filtering magnetic field current are fixed, the radio frequency power is changed alone, the reference data is subtracted, and the power deposition and power density distribution of the reverse positive ion current on the ion source component are measured;

[0012] The air pressure, radio frequency power, acceleration voltage and extraction voltage are fixed, the filtering magnetic field current is changed alone, the reference data is subtracted, and the power deposition and power density distribution of the reverse positive ion current on the ion source component are measured;

[0013] The proportion of the power deposition on the ion source component with respect to the change of different operating parameters is obtained, and the local heat exchange is optimized according to the measured deposition power and distribution.

[0014] Advantages:

[0015] 1、The present application realizes the measurement of the power density spatial distribution of the reverse positive ion current of the high-power negative ion source through the division and independent sensor layout of the cooling water path, the measurement unit adopted supports high-precision data acquisition and processing, and is suitable for long-pulse (>1000 s) operation scenarios; since the ion source works in a high-voltage condition, magnets that generate a field are installed in the Faraday cylinder and the back plate of the expansion chamber, on the one hand, there is not enough space to install a thermocouple, on the other hand, the magnetic field will reduce the measurement accuracy of the thermocouple, and the non-contact infrared measurement can avoid such problems.

[0016] 2. This invention designs and installs a one-dimensional CFC (carbon fiber) cylinder for the Faraday shield and expansion chamber backplate, and uses an infrared camera to analyze the energy distribution, thereby achieving cross-sectional analysis of the reverse positive ion flow and measurement of the energy deposition location. This provides a basis for optimizing the heat transfer of the expansion chamber backplate. The data update frequency is ≥50 Hz, meeting the real-time monitoring requirements, and can provide direct support for the heat dissipation design, fault warning, and life assessment of high-power negative ion sources. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the reaction process generated by the reverse positive ion flow in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the water flow thermal diagnostic system according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of carbon materials according to an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the measurement system according to an embodiment of the present invention;

[0021] Figure 5 This is a flowchart of the high-power negative ion source reverse positive ion current measurement method of the present invention. Detailed Implementation

[0022] 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.

[0023] like Figure 1 As shown, the radio frequency ion source consists of two parts: a plasma generator and an accelerator. A typical plasma generator structure mainly includes a driver (from outside to inside: coil, ceramic discharge chamber, and Faraday shield) and an expansion chamber. In the accelerator region, in addition to the electrostatic field between the electrodes affecting the trajectory of the reverse positive ions, the distribution of the magnetic field should also be considered. The magnetic field mainly comes from two parts: one is a filtering magnetic field to lower the electron temperature, and the other is a deflection magnetic field embedded in the extraction electrode (EG) to deflect electrons co-extracted with H-.

[0024] The plasma generated by the driver (i.e. Figure 1 The source plasma), after being extracted and accelerated by an accelerator, forms an ion beam (i.e., Figure 1 (The beam of plasma). The accelerator is conducting negative ion (H) - / D -The acceleration also causes positive ions generated by collision of high-energy ions with background gas and stripping loss in the acceleration region to be accelerated and returned into the expansion chamber and the driver (irremovable), and the high-energy positive ion flow brings heavy heat burden to the back plate of the expansion chamber and the back plate of the Faraday shield. The main mechanism of the reverse positive ion generation is electron stripping and ionization produced by collision of negative hydrogen ions with background neutral gas molecules, and the main reaction processes are as follows:

[0025] Stripping process: H - + H2→ H + + 2e + H2;

[0026] H - + H2→ H 0 + e + H2;

[0027] Ionization process: H - + H2→ H2 + + 2e + H 0 ;

[0028] H - + H2→ H + +2e + H2.

[0029] Figure 1 In the formula, PG represents a plasma grid, GG represents a grounded grid, and e represents an electron.

[0030] To solve the above technical problems, as shown in Figure 5 A method for measuring reverse positive ion flow of a high-power negative ion source according to the present application comprises the following steps:

[0031] Step 1: independent waterway design: the cooling waterway of the high-power negative ion source is divided into multiple independent channels (including channels of the expansion chamber sidewall, the expansion chamber back plate, the Faraday shield back plate and the Faraday shield sidewall), and each channel is equipped with an independent flow meter and a high-precision temperature sensor.

[0032] In the step 1, when the flow meter is selected, the following standards are considered: the accuracy is 0.5 level, the working environment temperature that can be supported is-10 ℃-80 ℃, the working pressure range is 0-2.5 MPa, the sampling rate of the flow acquisition module is 2 kHz, the resolution is 12 bit, the sampling rate of the temperature acquisition module is 50-1 kHz, the resolution is 12 bit, the thermocouple type is N type armored shell type, and the accuracy is better than ±0.5 ℃.

[0033] A measurement system was built to synchronously collect the flow rate and inlet and outlet water temperature rise values ​​of each channel through an embedded system. Assuming that all heat deposits on the components are carried away by the cooling water, the energy E deposited on the component (i.e., component energy deposition data) was calculated by using the mass of cooling water flowing through each component and the temperature curve of the cooling water over time.

[0034] (1)

[0035] Where m is the mass of cooling water passing through the component. This represents the temperature rise of the cooling water passing through this component. Let t be the specific heat capacity of water, and t be the time variable.

[0036] During the collection time of each shot Within, equation (1) can be transformed into:

[0037] (2)

[0038] In formula (2), the first term can be obtained by numerical integration of the temperature curve obtained from the experiment, and the second term is the sampling time per shot. The integral of the cooling water returning to its initial value can then be determined through data fitting evaluation.

[0039] Most components of a neutral beam injection heating system contain water-cooled channels. The heat load on the heat-bearing components of the system can be calculated by the temperature rise of the water flowing through these components. Figure 2 As shown, the water flow thermal diagnostic system mainly includes: a flow meter, a pressure gauge, a temperature sensor, a flow switch, an inlet valve, an outlet valve, a signal acquisition system, and corresponding data processing and analysis equipment (such as a computer). Cooling water in the water-cooling channel flows through the inlet valve and passes through the temperature sensor to obtain its initial temperature. It then flows to the heat-bearing components of the neutral beam injection heating system, sequentially passing through the pressure gauge, temperature sensor, flow switch, and flow meter, finally reaching the outlet valve. The data collected by the pressure gauge, temperature sensor, flow switch, and flow meter are transmitted to the computer via the signal acquisition system to calculate the temperature changes and corresponding heat deposition of the heat-bearing components of the neutral beam injection heating system.

[0040] To perform profile analysis of the reverse positive ion current, a special design is required for the expansion chamber backplate or the Faraday shield upper backplate. Specifically, blind holes are made in a specific distribution on the expansion chamber backplate or the Faraday shield upper backplate, and cylindrical one-dimensional carbon material is installed within each hole. Since the axial thermal conductivity of the one-dimensional carbon material is much greater than its radial thermal conductivity, the temperature at its tip can reflect the real-time temperature change of the backplate. Furthermore, its radial thermal conductivity is relatively low, effectively reducing measurement errors caused by radial heat transfer. Simultaneously, the one-dimensional carbon material has an emissivity close to 1, so its temperature can be clearly obtained from the background using an infrared imager. By measuring the temperature of the one-dimensional carbon material in plasma discharge mode and beam extraction mode, and using the plasma discharge mode as the background temperature, the profile distribution of the reverse ion current can be obtained by subtracting the values ​​from the measured temperature.

[0041] Step 2: Obtain the energy deposition values ​​on each component of the high-power negative ion source during beamless extraction, and use them as reference data, see formula (1) and formula (2). Fix the RF power, gas pressure, and extraction voltage, set a set of accelerating voltages, and subtract the energy deposition values ​​on each component of the high-power negative ion source under different accelerating voltages from the reference data to obtain the energy deposition caused by the reverse positive ion body under different accelerating voltages (i.e., Figure 5 The percentage of reverse positive ion energy deposition); combined with infrared imager measurements (i.e. Figure 5 (By cross-sectional analysis, the energy deposition distribution caused by the reverse positive ion body can be obtained.)

[0042] Step 3: Fix air pressure, accelerating voltage, radio frequency power, and filter magnetic field current (i.e., ... Figure 5 The PG current was used to obtain energy deposition values ​​on various components of the ion source during unguided extraction, which were then used as reference data. A set of ion source extraction voltages was set, and the energy deposition on each component of the ion source under different extraction voltages was subtracted from the reference data to obtain the trend of energy deposition caused by the reverse positive ion body as a function of extraction voltage; this was combined with the measurement results of the infrared imager (i.e., the PG current). Figure 5 (Profile analysis) can reveal the energy deposition distribution caused by the reverse positive ion body (i.e. Figure 5 The percentage of reverse positive ion energy deposition.

[0043] Step 4: Fix the RF power, extraction voltage, accelerating voltage, and filtered magnetic field current. Set a set of ion source gas pressures. Each time the gas pressure is changed, use the measurement results of the unguided extraction as reference data. Then, subtract the measurement results of the guided extraction at different gas pressures from the reference data to obtain the energy deposition caused by the reverse positive ion body at different gas pressures. Combine this with the measurement results of the infrared imager (i.e., Figure 5 (Profile analysis) can reveal the energy deposition distribution caused by the reverse positive ion body (i.e. Figure 5 The percentage of reverse positive ion energy deposition.

[0044] Step 5: Fix the gas pressure, extraction voltage, accelerating voltage, and filtered magnetic field current. Set a set of ion source powers. Each time the power is changed, use the measurement results of the unguided extraction as reference data. Then, subtract the measurement results of the guided extraction at different powers from the reference data to obtain the energy deposition caused by the reverse positive ion body at different powers. Combine this with the measurement results of the infrared imager (i.e., Figure 5 (Profiling analysis) can reveal the energy deposition distribution caused by the reverse positive ion body (i.e. Figure 5 The percentage of reverse positive ion energy deposition.

[0045] Step 6: Fix the gas pressure, radio frequency power, extraction voltage, and accelerating voltage. Set a set of ion source filtering magnetic field currents. Obtain the energy deposition values ​​on each component of the ion source when the filtering magnetic field current is 0, as reference data. Subtract the energy deposition on each component of the ion source under different filtering magnetic field currents from the reference data to obtain the energy deposition caused by the reverse positive ion body under different filtering magnetic field currents; combine this with the infrared imager measurement results (i.e., Figure 5 (Profiling analysis) can reveal the energy deposition distribution caused by the reverse positive ion body (i.e. Figure 5 The percentage of reverse positive ion energy deposition.

[0046] Step 7: Based on the measurement results, specifically enhance the cooling pipe design in high-load areas (i.e., obtain...) Figure 2 (High-power negative ion source with optimized heat exchange design).

[0047] Example:

[0048] In the implementation platform of this invention, the filtering magnetic field is generated by two sets of permanent magnets, located on both sides of the long side of the ion source diagnostic flange, and embedded in the bottom of the flange. The distance between the two sets of magnets is 210 mm, and the distance to the plasma electrode is 55 mm. Each magnet has the same three-dimensional dimensions (120 mm × 40 mm × 10 mm) and is made of Sm2Co. 17 The remanence of the magnets at their center is set to 1 T at the factory. Each set of magnets is installed within a non-ferromagnetic backplate frame for fixation. This magnetic field will affect H. + The trajectory.

[0049] The water flow thermal diagnostic system installed on the implementation platform of this invention, such as Figure 3As shown, the flow meters are installed inside the return water header. To enable real-time observation of the flow rate in each water path from the control room, all flow meters are equipped with remote data transmission capabilities, allowing for real-time monitoring both on-site and in the control room. Considering the complex electromagnetic interference and 1 MHz RF (radio frequency) interference present in the flow meter's operating environment, all flow meters are selected as differential pressure flow meters with strong anti-interference capabilities. The temperature rise of the cooling water is measured by installing thermocouples at the inlet and outlet, and the temperature rise data is obtained by differential calculation. Additionally, to monitor the cooling water pressure on-site, pressure gauges are installed on the inlet and return water headers, facilitating real-time observation of the cooling water pressure status from both the control room and the field.

[0050] The high-power negative ion source reverse positive ion current measurement method in this embodiment includes:

[0051] Step 1: By designing the water channels of the expansion chamber and the Faraday shield, the water channels of the back panel and side wall of the expansion chamber are separated, and the side wall of the Faraday shield is separated from the back panel.

[0052] The cooling water flow rates at the rear panel and side walls of the expansion chamber, and the side walls and rear panel of the Faraday shield were measured respectively. Simultaneously, the temperature rise of the inlet and outlet water for these four cooling water lines was measured; that is, energy deposition at these four locations was measured using a water flow thermal method. The upper back panel of the expansion chamber and the upper back panel of the Faraday shield underwent optimized design, such as... Figure 4 As shown, a one-dimensional carbon material is provided. (As...) Figure 4 As shown, one-dimensional carbon material is distributed on the upper back plate of the expansion chamber. ​ The circles in the image represent the locations of carbon materials, and the distribution of energy deposition locations can be measured using an infrared camera.

[0053] Step 2: Fix the RF power source power at 50 kW. In plasma mode, measure the energy deposition at four locations (back panel and sidewalls of the expansion chamber, and sidewalls and back panel of the Faraday shield). Obtain reference data in plasma mode (without beam extraction). In beam extraction mode, use an infrared camera to measure the infrared images of the energy distribution on the back panel of the expansion chamber and the upper back panel of the Faraday shield. By subtracting from the reference data, the temperature distribution caused by the reverse positive ion current bombardment can be determined, which reflects the cross-sectional distribution of the reverse positive ion current. Keep the RF power source output power and discharge pulse width constant, turn on the extraction power supply (-7 kV) and accelerating power supply (-150 kV), and set the beam extraction time to 10 s. Starting from -80 kV, measure the energy deposition and temperature distribution in each component under 8 accelerating voltage conditions in 10 kV increments. The difference from the reference data is the energy deposition and distribution generated by the reverse positive ion current under different accelerating voltages.

[0054] Step 3: Measure the temperature rise curves of the cooling water under different extraction voltages, perform numerical integration on the obtained temperature rise curves, and combine this with the flow rate of each cooling water stream to obtain the deposition energy. Obtain the energy distribution using an infrared camera. The reference data is the same as in Step 2. By subtracting this data, the energy deposition and distribution generated by the reverse positive ion current under different accelerating voltages can be obtained.

[0055] Step 4: With the extraction voltage, RF power, and filtering magnetic field unchanged, adjust the gas intake of the high-power negative ion source to change the neutral gas molecule density in the electrode acceleration region, and evaluate the effect of the ion source intake volume on the reverse positive ion current. At a certain accelerating voltage, adjust the ion source intake volume, the amount of which is read from a gas mass flow meter connected in series in the gas path, and adjust the discharge pressure upwards from 0.3 Pa in steps of 0.1 Pa. Analyze the infrared image to obtain the temperature distribution.

[0056] Step 5: Fix the air pressure, extraction voltage, acceleration voltage, and filter magnetic field current, set a set of ion source power, and obtain the changes in energy deposition and temperature distribution in each component of the high-power negative ion source under different radio frequency power.

[0057] Step 6: Fix the air pressure, radio frequency power, extraction voltage, and accelerating voltage. Set a set of ion source filtering magnetic field currents. Obtain the energy deposition values ​​on each component of the ion source when the filtering magnetic field current is 0, and use this as reference data. Subtract the energy deposition on each component of the high-power negative ion source under different filtering magnetic field currents from the reference data to obtain the energy deposition caused by the reverse positive ion body under different filtering magnetic field currents. Combined with the measurement results of the infrared imager, the energy deposition distribution caused by the reverse positive ion body can be obtained.

[0058] Step 7: Based on the obtained power deposition ratio and energy density distribution results, optimize the heat exchange design of cooling pipes in high-load areas, such as the expansion chamber backplane and Faraday shield backplane. For example, if excessive deposition power or overly concentrated heat distribution is found, indicating excessive heat in the component, it indicates a need to enhance heat exchange to dissipate heat. Therefore, conventional methods for enhancing heat exchange can be used as optimization approaches. For instance, increasing the water flow rate in the component's cooling pipes or increasing the number of cooling pipes can enhance heat exchange and reduce heat deposition. Alternatively, changing the material of the cooling pipes—currently copper water pipes—could be improved by plating the water pipes with molybdenum to enhance heat exchange and reduce heat deposition.

[0059] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes will be obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A method for measuring the reverse positive ion current of a high-power negative ion source, characterized in that, include: Design independent cooling water inlet and outlet circuits according to measurement requirements; With fixed RF power, gas pressure, extraction voltage, and filter magnetic field current, the component energy deposition data of the high-power negative ion source under beam extraction state is obtained under different acceleration voltages. The difference between the component energy deposition data obtained under no-beam extraction conditions and the reference data is obtained to obtain the energy deposition data caused by the reverse positive ion current. With fixed gas pressure, radio frequency power, accelerating voltage, and filtered magnetic field current, the extraction voltage is changed only, and the difference is made with the reference data to measure the power deposition and power density distribution of the reverse positive ion current on the ion source component. With fixed RF power, extraction voltage, accelerating voltage, and filtered magnetic field current, the gas pressure was changed only, and the difference was made with reference data to measure the power deposition and power density distribution of the reverse positive ion current on the ion source component. With fixed gas pressure, extraction voltage, accelerating voltage, and filtered magnetic field current, the radio frequency power is changed individually, and the difference is calculated with reference data to measure the power deposition and power density distribution of the reverse positive ion current on the ion source component. With fixed gas pressure, radio frequency power, accelerating voltage, and extraction voltage, the filter magnetic field current is changed only, and the difference is made with the reference data to measure the power deposition and power density distribution of the reverse positive ion current on the ion source component. The variation of the power deposition ratio on the ion source component with different operating parameters was obtained, and the local heat transfer was optimized based on the measured deposition power and its distribution.

2. The method for measuring the reverse positive ion current of a high-power negative ion source according to claim 1, characterized in that, The deposition power on different components is distinguished based on the temperature rise value of different water channels.

3. The method for measuring the reverse positive ion current of a high-power negative ion source according to claim 2, characterized in that, The backplate of the expansion chamber or the backplate of the Faraday shield of the high-power negative ion source is provided with one-dimensional carbon material, which reflects the deposition position of radio frequency power on the ion source component, thereby obtaining the power density distribution of the reverse positive ion current.

4. The method for measuring the reverse positive ion current of a high-power negative ion source according to claim 2, characterized in that, Based on the mass of the cooling water passing through the component, the temperature rise of the cooling water passing through the ion source component, and the specific heat capacity of water, the component energy deposition data is calculated within the acquisition time of each shot.

5. The method for measuring the reverse positive ion current of a high-power negative ion source according to claim 4, characterized in that, The formula for calculating the component energy deposition data E is: （1） Where m is the mass of cooling water passing through the component. This represents the temperature rise of the cooling water passing through the component. Let t be the specific heat capacity of water, and t be the time variable. During the collection time of each shot Inside, equation (1) is transformed into: （2） In formula (2), the first term is obtained by numerical integration of the temperature curve obtained from the experiment, and the second term is the sampling time per shot. Afterwards, the integral of the cooling water returning to its initial value is determined through data fitting evaluation.

6. The method for measuring the reverse positive ion current of a high-power negative ion source according to claim 1, characterized in that, With fixed gas pressure, radio frequency power, accelerating voltage, and filtered magnetic field current, the extraction voltage is changed only, and the difference is calculated with reference data. When measuring the power deposition and power density distribution of the reverse positive ion current on the ion source component, only one reference data is used.

7. The method for measuring the reverse positive ion current of a high-power negative ion source according to claim 4, characterized in that, With fixed RF power, extraction voltage, accelerating voltage, and filtered magnetic field current, and by simply changing the gas pressure, the power deposition and power density distribution of the reverse positive ion current on the ion source component are measured. Reference data are reacquired under beamless conditions every time the gas pressure is changed.

8. The method for measuring the reverse positive ion current of a high-power negative ion source according to claim 5, characterized in that, With fixed gas pressure, extraction voltage, accelerating voltage, and filtered magnetic field current, and by simply changing the radio frequency power, the power deposition and power density distribution of the reverse positive ion current on the ion source component are measured. Each time the radio frequency power is changed, reference data is reacquired under beam-free conditions.

9. A method for measuring the reverse positive ion current of a high-power negative ion source according to claim 6, characterized in that, With fixed gas pressure, radio frequency power, accelerating voltage, and extraction voltage, the filter magnetic field current is changed only to measure the power deposition and power density distribution of the reverse positive ion current on the ion source component. Reference data is reacquired under beam-free conditions each time the filter magnetic field current is changed.

10. A method for measuring the reverse positive ion current of a high-power negative ion source according to claim 3, characterized in that, One-dimensional carbon materials are cylindrical.

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