A method of offline analysis of powder ionization conditions

Abstract

This application discloses a method for offline analysis of powder ionization conditions, comprising the following steps: placing a silicon wafer on a target plate of a plasma device; generating a plasma beam under preset powder ionization conditions using the plasma device; injecting powder into the plasma device so that the plasma beam bombards the powder until powder injection is complete; detecting whether a first condition and a second condition are met, wherein the first condition includes at least 70% of the powder injected into the plasma device ablation and brightening upon bombardment by the plasma beam and / or forming a coating on the silicon wafer; the second condition includes the coating containing chemical bonds formed by elements of the powder and / or detecting spectral lines generated by ionization of the powder upon bombardment by the plasma beam. If the first and second conditions are met, the powder is determined to be effectively ionized. Otherwise, the powder is determined to be ineffectively ionized. The method of this application can obtain basic research data on the boronization of boron powder.

Description

Technical Field

[0001] This application relates to the field of controlled nuclear fusion, and more particularly to a method for offline analysis of powder ionization conditions. Background Technology

[0002] Impurity suppression and particle recirculation are important research directions for the high-parameter and steady-state operation of tokamak reactors. In the physics experiments of tokamak nuclear fusion devices, plasma impurities mainly originate from the interaction between the plasma and the first wall. The presence of impurities causes a significant loss of radiative energy, affecting the plasma energy balance and leading to plasma cooling or even extinguishing. Boration technology, as a wall treatment method to suppress high-Z impurities such as metals and carbon and oxygen, has been applied in major devices worldwide. After a certain number of discharges, the boron film prepared by the widely used glow discharge boration technology tends to corrode or become saturated, thus necessitating additional boration treatment on the inner wall of the fusion vacuum chamber. Real-time boron powder boration, as a supplement or alternative to glow discharge boration technology, does not require interruption of the discharge continuity. Currently, the feasibility of implementing solid-state boron powder boration technology has been confirmed internationally in high-parameter discharge fusion devices operating in high-confinement models (H-mode). However, for fusion devices with lower operating parameters, on the one hand, their low discharge parameters may not be sufficient to completely ionize the boron powder. On the other hand, even if the boron powder injected in the initial stage is completely ablated and ionized during a single powder injection process, it will still cause a drop in the local electron temperature of the plasma and radiative cooling. This may prevent the subsequent injection of boron powder from being effectively ionized, thereby posing a risk of contamination of the fusion device chamber by unablated boron powder. Therefore, it is particularly important to determine offline under what plasma parameters the boron powder can be effectively ionized before conducting boron powder injection experiments on the fusion device.

[0003] In the boronizing process, high-purity boron powder is used as the boron source. Solid boron powder is injected into the high-temperature plasma of the fusion device. The boron powder ablates and dissociates under the action of the plasma, and then a boron film is grown on the inner wall of the fusion device by physical deposition. This film suppresses impurities in the inner wall material, preventing them from entering the central plasma. Linear plasma devices can obtain long-pulse, highly stable, and diverse high-density, low-temperature plasmas. They are characterized by adjustable parameters, simple operation, low operating costs, and good repeatability. They are suitable for simulating the plasma environment of the boundary region of a fusion device and are currently an effective means of studying plasma-material interaction (PMI). Summary of the Invention

[0004] This application provides a method for offline analysis of powder ionization conditions, which can realize the analysis of powder ionization conditions, such as the analysis of boron powder ionization conditions, in order to obtain basic data and patterns to guide boronization experiments of boron powder carried out on fusion devices.

[0005] In a first aspect, embodiments of this application provide a method for offline analysis of powder ionization conditions, comprising the following steps: placing a silicon wafer on a target plate of a plasma device; generating a plasma beam under preset powder ionization conditions using the plasma device; injecting powder into the plasma device so that the plasma beam bombards the powder until powder injection is complete; detecting whether a first condition and a second condition are met. The first condition includes at least 70% of the powder injected into the plasma device ablation and brightening upon bombardment by the plasma beam and / or forming a coating on the silicon wafer. The second condition includes the coating containing chemical bonds formed by elements of the powder and / or detecting spectral lines generated by ionization of the powder upon bombardment by the plasma beam. If the first and second conditions are met, the powder is determined to be effectively ionized. Otherwise, the powder is determined to be ineffectively ionized, thus achieving the analysis of powder ionization conditions.

[0006] In some embodiments, powder is injected into the plasma device while the deviation between the plasma beam and the powder ionization conditions remains within a preset range for a preset time.

[0007] In some embodiments, the grayscale of a preset area on a photograph of the powder injected into the plasma device ablation and shines when the powder is bombarded by the plasma beam is obtained, and the grayscale is substituted into a pre-established comparison table of grayscale and powder ablation and shine ratio, to detect whether at least 70% of the powder injected into the plasma device ablates and shines when bombarded by the plasma beam.

[0008] In some embodiments, visible light spectroscopy is used to detect the spectral lines generated when the powder is ionized during bombardment by a plasma beam. X-ray photoelectron spectroscopy is used to detect whether the coating contains chemical bonds formed by elements of the powder.

[0009] In some embodiments, a filter screen is installed at the pump assembly connection of the plasma device before the plasma device generates a plasma beam under preset powder ionization conditions to prevent powder from being drawn into the pump assembly.

[0010] In some embodiments, after the filter screen protection device is installed, the edges of the filter screen protection device are sealed with insulating tape that can withstand at least 500°C.

[0011] In some embodiments, powder is injected into the plasma device via a powder injection device that is sealed and mounted on top of the plasma device, allowing the powder to fall freely into the plasma device.

[0012] In some embodiments, the base vacuum pressure of the plasma device and the powder injection device is evacuated to 10 before powder injection. -4 Pa level.

[0013] In some embodiments, the plasma beam is stopped within a preset time after powder injection is completed to avoid the plasma beam directly bombarding the silicon wafer.

[0014] In some embodiments, when the plasma beam is a hydrogen plasma beam, the density of the hydrogen plasma beam is 10. 18 m -3 The flux is 10 23 m -2 *s -1 When the plasma beam is a helium plasma beam or an argon plasma beam, the density of the helium plasma beam or argon plasma beam is 10. 19 m -3 The flux is 10 24 m -2 *s -1 The electron temperature of the plasma device is 1–2 eV. When the plasma beam is an argon plasma beam, the bias voltage of the plasma device is -20V. When the powder is boron powder, the particle size of the boron powder is 70 μm. The boron powder injection rate is 15 mg / s. The boron powder injection time is 2 s.

[0015] A method for offline analysis of powder ionization conditions according to an embodiment of this application includes the following steps: placing a silicon wafer on a target plate of a plasma device; generating a plasma beam under preset powder ionization conditions using the plasma device; injecting powder into the plasma device so that the plasma beam bombards the powder until the powder injection is complete; and detecting whether a first condition and a second condition are met. The first condition includes at least 70% of the powder injected into the plasma device ablation and brightening upon bombardment by the plasma beam and / or forming a coating on the silicon wafer. The second condition includes the coating containing chemical bonds formed by elements of the powder and / or detecting spectral lines generated by ionization of the powder upon bombardment by the plasma beam. If the first and second conditions are met, the powder is determined to be effectively ionized. Otherwise, the powder is determined to be ineffectively ionized, thus achieving the analysis of powder ionization conditions. The method of this application can realize the analysis of powder ionization conditions, such as the analysis of boron powder ionization conditions, thereby obtaining basic research data on boronization of boron powder, effectively guiding the boronization technology of fusion devices, and avoiding the risk of contamination of the vacuum environment of fusion devices due to incomplete ionization of boron powder. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the plasma device in an embodiment of this application;

[0018] Figure 2 These are images captured by a high-speed camera after powder injection in Embodiment 1 of this application;

[0019] Figure 3 This is an image of the coating on the silicon wafer in Embodiment 1 of this application;

[0020] Figure 4 , 5 The image shows the X-ray photoelectron spectrum of the coating in Embodiment 1 of this application.

[0021] Figure 6 This is an image captured by a high-speed camera after powder injection in Embodiment 2 of this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] See Figure 1-6 This application provides an embodiment of a method for offline analysis of powder ionization conditions. The powder used is a powder that can form a coating through ionization, such as boron powder or lithium powder. The method includes the following steps:

[0024] The first step is to place a silicon wafer 2 on the target plate 10 of the plasma device 1.

[0025] In the above steps, plasma device 1 can be a linear plasma device. Silicon wafer 2 can be a blank silicon wafer, that is, a pure silicon wafer with no other material on its surface except silicon, so as to facilitate the analysis of the composition of the coating formed on silicon wafer 2 in subsequent steps.

[0026] The above steps may further include sealing and installing a powder injection device 3 on the top of the plasma device 1, allowing powder to fall freely into the plasma device 1 in subsequent steps. The powder injection device 3 can be installed via a flange. Specifically, the powder injection device 3 can be a controllable powder injection device to control the injection speed and time of the powder.

[0027] The above steps may also include installing a filter screen at the pump assembly connection 11 of the plasma device 1 to prevent powder from being drawn into the pump assembly. It should be noted that the filter screen can shield the smallest particles in the powder; for example, if the powder is boron powder with a particle size of 50-100 μm, the filter screen can shield boron powder particles as small as 50 μm.

[0028] Furthermore, after the filter screen protection device is installed, its edges can be sealed with insulating tape that can withstand at least 500°C. The 500°C is determined by the temperature at the 11 points connecting the pump unit during the experiment. The insulating tape, which can withstand at least 500°C, can be polyimide tape.

[0029] The second step is to cause the plasma device 1 to generate a plasma beam under preset powder ionization conditions.

[0030] In the above steps, the preset powder ionization conditions may include plasma source power, working gas type, gas flow rate, output power, and magnetic field strength, so as to generate different plasma beams by adjusting plasma source power, working gas type, gas flow rate, output power, and magnetic field strength.

[0031] When the plasma beam is a hydrogen plasma beam, the density of the hydrogen plasma beam can be 10. 18 m -3 The flux can be 10 23 m -2 *s -1 When the plasma beam is a helium plasma beam or an argon plasma beam, the density of the helium plasma beam or argon plasma beam can be 10. 19 m -3 The flux can be 10 24 m -2 *s -1Additionally, the electron temperature of plasma device 1 can be 1–2 eV. When the plasma beam is an argon plasma beam, the bias voltage of the plasma device is -20V. The reason for setting the bias voltage is that when the plasma beam is an argon plasma beam, the temperature of the plasma beam at the target plate needs to be very high to effectively ionize the powder. Therefore, a bias voltage is set to attract the plasma beam, accelerate it, and heat it, thereby making the temperature of the plasma beam at the target plate very high, reaching 20 eV.

[0032] The third step is to inject powder into plasma device 1 so that the plasma beam bombards the powder until the powder injection is complete.

[0033] In the above steps, powder can be injected into the plasma device when the deviation between the plasma beam and the powder ionization conditions remains within a preset range for a preset time. Maintaining the deviation within the preset range for the preset time can mean maintaining the same order of magnitude as the powder ionization conditions within 10 minutes; for example, the preset flux of the plasma beam in the powder ionization conditions is 2 × 10⁻⁶. 23 m -2 *s -1 If the actual flux of the plasma beam within 10 minutes is 1×10 23 ~3×10 23 m -2 *s -1 If the flux fluctuates within a certain range, meaning it remains on the same order of magnitude as the preset flux within 10 minutes, then it is considered that the deviation from the powder ionization conditions remains within the preset range within the preset time.

[0034] In the above steps, powder can be injected into the plasma device through the powder injection device 3, which is sealed and installed on the top of the plasma device 1, so that the powder falls freely into the plasma device 1, and the injection speed and injection time of the powder can be controlled.

[0035] When the powder is boron powder, the particle size can be 50-100 μm, preferably 70 μm. The boron powder injection rate can be 10-20 mg / s, preferably 15 mg / s. The boron powder injection time can be 1-3 s, preferably 2 s. The above conditions are based on the following assumption: all injected boron powder is deposited in the form of pure boron (mass density 2.46 g*cm³). -3 ), uniformly on the first wall surface of the fusion device (40m) 2 The coating is achieved. Under the above conditions, the injection rate is 10 mg / s. -1 It is possible to achieve boron films at 1 nm*s -1Growth (for pure boron, 1 nm corresponds to ~5 monolayers). The above calculations show that at an implantation rate of 10 mg / s... -1 With an injection time of 1-3 seconds, a single injection can achieve the growth of several nanometer-sized monolayers on the first wall of the fusion device, as expected.

[0036] Furthermore, before injecting the powder, the background vacuum pressure of the plasma device 1 and the powder injection device 3 can be evacuated to 10. -4 Pa level.

[0037] In the above steps, the plasma beam can be stopped within a preset time after powder injection to avoid the plasma beam directly bombarding the silicon wafer 2, thereby preventing damage to the coating on the silicon wafer 2. The preset time can be the operator's reaction time, that is, the plasma beam is stopped immediately after powder injection.

[0038] The fourth step is to check whether the first and second conditions are met. The first condition includes at least 70% of the powder in the injected plasma device 1 ablation and brightening upon bombardment by the plasma beam and / or the formation of a coating on the silicon wafer 2. The second condition includes the presence of chemical bonds formed by elements of the powder in the coating composition and / or the detection of spectral lines generated by the ionization of the powder upon bombardment by the plasma beam. If both conditions are met, the powder is determined to be effectively ionized. Otherwise, the powder is determined to be ineffectively ionized, thus completing the analysis of the powder ionization conditions.

[0039] In the above steps, preferably, the first condition includes at least 70% of the powder in the plasma injection device 1 ablation and brightening when bombarded by the plasma beam, and the formation of a coating on the silicon wafer 2. The second condition includes the presence of chemical bonds formed by the elements of the powder in the composition of the coating, and the detection of spectral lines generated by the ionization of the powder when bombarded by the plasma beam. If the first and second conditions are met, that is, if the following four conditions are satisfied: "at least 70% of the powder in the plasma injection device 1 ablation and brightening when bombarded by the plasma beam," "a coating is formed on the silicon wafer 2," "the composition of the coating contains chemical bonds formed by the elements of the powder," and "spectral lines are detected by the ionization of the powder when bombarded by the plasma beam," then the powder is determined to be effectively ionized. Otherwise, the powder is determined to be ineffectively ionized.

[0040] In the above steps, the grayscale of a preset area on a photograph of the powder injected into the plasma device 1 when it ablates and shines when bombarded by the plasma beam can be obtained, and the grayscale can be substituted into a pre-established comparison table of grayscale and powder ablation and shine ratio to detect whether at least 70% of the powder injected into the plasma device 1 ablates and shines when bombarded by the plasma beam.

[0041] Specifically, a high-speed camera can be used to capture images of the powder injected into plasma device 1 as it ablates and glows when bombarded by a plasma beam. The grayscale values ​​of a preset region on the image can be obtained using existing image processing and analysis software. The preset region can be the area within the bombardment diameter of the plasma beam.

[0042] In the above steps, visible light spectroscopy can be used to detect the spectral lines generated when the powder is ionized during bombardment by a plasma beam. X-ray photoelectron spectroscopy (XPS) can be used to detect whether the coating contains chemical bonds formed by the elements of the powder. When the powder is boron powder, the chemical bonds formed by the elements of the powder are BB bonds.

[0043] In the above steps, quantitative analysis is achieved by detecting whether the first condition "at least 70% of the powder in the plasma injection device 1 ablates and shines when bombarded by the plasma beam" is met. Quantitative and qualitative analysis are achieved by detecting whether the first condition "a film is formed on the silicon wafer 2" is met. Qualitative analysis is achieved by detecting whether the second condition "the composition of the film contains chemical bonds formed by the elements of the powder" is met. Qualitative analysis is achieved by detecting whether the second condition "spectral lines generated by ionization of the powder when bombarded by the plasma beam" is met. This makes the method of this application scientific and accurate.

[0044] The technical solution and beneficial effects of this application are further illustrated below with reference to the embodiments.

[0045] Example 1

[0046] See Figure 2-5 This embodiment provides a method for offline analysis of boron powder ionization conditions, including the following steps:

[0047] We offer an SCU-PSI linear plasma array for boron powder ionization experiments. This array utilizes a three-cathode DC cascaded arc discharge plasma source with a maximum input power of 80kW, producing high-efficiency and stable plasma beams. It is equipped with an advanced plasma diagnostic system, including an OES, Langmuir probe, emission spectrometer, and laser interferometer, achieving a vacuum level of up to 10... -4 The pressure is in the Pa range, and the working pressure is 1 to 10 Pa.

[0048] A controlled powder injection device is installed on top of the linear plasma apparatus via a flange seal. A blank silicon wafer is placed on the target plate of the linear plasma apparatus.

[0049] The linear plasma device is set at a vacuum level of 10. -4Under Pa-level conditions, using argon as the working gas, and with a magnetic field strength of 0.34 T, an arc voltage of 110 V, and an arc current of 180 A, an ion flux and electron density of 10 were generated. 24 m -2 s -1 and 10 19 m -3 An argon plasma beam is applied, and a -20V bias voltage is simultaneously applied to the target plate. The specific settings parameters of the linear plasma device are shown in Table 1.

[0050] Table 1

[0051]

[0052] After the plasma beam stabilizes, powder is injected into the plasma device through the powder injection device. At the same time, the injection time and injection rate of the powder are precisely controlled by the signal generator connected to the powder injection device. The specific injection parameters of boron powder are shown in Table 2.

[0053] Table 2

[0054]

[0055] After the powder injection begins, the morphological changes of the powder in the plasma beam are observed through an observation window using a high-speed camera. Figure 2 Images captured by a high-speed camera after powder injection, from Figure 2 The images clearly show boron powder falling freely into the vacuum chamber of the linear plasma device. Under the influence of the plasma beam, the trajectory of the falling boron powder deviates towards the target plate, and then the boron powder interacts with the target plate. Furthermore, high-speed camera observations show that most of the boron powder ablates and glows after interacting with the plasma beam. The plasma beam is immediately stopped after the powder injection is complete.

[0056] The silicon wafer was removed from the target plate, and the coating on the silicon wafer was analyzed. Figure 3 Images of coatings on silicon wafers, from Figure 3 The effective growth of the coating on the silicon wafer can be clearly seen, and XPS analysis of the coating is performed. Figure 4 , 5 The XPS analysis graph of the coating is shown below. Figure 4 , 5 It can be seen that there are BB, BO and BC bonds in the coating, and the content of element B is about 33%.

[0057] In summary, under the boron powder ionization conditions in Table 1, most (>70%) of the injected boron powder was observed to ablate and shine under the action of the plasma beam, and a film was successfully deposited on the silicon wafer. Moreover, the film contained boron chemical bonds. Therefore, it can be concluded that the formation of the film originated from the ionization and deposition of the boron powder. Under the boron powder ionization conditions in Table 1, the boron powder was effectively ionized.

[0058] Example 2

[0059] See Figure 6 The only difference between this embodiment and Embodiment 1 is that no bias voltage is applied to the target plate and the ion temperature is different. The specific settings parameters of the linear plasma device are shown in Table 3.

[0060] Table 3

[0061]

[0062]

[0063] Figure 6 Images captured by a high-speed camera after powder injection, from Figure 6 The data clearly shows that boron powder falls freely into the vacuum chamber of the linear plasma device. Under the influence of the plasma beam, the trajectory of the boron powder deviates towards the target plate, and then the boron powder interacts with the target plate. Furthermore, when the boron powder acts on a target plate without bias, its morphology remains essentially unchanged. Therefore, it can be concluded that under the boron powder ionization conditions in Table 3, the boron powder is not effectively ionized.

[0064] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0065] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of analysing powder ionisation conditions offline, characterised in that, The method comprises the following steps: placing a silicon wafer on a target plate of a plasma device; causing the plasma device to generate a plasma beam under preset powder ionization conditions; injecting powder into the plasma device so that the plasma beam bombards the powder until the powder injection is completed; detecting whether a first condition and a second condition are met; wherein the first condition comprises that at least 70% of the powder injected into the plasma device is ablated and / or forms a coating on the silicon wafer when the plasma beam bombards the powder; the second condition comprises that the coating contains chemical bonds formed by elements of the powder and / or spectral lines generated by the powder when the plasma beam bombards the powder are detected; if the first condition and the second condition are met, it is determined that the powder is effectively ionized; otherwise, it is determined that the powder is not effectively ionized, and the analysis of the powder ionization conditions is achieved; The density of the hydrogen plasma beam is 10 18 m -3 , and the flux is 10 23 m -2 *s -1 ; the density of the helium plasma beam or the argon plasma beam is 10 19 m -3 , and the flux is 10 24 m -2 *s -1 . the electron temperature of the plasma device is 1-2 eV; when the plasma beam is an argon plasma beam, the bias voltage of the plasma device is -20 V; when the powder is boron powder, the particle size of the boron powder is 70 μm; the injection rate of the boron powder is 15 mg / s; and the injection time of the boron powder is 2 s.

2. The method of claim 1, wherein when the deviation of the plasma beam and the powder ionization conditions is kept within a preset range within a preset time, powder is injected into the plasma device.

3. The method of claim 1, wherein by obtaining the gray scale of a preset area on a photo of the powder injected into the plasma device when the powder is ablated and brightened when the plasma beam bombards the powder, and substituting the gray scale into a pre-established contrast table of gray scale and powder ablation and brightening ratio, it is detected whether at least 70% of the powder injected into the plasma device is ablated and brightened when the plasma beam bombards the powder.

4. The method of claim 1, wherein by visible spectrum detection, spectral lines generated by the powder when the plasma beam bombards the powder are detected; by x-ray photoelectron spectroscopy, it is detected whether the coating contains chemical bonds formed by elements of the powder.

5. The method of claim 1, wherein before causing the plasma device to generate a plasma beam under preset powder ionization conditions, a filter protection device is installed at the pump group communication of the plasma device to prevent the powder from being sucked into the pump group.

6. The method of claim 5, wherein after the installation of the filter protection device is completed, the edges of the filter protection device are sealed with an insulation tape that can withstand at least 500°C.

7. The method of claim 1, wherein powder is injected into the plasma device through a powder injection device sealed and installed on the top of the plasma device, so that the powder freely falls into the plasma device.

8. The method of claim 7, wherein, The base vacuum pressure of the plasma device and the powder injection device is drawn to 10 -4 The order of magnitude of Pa.

9. The method of claim 1, wherein, stopping the plasma beam at a preset time after the powder injection is completed to avoid direct bombardment of the silicon wafer by the plasma beam.

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