A method and system for evaluating particle size parameters of microparticle accumulation

Abstract

The present invention relates to a method and system for evaluating the particle size parameters of microparticle deposits. The method comprises the following steps: irradiating the surface of a microparticle deposit with a pulsed laser to induce the generation of a laser plasma; capturing a particle jet formed by acceleration of the laser plasma flow field; analyzing the captured particle jet to obtain a particle jet velocity or kinetic energy parameter; obtaining a particle diameter based on the obtained particle jet velocity or kinetic energy parameter to obtain a corresponding relationship between the particle jet velocity and the particle size parameter of the microparticle deposit; and using the particle jet velocity as an observable probe to evaluate the particle size parameter information of the microparticle deposit. The present invention uses the particle jet velocity as an observable probe for the particle size parameter of the microparticle deposit, enabling rapid, in-situ, and remote monitoring of the particle size parameter of the microparticle deposit.

Description

Technical Field

[0001] The present invention relates to the fields of laser plasma application and field research technology, and in particular to a method and system for evaluating particle size parameters of micro-particle accumulations. Background Art

[0002] In industrial production and field research, the problem of in-situ remote measurement of particle size is a common problem. A recent example that has attracted much attention is the Vulcan Mars rover's navigation and terrain camera, which was tasked with capturing the unique aeolian landforms on Mars in situ. When analyzing these images, surface particle size is one of the key parameters to be extracted. It is worth noting that the images acquired by the Vulcan Mars rover's navigation and terrain camera using remote sensing technology only have millimeter accuracy in identifying surface particle size. This limited resolution means that directly using remote sensing images cannot quantitatively obtain information on the surface microparticle size corresponding to fine aeolian landforms in the field.

[0003] Since the images obtained by existing remote sensing technology can only identify the surface particle size with millimeter accuracy, it is impossible to quantitatively obtain the information on the surface microparticle size corresponding to the fine sand landform area in the field. Therefore, there is an urgent need for a method that can realize in-situ remote measurement of microparticle size. Summary of the Invention

[0004] In order to overcome the problem that the images obtained by the above-mentioned existing remote sensing technology have only millimeter accuracy in identifying the surface particle size, and are unable to quantitatively obtain information on the surface microparticle size corresponding to the fine sand landform area in the field, the present invention provides a method and system for evaluating the particle size parameters of microparticle deposits. A beam of pulsed laser is used as an aid to first drive the generation of a particle jet, and then a camera is used to remotely monitor the macroscopically visible particle jet, thereby constructing a new method for in-situ evaluation of the particle size parameters of microparticle deposits. The method of evaluating the particle size parameters of microparticle deposits by monitoring the laser-driven particle jet has the characteristics of rapid, in-situ, and remote sensing monitoring.

[0005] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0006] A method for evaluating particle size parameters of microparticle accumulation comprises the steps of:

[0007] S10. irradiating the surface of the microparticle accumulation with a pulsed laser to induce the generation of laser plasma;

[0008] S20. Capturing the particle jet accelerated by the laser plasma flow field;

[0009] S30. Analyzing the captured particle jet to obtain particle jet velocity or kinetic energy parameters;

[0010] S40. Obtaining the particle diameter according to the obtained particle jet velocity or kinetic energy parameter to obtain the corresponding relationship between the particle jet velocity and the particle size parameter of the microparticle accumulation;

[0011] S50. Use the particle jet velocity as an observable probe to evaluate the particle size parameter information of the microparticle accumulation.

[0012] Furthermore, as a preferred technical solution, the pulse laser is a focused pulse laser, which is provided by a LIBS system, or is output by a pulse laser with fixed parameters and formed after passing through a focusing lens.

[0013] Furthermore, as a preferred technical solution, the microparticle accumulation is formed by the accumulation of microparticles of different particle sizes.

[0014] Furthermore, as a preferred technical solution, the particle jet is captured by a high-speed camera, and step S20 is specifically as follows:

[0015] A high-speed camera was used to capture the particle jets generated on the surface of microparticles of different sizes and accelerated by the laser plasma flow field.

[0016] Furthermore, as a preferred technical solution, step S30 is specifically as follows:

[0017] The captured particle jet is analyzed to obtain the particle jet velocity or kinetic energy parameters corresponding to the surface of microparticle accumulation of different particle sizes.

[0018] Furthermore, as a preferred technical solution, the kinetic energy parameters include:

[0019] The average impact force felt by the particles in the particle jet captured by the high-speed camera in the flow field, the cross-sectional area of ​​the particles felt by the impact force captured by the high-speed camera in the particle jet, the mass of the particles captured by the high-speed camera in the particle jet, and the particle velocity captured by the high-speed camera in the particle jet.

[0020] Furthermore, as a preferred technical solution, step S40 specifically includes:

[0021] According to the pressure relationship and the law of conservation of momentum, combined with the particle jet velocity or kinetic energy parameters corresponding to the surface of micro-particle deposits of different particle sizes, the particle diameter is obtained to obtain the corresponding relationship between the particle jet velocity and the particle size parameters of the micro-particle deposits.

[0022] Furthermore, as a preferred technical solution, the particle diameter is obtained by the following relationship:

[0023] F∝A;

[0024] A∝d 2 ;

[0025] mv∝F∝d 2 ;

[0026] v∝1 / d;

[0027] From the above relationship, it can be seen that there is an inverse relationship between the particle jet velocity and the particle size parameter of the microparticle accumulation;

[0028] Where: F∝A represents the force acting on the particles in the flow field based on the flow field resistance model; F represents the average impact force felt by the particles in the particle jet captured by the high-speed camera in the flow field; A represents the cross-sectional area of ​​the particles in the particle jet captured by the high-speed camera that feel the impact force; d represents the diameter of the particles in the particle jet captured by the high-speed camera; m represents the mass of the particles in the particle jet captured by the high-speed camera; and v represents the velocity of the particles in the particle jet captured by the high-speed camera.

[0029] Furthermore, as a preferred technical solution, the acquisition of the particle jet velocity specifically includes:

[0030] The particle jet velocity is obtained by calculating the change in the particle jet tip position recorded by a high-speed camera over time using imaging methods.

[0031] A system for evaluating particle size parameters of a microparticle accumulation, comprising:

[0032] A pulse laser and a focusing lens are used to provide focused pulse laser light to irradiate the surface of microparticle accumulations of different particle sizes and generate laser plasma through laser ablation;

[0033] A high-speed camera is used to capture and record the particle jet formed by acceleration through the laser plasma flow field;

[0034] The calculation module uses imaging methods to calculate the change in the position of particles in the particle jet recorded by the high-speed camera over time, calculates the velocity of the particles in the particle jet captured by the high-speed camera, obtains the particle jet velocity, and fits the relationship between the particle jet velocity and the particle size;

[0035] Among them, the microparticle deposit is composed of microparticles of different particle sizes and is used to generate laser plasma under the irradiation of focused pulsed laser.

[0036] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0037] The present invention uses the particle jet velocity as an observable probe of the particle size parameters of micro-particle deposits, which can quickly, in situ, and remotely monitor macroscopically visible particle jets, thereby constructing a new method for in situ evaluation of the particle size parameters of micro-particle deposits. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the flow chart of the particle size evaluation method of micro-particle accumulation corresponding to the present invention.

[0039] Figure 2 This is a graph showing the relationship between the tip velocity of the particle jet and the particle size parameters of the microparticle accumulation of the present invention.

[0040] Figure 3 This is a simplified diagram of the application scenario of a system for evaluating particle size parameters of micro-particle accumulation according to the present invention.

[0041] The accompanying drawings are for illustrative purposes only and should not be construed as limitations on this patent. To better illustrate this embodiment, some components of the accompanying drawings may be omitted, enlarged, or reduced in size and do not represent the actual dimensions of the product. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted from the accompanying drawings. The same or similar reference numerals correspond to the same or similar components. The terms describing positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limitations on this patent. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby more clearly defining the protection scope of the present invention.

[0043] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent.

[0044] In addition, if terms such as "first" and "second" are used for descriptive purposes only, they are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components, and cannot be understood as indicating or implying relative importance.

[0045] Example 1

[0046] In order to overcome the problem that images obtained by existing remote sensing technology can only identify surface particle size with millimeter accuracy and cannot quantitatively obtain information on the surface microparticle size corresponding to fine sandy landform areas in the wild, this embodiment provides a method for evaluating the particle size parameters of microparticle deposits. A beam of pulsed laser is used as an aid to first drive the generation of a particle jet, and then a camera is used to remotely monitor the macroscopically visible particle jet, thereby constructing a new method for in-situ evaluation of the particle size parameters of microparticle deposits. This method of evaluating the particle size parameters of microparticle deposits by monitoring the laser-driven particle jet has the characteristics of rapid, in-situ, and remote sensing monitoring.

[0047] It should be noted that the surface layer of fine aeolian sand is composed of discrete microparticles with sizes ranging from tens to hundreds of microns. When an intense pulsed laser interacts with the surface of a granular deposit with a certain porosity, the following physical processes occur: the particles irradiated by the laser melt and vaporize, forming a transient laser plasma that flows at high speed in an upward direction perpendicular to the target surface. Due to the presence of pores, the laser plasma generation site penetrates below the surface of the particle target. Due to the pressure gradient of the laser plasma flow field, the surface particles enclosed in the laser plasma flow field are directly accelerated by the laser plasma flow field perpendicular to the target surface and are ejected from the target surface at a specific speed (typically several to several hundred meters per second) along the direction of the laser plasma flow. Over time, the ejected particles form a particle jet whose density is easily identifiable macroscopically even at millimeter-scale sizes. Clearly, based on the fluid resistance model, when the particle material is determined, the initial velocity of these particles in the laser plasma flow field (i.e., the particle jet velocity) is directly related to the particle size information. Therefore, by changing the method from directly photographing the surface of the particle accumulation to obtain particle size information without improving the resolution performance of the existing camera, to first using a beam of pulsed laser as an aid to drive the generation of a particle jet, and then using camera remote sensing to monitor the macroscopically visible particle jet, a new method for in situ evaluation of the particle size parameters of microparticle accumulation can be constructed.

[0048] A method for evaluating the particle size parameters of microparticle accumulation in this embodiment is as follows: Figure 1 As shown, the steps include:

[0049] S10. Irradiate the surface of the microparticle accumulation with a pulsed laser to induce the generation of laser plasma.

[0050] In this step, the pulsed laser is a focused pulsed laser, which is provided by the LIBS system or can be generated by outputting a pulsed laser with fixed parameters and passing through a focusing lens. The microparticle accumulation is formed by the accumulation of microparticles of different particle sizes.

[0051] Therefore, the specific steps are:

[0052] The focused pulse laser output by a pulse laser with fixed parameters and formed after passing through a focusing lens irradiates the surface of a microparticle accumulation formed by the accumulation of microparticles of different particle sizes to induce the generation of laser plasma.

[0053] The generation process and principle of laser plasma can be found in the background technology, which is the existing technology and will not be elaborated on here.

[0054] S20. Capturing a particle jet accelerated by a laser plasma flow field.

[0055] In this step, the particle jet is captured by a high-speed camera. Therefore, this step is specifically as follows:

[0056] A high-speed camera was used to capture the particle jets generated on the surface of microparticles of different particle sizes and accelerated by the laser plasma flow field.

[0057] S30. Analyze the captured particle jet to obtain particle jet velocity or kinetic energy parameters.

[0058] This step is specifically as follows:

[0059] The captured particle jet is analyzed and the particle jet velocity or kinetic energy parameters corresponding to the surface of microparticle accumulation of different particle sizes are calculated.

[0060] Among them, the particle jet velocity is obtained by calculating the change of the particle jet tip position recorded by a high-speed camera over time through imaging methods.

[0061] Kinetic energy parameters include:

[0062] The average impact force felt by the particles in the particle jet captured by the high-speed camera in the flow field, the cross-sectional area of ​​the particles felt by the impact force captured by the high-speed camera in the particle jet, the mass of the particles captured by the high-speed camera in the particle jet, and the particle velocity captured by the high-speed camera in the particle jet.

[0063] S40. Obtain the particle diameter according to the obtained particle jet velocity or kinetic energy parameter to obtain a corresponding relationship between the particle jet velocity and the particle size parameter of the microparticle accumulation.

[0064] In this step, the particle diameter can be obtained based on the pressure relationship and the law of conservation of momentum, combined with the particle jet velocity or kinetic energy parameters corresponding to the surface of micro-particle deposits of different particle sizes, to obtain the corresponding relationship between the particle jet velocity and the particle size parameters of the micro-particle deposits.

[0065] Specifically: Based on the flow field resistance model, the force acting on the particles in the flow field can be obtained through the relationship F∝A, and A∝d2 , the momentum gained by the particle is mv∝F∝d 2 Therefore, through the above relationship, we can obtain v∝1 / d, which is the relationship between the particle jet velocity and the particle size, and thus we can obtain a one-to-one inverse relationship between the particle jet velocity and the particle size parameters of the microparticle accumulation.

[0066] Where: F∝A represents the force acting on the particles in the flow field based on the flow field resistance model; F represents the average impact force felt by the particles in the particle jet captured by the high-speed camera in the flow field; A represents the cross-sectional area of ​​the particles in the particle jet captured by the high-speed camera that feel the impact force; d represents the diameter of the particles in the particle jet captured by the high-speed camera; m represents the mass of the particles in the particle jet captured by the high-speed camera; and v represents the velocity of the particles in the particle jet captured by the high-speed camera.

[0067] S50. Using the particle jet velocity as an observable probe, the particle size parameter information of the microparticle accumulation can be evaluated.

[0068] This embodiment uses the particle jet velocity as an observable probe of the particle size parameters of micro-particle deposits, which can quickly, in situ, and remotely monitor macroscopically visible particle jets, thereby constructing a new method for in situ evaluation of the particle size parameters of micro-particle deposits.

[0069] Example 2

[0070] This embodiment discloses a method for evaluating the particle size parameters of micro-particle accumulation, and illustrates the method for evaluating the particle size parameters of micro-particle accumulation based on Example 1.

[0071] In this embodiment, a particle target formed by accumulation of glass sand microparticles is used as an example to illustrate a method for evaluating the particle size parameters of microparticle accumulations described in this embodiment 1.

[0072] This embodiment specifically includes the following steps:

[0073] S10. Discrete micron-sized glass sands of different particle sizes are naturally deposited in a sample box as microparticle deposits.

[0074] S20. Place the prepared particle accumulation samples with different particle sizes on the three-dimensional moving platform in turn, adjust the working parameters of the pulse laser, focus the pulse laser beam it outputs and irradiate it vertically to the surface of the particle accumulation sample, and generate laser plasma through laser ablation.

[0075] S30. Use a high-speed camera to directly record the particle jet formed by the acceleration of the laser plasma flow field; after each laser pulse event, the three-dimensional mobile platform moves once in the direction perpendicular to the laser transmission direction to ensure that the subsequent laser pulse acts on the surface area of ​​the microparticle accumulation that has not been disturbed by the previous laser pulse.

[0076] S40. Using imaging methods, calculate the change in the position of the particle jet tip over time corresponding to the high-speed camera in the case of different particle sizes, and obtain the particle jet tip velocity in turn.

[0077] S50. With the particle size as the horizontal coordinate and the particle jet tip velocity as the vertical coordinate, establish the relationship between the two, such as Figure 2 As shown in the figure, v∝1 / (d+a) is used for fitting (where a is a fitting parameter, and the fitting equation takes into account the effective cross-sectional area of ​​the flow field and the particles). In different embodiments, multiple regression, single variable fitting, partial least squares method, neural network and other methods can also be used to establish the calibration curve.

[0078] In this embodiment, the analysis process of the relationship between the particle size and the particle jet velocity is referred to in Example 1, which will not be repeated here.

[0079] This embodiment demonstrates an observable probe that uses the particle jet tip velocity as the particle size parameter of microparticle accumulation. There are also other ways in which observable probes defined based on particle jets can also establish a corresponding relationship with the particle size, which will not be shown here as examples.

[0080] Example 3

[0081] This embodiment discloses a system for evaluating the particle size parameters of micro-particle deposits. The system adopts a method for evaluating the particle size parameters of micro-particle deposits in Example 1 or Example 2 to quickly, in situ, and remotely monitor macroscopically visible particle jets, thereby constructing an in situ system for evaluating the particle size parameters of micro-particle deposits.

[0082] This embodiment discloses a system for evaluating the particle size parameters of microparticle accumulation, such as Figure 3 As shown, it includes: a pulsed laser and a focusing lens, a high-speed camera, and a computing module.

[0083] The pulse laser and focusing lens 1 are used to provide focused pulse laser 2 to irradiate the surface of microparticle accumulation 3 of different particle sizes, and generate laser plasma through laser ablation.

[0084] The microparticle accumulation 3 is a sample to be tested, which is formed by the accumulation of microparticles of different particle sizes, and can generate laser plasma under the irradiation of focused pulsed laser.

[0085] The high-speed camera 4 is used to capture and record the particle jet formed by being accelerated by the laser plasma flow field.

[0086] The calculation module 5 uses an imaging method to calculate the change in the position of the particles in the particle jet recorded by the high-speed camera 4 over time, calculates the velocity of the particles in the particle jet captured by the high-speed camera, obtains the particle jet velocity, and fits the relationship between the particle jet velocity and the particle size.

[0087] The specific implementation process of this example can be found in Example 1 or Example 2, and will not be elaborated in detail in this example.

[0088] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating particle size parameters of microparticle accumulation, characterized in that: Including steps: S10. Microparticles of different sizes are naturally deposited, and the surface of the microparticle deposits is irradiated with a pulsed laser to induce the generation of laser plasma; S20 captures the particle jet generated on the surface of the microparticle accumulation and accelerated by the laser plasma flow field; S30. Analyze the captured particle jet and calculate the change in the position of the particle jet tip over time using an imaging method to obtain the particle jet velocity corresponding to different particle sizes; S40. Based on the one-to-one inverse relationship between the particle jet velocity and the corresponding particle size, a calibration curve for evaluating the particle size parameters of the microparticle accumulation is obtained by fitting; S50. Based on the calibration curve, the particle jet velocity is used as an observable probe to evaluate the particle size parameter information of the unknown microparticle accumulation to be measured.

2. The method for evaluating particle size parameters of microparticle accumulation according to claim 1, characterized in that: The pulse laser is a focused pulse laser, which is output by a pulse laser with fixed parameters and formed after passing through a focusing lens.

3. The method for evaluating particle size parameters of microparticle accumulation according to claim 1, characterized in that: The particle jet is captured by a high-speed camera, and step S20 is specifically as follows: A high-speed camera was used to capture the particle jets generated on the surface of microparticles of different sizes and accelerated by the laser plasma flow field. Step S30 is specifically as follows: The captured particle jets were analyzed, and the changes in the particle jet tip position recorded by the high-speed camera over time were calculated using imaging methods to obtain the particle jet velocities corresponding to different particle sizes.

4. The method for evaluating particle size parameters of microparticle accumulation according to claim 1, characterized in that: Step S40 specifically includes: According to the pressure relationship and the law of conservation of momentum, an inverse relationship is obtained between the particle jet velocity in the laser plasma flow field and the particle size parameters of the microparticle accumulation.

5. The method for evaluating particle size parameters of microparticle accumulation according to claim 4, characterized in that: according to: F∝A; A∝d 2 ; mv∝F∝d 2 ; v∝1 / d; From the above relationship, it can be seen that there is an inverse relationship between the particle jet velocity and the particle size parameters of the microparticle accumulation; Where: F represents the average impact force felt by the particles in the particle jet captured by the high-speed camera in the flow field; A represents the cross-sectional area of ​​the particles in the particle jet captured by the high-speed camera that feel the impact force; d represents the diameter of the particles in the particle jet captured by the high-speed camera; m represents the mass of the particles in the particle jet captured by the high-speed camera; v represents the velocity of the particles in the particle jet captured by the high-speed camera.

6. A system for evaluating particle size parameters of microparticle accumulation based on the method according to any one of claims 1 to 5, characterized in that: include: A pulse laser and a focusing lens are used to provide focused pulse laser light to irradiate the surface of microparticle accumulations of different particle sizes and generate laser plasma through laser ablation; A high-speed camera is used to capture and record the particle jet formed by acceleration through the laser plasma flow field; The calculation module uses imaging methods to calculate the change in the top position of the particle jet recorded by the high-speed camera over time, calculates the particle velocity captured by the high-speed camera in the particle jet, obtains the particle jet velocity, and uses the inverse relationship between the particle jet velocity and the particle size parameter to fit the calibration curve for evaluating the particle size of microparticle accumulation.

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