Method and system for acquiring optimal point of energy utilization efficiency of plasma jet

Abstract

The embodiment of the invention provides a plasma jet energy utilization efficiency optimal point obtaining method and system and a plasma generation method, and belongs to the technical field of plasma. The acquisition method comprises the following steps: changing pulse voltages of a pulse driving power supply for multiple times, and acquiring pulse currents corresponding to different pulse voltages and time intervals of occurrence of the pulse currents, constructing a first association relationship between the pulse voltage and the pulse current and a second association relationship between the pulse current and a time interval when the pulse current appears; determining at least one peak point of the pulse current along with the change of the pulse voltage based on the first association relationship; and according to the pulse current of the peak point and the time interval of occurrence of the pulse current obtained based on the second association relationship, determining an energy utilization efficiency optimal point in the peak point. According to the embodiment of the invention, the plasma jet is excited to discharge by utilizing the optimal energy utilization efficiency, and the pulse discharge electron and particle density can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of plasma technology, and in particular to a method and system for acquiring an optimal point of energy utilization efficiency of a plasma jet, and a plasma generating method. Background Art

[0002] In recent years, low-temperature plasma technology has attracted extensive attention and development in environmental pollution control, biomedicine, and material modification and preparation due to its convenient operation and flexible application. Plasma jet, as one of the typical plasma technologies, can effectively generate high-energy and highly reactive plasma fluids with an apparent temperature close to room temperature, and has unique application advantages in material surface treatment, biomedicine, and sterilization and disinfection.

[0003] In the application process of low-temperature plasma technology, energy utilization efficiency is a key factor and important indicator affecting the application effect. The process of gas discharge to produce low-temperature plasma involves the conversion of electrical energy into the reaction energy of low-temperature plasma, so its energy utilization efficiency directly affects the degree of plasma excitation and ionization.

[0004] In order to achieve a more efficient gas discharge excitation ionization process, the research on pulse excitation gas discharge has developed rapidly in recent years. However, due to the transient nature and narrow time domain distribution characteristics of energy injection in the pulse excitation gas discharge process, the physical process of pulse excitation discharge is still unclear, and the energy utilization efficiency of plasma jets needs to be further improved. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a method and system for obtaining the optimal point of energy utilization efficiency of a plasma jet, and a plasma generation method. The embodiments of the present invention can solve or partially solve the problems existing in the prior art.

[0006] In order to achieve the above object, an embodiment of the present invention provides a method for obtaining the optimal point of plasma jet energy utilization efficiency, the method comprising:

[0007] Changing the pulse voltage of the pulse driving power supply multiple times, obtaining the pulse current corresponding to different pulse voltages and the time interval of the pulse current, and constructing a first correlation relationship between the pulse voltage and the pulse current, and a second correlation relationship between the pulse current and the time interval of the pulse current;

[0008] Based on the first association relationship, determining at least one peak point of the pulse current changing with the pulse voltage, wherein the peak point corresponds to a local maximum point of the pulse current;

[0009] The optimum point of energy utilization efficiency at the peak point is determined according to the pulse current at the peak point and the time interval of occurrence of the pulse current obtained based on the second association relationship.

[0010] Optionally, the peak point includes a first peak point and a second peak point, and the pulse voltage of the first peak point is smaller than the pulse voltage of the second peak point.

[0011] Determining the optimum point of energy utilization efficiency at the peak point according to the pulse current at the peak point and the time interval of the pulse current obtained based on the second association relationship, comprising:

[0012] Dividing the pulse current at the first peak point by the time interval of the pulse current obtained based on the second correlation relationship to obtain the discharge intensity at the first peak point;

[0013] Dividing the pulse current at the second peak point by the time interval of the pulse current obtained based on the second correlation relationship to obtain the discharge intensity at the second peak point;

[0014] The pulse current and the discharge intensity of the first peak point and the second peak point are compared to obtain a comparison result, and the optimum point of energy utilization efficiency is determined according to the comparison result.

[0015] Optionally, comparing the pulse current and the discharge intensity at the first peak point and the second peak point to obtain a comparison result, and determining the optimum point of energy utilization efficiency according to the comparison result, comprises:

[0016] When the pulse current at the second peak point is greater than the pulse current at the first peak point,

[0017] If the discharge intensity at the second peak point is not less than that at the first peak point, the second peak point is the optimum point for energy utilization efficiency;

[0018] If the discharge intensity at the second peak point is less than the discharge intensity at the first peak point, the energy utilization efficiency optimum point is determined based on the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, and the discharge intensity at the first peak point.

[0019] Optionally, determining the optimum point of energy utilization efficiency according to the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, and the discharge intensity at the first peak point, comprises:

[0020] If the discharge intensity at the first peak point is less than the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, the second peak point is the optimal point for energy utilization efficiency;

[0021] If the discharge intensity at the first peak point is not less than the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, the first peak point is the optimum point for energy utilization efficiency.

[0022] Optionally, comparing the pulse current and the discharge intensity at the first peak point and the second peak point to obtain a comparison result, and determining the optimum point of energy utilization efficiency according to the comparison result, comprises:

[0023] When the pulse current at the second peak point is equal to or less than the pulse current at the first peak point,

[0024] If the discharge intensity at the second peak point is not greater than the discharge intensity at the first peak point, the first peak point is the optimum point for energy utilization efficiency;

[0025] If the discharge intensity at the second peak point is greater than the discharge intensity at the first peak point, the energy utilization efficiency optimum point is determined based on the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, and the discharge intensity at the second peak point.

[0026] Optionally, determining the optimum point of energy utilization efficiency according to the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, and the discharge intensity at the second peak point, comprises:

[0027] If the discharge intensity at the second peak point is less than the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, the first peak point is the optimal point for energy utilization efficiency;

[0028] If the discharge intensity at the second peak point is not less than the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, the second peak point is the optimum point for energy utilization efficiency.

[0029] Optionally, the step of changing the pulse voltage of the pulse driving power supply includes:

[0030] According to whether the acquired pulse current is a positive polarity pulse current or a negative polarity pulse current, selecting a first method or a second method to determine the voltage step length;

[0031] The pulse voltage is gradually increased with the voltage step length until the growth coefficient of the pulse current is always 0, wherein the growth coefficient is the rate of change of the pulse current relative to the pulse voltage;

[0032] The first method: compare the growth coefficient K of the pulse current when the pulse voltage is increased for the i-th time i The growth coefficient K of the pulse current when the pulse voltage is increased for the i+1th time i+1 ;

[0033] When 0<K i ≤K i+1 When the pulse voltage is increased to 0<K with the set voltage step length i+1 ≤Ki ;

[0034] When 0<K i+1 ≤K i When the pulse voltage is increased to K with a step length of a1 times the set voltage i+1 =0;

[0035] When K i+1 ≤K i When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a1 times the set voltage. i ≤K i+1 <0;

[0036] When K i ≤K i+1 When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a2 times the set voltage. i+1 =0;

[0037] Among them, 1>a1>0, a1>a2>0;

[0038] The second method: compare the growth coefficient K of the pulse current when the pulse voltage is increased for the i-th time i The growth coefficient K of the pulse current when the pulse voltage is increased for the i+1th time i+1 ;

[0039] When K i+1 ≤K i When <0, increase the pulse voltage to K with the set voltage step length i ≤K i+1 <0;

[0040] When K i ≤K i+1 When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a1 times the set voltage. i+1 =0;

[0041] When 0<K i ≤K i+1 When the pulse voltage is increased by a1 times the set voltage step to 0<K i+1 ≤K i ;

[0042] When 0<K i+1 ≤K i When the pulse voltage is increased to K with a step length of a2 times the set voltage i+1 =0.

[0043] Optionally, according to whether the acquired pulse current is a positive polarity pulse current or a negative polarity pulse current, selecting a first method or a second method to determine the voltage step length includes:

[0044] When the acquired pulse current is a positive polarity pulse current, the first method is selected to determine the voltage step length;

[0045] When the acquired pulse current is a negative polarity pulse current, the second method is selected to determine the voltage step length.

[0046] Optionally, when the voltage step size is determined multiple times according to the first method / the second method, the set voltage step size decreases successively with the number of times the first method / the second method is used.

[0047] Accordingly, an embodiment of the present invention further provides a plasma generating method, the plasma generating method comprising:

[0048] The plasma jet discharge unit is excited by a pulse voltage at the optimal point of energy utilization efficiency determined according to the method for obtaining the optimal point of energy utilization efficiency of the plasma jet, so as to obtain plasma.

[0049] Accordingly, an embodiment of the present invention further provides a system for obtaining the optimal point of plasma jet energy utilization efficiency, the system comprising:

[0050] A plasma jet discharge device, comprising a plasma jet discharge unit, a pulse drive power supply, an electrical parameter measurement unit and a gas source unit, for measuring pulse currents corresponding to different pulse voltages and time intervals of pulse currents; and

[0051] A control device, used for changing the pulse voltage of the pulse driving power supply multiple times, obtaining the pulse current corresponding to different pulse voltages of the plasma jet discharge device and the time interval of the pulse current, and establishing a first correlation relationship between the pulse voltage and the pulse current, and a second correlation relationship between the pulse current and the time interval of the pulse current;

[0052] Based on the first association relationship, determining at least one peak point of the pulse current changing with the pulse voltage, wherein the peak point corresponds to a local maximum point of the pulse current;

[0053] The optimum point of energy utilization efficiency is determined according to the pulse current at the peak point and the time interval of occurrence of the pulse current obtained based on the second association relationship.

[0054] Optionally, the pulse driving power supply includes a high-voltage output terminal and a ground terminal, wherein the high-voltage output terminal is connected to the high-voltage electrode of the plasma jet discharge unit, and the ground terminal is grounded;

[0055] The electrical parameter measurement unit includes a high-voltage probe and a current probe, wherein the high-voltage probe is connected in parallel with the plasma jet discharge unit in the discharge circuit to measure the pulse voltage applied to the plasma jet discharge unit, and the current probe is connected in series with the plasma jet discharge unit in the discharge circuit to detect the pulse current during the discharge process;

[0056] The gas source unit is used to provide atmosphere conditions for the plasma jet discharge unit.

[0057] Optionally, the plasma jet discharge unit includes a dielectric and a metal electrode, wherein the metal electrode includes a high-voltage electrode and a low-voltage electrode, and the high-voltage electrode and the low-voltage electrode are parallelly attached to the outer surface of the dielectric with a certain distance therebetween.

[0058] In the embodiment of the present invention, the pulse voltage of the pulse driving power supply is changed multiple times to obtain the pulse current corresponding to different pulse voltages and the time interval of the pulse current, and the relationship between the pulse voltage, the pulse current and the time interval of the pulse current is constructed. Then, according to the pulse current and the discharge intensity, the energy utilization efficiency optimum point at the peak point where the pulse current changes with the pulse voltage is determined. The energy utilization efficiency optimum point is used to excite the plasma jet discharge unit, effectively improving the density of pulse discharge electrons and particles.

[0059] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0061] Figure 1 It is a flow chart of a method for obtaining the optimal point of plasma jet energy utilization efficiency provided by an embodiment of the present invention;

[0062] Figure 2 is a relationship diagram of a pulse voltage, a positive polarity pulse current and a time interval of the pulse current provided by an embodiment of the present invention;

[0063] Figure 3 is a relationship diagram of a pulse voltage, a negative polarity pulse current and a time interval of the pulse current provided by an embodiment of the present invention;

[0064] Figure 4 It is a structural diagram of a system for obtaining the optimal point of plasma jet energy utilization efficiency provided by an embodiment of the present invention;

[0065] Figure 5 It is a waveform diagram of plasma discharge jet voltage and current provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0067] Embodiment 1

[0068] Figure 1 is a flow chart of a method for obtaining the optimal point of plasma jet energy utilization efficiency provided by an embodiment of the present invention; Figure 1 As shown, the method for obtaining the optimal point of plasma jet energy utilization efficiency includes:

[0069] S110: changing the pulse voltage of the pulse driving power supply multiple times, obtaining the pulse currents corresponding to the different pulse voltages and the time intervals of the pulse currents, and constructing a first correlation relationship between the pulse voltage and the pulse current, and a second correlation relationship between the pulse current and the time intervals of the pulse currents;

[0070] S120: Based on the first association relationship, determine at least one peak point of the pulse current changing with the pulse voltage, wherein the peak point corresponds to a local maximum point of the pulse current;

[0071] S130: Determine the optimum point of energy utilization efficiency at the peak point according to the pulse current at the peak point and the time interval of occurrence of the pulse current obtained based on the second association relationship.

[0072] In step S110, when changing the pulse voltage of the pulse driving power supply, the first method or the second method can be selected to determine the voltage step length according to whether the acquired pulse current is a positive polarity pulse current or a negative polarity pulse current; specifically, when the acquired pulse current is a positive polarity pulse current, the first method is selected to determine the voltage step length; when the acquired pulse current is a negative polarity pulse current, the second method is selected to determine the voltage step length. The growth coefficient is the rate of change of the pulse current relative to the pulse voltage.

[0073] The two methods are introduced below.

[0074] The first method: compare the growth coefficient K of the pulse current when the pulse voltage is increased for the i-th time i The growth coefficient K of the pulse current when the pulse voltage is increased for the i+1th time i+1 ;

[0075] When 0<K i ≤K i+1 When the pulse voltage is increased to 0<K with the set voltage step length i+1 ≤K i ;

[0076] When 0<Ki+1 ≤K i When the pulse voltage is increased to K with a step length of a1 times the set voltage i+1 =0;

[0077] When K i+1 ≤K i When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a1 times the set voltage. i ≤K i+1 <0;

[0078] When K i ≤K i+1 When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a2 times the set voltage. i+1 =0;

[0079] Among them, 1>a1>0, a1>a2>0;

[0080] The second method: compare the growth coefficient K of the pulse current when the pulse voltage is increased for the i-th time i The growth coefficient K of the pulse current when the pulse voltage is increased for the i+1th time i+1 ;

[0081] When K i+1 ≤K i When <0, increase the pulse voltage to K with the set voltage step length i ≤K i+1 <0;

[0082] When K i ≤K i+1 When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a1 times the set voltage. i+1 =0;

[0083] When 0<K i ≤K i+1 When the pulse voltage is increased by a1 times the set voltage step to 0<K i+1 ≤K i ;

[0084] When 0<K i+1 ≤K i When the pulse voltage is increased to K with a step length of a2 times the set voltage i+1 =0.

[0085] As for when to stop increasing the pulse voltage, an embodiment of the present invention provides a preferred method, that is, gradually increasing the pulse voltage until the growth coefficient of the pulse current is constantly 0, thereby reducing energy loss and achieving the purpose of determining the optimal energy utilization efficiency.

[0086] In step S120, the peak points include a first peak point and a second peak point, and the pulse voltage of the first peak point is less than the pulse voltage of the second peak point. It should be noted that the embodiment of the present invention does not limit the number of peak points, and the peak points can be one or more. Therefore, the first peak point / second peak point here can represent one peak point or multiple peak points. When representing multiple peak points, the two peak points can be divided into a group, and the points with better energy utilization efficiency in the two peak points are selected in turn, and then the method provided by the embodiment of the present invention is used to compare the two points with better energy utilization efficiency to obtain the optimal energy utilization efficiency.

[0087] In step S130, when determining the optimal point of energy utilization efficiency in the peak point based on the pulse current at the peak point and the time interval of the pulse current obtained based on the second association relationship, the pulse current at the first peak point can be divided by the time interval of the pulse current obtained based on the second association relationship to obtain the discharge intensity of the first peak point; then, the pulse current at the second peak point is divided by the time interval of the pulse current obtained based on the second association relationship to obtain the discharge intensity of the second peak point; a comparison result is obtained by comparing the pulse current and the discharge intensity of the first peak point and the second peak point, and the optimal point of energy utilization efficiency is determined based on the comparison result.

[0088] Furthermore, the embodiment of the present invention compares the pulse current and discharge intensity of the first peak point and the second peak point to obtain a comparison result, and when determining the optimal point of energy utilization efficiency based on the comparison result, first compares the pulse current of the first peak point and the second peak point, and then compares the discharge intensity.

[0089] (1) When the pulse current at the second peak point is greater than the pulse current at the first peak point,

[0090] If the discharge intensity at the second peak point is not less than that at the first peak point, the second peak point is the optimum point for energy utilization efficiency;

[0091] If the discharge intensity at the second peak point is less than the discharge intensity at the first peak point, the optimal point of energy utilization efficiency is determined according to the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, and the discharge intensity at the first peak point. Specifically, if the discharge intensity at the first peak point is less than the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, the second peak point is the optimal point of energy utilization efficiency; if the discharge intensity at the first peak point is not less than the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, the first peak point is the optimal point of energy utilization efficiency.

[0092] The energy density proportionality factor is defined as:

[0093] n=(I / ∫0 T U(t)I(t)dt) i / (I / ∫0 T U(t)I(t)dt) i+1 ), the numerator represents the integral of the product of the pulse voltage and the pulse current in the time period from 0 to T after the pulse voltage is increased for the i-th time; the denominator represents the integral of the product of the pulse voltage and the pulse current in the time period from 0 to T after the pulse voltage is increased for the i+1th time.

[0094] (2) When the pulse current at the second peak point is equal to or less than the pulse current at the first peak point,

[0095] If the discharge intensity at the second peak point is not greater than the discharge intensity at the first peak point, the first peak point is the optimum point for energy utilization efficiency;

[0096] If the discharge intensity at the second peak point is greater than the discharge intensity at the first peak point, the optimal point of energy utilization efficiency is determined according to the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, and the discharge intensity at the second peak point. Specifically, if the discharge intensity at the second peak point is less than the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, the first peak point is the optimal point of energy utilization efficiency; if the discharge intensity at the second peak point is not less than the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, the second peak point is the optimal point of energy utilization efficiency.

[0097] In the embodiment of the present invention, the pulse voltage of the pulse driving power supply is changed multiple times to obtain the pulse current corresponding to different pulse voltages and the time interval of the pulse current, and the relationship between the pulse voltage, the pulse current and the time interval of the pulse current is constructed. Then, according to the pulse current and the discharge intensity, the energy utilization efficiency optimum point at the peak point where the pulse current changes with the pulse voltage is determined. The energy utilization efficiency optimum point is used to excite the plasma jet discharge unit, effectively improving the density of pulse discharge electrons and particles.

[0098] Embodiment 2

[0099] In the second specific embodiment, step S110 and step S120 increase the pulse voltage of the pulse driving power supply, and compare the growth coefficient K of the pulse current when the pulse voltage is increased for the i-th time. i The growth coefficient K of the pulse current when the pulse voltage is increased for the i+1th time i+1 ;

[0100] When 0<K i ≤K i+1 When the pulse voltage is increased to 0<K with the set voltage step length ΔU i+1 ≤K i ;

[0101] When 0<Ki+1 ≤K i When the pulse voltage is increased to K with a voltage step of ΔU / 2 i+1 =0, the point is determined as the first peak point;

[0102] When K i+1 ≤K i When <0, increase the pulse voltage to K with a voltage step of ΔU / 2 i ≤K i+1 <0;

[0103] When K i ≤K i+1 When <0, increase the pulse voltage to K with a voltage step of ΔU / 5 i+1 =0;

[0104] When 0<K i ≤K i+1 When the pulse voltage is increased to 0<K with a voltage step of ΔU / 5 i+1 ≤K i ;

[0105] When 0<K i+1 ≤K i When the pulse voltage is increased to K with a voltage step of ΔU / 10 i+1 =0, the point is determined as the second peak point;

[0106] When the pulse voltage is increased again, if the growth coefficient of the pulse current is always 0, the pulse voltage is stopped from being increased to obtain two peak points, and then it is determined which of the two peak points is the optimal point of energy utilization efficiency.

[0107] Step S130, assuming that the pulse current at the first peak point is Im1, the pulse current at the second peak point is Im2, when I m2 >I m1 When (I m / t m )2>(I m / t m )1 (indicating that the discharge intensity of the second peak point is greater than that of the first peak point), the second peak point is the optimal excitation point for energy efficiency utilization. m / t m )2<(I m / t m )1<k(I m / t m )2, the second peak point is the optimum point of pulse plasma jet energy utilization efficiency; if nI m / t m )2<(I m / t m)1, the first peak point is the optimal excitation point for energy efficiency utilization;

[0108] When I m2 ≤I m1 When (I m / t m )2≤(I m / t m )1, the first peak point is the optimal excitation point for energy efficiency utilization; if n(I m / t m )1>(I m / t m )2>(I m / t m )1(n is the energy density proportionality coefficient, k=(I / ∫0 T U(t)I(t)dt)1 / (I / ∫0 T U(t)I(t)dt)2), the first peak point is the optimal excitation point for energy efficiency utilization; when (I m / t m )3>k(I m / t m )1, the second peak point is the optimal excitation point for energy efficiency utilization.

[0109] In the embodiment of the present invention, the pulse voltage of the pulse driving power supply is changed multiple times to obtain the pulse current corresponding to different pulse voltages and the time interval of the pulse current, and the relationship between the pulse voltage, the pulse current and the time interval of the pulse current is constructed. Then, according to the pulse current and the discharge intensity, the energy utilization efficiency optimum point at the peak point where the pulse current changes with the pulse voltage is determined. The energy utilization efficiency optimum point is used to excite the plasma jet discharge unit, effectively improving the density of pulse discharge electrons and particles.

[0110] Embodiment 3

[0111] In the specific embodiment 3, by changing the pulse voltage amplitude, a relationship diagram of the pulse voltage, the positive polarity pulse current and the time interval of the pulse current is obtained, such as Figure 2 As shown in the figure (the column represents the interval time, and the curve of the positive polarity pulse current in the two curves is located above the discharge intensity curve), with I n is the pulse current at a certain moment, I m is the pulse current at the next adjacent moment, and the corresponding time intervals of the pulse current are t n and t m .

[0112] t0 is the initial moment of the pulse signal, the initial voltage amplitude is U0=5.36kV, the identification point is G0, the voltage is increased to U1=5.52kV at a step size of ΔU=0.16kV, and (Im -I n ) / ΔU (growth coefficient) and I m / t m (discharge intensity), define the growth coefficient K = (I m -I n ) / ΔU, the growth coefficient is used to characterize the increasing speed of the discharge intensity, K1 represents the increasing rate of the discharge intensity at a certain moment, and K2 represents the increasing rate of the discharge intensity at the next adjacent moment.

[0113] When the pulse voltage increases from ΔU=0.16kV to U=5.69kV, K2-K1>0, and when the pulse voltage continues to increase to U=5.85kV, K2-K1≤0 appears, and (I m -I n ) / ΔU>0, at this time, the pulse voltage is controlled to increase at a speed of ΔU / 2=0.08kV. When the pulse voltage increases to U=6.43kV, and its adjacent voltage U=6.59kV, (I m -I n ) / ΔU<0, and point G1 marks the time when U=6.43kV. The G0-G1 stage is the stage in which the plasma jet always maintains a stable enhancement;

[0114] After reaching G1, the voltage is increased at a speed of ΔU / 2=0.08kV. When the pulse voltage increases to U=6.59kV, K2-K1>0, the voltage is increased to U=6.67kV, and K2-K1<0 appears. At this time, the voltage is increased at a step size of ΔU / 5=0.032kV. When the voltage increases to U=6.76kV, and then increases to U=6.792kV, (I m -I n ) / ΔU>0, the point marked as U=6.76kV is G2. In the G1-G2 stage, the discharge pulse current always shows a weakening trend, that is, the gas excitation ionization intensity gradually weakens until the valley point G2.

[0115] Control the speed of ΔU / 5=0.032kV to increase the voltage to U=6.92kV, and continue to increase it to U=9.952kV, when K2-K1<0, at the same time (I m -I n ) / ΔU>0, at this time, the control voltage increases with a step size of ΔU / 10=0.016kV. When the voltage increases to U=7.25kV, it continues to increase by ΔU / 10=0.016 to U=7.266kV, (I m -I n ) / ΔU=0, stop pressurizing, mark U=7.25kV as point G3, compare I corresponding to point G3 and G1 m with Im / t m .

[0116] I3>I1, (I / t)3≤(I / t)1, so U=7.25kV is the optimal excitation point for energy efficiency. Then, as the voltage continues to increase, the current pulse amplitude does not change significantly, which can be understood as the gas molecules have reached a relatively saturated excitation state. Continuing to increase the energy injection can no longer significantly enhance the plasma intensity, and will cause excess energy loss.

[0117] Embodiment 4

[0118] In the fourth specific embodiment, by changing the pulse voltage amplitude, a pulse voltage, a negative polarity pulse current and a time interval of the pulse current are obtained, such as Figure 3 As shown in the figure (the column represents the interval time, and the negative polarity pulse current curve in the two curves is located above the discharge intensity curve), with I n is the pulse current at a certain moment, I m is the pulse current at the next adjacent moment, and the corresponding current pulse moments are t n and t m .

[0119] t0 is the initial moment of the pulse signal, the initial voltage amplitude is U0=5.36kV, the identification point is G0, the voltage is increased to U1=5.52kV at a step size of ΔU=0.16kV, and (I m -I n ) / ΔU and I m / t m , define the growth coefficient K = (I m -I n ) / ΔU. The growth coefficient is used to characterize the increasing speed of the discharge intensity. K1 represents the increasing speed of the discharge intensity at a certain moment, and K2 represents the increasing speed of the discharge intensity at the next adjacent moment. When the pulse voltage increases from ΔU=0.16kV to U=5.69kV, K2-K1>0, and when the pulse voltage continues to increase to U=5.85kV, (I m -I n ) / ΔU<0, the point marked as U=5.69kV is G1, which is the first peak point. The voltage is increased at a rate of ΔU=0.16kV. When the pulse voltage is increased to U=5.93kV, and then the voltage is increased to U=6.09kV, (I m -I n ) / ΔU>0, at this time, the mark U=5.93kV is G2. Continue to increase the voltage at U=6.09kV at a rate of ΔU=0.16kV to U=6.25kV, and (I m -I n) / ΔU<0, at this time it can be determined that U=6.09kV is the second peak point, marked as G3.

[0120] Compare I corresponding to point G3 and G1 m with I m / t m , I3<I1, (I / t)3≤(I / t)1, so G1 is temporarily the optimal excitation point for energy efficiency utilization; due to the large current pulse fluctuation in the G0-G3 stage, the voltage is adjusted at U=6.25kV and increased to U=6.33kV at a rate of ΔU / 2=0.08kV, and (I m -I n ) / ΔU>0, and the voltage continues to increase to U=6.41kV, (I m -I n ) / ΔU<0, so it can be determined that U=6.33kV is the third peak point, marked as G5. Compare the I corresponding to G5 and G1 m with I m / t m , I5<I1, (I / t)5≤(I / t)1, so G1 is temporarily the optimal excitation point for energy efficiency utilization;

[0121] When U=6.41kV, the voltage is increased to U=6.49kV at a step size of ΔU / 2=0.08kV, and K2-K1≤0 appears. At this time, the pulse voltage is controlled to increase the voltage at a speed of ΔU / 5=0.032kV. When the voltage increases to U=6.59kV, the voltage is increased to U=6.622kV, (I m -I n ) / ΔU>0, so it can be determined that U=6.59kV. Continue to increase the voltage with a step size of ΔU / 5=0.032kV. When the voltage increases to U=6.76kV, continue to increase the voltage to U=6.792kV, and K2-K1<0 appears, and (I m -I n ) / ΔU>0, at this time, the voltage is adjusted to increase the voltage with a step size of ΔU / 10=0.016kV. When the voltage increases to U=7.25kV, the voltage is further increased to U=7.266kV, and (I m -I n ) / ΔU=0, the voltage is still kept at (I m -I n ) / ΔU=0, mark U=7.25kV as G7, and compare the I corresponding to G7 and G1. m with I m / t m , I7>I1, (I / t)7≤(I / t)1<1.2*(I / t)7, so G1 is the optimal excitation point for energy efficiency utilization.

[0122] In the embodiment of the present invention, the pulse voltage of the pulse driving power supply is changed multiple times to obtain the pulse current corresponding to different pulse voltages and the time interval of the pulse current, and the relationship between the pulse voltage, the pulse current and the time interval of the pulse current is constructed. Then, according to the pulse current and the discharge intensity, the energy utilization efficiency optimum point at the peak point where the pulse current changes with the pulse voltage is determined. The energy utilization efficiency optimum point is used to excite the plasma jet discharge unit, effectively improving the density of pulse discharge electrons and particles.

[0123] Embodiment 5

[0124] Figure 4 It is a structural diagram of a system for obtaining the optimal point of plasma jet energy utilization efficiency provided by an embodiment of the present invention;

[0125] like Figure 4 As shown, the system for obtaining the optimal point of plasma jet energy utilization efficiency includes:

[0126] The plasma jet discharge device includes a plasma jet discharge unit, a pulse drive power supply, an electrical parameter measurement unit and a gas source unit, and is used to measure the pulse current corresponding to different pulse voltages and the time interval of the pulse current;

[0127] The control device is used to change the pulse voltage of the pulse driving power supply multiple times, obtain the pulse current corresponding to different pulse voltages of the plasma jet discharge device and the time interval of the pulse current, and establish a first correlation relationship between the pulse voltage and the pulse current, and a second correlation relationship between the pulse current and the time interval of the pulse current; and

[0128] Based on the first association relationship, determining at least one peak point of the pulse current changing with the pulse voltage, wherein the peak point corresponds to a local maximum point of the pulse current;

[0129] The optimum point of energy utilization efficiency is determined according to the pulse current at the peak point and the time interval of occurrence of the pulse current obtained based on the second association relationship.

[0130] The pulse driving power supply comprises a high voltage output terminal and a ground terminal, wherein the high voltage output terminal is connected to the high voltage electrode of the plasma jet discharge unit, and the ground terminal is grounded;

[0131] The electrical parameter measurement unit includes a high-voltage probe and a current probe, wherein the high-voltage probe is connected in parallel with the plasma jet discharge unit in the discharge circuit to measure the pulse voltage applied to the plasma jet discharge unit, and the current probe is connected in series with the plasma jet discharge unit in the discharge circuit to detect the pulse current during the discharge process;

[0132] The gas source unit is used to provide atmosphere conditions for the plasma jet discharge unit.

[0133] The plasma jet discharge unit comprises a dielectric and metal electrodes, wherein the metal electrodes comprise a high-voltage electrode and a low-voltage electrode, and the high-voltage electrode and the low-voltage electrode are parallelly attached to the outer surface of the dielectric with a certain distance therebetween.

[0134] Embodiment 6

[0135] Embodiment 6 provides a plasma generation method, the plasma generation method comprising:

[0136] The plasma jet discharge unit is excited by a pulse voltage at the optimal point of energy utilization efficiency determined according to the method for obtaining the optimal point of energy utilization efficiency of the plasma jet, so as to obtain plasma.

[0137] Figure 5 : is a plasma discharge jet voltage and current waveform diagram provided by an embodiment of the present invention, such as Figure 5 As shown, t0 is the starting time of the pulse signal, t1 is the time from the start of the pulse signal to the appearance of the positive polarity current pulse, t2 is the time from the start of the pulse signal to the appearance of the negative polarity current pulse, t1 and t2 represent the time when the positive and negative current pulses appear, respectively. i It is the moment when the pulse voltage reaches the maximum value. It can be considered that the moment t0-t1 is the pre-activation process before the pulse voltage ionizes the gas molecules. When the pulse signal develops to the moment t1, the discharge begins and then instantly excites the generation of high-energy active particles. i The process is the process in which the pulse voltage effectively drives the active particles and stimulates the production of more active particles. In the late stage of the pulse, the density of electrons and particles is relatively high.

[0138] Under the condition of the optimal excitation point voltage for energy utilization efficiency, the discharge current intensity reaches the maximum and the excitation discharge voltage is at the minimum. That is, under the premise of achieving the maximum pulse discharge excitation effect, the pre-ionization process of the pulse voltage on the gas molecules in the t0-t1 period is shortened to a minimum, and at the same time, the t1-ti period in which the pulse effectively drives the active particles in the later stage and stimulates the production of more living particles is longer, effectively increasing the density of pulse discharge electrons and particles.

[0139] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0140] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for obtaining the optimal point of plasma jet energy utilization efficiency, characterized in that: The acquisition method comprises: Changing the pulse voltage of the pulse driving power supply multiple times, obtaining the pulse current corresponding to different pulse voltages and the time interval of the pulse current, and constructing a first correlation relationship between the pulse voltage and the pulse current, and a second correlation relationship between the pulse current and the time interval of the pulse current; Based on the first association relationship, determining at least one peak point of the pulse current changing with the pulse voltage, wherein the peak point corresponds to a local maximum point of the pulse current; The optimum point of energy utilization efficiency at the peak point is determined according to the pulse current at the peak point and the time interval of occurrence of the pulse current obtained based on the second association relationship.

2. The method for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 1, characterized in that: The peak points include a first peak point and a second peak point, the pulse voltage of the first peak point is smaller than the pulse voltage of the second peak point, Determining the optimum point of energy utilization efficiency at the peak point according to the pulse current at the peak point and the time interval of the pulse current obtained based on the second association relationship, comprising: Dividing the pulse current at the first peak point by the time interval of the pulse current obtained based on the second correlation relationship to obtain the discharge intensity at the first peak point; Dividing the pulse current at the second peak point by the time interval of the pulse current obtained based on the second correlation relationship to obtain the discharge intensity at the second peak point; The pulse current and the discharge intensity of the first peak point and the second peak point are compared to obtain a comparison result, and the optimum point of energy utilization efficiency is determined according to the comparison result.

3. The method for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 2, characterized in that: Comparing the pulse current and the discharge intensity of the first peak point and the second peak point to obtain a comparison result, and determining the optimal point of energy utilization efficiency according to the comparison result, including: When the pulse current at the second peak point is greater than the pulse current at the first peak point, If the discharge intensity at the second peak point is not less than that at the first peak point, the second peak point is the optimum point for energy utilization efficiency; If the discharge intensity at the second peak point is less than the discharge intensity at the first peak point, the energy utilization efficiency optimum point is determined based on the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, and the discharge intensity at the first peak point.

4. The method for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 3, characterized in that: The optimal point of energy utilization efficiency is determined according to the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, and the discharge intensity at the first peak point, including: If the discharge intensity at the first peak point is less than the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, the second peak point is the optimal point for energy utilization efficiency; If the discharge intensity at the first peak point is not less than the product of the energy density proportionality coefficient and the discharge intensity at the second peak point, the first peak point is the optimum point for energy utilization efficiency.

5. The method for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 2, characterized in that: Comparing the pulse current and the discharge intensity at the first peak point and the second peak point to obtain a comparison result, and determining the optimum point of energy utilization efficiency according to the comparison result, including: When the pulse current at the second peak point is equal to or less than the pulse current at the first peak point, If the discharge intensity at the second peak point is not greater than the discharge intensity at the first peak point, the first peak point is the optimum point for energy utilization efficiency; If the discharge intensity at the second peak point is greater than the discharge intensity at the first peak point, the energy utilization efficiency optimum point is determined based on the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, and the discharge intensity at the second peak point.

6. The method for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 5, characterized in that: The optimal point of energy utilization efficiency is determined according to the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, and the discharge intensity at the second peak point, including: If the discharge intensity at the second peak point is less than the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, the first peak point is the optimal point for energy utilization efficiency; If the discharge intensity at the second peak point is not less than the product of the energy density proportionality coefficient and the discharge intensity at the first peak point, the second peak point is the optimum point for energy utilization efficiency.

7. The method for obtaining the optimal point of plasma jet energy utilization efficiency according to any one of claims 1 to 6, characterized in that: The step of changing the pulse voltage of the pulse driving power supply comprises: According to whether the acquired pulse current is a positive polarity pulse current or a negative polarity pulse current, selecting a first method or a second method to determine the voltage step length; The pulse voltage is gradually increased with the voltage step length until the growth coefficient of the pulse current is always 0, wherein the growth coefficient is the rate of change of the pulse current relative to the pulse voltage; The first method: compare the growth coefficient K of the pulse current when the pulse voltage is increased for the i-th time i The growth coefficient K of the pulse current when the pulse voltage is increased for the i+1th time i+1 ; When 0<K i ≤K i+1 When the pulse voltage is increased to 0<K with the set voltage step length i+1 ≤K i ; When 0<K i+1 ≤K i When the pulse voltage is increased to K with a step length of a1 times the set voltage i+1 =0; When K i+1 ≤K i When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a1 times the set voltage. i ≤K i+1 <0; When K i ≤K i+1 When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a2 times the set voltage. i+1 =0; Among them, 1>a1>0, a1>a2>0; The second method: compare the growth coefficient K of the pulse current when the pulse voltage is increased for the i-th time i The growth coefficient K of the pulse current when the pulse voltage is increased for the i+1th time i+1 ; When K i+1 ≤K i When <0, increase the pulse voltage to K with the set voltage step length i ≤K i+1 <0; When K i ≤K i+1 When the pulse voltage is less than 0, the pulse voltage is increased to K with a step length of a1 times the set voltage. i+1 =0; When 0<K i ≤K i+1 When the pulse voltage is increased by a1 times the set voltage step to 0<K i+1 ≤K i ; When 0<K i+1 ≤K i When the pulse voltage is increased to K with a step length of a2 times the set voltage i+1 =0.

8. The method for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 7, characterized in that: According to whether the acquired pulse current is a positive polarity pulse current or a negative polarity pulse current, a first method or a second method is selected to determine the voltage step length, including: When the acquired pulse current is a positive polarity pulse current, the first method is selected to determine the voltage step length; When the acquired pulse current is a negative polarity pulse current, the second method is selected to determine the voltage step length.

9. The method for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 8, characterized in that: When the voltage step length is determined multiple times according to the first method / the second method, the set voltage step length decreases successively with the number of times the first method / the second method is used.

10. A plasma generation method, characterized in that: The plasma generation method comprises: The plasma jet discharge unit is excited by a pulse voltage at the optimal point of energy utilization efficiency determined by the method for obtaining the optimal point of energy utilization efficiency of a plasma jet according to any one of claims 1 to 9 to obtain plasma.

11. A system for obtaining the optimal point of plasma jet energy utilization efficiency, characterized in that: The acquisition system comprises: A plasma jet discharge device, comprising a plasma jet discharge unit, a pulse drive power supply, an electrical parameter measurement unit and a gas source unit, for measuring pulse currents corresponding to different pulse voltages and time intervals of pulse currents; and A control device, used for changing the pulse voltage of the pulse driving power supply multiple times, obtaining the pulse current corresponding to different pulse voltages of the plasma jet discharge device and the time interval of the pulse current, and establishing a first correlation relationship between the pulse voltage and the pulse current, and a second correlation relationship between the pulse current and the time interval of the pulse current; Based on the first association relationship, determining at least one peak point of the pulse current changing with the pulse voltage, wherein the peak point corresponds to a local maximum point of the pulse current; The optimum point of energy utilization efficiency is determined according to the pulse current at the peak point and the time interval of occurrence of the pulse current obtained based on the second association relationship.

12. The system for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 11, characterized in that: The pulse driving power supply comprises a high voltage output terminal and a ground terminal, wherein the high voltage output terminal is connected to the high voltage electrode of the plasma jet discharge unit, and the ground terminal is grounded; The electrical parameter measurement unit includes a high-voltage probe and a current probe, wherein the high-voltage probe is connected in parallel with the plasma jet discharge unit in the discharge circuit to measure the pulse voltage applied to the plasma jet discharge unit, and the current probe is connected in series with the plasma jet discharge unit in the discharge circuit to detect the pulse current during the discharge process; The gas source unit is used to provide atmosphere conditions for the plasma jet discharge unit.

13. The system for obtaining the optimal point of plasma jet energy utilization efficiency according to claim 11, characterized in that: The plasma jet discharge unit comprises a dielectric and metal electrodes, wherein the metal electrodes comprise a high-voltage electrode and a low-voltage electrode, and the high-voltage electrode and the low-voltage electrode are parallelly attached to the outer surface of the dielectric with a certain distance therebetween.

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