Method for measuring plasma generated by electro-chemical coupling explosion

Abstract

The invention provides a method for measuring plasma generated by electro-chemical coupling explosion, which adopts a device for measuring plasma generated by electro-chemical coupling explosion, the device comprises an explosion cavity and an oscilloscope, and a Langmuir three-probe is arranged in the explosion cavity; and the Langmuir three-probe is connected with an oscilloscope. The Langmuir three-probe comprises a probe P1, a probe P2 and a probe P3. The device provided by the invention has the characteristics of being suitable for transient plasma diagnosis based on Langmuir three probes, simple in structure and convenient in data processing, voltage signals measured by a probe circuit are acquired and are converted into plasma electron temperature and density after being analyzed and calculated, and the electron density ne of the plasma is calculated according to the electron density ne of the plasma. Therefore, the plasma generated by the electro-chemical coupling explosion can be measured.

Description

Technical Field

[0001] The invention belongs to the technical field of explosion and damage, relates to plasma measurement, and specifically to a method for measuring plasma generated by electro-chemical coupling explosion. Background Art

[0002] The plasma generated by the explosion is of great significance for the performance evaluation of energetic materials, the study of combustion and detonation processes, the propagation law of detonation waves of complex detonation devices, and the output performance of micro-scale explosives. Therefore, in order to deepen the understanding of the electro-chemical coupled explosion process and improve the output performance of explosives, it is essential to measure the plasma generated by the electro-chemical coupled explosion.

[0003] In view of the demand for output performance testing of tiny amounts of energetic materials coupled with metal wire electric explosion, it is urgent to carry out research on plasma diagnostic technology produced by tiny amounts of explosives, break through the key technology of plasma diagnosis produced by electro-chemical coupled explosion, and then establish a plasma measurement method produced by electro-chemical coupled explosion.

[0004] During the electrochemical coupled explosion process, the plasma signal generated is a transient signal. The existing measurement methods are usually limited by the scanning voltage source, making it difficult to make an accurate diagnosis and having poor applicability. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for measuring plasma generated by electro-chemical coupled explosion, so as to solve the technical problem in the prior art that the accuracy of plasma measurement for small amounts of drugs needs to be further improved.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0007] The invention discloses a plasma measuring method generated by electro-chemical coupling explosion, which adopts a plasma measuring device generated by electro-chemical coupling explosion.

[0008] The plasma measurement device generated by the electro-chemical coupled explosion comprises an explosion cavity and an oscilloscope, and is characterized in that a Langmuir three-probe is arranged in the explosion cavity; and the Langmuir three-probe is connected to the oscilloscope.

[0009] The Langmuir three-probe comprises probe P1, probe P2 and probe P3.

[0010] The electron density of the plasma is n e The calculation method is:

[0011]

[0012] V d2 =V2-V1

[0013] Where:

[0014] n e Indicates the electron density of plasma, unit: electrons / m 3 ;

[0015] m i Indicates the mass of the ion, in kg;

[0016] I represents the current passing through the probe, in μA;

[0017] S represents the probe collection area, unit: mm 2 ;

[0018] k b represents the Boltzmann constant, in J / K;

[0019] T e Indicates the plasma electron temperature, unit: K;

[0020] φ represents the calculated intermediate value, the unit is: C / J;

[0021] e represents elementary charge, unit: C;

[0022] V d2 Indicates the bias voltage of probe P2 relative to probe P1, in V;

[0023] V1 represents the voltage on probe P1, the unit is: V;

[0024] V2 represents the voltage on probe P2, the unit is: V;

[0025] V out2 It represents the second output voltage of the oscilloscope corresponding to the Langmuir three-probe, in V.

[0026] R represents the resistance value of the resistor, the unit is: Ω.

[0027] The present invention also has the following technical features:

[0028] The probe P2 is in a suspended state, and a resistor and a fixed voltage are connected in series between the probe P1 and the probe P3.

[0029] A pair of parallel ground electrodes and high-voltage electrodes are arranged in the explosion cavity. The ground electrode is connected to the explosion cavity and grounded. The ground electrode is connected to one end of a metal wire-energetic material load, and the other end of the metal wire-energetic material load is connected to the high-voltage electrode; the high-voltage electrode is connected to a first end of a three-electrode gas switch, and the second end of the three-electrode gas switch is connected to a pulse capacitor, and the pulse capacitor is connected to a high-voltage pulse power supply to form an electric explosion circuit.

[0030] The third end of the three-electrode gas switch is connected to the trigger through a coaxial cable; a Rogowski coil is mounted on the high-voltage electrode, and the Rogowski coil is connected to the oscilloscope; a high-voltage probe is connected to the high-voltage electrode, and the high-voltage probe is connected to the oscilloscope.

[0031] The metal wire-energetic material load includes a metal wire on which an energetic material capsule is arranged; the ground electrode is connected to one end of the metal wire, and the other end of the metal wire is connected to the high-voltage electrode; the center of the energetic material capsule is located on the central axis of the Langmuir three-probe.

[0032] The explosion chamber is provided with six flanges outside, one of which is installed with a Langmuir three-probe and serves as a plasma measurement window.

[0033] The Langmuir three-probe is connected to an oscilloscope via a plasma detector.

[0034] The Langmuir three-probe is fixed in the explosion cavity through a stainless steel bracket.

[0035] Compared with the prior art, the present invention has the following technical effects:

[0036] (I) The device of the present invention is suitable for transient plasma diagnosis based on the Langmuir three-probe, and has the characteristics of simple structure and convenient data processing. By acquiring the voltage signal measured by the probe circuit, it is converted into plasma electron temperature and density after analysis and calculation, thereby realizing the measurement of plasma generated by electro-chemical coupled explosion.

[0037] (II) The measurement method provided by the present invention can accurately obtain the distribution of plasma electron temperature and density parameters generated during the electro-chemical coupling explosion, and further explore the ionization characteristics and laws of the electro-chemical coupling explosion.

[0038] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the overall structure of the plasma measurement device generated by electro-chemical coupled explosion.

[0040] Figure 2 Schematic diagram of the assembly relationship of metal wire-energetic material load.

[0041] Figure 3 Schematic diagram of the internal structure of the Langmuir triple probe.

[0042] Figure 4 Schematic diagram of the test principle of the Langmuir three-probe.

[0043] Figure 5 This is a physical photo of the explosion cavity.

[0044] Figure 6 The charging voltage was 30 kV, 0.4 g of energetic material was loaded, and the distance from the explosion center was 11 cm. The Langmuir three-probe measured the change of plasma electron temperature over time generated by the electro-chemical coupled explosion.

[0045] Figure 7 The charging voltage was 30 kV, 0.4 g of energetic material was loaded, and the distance from the explosion center was 11 cm. The Langmuir three-probe measured the change of plasma electron density over time generated by the electro-chemical coupled explosion.

[0046] The meanings of the numbers in the figure are: 1-explosion chamber, 2-oscilloscope, 3-Langmuir three-probe, 4-ground electrode, 5-high-voltage electrode, 6-metal wire-energetic material load, 7-three-electrode gas switch, 8-pulse capacitor, 9-high-voltage pulse power supply, 10-coaxial cable, 11-trigger, 12-Rogowski coil, 13-high-voltage probe, 14-plasma detector.

[0047] 301-tungsten probe, 302-alumina hollow cylindrical ceramic, 303-metal shell, 304-epoxy resin, 305-sealing cover.

[0048] 601-metal wire, 602-energetic material capsule. DETAILED DESCRIPTION

[0049] It should be noted that, unless otherwise specified, all raw materials and equipment in the present invention are raw materials and equipment known in the prior art and can be obtained from commercial channels.

[0050] The technical concept of the present invention is: after the metal wire-energetic material coupling load is detonated, the generated plasma and the Langmuir three-probe circuit form a loop, and the two output voltage signals can be measured by a plasma detector and an oscilloscope, and the electron temperature and density of the plasma can be obtained by analyzing and calculating them.

[0051] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0052] Example:

[0053] This embodiment provides a method for measuring plasma generated by electro-chemical coupled explosion. The method uses a device for measuring plasma generated by electro-chemical coupled explosion.

[0054] like Figure 1As shown, the plasma measurement device generated by the electro-chemical coupled explosion includes an explosion cavity 1 and an oscilloscope 2 . A Langmuir three-probe 3 is arranged in the explosion cavity 1 ; the Langmuir three-probe 3 is connected to the oscilloscope 2 .

[0055] As a preferred solution of this embodiment, Figure 1 As shown, a pair of parallel ground electrodes 4 and high-voltage electrodes 5 are provided in the explosion cavity 1. The ground electrode 4 is connected to the explosion cavity 1 and is grounded. The ground electrode 4 is connected to one end of a metal wire-energetic material load 6, and the other end of the metal wire-energetic material load 6 is connected to the high-voltage electrode 5; the high-voltage electrode 5 is connected to a first end of a three-electrode gas switch 7, and a second end of the three-electrode gas switch 7 is connected to a pulse capacitor 8, and the pulse capacitor 8 is connected to a high-voltage pulse power supply 9 to form an electric explosion circuit.

[0056] As a preferred solution of this embodiment, Figure 1 As shown, the third end of the three-electrode gas switch 7 is connected to the trigger 11 through the coaxial cable 10; the high-voltage electrode 5 is provided with a Rogowski coil 12, which is connected to the oscilloscope 2; the high-voltage electrode 5 is connected with a high-voltage probe 13, which is connected to the oscilloscope 2.

[0057] As a preferred solution of this embodiment, Figure 2 As shown, the metal wire-energetic material load 6 includes a metal wire 601, on which an energetic material capsule 602 is arranged; the ground electrode 4 is connected to one end of the metal wire 602, and the other end of the metal wire 601 is connected to the high-voltage electrode 5; the center of the energetic material capsule 602 is located on the central axis of the Langmuir three-probe 3.

[0058] In this embodiment, the metal wire 601 is made of tungsten, gold, silver, copper, iron, aluminum or nickel; the energetic materials include TNT (trinitrotoluene), RDX (cyclotrimethylene trinitramine, commonly known as RDX), HMX (cyclotetramethylene tetranitramine, commonly known as octogen), CL-20 (hexanitrohexaazaisowurtzitane) and TKX-50 (5,5'-tetraazole-1,1'-dioxydihydroxyamine salt).

[0059] In this embodiment, the coupling modes of the metal wire 601 and the energetic material capsule 602 include series connection, parallel connection or Z-type connection.

[0060] In this embodiment, the electric explosion circuit can apply a pulsed large current with a rise time of less than 7μs and a peak current of about 25kA to the metal wire, and a three-electrode gas switch 7 is used as an energy conversion unit. The three-electrode gas switch 7 and the pulse capacitor 8 are connected in series and integrated to effectively reduce the loop inductance. One end of the pulse capacitor 8 is grounded, and multiple pulse capacitors 8 are used in parallel, and the electric explosion circuit single-point grounding and electromagnetic compatibility technology are used.

[0061] In this embodiment, the Langmuir triple probe 3 adopts a commonly used Langmuir triple probe known in the art. Figure 3 As shown, the Langmuir three-probe 3 uses three tungsten probes 301 made of high-strength tungsten alloy, the diameter of the tungsten probe 301 is 1mm, the distance between the tungsten probes 301 is 1.5mm, and the shape is spherical. The three tungsten probes 301 are shielded by alumina hollow cylindrical ceramics 302. The outer layer of the three tungsten probes 301 is a metal shell 303, which can effectively shield the external electromagnetic field. The hollow material-free part of the alumina hollow cylindrical ceramics 302 is sealed with epoxy resin 304. One end of the Langmuir three-probe 3 is the test end, and the other end is connected to the three-core aviation plug.

[0062] As a preferred solution of this embodiment, Figure 1 As shown, the Langmuir three-probe 3 is connected to the oscilloscope 2 through a plasma detector 14. The plasma detector 14 adopts a commonly used plasma detector known in the art. The plasma detector 14 includes three signal channels, each of which includes an input end and two output ends, the input end is connected to the Langmuir three-probe 3, and the output end is connected to the oscilloscope 2.

[0063] As a preferred solution of this embodiment, the three Langmuir probes 3 are fixed in the explosion cavity by a stainless steel bracket.

[0064] As a preferred solution of this embodiment, Figure 4 As shown, there are six flanges outside the explosion chamber 1, one of which is installed with a Langmuir triple probe 3, and the flange serves as a plasma measurement window.

[0065] In this embodiment, the high-voltage probe 13 uses silicone resin as a dielectric, has a bandwidth compensation range of not less than 5pF, and a decay rate of more than 1000 times. The probe has the ability to measure 35kV high-voltage pulse voltage signals, and the bandwidth can reach 70MHz. Before use, check whether the high-voltage probe 13 is firmly connected, and ensure that the signal line is well connected to the circuit under test to ensure that the oscilloscope 2 can be triggered normally and accurately record the signal.

[0066] In this embodiment, when checking the circuit, it should be ensured that the shell of the explosion chamber 1 has been grounded, and the connection between the high-voltage probe 13 and the high-voltage electrode 5 has been wrapped with insulating tape to avoid surface flashover discharge.

[0067] In this embodiment, the technical indicators of the high-voltage pulse power supply 9 are as follows: working voltage is 0-35kV, pulse current is 0-25kA, total power is 25kVA, energy storage of energy components is 3kJ, charging repetition accuracy is ≤±3‰, and power transmission efficiency is ≥85%.

[0068] The method comprises the following steps:

[0069] Step 1: Use a stainless steel bracket to fix the Langmuir three-probe 3 in the explosion cavity 1, and determine the position of the Langmuir three-probe 3 according to the test requirements.

[0070] Step 2: Connect the Langmuir triple probe 3 to the plasma detector 14 , and then connect the plasma detector 14 to the oscilloscope 2 .

[0071] Step three, connecting the two ends of the metal wire 601 of the metal wire-energetic material load 6 to the high voltage electrode 5 and the ground electrode 4 in the explosion cavity 1 respectively.

[0072] Step 4: Use a coaxial cable 10 to connect the high-voltage probe 13 outside the explosion cavity 1 and the oscilloscope 2. The trigger signal uses the voltage signal during the explosion process to ensure that the trigger 11 and the oscilloscope 2 are triggered synchronously.

[0073] Step 5: Check whether all lines are operating normally. If there is no abnormality, you can proceed with the detonation operation.

[0074] Step 6, test principle as follows Figure 4 As shown, in the plasma to be tested, probe P2 is in a suspended state, and a resistor and a fixed voltage are connected in series between probes P1 and P3. According to the circuit, the potential between the three probes can be preliminarily determined. From the direction of the electron flow and ion flow in the figure, assuming that the counterclockwise direction is positive, the total current on each probe can be obtained as follows:

[0075] -I1=-SJ e exp(φV1)+SJ i (V1)

[0076] I2=-SJ e exp(φV2)+SJ i (V2)

[0077] I3=-SJ e exp(φV3)+SJ i (V3)

[0078] φ≡e / (k b T e ).

[0079] Where:

[0080] V1 represents the voltage on probe P1, the unit is: V;

[0081] V2 represents the voltage on probe P2, the unit is: V;

[0082] V3 represents the voltage on probe P3, the unit is: V;

[0083] I1 represents the total current on probe P1, in μA;

[0084] I2 represents the total current on probe P2, in μA;

[0085] I3 represents the total current on probe P3, in μA;

[0086] S represents the probe collection area, unit: mm 2 ;

[0087] k b represents the Boltzmann constant, in J / K;

[0088] T e Indicates the plasma electron temperature, unit: K;

[0089] e represents elementary charge, unit: C;

[0090] φ represents the calculated intermediate value, the unit is: C / J;

[0091] J e =en e (k b T e / 2πm e ) 1 / 2 , represents the electron current density, unit: A / mm 2 ;

[0092] m e Indicates the mass of the electron, in kg;

[0093] Similarly, the ion current density J can be calculated i .

[0094] Eliminating the electron current density, we can obtain:

[0095]

[0096] V d =V d3 -V d2

[0097] Where:

[0098] V d Indicates V d2 With V d3 The difference, unit: V;

[0099] V d2 Indicates the bias voltage of probe P2 relative to P1, in V;

[0100] V d3Represents the bias voltage of probe P3 relative to P1, in V.

[0101] When probe P2 is suspended, I1 = 0, I2 = I3, and it is assumed that the ion current density between the three probes has little to do with the potential of each probe. Therefore, the calculation method of plasma electron temperature can be obtained:

[0102]

[0103] V d2 =V2-V1

[0104] V d3 =V3-V1

[0105] |V d2 |=|V out1 |

[0106] |V d3 |=||V out2 |-V fix |

[0107] Where:

[0108] V out1 It indicates the first output voltage of the oscilloscope corresponding to the Langmuir three-probe, in V.

[0109] V out2 It represents the second output voltage of the oscilloscope corresponding to the Langmuir three-probe, in V.

[0110] V fix Indicates fixed voltage, unit: V.

[0111] Combining the above equations, we can get the plasma electron density n e Calculation method:

[0112]

[0113] V d2 =V2-V1

[0114] Where:

[0115] n e Indicates the electron density of plasma, unit: electrons / m 3 ;

[0116] m i Indicates the mass of the ion, in kg;

[0117] I represents the current passing through the probe, in μA;

[0118] S represents the probe collection area, unit: mm2 ;

[0119] k b represents the Boltzmann constant, in J / K;

[0120] T e Indicates the plasma electron temperature, unit: K;

[0121] φ represents the calculated intermediate value, the unit is: C / J;

[0122] e represents elementary charge, unit: C;

[0123] V d2 Indicates the bias voltage of probe P2 relative to probe P1, in V;

[0124] V1 represents the voltage on probe P1, the unit is: V;

[0125] V2 represents the voltage on probe P2, the unit is: V;

[0126] V out2 It represents the second output voltage of the oscilloscope corresponding to the Langmuir three-probe, in V.

[0127] R represents the resistance value of the resistor, the unit is: Ω.

[0128] Specifically, in this embodiment, the charging voltage is 30 kV, 0.4 g of energetic material is loaded, and the distance from the explosion center is 11 cm. The change of the plasma electron temperature generated by the electro-chemical coupled explosion measured by the Langmuir three-probe over time is as follows: Figure 6 shown.

[0129] Specifically, in this embodiment, the charging voltage is 30 kV, 0.4 g of energetic material is loaded, and the distance from the explosion center is 11 cm. The change of the plasma electron density generated by the electro-chemical coupled explosion measured by the Langmuir three-probe over time is as follows: Figure 7 shown.

[0130] The charging voltage refers to the working voltage of the high-voltage pulse power supply 9 , that is, the voltage applied by the high-voltage pulse power supply 9 to the metal wire 601 .

Claims

1. A method for measuring plasma generated by electrochemical coupled explosion, characterized in that: The method uses a plasma measurement device generated by an electro-chemical coupled explosion; The plasma measurement device generated by the electro-chemical coupled explosion comprises an explosion cavity (1) and an oscilloscope (2), and is characterized in that a Langmuir three-probe (3) is arranged in the explosion cavity (1); the Langmuir three-probe (3) is connected to the oscilloscope (2); The Langmuir triple probe (3) comprises probe P1, probe P2 and probe P3; The electron density of the plasma is n e The calculation method is: V d2 =V2-V1 Where: n e Indicates the electron density of plasma, unit: electrons / m 3 ; m i Indicates the mass of the ion, in kg; I represents the current passing through the probe, in μA; S represents the probe collection area, unit: mm 2 ; k b represents the Boltzmann constant, in J / K; T e Indicates the plasma electron temperature, unit: K; φ represents the calculated intermediate value, the unit is: C / J; e represents elementary charge, unit: C; V d2 Indicates the bias voltage of probe P2 relative to probe P1, in V; V1 represents the voltage on probe P1, the unit is: V; V2 represents the voltage on probe P2, the unit is: V; V out2 It represents the second output voltage of the oscilloscope corresponding to the Langmuir three-probe, in V. R represents the resistance value of the resistor, the unit is: Ω.

2. The plasma measurement method generated by electrochemical coupled explosion according to claim 1, characterized in that: The probe P2 is in a suspended state, and a resistor and a fixed voltage are connected in series between the probe P1 and the probe P3.

3. The plasma measurement method generated by electrochemical coupled explosion according to claim 1, characterized in that: A pair of parallel ground electrodes (4) and high-voltage electrodes (5) are arranged in the explosion cavity (1). The ground electrode (4) is connected to the explosion cavity (1) and is grounded. The ground electrode (4) is connected to one end of a metal wire-energetic material load (6). The other end of the metal wire-energetic material load (6) is connected to the high-voltage electrode (5). The high-voltage electrode (5) is connected to a first end of a three-electrode gas switch (7). The second end of the three-electrode gas switch (7) is connected to a pulse capacitor (8). The pulse capacitor (8) is connected to a high-voltage pulse power supply (9) to form an electric explosion circuit.

4. The plasma measurement method generated by electrochemical coupled explosion according to claim 3, characterized in that: The third end of the three-electrode gas switch (7) is connected to a trigger (11) via a coaxial cable (10); a Rogowski coil (12) is mounted on the high-voltage electrode (5), and the Rogowski coil (12) is connected to the oscilloscope (2); a high-voltage probe (13) is connected to the high-voltage electrode (5), and the high-voltage probe (13) is connected to the oscilloscope (2).

5. The method for measuring plasma generated by electrochemical coupled explosion according to claim 4, characterized in that: The metal wire-energetic material load (6) comprises a metal wire (601), on which an energetic material capsule (602) is arranged; the ground electrode (4) is connected to one end of the metal wire (602), and the other end of the metal wire (601) is connected to the high-voltage electrode (5); the center of the energetic material capsule (602) is located on the central axis of the Langmuir three-probe (3).

6. The method for measuring plasma generated by electrochemical coupled explosion according to claim 1, characterized in that: The explosion chamber (1) has six flanges on the outside, one of which is installed with a Langmuir triple probe (3), and the flange serves as a plasma measurement window.

7. The method for measuring plasma generated by electrochemical coupled explosion according to claim 1, characterized in that: The Langmuir triple probe (3) is connected to the oscilloscope (2) via a plasma detector (14).

8. The method for measuring plasma generated by electrochemical coupled explosion according to claim 1, characterized in that: The Langmuir three-probe (3) is fixed in the explosion cavity (1) via a stainless steel bracket.

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