A system and method for detecting ammonium nitrate crystals

Abstract

The application provides a kind of ammonium nitrate crystal detection system and detection method, the ammonium nitrate crystal detection system includes power supply device, detection device, vacuum device, gas supply device and analysis device;Detection device includes detection cavity, cathode, anode and probe, detection cavity is the tubular structure of two ends opening, cathode and anode are located at the two ends of detection cavity respectively, and are sealedly connected with detection cavity, gas injection port is provided on the side wall of detection cavity, probe is located in detection cavity, and is located between cathode and anode;Vacuum device and gas supply device are connected with detection device through gas injection port;Power supply device is electrically connected with cathode, anode and probe respectively;Analysis device is connected with probe communication, for the detection result obtained by probe is analyzed.The ammonium nitrate crystal detection system provided by the application is small in size, strong in portability, easy to operate, specific to ammonium nitrate crystal, and can quickly and accurately determine whether the sample to be tested is ammonium nitrate crystal.

Description

Technical Field

[0001] This invention relates to the field of chemical detection technology, and more specifically, to an ammonium nitrate crystal detection system and method. Background Technology

[0002] Ammonium nitrate can be used as fertilizer or combined with other substances to make explosives. Therefore, the detection of ammonium nitrate is a very important aspect of the safety management of explosives. Currently, the main methods for detecting ammonium nitrate include wet chemical detection and X-ray analysis. However, wet chemical detection is cumbersome and time-consuming, while X-ray analysis has low specificity and the accuracy of the results is difficult to guarantee, both of which have significant limitations. Summary of the Invention

[0003] The problem solved by this invention is to provide a detection system that can quickly and accurately detect ammonium nitrate crystals.

[0004] To address the above problems, the present invention provides an ammonium nitrate crystal detection system, comprising a power supply device, a detection device, a vacuum device, a gas supply device, and an analysis device;

[0005] The detection device includes a detection chamber, a cathode, an anode, and a probe. The detection chamber is a tubular structure with openings at both ends. The cathode and the anode are located at the two ends of the detection chamber and are respectively sealed to the detection chamber. A gas injection port is provided on the side wall of the detection chamber. The probe is located inside the detection chamber and between the cathode and the anode.

[0006] The vacuum device and the gas supply device are connected to the detection device through the gas injection port, wherein the gas supply device is used to supply helium to the detection device;

[0007] The power supply device is electrically connected to the cathode, the anode and the probe respectively;

[0008] The analysis device is communicatively connected to the probe and is used to analyze the detection results acquired by the probe.

[0009] Preferably, the cathode and the anode are cylindrical structures with one end open, and the openings of the cathode and the anode face into the detection cavity, and the cathode and the anode are detachably connected to the detection cavity.

[0010] Preferably, the power supply device includes a first power supply and a second power supply, the first power supply being electrically connected to the cathode and the anode respectively, the second power supply being electrically connected to the probe and the anode respectively, and the first power supply being an adjustable DC power supply.

[0011] Preferably, the detection results collected by the probe include a current-voltage characteristic curve, and the analysis device is used to perform second-order differentiation on the current-voltage characteristic curve to obtain an electron distribution function with characteristic fast electrons.

[0012] Preferably, the cathode and the anode are tungsten rods, and the probe is a ring-shaped probe formed of molybdenum wire.

[0013] Preferably, the vacuum device includes a mechanical pump and a vacuum pump.

[0014] This invention comprises an ammonium nitrate crystal detection system consisting of a power supply device, a detection device, a vacuum device, a gas supply device, and an analysis device. The detection device includes a detection chamber and a cathode, an anode, and a probe located within it. After the sample to be tested is placed in the detection chamber, the cathode and anode seal both ends of the chamber, forming a sealed cavity. The vacuum device evacuates the chamber, and the gas supply device fills it with helium gas at a certain pressure. The power supply device powers the cathode and anode. This allows the sample to evaporate upon heating. Furthermore, if the sample is ammonium nitrate, due to its unstable nature, it undergoes various decomposition reactions at high temperatures. Metastable helium atoms can undergo Penning ionization reactions with impurity atoms or molecules (ammonium nitrate or its reaction products). Since different impurities have different ionization energies, the detection results obtained through the probe are analyzed by the analysis device. The ionization energy of the impurity atoms or molecules is determined based on the energy of different electrons, thereby identifying the impurities present in the detection chamber and determining whether the sample is ammonium nitrate crystal. The ammonium nitrate crystal detection system provided by this invention is small in size, highly portable, easy to operate, and highly specific for ammonium nitrate crystals, enabling it to quickly and accurately determine whether a sample to be tested is an ammonium nitrate crystal.

[0015] On the other hand, the present invention also provides a method for detecting ammonium nitrate crystals, based on the ammonium nitrate crystal detection system described above, comprising the following steps:

[0016] Step S1: Place the sample to be tested in the detection chamber near the cathode, and seal the detection chamber through the cathode and anode;

[0017] Step S2: Evacuate the detection chamber using a vacuum device, and then fill the detection chamber with helium using a gas supply device;

[0018] Step S3: Power the cathode, anode and probe through the power supply device to generate a discharge current in the detection chamber and convert the sample to be tested into gas;

[0019] Step S4: Acquire the current-voltage characteristic curve in the detection cavity through the probe, and analyze the current-voltage characteristic curve through the analysis device to obtain the analysis results;

[0020] Step S5: Based on the analysis results, determine whether the sample to be tested is ammonium nitrate crystal.

[0021] Preferably, step S2 includes:

[0022] Turn on the mechanical pump in the vacuum device to reduce the gas pressure in the detection chamber to 10⁻¹ Pa, then turn off the mechanical pump and turn on the molecular pump in the vacuum device to reduce the gas pressure in the detection chamber to 10⁻⁵ Pa, then turn off the molecular pump and fill the detection chamber with helium through the gas supply device. Repeat the vacuuming and helium filling process three times to maintain the gas pressure in the detection chamber at 300 Pa.

[0023] Preferably, step S3 includes:

[0024] Turn on the power supply device, and by adjusting the voltage of the first power supply in the power supply device, generate discharge currents of 7mA and 13mA in the detection chamber respectively, and convert the sample to be tested into gas.

[0025] Preferably, step S5 includes:

[0026] The characteristic peaks in the analytical results obtained under different discharge currents are compared with the characteristic peaks of the ammonium nitrate reaction products under different discharge currents to determine whether the sample to be tested is ammonium nitrate crystal.

[0027] The beneficial effects of the method for detecting ammonium nitrate crystals provided by this invention compared to the prior art are the same as those of the nitrate crystal detection system, and will not be repeated here. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the detection device in an embodiment of the present invention;

[0029] Figure 2 This is a schematic flowchart of the method for detecting ammonium nitrate crystals in an embodiment of the present invention;

[0030] Figure 3 This is an analysis diagram of the electron distribution function with characteristic fast electrons in an embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Detection chamber; 11. Gas injection port; 2. Cathode; 3. Anode; 4. Probe. Detailed Implementation

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0034] It should be noted that, unless otherwise specified, the features in the embodiments of this invention can be combined with each other. The terms "comprising," "including," "containing," and "having" are non-limiting, meaning that other steps and other components that do not affect the results can be added. The above terms cover the terms "composed of" and "substantially composed of." Unless otherwise specified, the materials, equipment, and reagents are commercially available.

[0035] The combination of plasma physics and plasma chemistry has opened up possibilities for the analysis and detection of impurity gases, enabling selective action on a specific set of electrons in a particular object. The form of the nonlocal EDF (Electron Deposition Function) essentially depends on the self-consistent bipolar potential value, which traps electrons in the plasma and ensures their quasi-neutrality. Locked (thermal) electrons have energies less than the bipolar potential energy (several electron temperatures), preventing them from reaching the plasma boundary. These electron energies relax in the plasma, and their EDF has the standard form of an energy smoothing function. Fast electrons with energies exceeding the free potential energy reach the plasma boundary in a state of free diffusion, with no time for energy release during diffusion. Electrons with different energies will reach the plasma boundary retaining their respective initial energies. For example, the metastable state of gases and the Penning ionization reaction of impurity atoms (molecules) can be expressed by the following formula:

[0036] A * +M→A+M + +e{E f};

[0037] Because impurity atoms (molecules) have different ionization energies E i This results in the obtained Penning electrons having different initial energies E. f Therefore, the ionization energy of impurity atoms (molecules) can be easily determined by analyzing the energies of different electrons, specifically using Ei. i =E m -E f This allows for the identification of impurities.

[0038] This invention provides an ammonium nitrate crystal detection system, including a power supply device, a detection device, a vacuum device, a gas supply device, and an analysis device;

[0039] The detection device includes a detection chamber 1, a cathode 2, an anode 3, and a probe 4. The detection chamber 1 is a tubular structure with openings at both ends. The cathode 2 and the anode 3 are located at the two ends of the detection chamber 1 and are respectively sealed to the detection chamber 1. A gas injection port 11 is provided on the side wall of the detection chamber 1. The probe 4 is located inside the detection chamber 1 and between the cathode 2 and the anode 3.

[0040] The vacuum device and the gas supply device are connected to the detection device through the gas injection port 11, wherein the gas supply device is used to supply helium to the detection device;

[0041] The power supply device is electrically connected to the cathode 2, the anode 3 and the probe 4 respectively;

[0042] The analysis device is communicatively connected to the probe 4 and is used to analyze the detection results obtained by the probe 4.

[0043] This invention provides an ammonium nitrate crystal detection system comprised of a power supply device, a detection device, a vacuum device, a gas supply device, and an analysis device. The detection device includes a detection chamber 1 and a cathode 2, an anode 3, and a probe 4 located within it. After the sample to be tested is placed in the detection chamber 1, the cathode 2 and anode 3 seal both ends of the chamber, forming a sealed cavity. The vacuum device evacuates the chamber 1, and then the gas supply device fills it with helium gas at a certain pressure. The power supply device powers the cathode 2 and anode 3. This allows the sample to be heated and evaporated. Furthermore, if the sample is ammonium nitrate, due to its unstable nature, it undergoes various decomposition reactions at high temperatures. Metastable helium atoms can undergo Penning ionization reactions with impurity atoms or molecules (ammonium nitrate or its reaction products). Since different impurities have different ionization energies, the detection results obtained through the probe 4 are analyzed by the analysis device. By analyzing the energies of different electrons, the ionization energies of the impurity atoms or molecules are determined, thereby identifying the impurities present in the detection chamber 1 and determining whether the sample is ammonium nitrate crystal. The ammonium nitrate crystal detection system provided by this invention is small in size, highly portable, easy to operate, and highly specific for ammonium nitrate crystals, enabling it to quickly and accurately determine whether a sample to be tested is an ammonium nitrate crystal.

[0044] In one embodiment, the cathode 2 and the anode 3 are cylindrical structures with one open end, and the openings of the cathode 2 and the anode 3 face into the detection chamber 1. The cathode 2 and the anode 3 are detachably connected to the detection chamber 1. During detection, the sample to be tested can be placed into the cavity of the cathode 2 through the opening. When discharge occurs through the cathode 2 and the anode 3, the discharge current can better act on the sample to be tested, causing the sample to vaporize. The detachable connection between the cathode 2 and the anode 3 and the detection chamber 1 facilitates placing the sample to be tested into the detection chamber 1 before detection begins, and removing any remaining sample and cleaning the detection chamber 1 after detection.

[0045] In one embodiment, the power supply device includes a first power supply and a second power supply. The first power supply is electrically connected to the cathode and the anode, respectively, and the second power supply is electrically connected to the probe and the anode, respectively. The first power supply is an adjustable DC power supply. The negative and positive terminals of the first power supply are electrically connected to the cathode 2 and the anode 3, respectively. When the first power supply is turned on, a discharge current is generated in the detection chamber 1, causing the sample to be tested to vaporize and undergo an ionization reaction. The negative and positive terminals of the second power supply are electrically connected to the probe 4 and the anode 3, respectively. The second power supply provides a scanning operating voltage to the probe 4, enabling the probe 4 to acquire detection results. The first power supply is an adjustable DC power supply. By adjusting the adjustable DC power supply, different discharge currents can be generated in the detection chamber, correspondingly generating different discharge temperatures. Since ammonium nitrate crystals are extremely unstable and can undergo different reactions at different temperatures, ammonium nitrate crystals undergo different reactions under different discharge current conditions, producing different reaction products. Impurities under different discharge current conditions are specifically identified by plasma energy dispersive spectroscopy, and the identification results determine whether the sample to be tested is ammonium nitrate crystal. Because of the unstable nature of ammonium nitrate, different reaction products can be identified under different discharge currents, which can improve the specificity of ammonium nitrate crystal identification. In addition, the plasma detection device is small in size, highly portable, and easy to operate.

[0046] For example, probe 4 in the detection device is a Langmuir probe, and its main body in the detection cavity 1 is annular.

[0047] Since the energy of the metastable He (helium) atom is E m =19.8 eV, which is sufficient to ionize any impurity atoms (molecules) except neon. Therefore, helium was chosen as the transport gas for qualitative analysis of ammonium nitrate crystals.

[0048] like Figure 1 As shown, in the detection device, cathode 2 and anode 3 are located at both ends of detection chamber 1 and are sealed to detection chamber 1, which can form a sealed cavity. Cathode 2 and anode 3 are connected to the power supply device. The sample to be tested is placed near cathode 2. The detection chamber 1 is evacuated by a vacuum device and helium is supplied to the detection chamber 1 by a gas supply device, so that the detection chamber 1 is filled with helium. The power supply device is adjusted to generate different discharge currents. After maintaining this for a period of time, ammonium nitrate crystals can be converted into ammonium nitrate vapor. The ammonium nitrate vapor consists of two parts: one part is the evaporation of ammonium nitrate due to the heating effect of cathode 2, and the other part is the direct sputtering ionization of ammonium nitrate by electrons generated by cathode 2.

[0049] For example, the detection chamber 1 can be a glass tube.

[0050] Specifically, because ammonium nitrate crystals are extremely unstable, they readily undergo the following reactions at different temperatures:

[0051] Reaction 1: When the ambient temperature is 110℃: NH4NO3→NH3+HNO3;

[0052] Reaction 2: When the ambient temperature is 185-200℃: NH4NO3→N2O+2H2O;

[0053] Reaction 3: When the ambient temperature is 230℃: 2NH4NO3→2N2+O2+4H2O;

[0054] Reaction 4: When the ambient temperature is 400℃: 4NH4NO3→3N2+2NO2+8H2O;

[0055] Therefore, the reaction products obtained by the reaction of ammonium nitrate crystals under different discharge current conditions can be used to determine whether the sample to be tested is ammonium nitrate.

[0056] For example, the ionization reactions of different reaction products with metastable helium atoms are as follows:

[0057] He(2 3 S1) + N2O → He + N2O + +e{6.9eV};

[0058]

[0059] The probe 4 in the detection device can collect the current-voltage characteristic curves under different discharge current conditions in the detection chamber 1. The collected current-voltage characteristic curves are analyzed by the analysis device. After taking the second derivative, the electron distribution function with characteristic fast electrons is obtained. Based on the analysis results, it is determined whether the characteristic peaks at the corresponding discharge current correspond to the characteristic peaks of the reaction products of ammonium nitrate crystals at different discharge currents. If they correspond to each other, it indicates that the sample to be tested is ammonium nitrate crystal.

[0060] In one embodiment, the cathode 2 and the anode 3 are tungsten rods, and the probe 4 is a ring-shaped probe formed of molybdenum wire. Tungsten rods have low thermal expansion and good thermal conductivity, as well as a high elastic modulus. Using them as cathode 2 and anode 3 provides good thermal conductivity and stability. Molybdenum wire has high tensile strength, is not easily broken, and has good corrosion resistance.

[0061] In one embodiment, the vacuum device includes a mechanical pump and a molecular pump. The two-stage pump vacuum device, consisting of a mechanical pump and a molecular pump, can improve the vacuum pumping capability, reducing the vacuum level within the detection chamber to a lower level, thereby ensuring the purity of the subsequently introduced helium and reducing the influence of impurities.

[0062] Another embodiment of the present invention provides a method for detecting ammonium nitrate crystals, based on the ammonium nitrate crystal detection system described above, such as... Figure 2 As shown, it includes the following steps:

[0063] Step S1: Place the sample to be tested in the detection chamber near the cathode, and seal the detection chamber through the cathode and anode;

[0064] Step S2: Evacuate the detection chamber using a vacuum device, and then fill the detection chamber with helium using a gas supply device;

[0065] Step S3: Power the cathode, anode and probe through the power supply device to generate a discharge current in the detection chamber and convert the sample to be tested into gas;

[0066] Step S4: Acquire the current-voltage characteristic curve in the detection cavity through the probe, and analyze the current-voltage characteristic curve through the analysis device to obtain the analysis results;

[0067] Step S5: Based on the analysis results, determine whether the sample to be tested is ammonium nitrate crystal.

[0068] Currently, there are two principles for detecting impurity components using plasma electron spectroscopy. One is direct discharge detection of gaseous impurities, which can be achieved with a relatively low current. However, for solid substances such as metals, a larger current needs to be applied to the cathode material and the analyte before detection, causing electrons from the analyte to be sputtered into the carrier gas for qualitative analysis. For non-conductive inorganic crystals like ammonium nitrate, detection can be performed similarly to detecting conventional gases, by applying a relatively large current to sublimate the ammonium nitrate crystal into a gas, but this method is more difficult and has lower accuracy.

[0069] The method for detecting ammonium nitrate crystals provided in this embodiment of the invention takes into account the instability of ammonium nitrate under heat. By generating different discharge currents in the detection chamber, and with the change of discharge temperature, the ammonium nitrate crystals produce different reactions. By analyzing the results under different discharge currents, it is possible to specifically determine whether the sample to be tested is ammonium nitrate.

[0070] In step S1, the cathode 2 is a cylindrical structure with one end open. The sample to be tested is placed at the bottom of the hollow cavity in the cathode 2. Then, the detection cavity 1 is sealed by the cathode 2 and the anode 3. Since the sample to be tested is close to the cathode 2, when the power supply is provided to generate a discharge current in the cathode 2 and the anode 3, the sample to be tested is affected by the temperature of the discharge current and thus reacts.

[0071] In one embodiment, before step S1, the method further includes grinding the sample to be tested to obtain a powder. Grinding can increase the influence of the discharge current on the sample to be tested, making the sample to be tested easier to vaporize.

[0072] In one embodiment, step S2 includes:

[0073] The mechanical pump in the vacuum device is activated, reducing the air pressure in the detection chamber 1 to 10. -1 Pa, then turn off the mechanical pump and turn on the molecular pump in the vacuum device to reduce the gas pressure in the detection chamber 1 to 10. -5 Pa, then turn off the molecular pump, and fill the detection chamber 1 with helium through the gas supply device. Repeat the evacuation and helium filling process 3 times to maintain the gas pressure in the detection chamber 1 at 300 Pa.

[0074] Mechanical and molecular pumps can better expel the gas in detection chamber 1, creating a vacuum environment. By repeatedly evacuating and filling with helium, impurity gases in detection chamber 1 can be fully purged, improving the purity of helium in detection chamber 1 and reducing the influence of impurities.

[0075] It should be noted that the concentration of the helium gas used is 99.9999%.

[0076] In one embodiment, step S3 includes:

[0077] Turn on the power supply device, and by adjusting the voltage of the first power supply in the power supply device, generate discharge currents of 7mA and 13mA in the detection chamber 1 respectively, so as to convert the sample into gas.

[0078] When the discharge current is 7mA, the discharge temperature is relatively low, and ammonium nitrate crystals are more likely to undergo reaction one. However, when the discharge current is 13mA, the discharge temperature is relatively high, and ammonium nitrate crystals are more likely to undergo reaction two. That is, when the discharge current is 7mA, the reaction product of ammonium nitrate is mainly NH3, while when the discharge current is 13mA, the reaction product is mainly N2O.

[0079] Step S4 includes:

[0080] The probe 4 is used to collect the current-voltage characteristic curve in the detection cavity 1, and the second derivative of the current-voltage characteristic curve is obtained by the analysis device to obtain the electron distribution function with characteristic fast electrons, thus obtaining the analysis result.

[0081] Step S5 includes:

[0082] The characteristic peaks in the analytical results obtained under different discharge currents are compared with the characteristic peaks of the ammonium nitrate reaction products under different discharge currents to determine whether the sample to be tested is ammonium nitrate crystal.

[0083] If the characteristic peak in the analysis results corresponds to the characteristic peak of NH3 when the discharge current is 7mA, and the characteristic peak in the analysis results corresponds to the characteristic peak of N2O when the discharge current is 13mA, then the sample to be tested is ammonium nitrate crystal; otherwise, it is not ammonium nitrate crystal.

[0084] Based on the foregoing, if the characteristic peak of 9.6 eV is more obvious in the analysis results when the discharge current is 7 mA, and the characteristic peak of 6.9 eV is more obvious when the discharge current is 13 mA, it indicates that the sample under test reacted to produce NH3 and N2O at discharge currents of 7 mA and 13 mA, respectively, and the sample under test is ammonium nitrate crystal.

[0085] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to the conditions recommended by the manufacturer.

[0086] Example 1

[0087] 1.1 Weigh 0.5g of ammonium nitrate crystals and place them in an agate mortar. Grind them thoroughly until the ammonium nitrate crystals are in powder form.

[0088] 1.2 Place ammonium nitrate powder at the bottom of the hollow cavity of the cathode, and then seal the detection cavity through the cathode and anode;

[0089] 1.3 After sealing the detection chamber completely, turn on the mechanical pump in the vacuum device to evacuate the air pressure in the detection chamber to 10. -1 Then, turn off the mechanical pump and turn on the molecular pump in the vacuum device to continue pumping the gas pressure in the detection chamber to 10 Pa. -5 Pa, then turn off the molecular pump, and use the gas supply device to fill the detection chamber with helium gas at a concentration of 99.9999%. After 3 cycles, maintain the gas pressure in the detection chamber at 300 Pa by filling with helium gas.

[0090] 1.4 Turn on the adjustable DC power supply and set the discharge current in the detection chamber to 7mA and 13mA respectively, and maintain it for 5s to convert the ammonium nitrate powder into ammonium nitrate vapor;

[0091] 1.5. The current-voltage characteristic curve in the detection cavity is acquired by Langmuir probe, and then the second derivative of the current-voltage characteristic curve is obtained by analysis device to obtain the electron distribution function with characteristic fast electrons.

[0092] 1.6. Analyze the characteristic peaks in the electron distribution function with characteristic fast electrons obtained under different discharge current conditions.

[0093] The electron distribution function with characteristic fast electrons obtained in this embodiment is as follows: Figure 3 As shown, the characteristic peak of 9.6 eV is more obvious when the discharge current is 7 mA, while the characteristic peak of 6.9 eV is more obvious when the discharge current is 13 mA. This corresponds to the characteristic that ammonium nitrate is more likely to undergo reaction one to produce NH3 when the discharge temperature is low at low current, and more likely to undergo reaction two to produce N2O when the discharge temperature is high at high current. This characteristic can specifically identify ammonium nitrate crystals.

[0094] Example 2

[0095] 2.1 Weigh 0.5g of ammonium nitrate crystals and place them at the bottom of the hollow cavity in the cathode. Then seal the detection cavity through the cathode and anode.

[0096] 2.2 After sealing the detection chamber completely, turn on the mechanical pump in the vacuum device to evacuate the air pressure in the detection chamber to 10. -1 Then, turn off the mechanical pump and turn on the molecular pump in the vacuum device to continue pumping the gas pressure in the detection chamber to 10 Pa. -5 Pa, then turn off the molecular pump, and use the gas supply device to fill the detection chamber with helium gas at a concentration of 99.9999%. After 3 cycles, maintain the gas pressure in the detection chamber at 300 Pa by filling with helium gas.

[0097] 2.3 Turn on the adjustable DC power supply and set the discharge current in the detection chamber to 7mA and 13mA respectively, and maintain it for 5s to convert the ammonium nitrate powder into ammonium nitrate vapor;

[0098] 2.4. The current-voltage characteristic curve in the detection cavity is acquired by the Langmuir probe, and then the second derivative of the current-voltage characteristic curve is obtained by the analysis device to obtain the electron distribution function with characteristic fast electrons.

[0099] 2.5. Analyze the characteristic peaks in the electron distribution function with characteristic fast electrons obtained under different discharge current conditions.

[0100] The electron distribution function with characteristic fast electrons obtained in this embodiment is consistent with that in Embodiment 1.

[0101] In summary, the ammonium nitrate crystal detection system and method provided by the embodiments of the present invention can detect ammonium nitrate crystals by inductively coupled plasma spectroscopy. It makes full use of the characteristic that ammonium nitrate undergoes different reactions at different temperatures, thereby improving the detection specificity and accuracy. Moreover, the system is small in size, highly portable, and easy to operate, providing a rapid and accurate detection method for the explosive substance ammonium nitrate crystals.

[0102] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A method for detecting ammonium nitrate crystals, characterized in that, An ammonium nitrate crystal detection system is applied, comprising a power supply device, a detection device, a vacuum device, a gas supply device, and an analysis device. The detection device includes a detection chamber (1), a cathode (2), an anode (3), and a probe (4). The detection chamber (1) is a tubular structure open at both ends. The cathode (2) and the anode (3) are located at opposite ends of the detection chamber (1) and are respectively sealed to the detection chamber (1). A gas injection port (11) is provided on the side wall of the detection chamber (1). The probe (4) is located inside the detection chamber (1) and between the cathode (2) and the anode (3). The vacuum device and the gas supply device... The device is connected to the detection device through the gas injection port (11), wherein the gas supply device is used to supply helium to the detection device; the power supply device is electrically connected to the cathode (2), the anode (3) and the probe (4) respectively; the analysis device is communicatively connected to the probe (4) and is used to analyze the detection results obtained by the probe (4); the power supply device includes a first power supply and a second power supply, the first power supply is electrically connected to the cathode (2) and the anode (3) respectively, the second power supply is electrically connected to the probe (4) and the anode (3) respectively, and the first power supply is an adjustable DC power supply; the detection method of ammonium nitrate crystals includes the following steps: Step S1: Place the sample to be tested in the detection chamber (1) near the cathode (2), and seal the detection chamber (1) through the cathode (2) and the anode (3); Step S2: Evacuate the detection chamber (1) using the vacuum device, and then fill the detection chamber (1) with helium using the gas supply device; Step S3: Power the cathode (2), anode (3) and probe (4) through the power supply device to generate a discharge current in the detection chamber (1) and convert the sample to be tested into gas; Step S3 includes: turning on the power supply device and adjusting the voltage of the first power supply in the power supply device to generate a discharge current of 7mA and 13mA in the detection chamber (1) respectively, and converting the sample to be tested into gas; Step S4: Acquire the current-voltage characteristic curve in the detection cavity (1) through the probe (4), and analyze the current-voltage characteristic curve through the analysis device to obtain the analysis result; Step S5: Based on the analysis results, determine whether the sample to be tested is ammonium nitrate crystal; Step S5 includes: comparing the characteristic peaks in the analysis results obtained under different discharge currents with the characteristic peaks of the ammonium nitrate reaction products under different discharge currents to determine whether the sample to be tested is ammonium nitrate crystal.

2. The method for detecting ammonium nitrate crystals according to claim 1, characterized in that, The cathode (2) and the anode (3) are cylindrical structures with one end open, and the openings of the cathode (2) and the anode (3) face into the detection cavity (1). The cathode (2) and the anode (3) are detachably connected to the detection cavity (1).

3. The method for detecting ammonium nitrate crystals according to claim 1, characterized in that, The detection results collected by the probe (4) include the current-voltage characteristic curve. The analysis device is used to perform second-order differentiation on the current-voltage characteristic curve to obtain the electron distribution function with characteristic fast electrons.

4. The method for detecting ammonium nitrate crystals according to claim 1, characterized in that, The cathode (2) and the anode (3) are tungsten rods, and the probe (4) is a ring-shaped probe formed by molybdenum wire.

5. The method for detecting ammonium nitrate crystals according to claim 1, characterized in that, The vacuum device includes a mechanical pump and a vacuum pump.

6. The method for detecting ammonium nitrate crystals according to claim 1, characterized in that, Step S2 includes: Turn on the mechanical pump in the vacuum device to reduce the gas pressure in the detection chamber (1) to 10-1 Pa, then turn off the mechanical pump and turn on the molecular pump in the vacuum device to reduce the gas pressure in the detection chamber (1) to 10-5 Pa, then turn off the molecular pump and fill the detection chamber (1) with helium through the gas supply device. Repeat the vacuuming and helium filling process 3 times to maintain the gas pressure in the detection chamber (1) at 300 Pa.

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