Atmospheric pressure floating electrode enhanced and magnetic confinement dielectric barrier discharge ion source

Abstract

The application belongs to the technical field of mass spectrum analysis, and particularly relates to a kind of atmospheric pressure floating electrode enhancement and magnetic confinement dielectric barrier discharge ion source. Mainly solve the problem of existing dielectric barrier discharge ion source limited ionization efficiency and low ion transmission efficiency. The outer wall of the cavity in the dielectric barrier discharge ion source is sleeved with a floating electrode, the floating electrode is located between the ground electrode and the gas outlet, between the ground electrode and the high-voltage electrode, or between the high-voltage electrode and the gas inlet; two annular permanent magnets are coaxially arranged along the axis of the cavity, one annular permanent magnet is sleeved on the periphery of the cavity and close to the gas inlet, and the other annular permanent magnet is located downstream of the gas outlet, so that the magnetic field generated by the two annular permanent magnets is in the dielectric barrier discharge region and the plasma jet region downstream of the gas outlet, and the direction is basically parallel to the axial direction of the cavity. The ionization efficiency and ion transmission efficiency are enhanced to promote the performance improvement of the ion source in the trace analysis of substances.

Description

Technical Field

[0001] This invention pertains to mass spectrometry analysis devices, specifically relating to an atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source. Background Technology

[0002] Mass spectrometry, a powerful tool for qualitative, quantitative, and structural analysis, has been widely applied in numerous fields, including life sciences, environmental monitoring, food safety, drug development, and clinical diagnostics. The core working principle of a mass spectrometer is to convert analyte molecules in a sample into charged ions in the gas phase, and then separate and detect them based on their mass-to-charge ratio. In this process, the ion source, acting as the "sample entry gateway" and "ionization heart" of the mass spectrometer, directly determines the sensitivity, accuracy, analytical throughput, and the range of samples and molecular types that can be studied.

[0003] Traditional mass spectrometry ion sources mostly operate in a vacuum environment, limiting their ability to directly analyze raw samples at atmospheric pressure. To overcome this limitation, atmospheric pressure ion sources based on gas discharge have emerged. These sources generate plasma by exciting the working gas with an electric field, utilizing the abundant active particles (such as electrons, ions, and excited-state species) to directly ionize sample molecules under atmospheric pressure. This allows for direct coupling with a mass spectrometer without complex pretreatment. Among various gas discharge ion sources, atmospheric pressure plasma jet-based ion sources possess the unique advantage of physically separating the discharge region from the sample reaction region, avoiding contamination of the discharge electrode by sample vapors or sputterings, and improving the stability of the ion source operation.

[0004] Chinese patent CN106601584B discloses an "Atmospheric Pressure Magnetic Enhancement and Magnetic Confinement DC Glow Discharge Ion Source". This patent uses the atmospheric pressure plasma jet generated by DC glow discharge as a mass spectrometry ion source. By applying a vertical magnetic field to the DC discharge region and a parallel magnetic field to the plasma jet development region, the ionization efficiency and ion transport efficiency of this type of ion source are improved to a greater extent, ultimately achieving an improved signal enhancement effect for mass spectrometry trace detection and analysis.

[0005] Besides DC glow discharge, dielectric barrier discharge is another common method for generating atmospheric pressure plasma jets. Compared to the significant Joule heat loss in the ballast resistor during DC glow discharge, dielectric barrier discharge consumes less power and produces a more stable plasma jet. However, when used as an ion source in conjunction with a mass spectrometer, it also suffers from poor detection sensitivity, high detection limits, and insufficient trace detection capabilities. This is because: firstly, the ionization efficiency of active species in the plasma jet generated by dielectric barrier discharge is limited; secondly, similar to DC glow discharge ion sources, under the influence of gas convection and diffusion, only a small portion of ions are collected at the mass spectrometer inlet, while a considerable number escape into the surrounding air and recombine, resulting in low ion transfer efficiency from the ion source to the mass spectrometer inlet. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of low ionization efficiency and ion transport efficiency in existing dielectric barrier discharge ion sources, and to provide an atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source.

[0007] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0008] An atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source includes a cylindrical insulating cavity with an air inlet port and an air outlet port, and two ring electrodes.

[0009] The cavity is connected to an external gas supply system to receive working gas;

[0010] Two ring electrodes are sleeved on the outer wall of the cavity, with an axial gap between them, and are connected to an external AC or pulse power supply; the ring electrode located on the side of the air inlet port serves as a high-voltage electrode; the ring electrode located on the side of the air outlet port serves as a ground electrode with zero potential.

[0011] Its special feature is:

[0012] A floating electrode is fitted on the outer wall of the cavity. The floating electrode is located between the grounding electrode and the outlet port, between the grounding electrode and the high-voltage electrode, or between the high-voltage electrode and the inlet port. The axial distance between the floating electrode and the adjacent grounding electrode and / or high-voltage electrode is 1mm–20mm.

[0013] Two identical ring-shaped permanent magnets are placed coaxially along the cavity axis. One ring-shaped permanent magnet is fitted around the cavity periphery and close to the air inlet port, while the other ring-shaped permanent magnet is located downstream of the air outlet port. This ensures that the magnetic fields generated by the two ring-shaped permanent magnets are in a direction that is basically parallel to the cavity axis in the dielectric barrier discharge region and the plasma jet region downstream of the air outlet port.

[0014] Furthermore, the insulating cavity is made of quartz glass, ceramic, polytetrafluoroethylene, or alumina, and the inner diameter of the cavity is no more than 1 mm.

[0015] Furthermore, the high-voltage electrode, grounding electrode, and floating electrode are all made of copper, aluminum, iron, tungsten, nickel, tantalum, platinum, or their alloys.

[0016] The high-voltage electrode, grounding electrode, and floating electrode are all thin-film cylindrical structures with a thickness of no more than 1 mm and an axial length of 1 mm–15 mm.

[0017] Furthermore, the external AC or pulse power supply applies an AC or pulse waveform to the high-voltage electrode, with the frequency adjustable from the power frequency to the radio frequency range of 13.56 MHz, and the voltage amplitude ranging from 1 kV to 10 kV.

[0018] The inner diameter of the toroidal permanent magnet is 5 mm–25 mm, the outer diameter is 10 mm–30 mm, and the height is 5 mm–10 mm. The parallel magnetic field it generates is no greater than 200 Gauss.

[0019] The working gas is a mixture of one or more of helium, argon, nitrogen, hydrogen and air, with the gas flow rate controlled between 0.01 L / min and 10 L / min.

[0020] Furthermore, a ring-shaped bias electrode is coaxially arranged in the rear stage of the ring permanent magnet downstream of the outlet port along the cavity axis. The bias electrode is connected to an external DC power supply to form an electric field that is as parallel as possible to the direction of plasma jet propagation.

[0021] Meanwhile, the present invention also provides another atmospheric pressure floating electrode enhanced and magnetic confinement dielectric barrier discharge ion source, including a cylindrical insulating cavity with an air inlet port and an air outlet port and a ring electrode;

[0022] The cavity is connected to an external gas supply system to receive working gas;

[0023] The ring electrode is sleeved on the outer wall of the cavity and serves as a high-voltage electrode, which is connected to an external AC or pulse power supply.

[0024] Its special feature is:

[0025] A floating electrode is fitted on the outer wall of the cavity. The floating electrode is located between the high-voltage electrode and the air inlet port or between the high-voltage electrode and the air outlet port. The axial distance between the floating electrode and the high-voltage electrode is 1mm–20mm.

[0026] Two identical ring-shaped permanent magnets are placed coaxially along the cavity axis. One ring-shaped permanent magnet is fitted around the cavity periphery and close to the air inlet port, while the other ring-shaped permanent magnet is located downstream of the air outlet port. This ensures that the magnetic fields generated by the two ring-shaped permanent magnets are in a direction that is basically parallel to the cavity axis in the dielectric barrier discharge region and the plasma jet region downstream of the air outlet port.

[0027] Furthermore, the cavity is made of quartz glass, ceramic, polytetrafluoroethylene, or alumina, and its inner diameter is no greater than 1 mm.

[0028] Furthermore, both the high-voltage electrode and the floating electrode are made of copper, aluminum, iron, tungsten, nickel, tantalum, platinum, or their alloys.

[0029] Both the high-voltage electrode and the floating electrode are thin-film cylindrical structures with a thickness of no more than 1 mm and an axial length of 1 mm–15 mm.

[0030] Furthermore, the voltage applied to the high-voltage electrode by the AC or pulse power supply is an AC or pulse waveform, with a frequency adjustable from the power frequency to a radio frequency range of 13.56MHz, and a voltage amplitude of 1kV–10kV.

[0031] The inner diameter of the ring-shaped permanent magnet is 5mm–25mm, the outer diameter is 10mm–30mm, the height is 5mm–10mm, and the magnetic field it generates is no greater than 200 Gauss.

[0032] The working gas is one or a mixture of several of helium, argon, nitrogen, hydrogen and air, with a gas flow rate of 0.01 L / min–10 L / min.

[0033] Furthermore, a ring-shaped bias electrode is coaxially arranged after the annular permanent magnet downstream of the outlet port along the cavity axis. The bias electrode is connected to an external DC power supply to form an electric field that is as parallel as possible to the direction of plasma jet propagation.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] 1) During operation of the ion source, the sample undergoes a series of complex chemical reactions with active species in the plasma jet and N2, O2, and H2O in the ambient air, resulting in ionization of sample molecules. Ions with different mass-to-charge ratios are then blown into the mass spectrometer inlet for detection. By placing floating electrodes on the outer wall of the chamber, the concentration of active species in the plasma jet increases under the same operating voltage and working gas flow rate, resulting in higher ionization efficiency for the same sample. By placing a pair of ring-shaped permanent magnets coaxially around the chamber, the Lorentz force confinement of the magnetic field further enhances the transport efficiency of charged ions to the mass spectrometer inlet under the same operating voltage and working gas flow rate. The enhanced ionization efficiency and ion transport efficiency jointly contribute to the improved performance of the ion source in trace analysis.

[0036] 2) Compared with Chinese Patent CN106601584B, the plasma jet in this application is generated through dielectric barrier discharge. This difference in generation method determines the difference in the enhancement of ion source ionization efficiency. In a DC glow discharge plasma jet ion source generator, the electrode structure is simple, with the cathode and anode facing each other, and the electric field direction perpendicular to the gas flow direction. Since the direction of the applied magnetic field is perpendicular to both the electric field and the gas flow, the direction of E×B drift of charged particles under the action of the Lorentz force is exactly consistent with the gas flow direction. This electrode structure ensures that while the ionization efficiency of the ion source is improved, the plasma jet will not be quenched due to contact with the wall of the discharge chamber. In contrast, in a dielectric barrier discharge plasma jet ion source generator, the electrodes are usually coaxial needle-ring or coaxial ring-ring structures. The direction of the electric field relative to the gas flow is different at different positions in the three-dimensional discharge space. Therefore, no magnetic field in a certain direction can play its due role in improving the ionization efficiency of the ion source. Applying a floating electrode can improve the ionization efficiency of a dielectric barrier discharge ion source without increasing the input energy or the volume of the ion source, by enhancing the Laplace electric field inside the cavity, increasing the surface charge accumulated on the inner wall of the cavity, and improving the energy deposition of gas discharge. Attached Figure Description

[0037] Figure 1 This is a structural schematic diagram of Embodiment 1 of the present invention. Figure 1 (No floating electrodes and ring-shaped permanent magnets were configured);

[0038] Figure 2 This is a structural schematic diagram of Embodiment 1 of the present invention. Figure 2 (No toroidal permanent magnet configured);

[0039] Figure 3 This is a structural schematic diagram of Embodiment 1 of the present invention. Figure 3 ;

[0040] Figure 4This is a schematic diagram illustrating the working principle of Embodiment 1 of the present invention;

[0041] Figure 5 The plasma jet emission spectra are shown for the scheme with only floating electrodes in Embodiment 1 of the present invention and the traditional scheme (without floating electrodes and ring permanent magnets).

[0042] Figure 6 The images show the ion mass spectra of aspirin solution in Embodiment 1 of the present invention, which only uses a ring permanent magnet, and the traditional scheme (without floating electrodes and ring permanent magnets).

[0043] Figure 7 The images show the ion mass spectra of aspirin solution in Embodiment 1 of the present invention and the conventional scheme (without floating electrodes and ring permanent magnets).

[0044] Explanation of icon numbers:

[0045] 01-AC or pulse power supply; 02-DC power supply; 03-Mass spectrometer inlet; 04-High-pressure gas cylinder; 05-Gas flow meter; 06-Gas transport pipeline;

[0046] 1-Cavity; 2-Inlet port; 3-Outlet port; 4-High voltage electrode; 5-Grounding electrode; 6-Floating electrode; 7-Ring permanent magnet; 8-Bias electrode; 9-Plasma jet. Detailed Implementation

[0047] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0048] The working principle of this invention is as follows:

[0049] 1) A floating electrode 6 is installed on the outer wall of cavity 1, which enhances the Laplace electric field strength inside cavity 1 and the accumulated surface charge number density on the inner wall of cavity 1, thereby enhancing the dielectric barrier discharge inside cavity 1 and improving plasma chemical activity. After the plasma jet 9 is ejected from cavity 1, the floating electrode 6 promotes the injection of more free charges along the axial direction into the jet channel, improving the energy deposition efficiency of gas discharge, and thus significantly increasing the concentration of active particles in plasma jet 9. During the operation of the ion source, the sample to be tested undergoes a series of complex chemical reactions with the active species in plasma jet 9 and N2, O2, and H2O in the ambient air, causing the sample molecules to ionize. Under the action of the floating electrode 6, the increase in the concentration of active particles in plasma jet 9 helps to enhance the ionization efficiency of the ion source for the sample to be tested.

[0050] 2) A pair of ring-shaped permanent magnets 7 are placed coaxially around the periphery of cavity 1, thereby generating a magnetic field parallel to the gas flow direction in the plasma jet development region 9. During the transport of the sample ions to the mass spectrometer inlet 03, ions with a velocity component perpendicular to this parallel magnetic field undergo helical motion along the axial direction around the magnetic field lines under the influence of the Lorentz force of the parallel magnetic field. During this helical motion, collisions between ions and neutral species consume some kinetic energy, causing the confinement radius of the helical motion to gradually decrease. This process effectively prevents some ions from escaping away from the central axis into the ambient air, allowing ions at a larger solid angle to flow into the mass spectrometer inlet 03. In other words, the application of the ring-shaped permanent magnets 7, with the Lorentz force confinement of the parallel magnetic field, helps enhance the transport efficiency of the ion source for the sample ions.

[0051] Compared with the "Atmospheric Pressure Magnetically Enhanced and Magnetically Confined DC Glow Discharge Ion Source" disclosed in Chinese Patent CN106601584B, the structural improvements of the device in this invention are mainly reflected in the following:

[0052] 1) Replacing DC glow discharge with dielectric barrier discharge not only avoids energy loss caused by series ballast resistors in the circuit and improves energy utilization efficiency, but also improves the repeatability of mass spectrometry detection by improving the stability of plasma jet 9.

[0053] 2) By applying the floating electrode 6, the concentration of active particles in the dielectric barrier discharge plasma jet 9 is increased through three mechanisms: enhancing the Laplace electric field inside the cavity 1, increasing the surface charge accumulated on the inner wall of the cavity 1, and improving the energy deposition of the gas discharge. This improves the ionization efficiency of the ion source without increasing the input energy. The pair of square permanent magnets used to generate the vertical magnetic field are eliminated, reducing the size of the ion source and making it more suitable for integration with a mass spectrometer, further advancing the development of high-performance portable mass spectrometry technology.

[0054] 3) In the development of mass spectrometry ion sources, the combined use of floating electrode 6 enhancement and magnetic confinement was realized for the first time. The synergistic effect of the two significantly improved the trace detection capability of the ion source.

[0055] Example 1

[0056] The structure and operation of this embodiment are further described in detail below with reference to the accompanying drawings:

[0057] like Figure 1 As shown, the atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source in this embodiment includes a cylindrical insulating cavity 1. The cavity 1 has two ports: an inlet port 2 and an outlet port 3. The cavity 1 is made of quartz glass, ceramic, polytetrafluoroethylene, or alumina, and its inner diameter is no greater than 1 mm.

[0058] like Figure 1 and Figure 2 As shown, the dielectric barrier discharge ion source also includes three electrodes: a high-voltage electrode 4, a grounding electrode 5, and a floating electrode 6. All three electrodes are made of copper, aluminum, iron, tungsten, nickel, tantalum, platinum, or their alloys, and are all thin-film cylindrical structures with a thickness of no more than 1 mm and an axial length of 1 mm–15 mm.

[0059] Three electrodes are sequentially arranged around the outer wall of cavity 1, without contact between any two electrodes. High-voltage electrode 4 is closer to the inlet port 2, and grounding electrode 5 is located on the outlet port 3 side. Floating electrode 6 is located between grounding electrode 5 and outlet port 3, between grounding electrode 5 and high-voltage electrode 4, or between high-voltage electrode 4 and inlet port 2; the axial distance between floating electrode 6 and the adjacent grounding electrode 5 and / or high-voltage electrode 4 is 1mm–20mm. See also... Figure 2 In this embodiment, the floating electrode 6 is located between the ground electrode 5 and the air outlet port 3 as an example.

[0060] like Figure 3 As shown, the dielectric barrier discharge ion source also includes a pair of identical ring-shaped permanent magnets 7. The inner diameter of each ring-shaped permanent magnet 7 is 5mm–25mm, the outer diameter is 10mm–30mm, and the height is 5mm–10mm, generating a magnetic field no greater than 200 Gauss. One ring-shaped permanent magnet 7 is fitted around the periphery of the cavity 1 and close to the inlet port 2, while the other ring-shaped permanent magnet 7 is located downstream of the outlet port 3. Both ring-shaped permanent magnets 7 are coaxially placed with the cavity 1. The magnetic field generated by the two ring-shaped permanent magnets 7 in the dielectric barrier discharge region and the plasma jet 9 region downstream of the outlet port 3 is generally parallel to the axis of the cavity 1.

[0061] Figure 4 This is a schematic diagram illustrating the operation of the atmospheric pressure floating electrode enhancement and magnetic confinement dielectric barrier discharge ion source in this embodiment. A gas supply system consisting of a high-pressure gas cylinder 04, a gas flow meter 05, and a gas transport pipeline 06 is connected to the cavity 1, delivering the working gas from the inlet port 2 into the cavity 1. The gas flow meter 05 is located between the high-pressure gas cylinder 04 and the inlet port 2, used to measure the gas flow rate in the gas transport pipeline 06, thereby achieving precise control of the working gas flow rate within the cavity 1. The working gas is one or a mixture of several of helium, argon, nitrogen, hydrogen, and air, with the gas flow rate controlled between 0.01 L / min and 10 L / min.

[0062] Two ring electrodes are connected to the positive and negative terminals of an external AC or pulse power supply 01, respectively, to provide AC or pulse voltage to the high-voltage electrode 4 and form a discharge circuit with the ground electrode 5. The frequency of the AC or pulse power supply 01 is adjustable from the power frequency to the radio frequency range of 13.56 MHz, and the voltage amplitude is 1kV–10kV. The bias electrode 8 is connected to an external DC power supply 02 to provide a DC bias voltage to form an electric field that is as parallel as possible to the propagation direction of the plasma jet 9.

[0063] When the ion source is running, the working gas is released from the high-pressure gas cylinder 04 and continuously flows into the cavity 1 from the inlet port 2 via the gas transport pipe 06. After the working gas flows through the dielectric barrier discharge region between the high-pressure electrode 4 and the ground electrode 5, the power supply equipment is activated to apply a sufficiently high voltage to the high-pressure electrode 4 and the ground electrode 5. The gas is broken down, forming a plasma containing a large number of active species inside the cavity 1. Under the combined action of the Coulomb force of the electric field and the traction force of the airflow, the plasma flows through the region where the floating electrode 6 is located and is ejected from the outlet port 3, forming a plasma jet 9. The sample to be tested is then injected into the location of the plasma jet 9. The active species in the plasma react with the sample to be tested and H2O, O2, and N2 in the air, causing the sample molecules to ionize. The sample molecular ions are gradually transported to the mass spectrometer inlet 03 under the combined action of the magnetic field generated by the ring permanent magnet 7 and the electric field generated by the bias voltage on the bias electrode 8, finally completing the mass spectrometry analysis of the sample to be tested.

[0064] To clearly verify the technical effect of the present invention, the ion source was characterized under three conditions: only the floating electrode 6 was added, only the annular permanent magnet 7 was added, and both the floating electrode 6 and the annular permanent magnet 7 were added. The results were compared with the ion source without the floating electrode 6 and the annular permanent magnet 7.

[0065] The experiment was conducted in an atmospheric environment. Chamber 1 was made of quartz glass, with an inner diameter of 0.5 mm and an outer diameter of 1.2 mm. The working gas was pure helium, with a flow rate of 1 L / min. Both the high-voltage electrode 4 and the grounding electrode 5 were 2 mm long, with a distance of 12 mm between them. The pulse voltage applied to the high-voltage electrode 4 had an amplitude of 5 kV, a frequency of 25 kHz, and a pulse width of 2 µs. An external floating electrode 6, 5 mm long, was located 2 mm from the outlet port. Figure 5As shown, under the condition that other operating conditions remain unchanged, the emission spectra of plasma jet 9 were compared in two cases: with and without floating electrode 6. Regardless of whether floating electrode 6 is applied, emission lines of various active species, such as OH radicals, excited-state N2, excited-state N+2, and metastable He, at different wavelengths can be observed in the emission spectrum of dielectric barrier discharge plasma jet 9. With floating electrode 6, the emission intensity of various spectral lines is 2–3 times that without floating electrode 6. The increase in spectral intensity indicates an increase in the concentration of active species in plasma jet 9 and an improvement in the ionization efficiency of the ion source.

[0066] Keeping the experimental conditions unchanged, without configuring the floating electrode 6, a pair of annular permanent magnets 7 are applied around the periphery of cavity 1 to generate a magnetic field of approximately 50 Gs in the plasma jet development region, with the magnetic field direction basically consistent with the gas flow direction. Near the outlet port 3, a 10.0 ppb aspirin solution is injected into the plasma jet 9 using a syringe pump. Figure 6 As shown, the mass spectrometry signals of the ion source were compared in two scenarios: with only the ring magnet 7 and without the floating electrode 6 and the ring magnet 7 (traditional scheme). Regardless of whether the ring magnet 7 was applied, the aspirin solution underwent a series of complex reactions with the active species in the plasma jet 9, as well as air and water vapor in the atmosphere. Therefore, sample molecular ions with different mass-to-charge ratios (m / z) could be observed in the mass spectra of the ion source in both scenarios. Under the parallel magnetic field generated by the ring magnet 7, the relative intensity of many ions was significantly enhanced, becoming 5–8 times that without a magnetic field. The increase in mass intensity indicates an increase in the ion transport efficiency of the ion source under magnetic field confinement.

[0067] Keeping other experimental conditions unchanged, when the floating electrode 6 and the ring permanent magnet 7 are applied simultaneously, the ionization efficiency and ion transport efficiency of the ion source are both enhanced. Similarly, a 10.0 ppb aspirin solution is injected into the plasma jet 9 near the outlet port 3 using a syringe pump, and detected by a mass spectrometer. Figure 7 The effect of simultaneously applying the floating electrode 6 and the ring permanent magnet 7 (this scheme) on the mass spectrometry signal is shown. Compared with the ion source without the floating electrode 6 and the ring permanent magnet 7 (traditional scheme), the mass spectrometry intensity of many ions is enhanced by 10–20 times. This enhancement factor is greater than... Figure 6The case where only the ring-shaped permanent magnet 7 is configured is more common, indicating that the increase in ionization efficiency and ion transport efficiency jointly promotes the performance improvement of the ion source in trace analysis of substances.

[0068] Example 2

[0069] The difference between this embodiment and Embodiment 1 is that the grounding electrode 5 is not provided, and the floating electrode 6 is located between the high-voltage electrode 4 and the air inlet port 2 or between the high-voltage electrode 4 and the air outlet port 3; the axial distance between the floating electrode 6 and the high-voltage electrode 4 is 1mm–20mm. The rest of the structure is the same as in Embodiment 1.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. An atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source, comprising a cylindrical insulating cavity (1) having an air inlet port (2) and an air outlet port (3) and two ring electrodes; The cavity (1) is connected to an external gas supply system to receive working gas; Two ring electrodes are sleeved on the outer wall of the cavity (1), with an axial gap between the two ring electrodes, and connected to an external AC or pulse power supply (01); the ring electrode located on the side of the air inlet port (2) serves as a high-voltage electrode (4); the ring electrode located on the side of the air outlet port (3) serves as a ground electrode (5), with a potential of zero. Its features are: A floating electrode (6) is sleeved on the outer wall of the cavity (1). The floating electrode (6) is located between the ground electrode (5) and the air outlet (3), between the ground electrode (5) and the high voltage electrode (4), or between the high voltage electrode (4) and the air inlet (2). The axial distance between the floating electrode (6) and the adjacent ground electrode (5) and / or high voltage electrode (4) is 1mm–20mm. Two identical ring-shaped permanent magnets (7) are placed coaxially along the axial direction of the cavity (1). One ring-shaped permanent magnet (7) is sleeved around the periphery of the cavity (1) and close to the air inlet port (2). The other ring-shaped permanent magnet (7) is located downstream of the air outlet port (3), so that the magnetic field generated by the two ring-shaped permanent magnets (7) is parallel to the axial direction of the cavity (1) in the dielectric barrier discharge region and the plasma jet (9) region downstream of the air outlet port (3).

2. The atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source according to claim 1, characterized in that: The cavity (1) is made of quartz glass, ceramic, polytetrafluoroethylene or alumina, and its inner diameter is no more than 1 mm.

3. The atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source according to claim 2, characterized in that: The high-voltage electrode (4), grounding electrode (5) and floating electrode (6) are all made of copper, aluminum, iron, tungsten, nickel, tantalum, platinum or their alloys; The high-voltage electrode (4), grounding electrode (5) and floating electrode (6) are all thin-film cylindrical structures with a thickness of no more than 1 mm and an axial length of 1 mm–15 mm.

4. The atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source according to claim 3, characterized in that: The AC or pulse power supply (01) applies an AC or pulse waveform to the high-voltage electrode (4), with the frequency adjustable from power frequency to 13.56 MHz radio frequency, and the voltage amplitude is 1kV–10kV. The inner diameter of the ring-shaped permanent magnet (7) is 5mm–25mm, the outer diameter is 10mm–30mm, the height is 5mm–10mm, and the magnetic field generated is no greater than 200 Gauss. The working gas is one or a mixture of several of helium, argon, nitrogen, hydrogen and air, with a gas flow rate of 0.01 L / min–10 L / min.

5. The atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source according to any one of claims 1-4, characterized in that: Along the axial direction of the cavity (1), a ring-shaped bias electrode (8) is coaxially arranged after the ring permanent magnet (7) downstream of the outlet port (3). The bias electrode (8) is connected to an external DC power supply (02) to form an electric field that is as parallel as possible to the propagation direction of the plasma jet (9).

6. An atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source, comprising a cylindrical insulating cavity (1) having an air inlet port (2) and an air outlet port (3) and a ring electrode; The cavity (1) is connected to an external gas supply system to receive working gas; The ring electrode is sleeved on the outer wall of the cavity (1) and serves as a high-voltage electrode (4), which is connected to an external AC or pulse power supply (01). Its features are: A floating electrode (6) is sleeved on the outer wall of the cavity (1). The floating electrode (6) is located between the high voltage electrode (4) and the air inlet (2) or between the high voltage electrode (4) and the air outlet (3). The axial distance between the floating electrode (6) and the high voltage electrode (4) is 1mm–20mm. Two annular permanent magnets (7) of the same specification are placed coaxially along the axial direction of the cavity (1). One annular permanent magnet (7) is sleeved around the cavity (1) and close to the air inlet port (2). The other annular permanent magnet (7) is located downstream of the air outlet port (3), so that the magnetic field generated by the two annular permanent magnets (7) is parallel to the axial direction of the cavity (1) in the dielectric barrier discharge region and the plasma jet (9) region downstream of the air outlet port (3).

7. The atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source according to claim 6, characterized in that: The cavity (1) is made of quartz glass, ceramic, polytetrafluoroethylene or alumina, and its inner diameter is no more than 1 mm.

8. The atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source according to claim 7, characterized in that: The high-voltage electrode (4) and the floating electrode (6) are both made of copper, aluminum, iron, tungsten, nickel, tantalum, platinum or their alloys; Both the high-voltage electrode (4) and the floating electrode (6) are thin-film cylindrical structures with a thickness of no more than 1 mm and an axial length of 1 mm–15 mm.

9. The atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source according to claim 8, characterized in that: The AC or pulse power supply (01) applies an AC or pulse waveform to the high-voltage electrode (4), with the frequency adjustable from power frequency to 13.56MHz radio frequency range and the voltage amplitude being 1kV–10kV. The inner diameter of the ring-shaped permanent magnet (7) is 5mm–25mm, the outer diameter is 10mm–30mm, the height is 5mm–10mm, and the magnetic field generated is no greater than 200 Gauss. The working gas is one or a mixture of several of helium, argon, nitrogen, hydrogen and air, with a gas flow rate of 0.01 L / min–10 L / min.

10. The atmospheric pressure floating electrode enhanced and magnetically confined dielectric barrier discharge ion source according to any one of claims 6-9, characterized in that: Along the axial direction of the cavity (1), a ring-shaped bias electrode (8) is coaxially arranged after the ring permanent magnet (7) downstream of the outlet port (3). The bias electrode (8) is connected to an external DC power supply (02) to form an electric field that is as parallel as possible to the propagation direction of the plasma jet (9).

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