ECD detector without radioactive source

Abstract

According to the radioactive-source-free ECD detector provided by the invention, each external terminal of the vacuum electron source is connected with the excitation power supply, the lamp filament emits electrons outwards in the electric field of the accelerating electrode, and the electrons enter the constant magnetic field of the focusing coil to do spiral motion and are focused on the plating layer of the anode to release deep ultraviolet photons. Sample gas and carrier gas flow into the detection chamber and the ionization chamber through the hollow column, gas in the ionization chamber is excited by deep ultraviolet photons and converted into anions, the anions reach the collecting electrode under the action of an electric field of the bias electrode, and the anions lose electrons and are converted into neutral atoms to be exhausted from the exhaust port. And the collecting electrode can convert the electrons into available data after obtaining the electrons. Physical properties of electrons generated by the vacuum electron source are determined by filament temperature, accelerating electrode voltage, focusing coil current and anode voltage. When the excitation power supply is stable, the electron energy and the electron flow density are constant and are irrelevant to the components and the flow of the carrier gas and the sample gas in the ionization chamber. A linear algorithm is used for calibrating and calibrating the concentration of the detected gas, so that the detection difficulty can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of detectors, and in particular relates to an ECD detector without a radioactive source. Background Art

[0002] ECD detector (full name Electron Capture Detector) is an ionization detector used to detect gaseous substances. It has high sensitivity for detecting electronegative substances and is one of the detector types widely used in food inspection, environmental testing and other fields.

[0003] Currently, most ECD detectors on the market contain radioactive substances and are controlled Class V radiation sources. Their installation, transportation, and recycling must comply with relevant regulations. If they are handled incorrectly, radioactive contamination will occur. Therefore, developing an ECD detector that does not contain radiation sources to replace ECD detectors containing radiation sources will bring high economic and environmental value.

[0004] However, the existing ECD detector solution without radioactive source uses a high voltage power supply with a discharge needle and a discharge aperture plate to produce an ionization effect, which has the following disadvantages:

[0005] (1) The carrier gas and the gas to be measured flow directly through the discharge needle and the discharge orifice plate. The atoms of the carrier gas and the gas to be measured will be directly ionized on the discharge needle and the discharge orifice plate. For the atoms of the gas to be measured, the ionization energy is significantly lower than that of β rays, and the maximum does not exceed the first ionization energy of He atoms. In order to ensure the extensiveness of detection, high-purity helium must be used as the carrier gas, which is relatively expensive.

[0006] (2) When other rare gas atoms are mixed in the carrier gas (He) or the concentration of the measured gas is high, the discharge needle and the discharge orifice plate will directly ionize other rare gas atoms or measured gas atoms. Due to the bandwidth characteristics of the high-voltage discharge energy, in addition to being ionized, a certain proportion of the rare gas atoms and measured gas atoms will be excited to an excited state and quickly transition back to the ground state, releasing energy lower than the first ionization energy of the atom and will not be captured by the detection electrode, resulting in a decrease in the detector response effect. Therefore, when the concentration of the measured gas is high, the detector response is nonlinear, and the calibration and processing complexity of converting the detector signal into measurement data is high;

[0007] (3) The carrier gas and the measured gas flow from the detection chamber to the discharge chamber, which is opposite to the direction of movement of the gas ions after ionization. Only a certain proportion of the ionized gas ions are captured by the detection electrode. As the carrier gas flow rate increases, the capture ratio decreases. Therefore, the detector's response to the carrier gas flow rate is also nonlinear, causing the measurement baseline to be more sensitive to flow rate changes and more difficult to control.

[0008] Therefore, how to overcome the above technical defects is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0009] The object of the present invention is to provide an ECD detector without a radioactive source, which can reduce the concentration requirements of carrier gas and sample gas and reduce the difficulty of detection.

[0010] In order to solve the above technical problems, the present invention provides an ECD detector without radioactive source, comprising a vacuum electron source, an ionization chamber and a detection chamber.

[0011] The vacuum electron source comprises a tube body, a filament, a first accelerating electrode, a second accelerating electrode, a focusing coil and an anode. The first accelerating electrode and the second accelerating electrode are metal cylinders with one end open and the bottom of the metal cylinder is provided with an opening. The filament is provided at one end of the tube body. The first accelerating electrode and the second accelerating electrode are sequentially covered on the outside of the filament, and the tip of the filament faces the opening of the first accelerating electrode and the second accelerating electrode. The focusing coil is provided on the outside of the second accelerating electrode. The anode is a conductive fluorescent material coating plated on the inner wall of the other end of the tube body. The filament, the first accelerating electrode, the second accelerating electrode, the focusing coil and the anode all have external terminals, and each external terminal of the vacuum electron source is respectively connected to an excitation power supply.

[0012] One end of the ionization chamber is connected to the other end of the tube body;

[0013] The detection chamber includes a bias electrode, a first detection tube, a collecting electrode and a second detection tube connected in sequence. The detection chamber also includes a hollow column, one end of which serves as an air inlet for introducing sample gas and carrier gas, and the other end of the hollow column is inserted into the detection chamber. The bias electrode is connected to the other end of the ionization chamber, and the detection chamber is also provided with an exhaust port.

[0014] Optionally, in the above-mentioned ECD detector without a radioactive source, the tip of the filament, the opening of the first accelerating electrode, the opening of the second accelerating electrode and the axis of the focusing coil are all colinear with the axis of the tube body.

[0015] Optionally, in the above-mentioned ECD detector without a radiation source, the external terminals of the filament, the first accelerating electrode, the second accelerating electrode and the focusing coil are located at the tail of the tube body, and the external terminals of the anode are located at the head of the tube body.

[0016] Optionally, in the above-mentioned ECD detector without a radioactive source, the excitation power supply includes a cathode current source, a first accelerating electrode voltage source, a second accelerating electrode voltage source, a focusing coil current source and an anode voltage source respectively connected to the external terminals of the filament, the first accelerating electrode, the second accelerating electrode, the focusing coil and the anode;

[0017] And / or, the bias electrode and the collecting electrode are connected to a bias voltage source and a signal sampling and processing circuit respectively through lead terminals.

[0018] Optionally, in the above-mentioned ECD detector without radioactive source, the tube body is a glass tube;

[0019] And / or, the tube body is a cylindrical tube;

[0020] And / or, the interior of the tube body is in a vacuum state, and a vacuum exhaust port is provided on the tube body.

[0021] Optionally, in the above-mentioned ECD detector without a radioactive source, the filament is a V-shaped filament, and the tip of the filament is inlaid with a single crystal tungsten layer;

[0022] And / or, the focusing coil is a hollow metal solenoid.

[0023] Optionally, in the above-mentioned ECD detector without radioactive source, the ionization chamber is a quartz tube, and the ionization chamber is connected to the tube body through an insulating gasket;

[0024] And / or, the first detection tube and the second detection tube are quartz tubes;

[0025] And / or, the bias electrode and the collecting electrode are both annular metal components.

[0026] Optionally, in the above-mentioned ECD detector without a radioactive source, the inner diameter, outer diameter and material of the ionization chamber, the first detection tube and the second detection tube are all the same.

[0027] Optionally, in the above-mentioned ECD detector without a radioactive source, the other end of the hollow column is inserted into the first detection tube through the second detection tube and the collecting electrode;

[0028] And / or, the exhaust port is connected to the second detection tube.

[0029] Optionally, the above-mentioned ECD detector without a radioactive source further includes a detector housing for encapsulating the vacuum electron source, the ionization chamber and the detection chamber, and the detector housing is grounded in a working state.

[0030] The present invention provides an ECD detector without a radioactive source, which has the following beneficial effects:

[0031] When working, each external terminal of the vacuum electron source is connected to an excitation power supply, and the filament is accelerated under the electric field provided by the first accelerating electrode and the second accelerating electrode, and emits electrons outward and into the focusing coil. The constant current inside the focusing coil generates a constant magnetic field. The accelerated electrons move in a spiral motion under the action of the Lorentz force in the magnetic field, and finally focus on the anode. A part of them excites the atoms of the anode fluorescent material, releases deep ultraviolet photons, and enters the ionization chamber. The fully mixed sample gas and carrier gas flow into the detection chamber from the bottom of the detector through the hollow column at a constant flow rate and diffuse into the ionization chamber. The gas in the ionization chamber is excited by the deep ultraviolet photons, and its electronegative atoms are transformed from neutral atoms to negatively charged anions. They move toward the collecting electrode under the action of the electric field of the bias electrode and the collecting electrode, and lose electrons when reaching the collecting electrode and become neutral atoms again, and are discharged from the exhaust port. The collecting electrode can convert the electrons into usable data after obtaining them.

[0032] The physical properties of electrons generated by the vacuum electron source are determined by the temperature of the filament, the voltage of the first accelerating electrode and the second accelerating electrode, the current of the focusing coil and the voltage of the anode. When the external excitation power supply is stable, the electron energy and electron current density are constant, which is independent of the composition and flow rate of the carrier gas and sample gas in the ionization chamber. The number of excited anions in the ionization chamber is proportional to the number of electronegative atoms, that is, the response signal intensity is proportional to the concentration of the component to be measured.

[0033] Therefore, by adopting the above structure, the concentration requirements of the carrier gas and the sample gas can be reduced, and the calibration and calibration of the measured gas concentration using a linear algorithm can reduce the difficulty of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0035] Figure 1 A schematic structural diagram of an ECD detector without a radioactive source provided by an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of the circuit connection between the pins of the vacuum electron source and the external excitation power supply provided in an embodiment of the present invention;

[0037] Figure 3 A working principle diagram of an ECD detector without a radioactive source provided in an embodiment of the present invention.

[0038] In the above picture:

[0039] S-ECD detector without radioactive source;

[0040] 100-tube body; 101-vacuum exhaust port; 110-filament; 111, 112-filament terminal; 120-first accelerating electrode; 121-first accelerating electrode terminal; 130-second accelerating electrode; 131-second accelerating electrode terminal; 140-focusing coil; 141, 142-accelerating coil terminal; 150-anode; 151-anode terminal;

[0041] 201-insulating gasket; 202-bias electrode; 203-collecting electrode; 204-ionization chamber; 205-first detection tube; 206-second detection tube; 207, 208-lead ends; 209-hollow column; 210-exhaust port;

[0042] 301-focusing coil current source; 302-cathode current source; 303-first accelerating electrode voltage source; 304-second accelerating electrode voltage source; 305-anode voltage source;

[0043] 401 - excitation power supply; 402 - bias voltage source; 403 - signal sampling and processing circuit. DETAILED DESCRIPTION

[0044] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0045] The core of the present invention is to provide an ECD detector without a radioactive source, which can reduce the concentration requirements of carrier gas and sample gas and reduce the difficulty of detection.

[0046] In order to enable those skilled in the art to better understand the technical solution provided by the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0047] Specifically, please refer to Figure 1-Figure 3 The present invention provides an ECD detector S without a radioactive source, comprising: a vacuum electron source, an ionization chamber 204 and a detection chamber.

[0048] The vacuum electron source is a specially designed vacuum electron tube, which mainly includes a tube body 100 , a filament 110 , a first accelerating electrode 120 , a second accelerating electrode 130 , a focusing coil 140 and an anode 150 .

[0049] The tube body 100 is used as a receiving and supporting component for the filament 110, the first accelerating electrode 120, the second accelerating electrode 130, the focusing coil 140 and the anode 150. The filament 110 is disposed at one end of the tube body 100.

[0050] After the current passes through the filament 110, it is accelerated under the electric field provided by the first accelerating electrode 120, and emits a large number of free electrons.

[0051] The first accelerating electrode 120 and the second accelerating electrode 130 are metal cylinders with one end open, and the bottom of the metal cylinder is provided with an opening. The accelerating electrodes after being energized are based on the electric field acceleration principle. When charged particles enter the accelerating electrodes, the particles will gain energy and accelerate due to the electric field between the electrodes. The first accelerating electrode 120 and the second accelerating electrode 130 are sequentially covered on the outside of the filament 110, and the open end of the metal cylinder is connected to one end surface of the tube body 100. The tip of the filament 110 faces the openings of the first accelerating electrode 120 and the second accelerating electrode 130.

[0052] The focusing coil 140 is disposed outside the second accelerating electrode 130 . When the focusing coil 140 is powered on, the constant current inside it generates a constant magnetic field. The accelerated electrons move in a spiral motion in the magnetic field under the action of the Lorentz force and are finally focused on the anode 150 .

[0053] The anode 150 is a conductive fluorescent material coating coated on the inner wall of the other end of the tube body 100. Part of the accelerated electrons are converted into heat on the outer wall of the anode 150 and the tube body 100, and part of them excite the fluorescent material atoms of the conductive fluorescent material coating, releasing deep ultraviolet photons with a wavelength of 120mm-250nm and entering the ionization chamber.

[0054] The filament 110, the first accelerating electrode 120, the second accelerating electrode 130, the focusing coil 140 and the anode 150 all have external terminals. The external terminals of the vacuum electron source are respectively connected to the excitation power supply 401 to provide electrical energy for each component.

[0055] One end of the ionization chamber 204 is connected to the other end of the tube body 100. Since deep ultraviolet photons have high energy, they can interact with the gas molecules in the ionization chamber, causing the gas molecules to be ionized. Therefore, the gas in the ionization chamber 204 can be excited by the deep ultraviolet photons of the vacuum electron source, and its atoms with higher electronegativity are converted from neutral atoms to negatively charged anions.

[0056] The detection chamber includes a bias electrode 202, a first detection tube 205, a collecting electrode 203 and a second detection tube 206 connected in sequence. The detection chamber also includes a hollow column 209. One end of the hollow column 209 serves as an air inlet for introducing sample gas and carrier gas. The other end of the hollow column 209 is inserted into the detection chamber. The bias electrode 202 is connected to the other end of the ionization chamber 204. The detection chamber is also provided with an exhaust port 210 for discharging sample gas and carrier gas.

[0057] The present solution provides an ECD detector S without a radioactive source. When working, each external terminal of the vacuum electron source is connected to an excitation power supply 401, and the filament 110 is accelerated under the electric field provided by the first accelerating electrode 120 and the second accelerating electrode 130, and emits electrons outward and injects them into the interior of the focusing coil 140. The constant current inside the focusing coil 140 generates a constant magnetic field, and the accelerated electrons are subjected to the Lorentz force in the magnetic field to perform spiral motion, and are finally focused on the anode 150, and a part of them excites the anode fluorescent material atoms, releases deep ultraviolet photons, and enters the ionization chamber. The fully mixed sample gas and carrier gas flow into the detection chamber from the bottom of the detector through the hollow column 209 at a constant flow rate and diffuse into the ionization chamber. The gas in the ionization chamber is excited by the deep ultraviolet photons, and its electronegative atoms are transformed from neutral atoms to negatively charged anions, and move toward the collecting electrode under the electric field of the bias electrode 202 and the collecting electrode 203, and lose electrons when reaching the collecting electrode 203 and become neutral atoms again, and are discharged from the exhaust port 210. The collecting electrode 203 can convert the acquired electrons into usable data.

[0058] The physical properties of the electrons generated by the vacuum electron source are determined by the temperature of the filament 110, the voltage of the first accelerating electrode 120 and the second accelerating electrode 130, the current of the focusing coil 140 and the voltage of the anode 150. When the external excitation power supply 401 is stable, the electron energy and electron current density are constant, and are independent of the composition and flow rate of the carrier gas and the sample gas in the ionization chamber. The number of anions excited in the ionization chamber is proportional to the number of electronegative atoms, that is, the response signal intensity is proportional to the concentration of the component to be measured.

[0059] Therefore, by adopting the above structure, the concentration requirements of the carrier gas and the sample gas can be reduced, and the calibration and calibration of the measured gas concentration using a linear algorithm can reduce the difficulty of detection.

[0060] In a specific embodiment, the tip of the filament 110, the opening center of the first accelerating electrode 120, the opening center of the second accelerating electrode 130 and the axis of the focusing coil 140 are all colinear with the axis of the tube body 100, so that electrons can be emitted outward through each component in sequence.

[0061] In a specific embodiment, the external terminals of the filament 110, the first accelerating electrode 120, the second accelerating electrode 130 and the focusing coil 140 are located at the tail of the tube body 100, and the external terminals of the anode 150 are located at the head of the tube body 100, which is installed facing the ionization chamber.

[0062] The anode 150 is connected to the anode terminal 151 through a metal wire lead (or a wire), and the filament 110 can be regarded as a cathode. The external terminals of the vacuum electron source (filament 110, first accelerating electrode 120, second accelerating electrode 130, focusing coil 140) pass through the tube wall at the tail of the tube body 100, which are filament terminals 111 and 112, first accelerating electrode terminal 121, second accelerating electrode terminal 131, and accelerating coil terminals 141 and 142. The arrangement of the above electrode terminals can refer to Figure 2 .

[0063] Each external terminal of the vacuum electron source is connected to the excitation power supply 401 through a wire passing through the detector housing. The excitation power supply 401 refers to a high voltage power supply with a specific combination and voltage range that needs to be connected externally when the vacuum electron source is working normally. Figure 2 .

[0064] Specifically, the excitation power supply 401 includes a cathode current source 302, a first accelerating electrode voltage source 303, a second accelerating electrode voltage source 304, a focusing coil current source 301 and an anode voltage source 305, which are respectively connected to the external terminals of the filament 110, the first accelerating electrode 120, the second accelerating electrode 130, the focusing coil 140 and the anode 150. Among them, the cathode current source 302 is used to heat the filament, the first accelerating electrode voltage source 303, the second accelerating electrode voltage source 304 and the anode voltage source 305 are used to accelerate electrons, and the focusing coil current source 301 is used to generate a focusing magnetic field to guide the electron flow to focus on the anode.

[0065] The bias electrode 202 and the collecting electrode 203 are connected to the bias voltage source 402 and the signal sampling and processing circuit 403 through lead terminals, respectively. Figure 3 The bias electrode 202 and the collecting electrode 203 are connected to the bias voltage source 402 and the signal sampling and processing circuit 403 through the lead terminals 207 and 208. After receiving the electrons, the collecting electrode 203 generates a weak current in the signal sampling and processing circuit 403, which is converted into usable data after amplification and sampling.

[0066] By adjusting the operating parameters of the above-mentioned voltage source and current source, the detector can operate in different concentration detection ranges and material sensitivity ranges, thereby achieving the optimal configuration for different detection scenarios.

[0067] Since the electrons in the vacuum electron source eventually release deep ultraviolet photons on the conductive fluorescent material coating of the anode 150, in order to allow the deep ultraviolet photons to enter the ionization chamber, the tube body 100 needs to be designed as a tube body of a transparent material. In particular, the tube body 100 can be a glass tube. Specifically, the shape of the tube body 100 is a cylindrical tube with a spherical shell at one end.

[0068] The interior of the tube body 100 is in a vacuum state. A vacuum exhaust port 101 is provided on the tube body 100 . The vacuum exhaust port 101 can be located at one end of the tube body 100 close to the cathode terminal. After the vacuuming is completed, the vacuum exhaust port 101 can be blocked.

[0069] In a specific embodiment, the filament 110 is made of a "V"-shaped tungsten filament with a single crystal tungsten embedded at the tip. Of course, the filament 110 can also be made of other materials. The filament is designed to be V-shaped, with the tip facing downward, and the other two ends are connected to the cathode current source 302. The main purpose of this design is to improve the performance of the electron gun. For example, the V-shaped tip design helps to concentrate the current, thereby generating a stronger electric field at the tip, thereby enhancing the emission efficiency of electrons, allowing more electrons to escape from the tip of the filament to form a stable electron beam; by concentrating the current at the tip, it is easier to control and focus the electron beam; because the electron emission is concentrated at the tip, this reduces the uneven current distribution in other parts, thereby reducing the thermal stress of the filament and extending the service life of the filament. The role of embedding single crystal tungsten at the tip of the filament is mainly reflected in: it can significantly improve the high temperature resistance of the filament, enhance the continuous strength of the filament, and more importantly, reduce the presence of grain boundaries, thereby improving the uniformity and efficiency of electron emission.

[0070] The focusing coil 140 is a hollow metal solenoid, so that electrons can move in a spiral motion in the hollow cavity.

[0071] In a specific embodiment, the ionization chamber 204 is a quartz tube in a hollow cylindrical shape. The ionization chamber 204 is connected to the tube body 100 through an insulating gasket 201. The central opening of the insulating gasket 201, the central axis of the ionization chamber 204, the insulating gasket 201 and the tube body 100 coincide, and photons can pass through the central opening of the insulating gasket 201 into the ionization chamber 204.

[0072] Similarly, the first detection tube 205 and the second detection tube 206 are the same as the ionization chamber 204, and both can be made of quartz tubes. Further, the inner diameter, outer diameter and material of the ionization chamber 204, the first detection tube 205 and the second detection tube 206 are the same. The bias electrode 202, the collecting electrode 203, the first detection tube 205, the second detection tube 206 and the ionization chamber 204 can be arranged according to the Figure 1 Coaxial arrangement shown.

[0073] The bias electrode 202 and the collecting electrode 203 are both ring-shaped metal components.

[0074] When the detector is working, the pins of the vacuum electron source are Figure 2As shown, an excitation power supply 401 is applied. At this time, the current flowing through the filament terminals 111 and 112 causes the filament 110 to heat up to above 1500K, and the single crystal tungsten at the tip of the filament is accelerated by the electric field provided by the first accelerating electrode 120, and emits electrons outward. The electrons are further accelerated in the electric field provided by the second accelerating electrode 130 and injected into the interior of the focusing coil 140. At this time, the constant current inside the focusing coil 140 generates a constant magnetic field, and the accelerated electrons move in a spiral motion in the magnetic field under the action of the Lorentz force, and finally focus on the anode 150. The current flowing through the focusing coil is adjusted so that the focusing point of the electron beam on the anode is just within the inner diameter of the insulating gasket. Part of the accelerated electrons are converted into heat on the anode and the outer wall of the vacuum electron source, and part of them excite the atoms of the anode fluorescent material, releasing deep ultraviolet photons with a wavelength of 120nm-250nm, and entering the ionization chamber.

[0075] As the electron source of the ECD detector, the vacuum electron source adopts a special structural design to generate, accelerate and focus the electron flow. Its working characteristics determine the linear response of the detector signal to the material concentration, reducing the complexity of signal acquisition, processing and calibration. The normal operation of the vacuum electron source depends on the correct combination of excitation power supplies, including but not limited to the filament current source, the acceleration voltage source, the focusing current source, etc. The normal operation of the collection electrode 203 depends on the correct setting of the bias voltage source 402.

[0076] In a specific embodiment, the other end of the hollow column 209 is inserted into the first detection tube 205 from the bottom of the detector along the central axis through the second detection tube 206 and the collecting electrode 203. Specifically, the gas outlet end of the hollow column 209 is located inside the first detection tube 205, 3mm-5mm away from the center of the bias electrode 202.

[0077] The exhaust port 210 is communicated with the second detection tube 206 .

[0078] This solution also includes a detector housing for encapsulating the vacuum electron source, ionization chamber and detection chamber, and the detector housing is grounded in the working state. The vacuum electron source, ionization chamber 204 and detection chamber are encapsulated in the same detector housing to form the detector body, and the excitation power supply 401, bias voltage source 402 and signal sampling and processing circuit 403 are located outside the detector housing. The detector housing is made of stainless steel.

[0079] In summary, this scheme provides an ECD detection method for non-radioactive substances with low consumption cost, good linearity, simple signal processing method and flow control method for the existing non-radioactive ECD detection scheme, and has the following characteristics:

[0080] 1. No need to use high-purity helium as carrier gas, saving usage costs;

[0081] 2. The calibration and calibration of the measured gas concentration uses a linear algorithm, which has a small workload and simple calculation;

[0082] 3. The stability requirement of carrier gas flow is not high, and the control difficulty is reduced.

[0083] In the description of this application, the meaning of "plurality" is more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing the technical features, and it cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0084] In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0085] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0086] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0087] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An ECD detector without radioactive source, characterized in that: It includes a vacuum electron source, an ionization chamber (204) and a detection chamber, The vacuum electron source comprises a tube body (100), a filament (110), a first accelerating electrode (120), a second accelerating electrode (130), a focusing coil (140) and an anode (150); the first accelerating electrode (120) and the second accelerating electrode (130) are metal cylinders with an opening at one end and an opening is provided at the bottom of the metal cylinder; the filament (110) is provided at one end of the tube body (100); the first accelerating electrode (120) and the second accelerating electrode (130) are sequentially covered on the outside of the filament (110); The tip of the vacuum electron source is directed toward the openings of the first accelerating electrode (120) and the second accelerating electrode (130); the focusing coil (140) is disposed on the outer side of the second accelerating electrode (130); the anode (150) is a conductive fluorescent material coating plated on the inner wall of the other end of the tube body (100); the filament (110), the first accelerating electrode (120), the second accelerating electrode (130), the focusing coil (140) and the anode (150) all have external wiring terminals; and each external wiring terminal of the vacuum electron source is connected to an excitation power supply (401) respectively; One end of the ionization chamber (204) is connected to the other end of the tube body (100); The detection chamber comprises a bias electrode (202), a first detection tube (205), a collecting electrode (203) and a second detection tube (206) which are connected in sequence. The detection chamber also comprises a hollow column (209). One end of the hollow column (209) serves as an air inlet for introducing sample gas and carrier gas. The other end of the hollow column (209) is inserted into the detection chamber. The bias electrode (202) is connected to the other end of the ionization chamber (204). The detection chamber is also provided with an exhaust port (210).

2. The ECD detector without radioactive source according to claim 1, characterized in that: The tip of the filament (110), the opening of the first accelerating electrode (120), the opening of the second accelerating electrode (130), and the axis of the focusing coil (140) are all colinear with the axis of the tube body (100).

3. The ECD detector without radioactive source according to claim 1, characterized in that: The external wiring terminals of the filament (110), the first accelerating electrode (120), the second accelerating electrode (130) and the focusing coil (140) are located at the tail of the tube body (100), and the external wiring terminal of the anode (150) is located at the head of the tube body (100).

4. The ECD detector without radioactive source according to claim 3, characterized in that: The excitation power supply (401) comprises a cathode current source (302), a first accelerating electrode voltage source (303), a second accelerating electrode voltage source (304), a focusing coil current source (301) and an anode voltage source (305) respectively connected to the external terminals of the filament (110), the first accelerating electrode (120), the second accelerating electrode (130), the focusing coil (140) and the anode (150); And / or, the bias electrode (202) and the collecting electrode (203) are respectively connected to a bias voltage source (402) and a signal sampling and processing circuit (403) via lead terminals.

5. The ECD detector without radioactive source according to claim 1, characterized in that: The tube body (100) is a glass tube; And / or, the tube body (100) is a cylindrical tube; And / or, the interior of the tube body (100) is in a vacuum state, and a vacuum exhaust port (101) is provided on the tube body (100).

6. The ECD detector without radioactive source according to claim 1, characterized in that: The filament (110) is a V-shaped filament, and the tip of the filament (110) is inlaid with a single crystal tungsten layer; And / or, the focusing coil (140) is a hollow metal solenoid.

7. The ECD detector without radioactive source according to claim 1, characterized in that: The ionization chamber (204) is a quartz tube, and the ionization chamber (204) is connected to the tube body (100) via an insulating gasket (201); And / or, the first detection tube (205) and the second detection tube (206) are quartz tubes; And / or, the bias electrode (202) and the collecting electrode (203) are both annular metal components.

8. The ECD detector without radioactive source according to claim 7, characterized in that: The inner diameter, outer diameter and material of the ionization chamber (204), the first detection tube (205) and the second detection tube (206) are all the same.

9. The ECD detector without radioactive source according to claim 1, characterized in that: The other end of the hollow column (209) is inserted into the first detection tube (205) via the second detection tube (206) and the collecting electrode (203); And / or, the exhaust port (210) is in communication with the second detection tube (206).

10. The ECD detector without radioactive source according to claim 1, characterized in that: It also includes a detector housing for encapsulating the vacuum electron source, the ionization chamber and the detection chamber. The detector housing is grounded in a working state.

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