A multi-window ultraviolet lamp and its preparation method

Abstract

The present invention discloses a multi-window ultraviolet lamp and a preparation method thereof, relating to the technical field of photoionization gas detection. The multi-window ultraviolet lamp includes: a glass cavity, excitation electrodes, and N ultraviolet windows. The glass cavity includes N openings, and each ultraviolet window is respectively and correspondingly arranged at the opening of the glass cavity. A working gas is filled in the glass cavity. The excitation electrodes are arranged on the outer wall of the glass cavity. The excitation electrodes are used to activate the working gas in the glass cavity to generate ultraviolet light after being powered on, and ionize the gas molecules to be detected through each ultraviolet window, wherein N>1. This solution is applicable to the photoionization of the gas to be measured in a gas detection device. Compared with the traditional multi-ultraviolet lamp solution, it improves the consistency of the light source, reduces the energy consumption, reduces the corresponding multiple sets of drive circuits, and reduces the necessary volume and weight of the device from the lamp and the circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of photoionization gas detection, and particularly to a multi-window ultraviolet lamp and a preparation method thereof. Background Art

[0002] Vacuum ultraviolet lamps are a type of light source that can efficiently generate effective ultraviolet light and are often used to ionize gases for detecting the properties and concentrations of gases. For example, a photoionization detector consists of a vacuum ultraviolet lamp and an ionization chamber. Its working principle is as follows: The gas to be measured absorbs photons emitted by the vacuum ultraviolet lamp that are higher than the ionization energy of the gas molecules, generating ionization. Under the action of an externally applied electric field, the charged particles shift to form a weak current. The generated weak current is generally converted into a voltage value that can be conveniently measured by using a large resistor. Since the concentration of the gas to be measured is linearly related to the photoionization current within a certain range, therefore, by detecting the response value of the photoionization detector, the concentration of the gas to be detected can be known, thereby determining whether the gas to be measured exists or exceeds the standard.

[0003] Currently, a relatively convenient method for obtaining ultraviolet light is to achieve it by exciting a certain concentration of rare gases to generate plasma emission. The encapsulation method of traditional vacuum ultraviolet lamps is as Figure 1 shown. Among them, the glass cavity 1 is a cylindrical glass cavity. The glass cavity 1 and the ultraviolet window 2 are bonded with substances such as low-temperature glass powder. The gas adsorbent 3 can be selectively placed. Subsequently, the other end of the glass cavity 1 is heated and melted under a low-pressure environment of rare gases mainly composed of working gases and sealed by pulling force to form Figure 1 the conical seal shown, and finally the driving electrode 4 is installed outside the glass cavity 1 to form a workable vacuum ultraviolet lamp.

[0004] However, traditional vacuum ultraviolet lamps have only one ultraviolet window through which ultraviolet light can pass and be utilized. If multiple ultraviolet lamps need to be used together, due to uncontrollable production differences in various aspects such as the contact tightness of the excitation electrodes, excitation voltage, gas type, gas concentration, purity, and window cleanliness of different ultraviolet lamps, the attenuation rates of air leakage and other problems of different ultraviolet lamp bodies are also different during use. Therefore, there are many initial matching problems and calibration problems during joint use, resulting in poor consistency of multiple ultraviolet lamps and possible additional maintenance problems in the later stage. In addition, using multiple ultraviolet lamps independently not only has a large volume but also requires additional multiple sets of driving circuits, which also increases the weight and volume of the equipment. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a multi-window ultraviolet lamp and a preparation method thereof in view of the deficiencies of the prior art.

[0006] The technical solution of the present invention for solving the above technical problems is as follows:

[0007] A multi-window ultraviolet lamp, comprising: a glass cavity, excitation electrodes, and N ultraviolet windows, wherein the glass cavity includes N openings, each of the ultraviolet windows is respectively disposed at the opening of the glass cavity, a working gas is filled in the glass cavity, the excitation electrodes are disposed on the outer wall of the glass cavity, and the excitation electrodes are used to activate the working gas in the glass cavity to generate ultraviolet light after being electrified, and ionize the gas molecules to be measured through each ultraviolet window, where N > 1.

[0008] The multi-window ultraviolet lamp provided by this solution is applicable to the photoionization of the gas to be measured in a gas detection device. By respectively arranging ultraviolet windows at each opening of the glass cavity and using a closed working gas to generate ultraviolet light, the light intensity of each ultraviolet window can be synchronously kept consistent. And compared with the traditional multi-ultraviolet lamp solution, the consistency of the light source is improved. Subsequently, different materials can be used to prepare the ultraviolet windows, so as to selectively allow ultraviolet light of different wavelengths to pass through according to the setting, realizing the simultaneous use of multiple wavelengths without increasing the number of lamps. In addition, since only one light source is driven in this solution, the energy consumption is reduced, and the corresponding multiple sets of drive circuits are reduced, reducing the necessary volume and weight of the device from the aspects of the lamp and the circuit.

[0009] Another technical solution for the present invention to solve the above technical problems is as follows:

[0010] A preparation method of a multi-window ultraviolet lamp, comprising:

[0011] Bonding N - 1 ultraviolet windows to the openings of the glass cavity respectively using a preset bonding method;

[0012] Putting the glass cavity bonded with N - 1 ultraviolet windows into a closed environment, filling the working gas into the closed environment, and using the preset bonding method to bond the remaining one ultraviolet window to the remaining opening of the glass cavity in the environment where the working gas is maintained, so that the working gas is filled in the glass cavity and the working gas is sealed;

[0013] Installing excitation electrodes on the outer wall of the glass cavity.

[0014] The multi-window ultraviolet lamp preparation method provided by this solution can conveniently realize the preparation of a multi-window ultraviolet lamp. The prepared ultraviolet lamp is applicable to the photoionization of the gas to be detected in a gas detection device. By respectively arranging ultraviolet windows at each opening of the glass cavity and using a closed working gas to generate ultraviolet light, the light intensity of each ultraviolet window can be synchronously kept consistent. Moreover, compared with the traditional multi-ultraviolet lamp solution, the consistency of the light source is improved. Subsequently, different materials can be used to prepare the ultraviolet windows, so as to selectively allow ultraviolet light of different wavelengths to pass through according to the setting, realizing the simultaneous use of multiple wavelengths without increasing the number of lamps. In addition, since only one light source is driven in this solution, the energy consumption is reduced, and the corresponding multiple sets of drive circuits are reduced, reducing the necessary volume and weight of the device from the aspects of the lamp and the circuit.

[0015] Another technical solution for the present invention to solve the above technical problems is as follows:

[0016] A gas detection device includes the multi-window ultraviolet lamp as described in the above technical solution.

[0017] The gas detection device provided by the present invention has better consistency of the light source because it uses a multi-window ultraviolet lamp, can perform more accurate ionization control on the gas, so that the final detection result is more accurate. And since only one light source is driven, the energy consumption is reduced, and the corresponding multiple sets of drive circuits are reduced, reducing the necessary volume and weight of the device from the aspects of the lamp and the circuit.

[0018] Advantages of additional aspects of the present invention will be partly given in the following description, partly will become obvious from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of a single-window ultraviolet lamp in the prior art;

[0020] Figure 2 It is a schematic structural diagram provided for an embodiment of the multi-window ultraviolet lamp of the present invention;

[0021] Figure 3 It is another schematic structural diagram provided for an embodiment of the multi-window ultraviolet lamp of the present invention;

[0022] Figure 4 It is still another schematic structural diagram provided for an embodiment of the multi-window ultraviolet lamp of the present invention;

[0023] Figure 5 It is a schematic flow diagram provided for an embodiment of the preparation method of the multi-window ultraviolet lamp of the present invention. Detailed Embodiments

[0024] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The embodiments given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0025] Ultraviolet lamps are commonly used in ultraviolet photoionization methods. The ionization process of ultraviolet photoionization methods is stable, less affected by factors such as environmental humidity and pollution, and has advantages such as a small volume of the drive circuit, and has been widely studied.

[0026] The ionization process will be described below by taking the ion mobility spectrometry method as an example.

[0027] Ion mobility spectrometry is a detection method that ionizes the gaseous substance to be detected and determines the type of the species to be detected by measuring the migration time of such ions under the action of a specific electric field. Due to the different tendencies of the substances to be detected to gain or lose electrons, different substances to be detected can be ionized by ultraviolet light to form positive ions and electrons, or the photoelectric effect can be generated by ultraviolet light exciting the metal coating. These low-energy electrons combine with oxygen molecules to form negatively charged ions such as O2 - and other negatively charged ions. The gas molecules to be detected combine with them to form negative ions, completing the ionization process. These positive and negative product ions enter the migration region through the ion gate that is periodically opened under the action of electric fields in different directions. In order to prevent the generated ions of the substance to be detected from recombining with other ions of the opposite electric charge to become neutral molecules, there is an electric field in the ionization region to move the gas to be detected to the front of the ion gate and keep the ions of other electricities away from the ion gate. When the ion gate is opened, in the migration region, the ions obtain energy from the electric field to make a directional drift on the one hand, and on the other hand, continuously collide with the neutral migration gas molecules flowing in the reverse direction and lose energy. Since the masses, charges, collision cross-sections and spatial configurations of these product ions are different, their migration rates in the electric field are different, so that different ions reach the detector at different times, thus achieving separation. In order to detect gases that may generate positive ions and negative ions at the same time, some ion mobility spectrometry devices use a dual ionization region and migration region design, so at least two photoionization light sources are required.

[0028] At present, for scenarios that require multiple ultraviolet lamps for ionization, the method of connecting multiple ultraviolet lamps in series is usually used, which easily leads to problems such as poor consistency between multiple ultraviolet lamps. Based on this, this patent proposes a multi-window ultraviolet lamp and its preparation method, as well as a gas ionization device including the multi-window ultraviolet lamp. Each ultraviolet window of the multi-window ultraviolet lamp faces an ionization region, and the substance to be detected can be ionized simultaneously while only using the same light source.

[0029] It should be noted that the number of ultraviolet windows can be set according to actual needs. For example, the specific design structure of an ultraviolet lamp with a single lamp body and two ultraviolet windows can refer to Figure 2 and the specific design structure of an ultraviolet lamp with a single lamp body and three ultraviolet windows can refer toFigure 3 , the specific design structure of the ultraviolet lamp with a single lamp body and four ultraviolet windows can be referred to Figure 4 . It should be understood that these ultraviolet lamps all have a single lamp body, and the only difference is the number of openings. Taking the double-window ultraviolet lamp as an example for illustration below, the same applies to other structures and will not be elaborated further.

[0030] As Figure 2 shown, it is a schematic structural diagram provided for an exemplary embodiment of a double-window ultraviolet lamp. The double-window ultraviolet lamp includes: a glass cavity 1, a first ultraviolet window 2, a second ultraviolet window 3, and an excitation electrode 4. The first ultraviolet window 2 and the second ultraviolet window 3 are respectively arranged at both ends of the glass cavity 1. The glass cavity 1 is filled with a working gas. The excitation electrode 4 is arranged on the outer wall of the glass cavity 1. The excitation electrode 4 is used to activate the working gas in the glass cavity 1 to generate ultraviolet light after being electrified, and ionize the gas molecules to be measured through each ultraviolet window.

[0031] After the excitation electrode 4 on the outer wall of the glass cavity 1 is electrified, it can stimulate the ultraviolet lamp tube filled with the working gas to emit ultraviolet light of a certain intensity. This ultraviolet light can ionize some organic and inorganic gas molecules near the light source to generate ions.

[0032] With the occurrence of photoionization, the generated ions can be collected through the positive and negative electrode plates near the light source to generate a weak current. This current is amplified by an amplifier circuit and finally generates an analog output of a low-resistance voltage signal, thereby completing the detection of gas molecules. The gas molecule ions generated by ultraviolet light excitation are approximately proportional to the concentration of gas molecules. Because when the gas type is known, the concentration of gas molecules can be determined.

[0033] Optionally, the ultraviolet window can be made of vacuum ultraviolet light-penetrating materials such as LiF, MgF2, or CaF2. The excitation electrode 4 can be made of metal coatings such as Cu or Au. The working gas can be noble gases such as Kr or Xe.

[0034] Optionally, the material of each ultraviolet window can be selected and set according to actual needs, so that ultraviolet light of different wavelengths can pass through to meet different ionization requirements.

[0035] The multi-window ultraviolet lamp provided in this embodiment is applicable to the photoionization of the gas to be measured in a gas detection device. By respectively arranging ultraviolet windows at each opening of the glass cavity and using a closed working gas to generate ultraviolet light, the light intensity of each ultraviolet window can be synchronously kept consistent. Moreover, compared with the traditional multi-ultraviolet lamp scheme, the consistency of the light source is improved. Subsequently, different materials can be used to prepare the ultraviolet windows, so as to selectively allow ultraviolet light of different wavelengths to pass through according to the setting, realizing the simultaneous use of multiple wavelengths without increasing the number of lamps. In addition, since only one light source is driven in this scheme, the energy consumption is reduced, and the corresponding multiple sets of driving circuits are reduced, thereby reducing the necessary volume and weight of the device in terms of the lamp and the circuit.

[0036] Optionally, in some possible implementation manners, a gas absorbent 5 is further arranged in the glass cavity 1.

[0037] Optionally, the gas absorbent 5 can adopt an alloy material containing Zr, Al, and V.

[0038] Optionally, in some possible implementation manners, a metal gauze or a thin film is arranged on the outer surface of the ultraviolet window.

[0039] It should be understood that different substances to be measured can be photoionized by ultraviolet light to form positive ions and electrons, or the photoelectric effect can be generated by ultraviolet light exciting the metal coating. These low-energy electrons combine with oxygen molecules to form negatively charged ions such as O2 - and other negatively charged ions. The gas molecule to be detected combines with them to form negative ions, completing the ionization process. Therefore, the ultraviolet window provided with the metal gauze or the thin film corresponds to the negative ionization region.

[0040] Optionally, in some possible implementation manners, each ultraviolet window adopts a different vacuum ultraviolet light-penetrable material.

[0041] It should be noted that since the method for obtaining ultraviolet light is realized by exciting the plasma emission of rare gases, and the plasma emission wavelength of a specific atom depends on its internal shell electron structure. Although there are many emission wavelengths, each emission wavelength is basically a fixed value and is difficult to change after the encapsulated working substance is selected, or the wavelength selection is realized by using materials with different transmittances for ultraviolet light of different wavelengths to select part of the ultraviolet light to pass through the window. For example, for the common working substance Kr gas, the stronger ultraviolet wavelengths in its spectrum are 116.5 nm and 123.6 nm, corresponding to photon energies of 10.6 eV and 10.0 eV. Therefore, appropriate ultraviolet window materials can be used to select the above wavelengths to pass through.

[0042] Therefore, traditional methods have only one ultraviolet window through which ultraviolet light can pass and be utilized, and can only use ultraviolet light of a fixed wavelength combination. If it is necessary to use ultraviolet light of other specific wavelengths to exclude background interference, multiple ultraviolet lamps often need to be used in series. Due to the inevitable production differences in various aspects such as the excitation voltage, gas type, gas concentration, purity, and window cleanliness of different ultraviolet lamps, the attenuation rates of different ultraviolet lamp bodies such as air leakage are also different during use. Therefore, there are many initial matching problems and calibration problems during joint use, and there may be additional maintenance problems in the later stage.

[0043] However, the vacuum ultraviolet light transmissive materials of each ultraviolet window in the above embodiments are different, so that it is possible to simultaneously use multiple wavelengths without increasing the number of lamps, and these light sources also have good consistency, thereby improving the accuracy of gas detection.

[0044] It can be understood that in some embodiments, it may include some or all of the above embodiments.

[0045] As Figure 5 shown, the flowchart provided by the embodiment of the preparation method of the multi-window ultraviolet lamp of the present invention is shown. Taking the preparation of a dual-window ultraviolet lamp as an example, the preparation method includes:

[0046] S1, bonding the first ultraviolet window to one end of the glass cavity using a preset bonding method;

[0047] S2, placing the glass cavity bonded with the first ultraviolet window in a closed environment, filling the closed environment with working gas, and using the preset bonding method to bond the second ultraviolet window to the other end of the glass cavity in an environment where the working gas is maintained, so that the glass cavity is filled with working gas and the working gas is sealed;

[0048] S3, installing excitation electrodes on the outer wall of the glass cavity.

[0049] It should be understood that for multiple windows, only the last ultraviolet window needs to be reserved and the working gas is filled in the closed environment. The preparation methods of the remaining ultraviolet windows are the same as those of the first ultraviolet window, and will not be elaborated here.

[0050] It should be understood that the preset bonding method can be selected and set according to actual needs. For example, it can be selected to place glass powder between the ultraviolet window and the glass cavity port, and then heat to melt the glass powder to bond the ultraviolet window and the glass cavity. It can also be sintered using metal powder, etc., and will not be elaborated here.

[0051] The following gives a specific preparation embodiment.

[0052] Place low-temperature glass powder on the first ultraviolet window, and then heat it to the working temperature of the low-temperature glass powder to melt the low-temperature glass powder, bonding the first ultraviolet window and a port of the glass cavity to obtain a structure with one open side and one closed side. Optionally, a gas absorbent is placed afterwards, and then substances such as low-temperature glass powder are added to the second ultraviolet window. The second ultraviolet window and the semi-closed structure are placed in a closed environment equipped with a robotic arm, and the closed environment is evacuated to a vacuum state, and then the working gas is injected multiple times to obtain a low-pressure environment filled with high-purity working gas. For example, the low-pressure environment can be 100 - 500 Pa. Then it is heated to the working temperature of the low-temperature glass powder. For example, the working temperature can be 500 degrees to melt the low-temperature glass powder. Use the robotic arm to move the second ultraviolet window to the other port of the glass cavity and bond it, so that the working gas is enclosed in the glass cavity. Then it is cooled down and connected to the atmosphere, and excitation electrodes are installed at preset positions on the outer wall of the glass cavity to obtain an ultraviolet lamp with double windows.

[0053] It should be understood that the second ultraviolet window can also be preferentially bonded, which will not be elaborated here.

[0054] The multi-window ultraviolet lamp produced by the preparation method provided in this embodiment can be used for simultaneous photoionization of the gas to be measured in an ion mobility spectrometry device with positive and negative transfer tubes. Ultraviolet windows are respectively arranged at both ends of the glass cavity through a preset bonding method, and a working gas is filled in the glass cavity. Each ultraviolet window faces an ionization region and can be respectively used for positive ion ionization and negative ion ionization, realizing simultaneous ionization of the analyte when only one light source is used. The light intensities of the two ultraviolet windows can be synchronously kept consistent, improving the correlation of positive and negative ion mobilities, ensuring that the ionization efficiencies on both sides are close, and reducing the occupation of the lamp body on the volume of the ion mobility spectrometry device. And since only one lamp is driven, the energy consumption is reduced, and a set of drive circuits is reduced, reducing the necessary volume and weight of the device from the lamp and the circuit.

[0055] Optionally, in some possible implementation manners, the preset bonding method is: place low-temperature glass powder between the ultraviolet window and the glass cavity, heat the low-temperature glass powder to the working temperature to melt the low-temperature glass powder, and bond the ultraviolet window and the glass cavity.

[0056] Optionally, in some possible implementation manners, before placing the glass cavity bonded with N - 1 ultraviolet windows into the closed environment, it further includes:

[0057] Place a gas absorbent in the glass cavity bonded with N - 1 ultraviolet windows.

[0058] Optionally, in some possible implementation manners, it further includes:

[0059] Set a metal mesh or film on the outer surface of the ultraviolet window.

[0060] Optionally, in some possible embodiments, each ultraviolet window is prepared using different vacuum ultraviolet light transmissive materials.

[0061] It should be understood that specific descriptions of the structural composition of the multi-window ultraviolet lamp can be referred to the prior embodiments and will not be elaborated herein.

[0062] It can be understood that in some embodiments, it may include some or all of those in the above various embodiments.

[0063] The present invention also provides a gas detection device, which includes the multi-window ultraviolet lamp disclosed in any of the above embodiments.

[0064] It should be understood that the multi-window ultraviolet lamp, as the light source of the gas detection device, can be used for ionization detection of gases. The gas detection device can be a photoionization detector, an ion mobility spectrometry device, and improved devices based on these devices, etc.

[0065] Readers should understand that in the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0066] In several embodiments provided by the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. For example, the method embodiments described above are merely illustrative. For example, the division of steps is only a logical function division. In actual implementation, there may be other division methods. For example, multiple steps can be combined or integrated into another step, or some features can be ignored or not executed.

[0067] The above are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A multi-window ultraviolet lamp, characterized in that, Comprising: A glass cavity, excitation electrodes, and N ultraviolet windows. The glass cavity includes N openings, and each of the ultraviolet windows is respectively disposed at the opening of the glass cavity. The glass cavity is filled with a working gas. The excitation electrodes are disposed on the outer wall of the glass cavity. The excitation electrodes are used to activate the working gas in the glass cavity to generate ultraviolet light after being energized, and ionize the gas molecules to be measured through each ultraviolet window, where N>1; A metal screen or film is disposed on the outer surface of the ultraviolet window; Each of the ultraviolet windows is made of a different vacuum ultraviolet light transmissive material.

2. The multi-window ultraviolet lamp according to claim 1, wherein, A gas absorbent is further disposed in the glass cavity.

3. A method for preparing a multi-window ultraviolet lamp, characterized in that, The multi-window ultraviolet lamp is as described in claim 1 or 2, and the preparation method includes: Using a preset bonding method to bond N-1 ultraviolet windows to the openings of the glass cavity respectively; Placing the glass cavity bonded with N-1 ultraviolet windows in a closed environment, filling the working gas into the closed environment, and using the preset bonding method to bond the remaining one ultraviolet window to the remaining opening of the glass cavity in the environment where the working gas is maintained, so that the glass cavity is filled with the working gas and the working gas is sealed; Installing excitation electrodes on the outer wall of the glass cavity.

4. The preparation method of the multi-window ultraviolet lamp according to claim 3, characterized in that, The preset bonding method is: placing low-temperature glass powder between the ultraviolet window and the glass cavity, heating the low-temperature glass powder to the working temperature to melt the low-temperature glass powder, and bonding the ultraviolet window and the glass cavity.

5. The preparation method of the multi-window ultraviolet lamp according to claim 3, characterized in that, Before placing the glass cavity bonded with N-1 ultraviolet windows in a closed environment, it further includes: Placing a gas absorbent in the glass cavity bonded with N-1 ultraviolet windows.

6. The preparation method of the multi-window ultraviolet lamp according to claim 3, characterized in that, Further comprising: Setting a metal screen or film on the outer surface of the ultraviolet window.

7. The preparation method of the multi-window ultraviolet lamp according to any one of claims 3 to 6, characterized in that, Preparing each of the ultraviolet windows with different vacuum ultraviolet light transmissive materials.

8. A gas detection device, characterized in that, Including the multi-window ultraviolet lamp according to any one of claims 1 or 2.

Images