Trace gas mixed gas inlet system for mass spectrometer ion source and control method

Abstract

The invention relates to a trace gas mixed gas inlet system for a mass spectrometer ion source and a control method, the system comprises a vacuum subsystem, at least two sample gas inlet subsystems and a recovery subsystem which are respectively connected with a gas mixing chamber, and the gas mixing chamber is connected with the ion source through a trace gas inlet flow control subsystem. The vacuum subsystem is used for enabling the gas mixing chamber to be in a vacuum state before the gas sample is introduced; the sample gas inlet subsystem is used for introducing different gas samples into the gas mixing chamber according to a set flow rate and uniformly mixing the different gas samples in the gas mixing chamber; the trace gas inlet flow control subsystem is used for conveying the mixed gas sample to an ion source according to a set flow; and the recovery subsystem is used for recovering residual gas samples in the whole system. According to the invention, quantitative and fixed-proportion mixing of various trace gases required by the mass spectrometer is realized in a vacuum environment, and the measurement accuracy after gas mixing and the operation safety of toxic and harmful gases are ensured.

Description

Technical Field

[0001] The invention belongs to trace gas mixing technology, and in particular relates to a trace gas mixing intake system for a mass spectrometer ion source and a control method. Background Art

[0002] A mass spectrometer (AMS) is a precision instrument used to analyze the composition and structure of substances. Its core parts include an ion source, a mass analyzer, and a detector. The ion source is an important component of a mass spectrometer. Its function is to ionize the substance to be tested into ions and provide samples for subsequent mass analysis.

[0003] When using an AMS to analyze and measure the composition and proportion of a mixture of multiple trace gas samples (gas volume is calculated in milliliters, such as 5 sccm), it is necessary to mix the multiple gases in equal proportions while ensuring the purity of the sample in order to achieve accurate measurement of the composition of the gas mixture.

[0004] The specific process is that multiple independently loaded gases are mixed through pipelines and then injected into the ion source of the AMS. The ion source accelerates the mixed gas and separates the mixed gas through the AMS body. The detector is used to identify the components and measure the proportion of the substances in the sample, so as to achieve the goal of measuring multiple gas components at one time. However, there is currently a lack of an intake system and corresponding method that can effectively achieve the precise mixing of multiple trace gas samples and transport them to the ion source. Summary of the invention

[0005] The purpose of the present invention is to provide a trace gas mixing intake system and control method for a mass spectrometer ion source in view of the deficiencies in the prior art, so as to achieve precise mixing of two or more trace gases, thereby simultaneously measuring multiple gas components at one time through a mass spectrometer.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A trace gas mixing intake system for a mass spectrometer ion source comprises a vacuum subsystem, at least two sample intake subsystems and a recovery subsystem respectively connected to a gas mixing chamber, wherein the gas mixing chamber is connected to the ion source via a trace intake flow control subsystem,

[0008] The vacuum subsystem is used to put the gas mixing chamber into a vacuum state before the gas sample is introduced;

[0009] The sample gas inlet subsystem is used to pass different gas samples into the gas mixing chamber according to a set flow rate and mix them evenly in the gas mixing chamber;

[0010] The micro-intake flow control subsystem is used to deliver the mixed gas sample to the ion source at a set flow rate;

[0011] The recovery subsystem is used to recover residual gas samples in the entire system.

[0012] Further, in a specific embodiment, the mass spectrometer ion source uses a trace gas mixing intake system as described above, wherein the vacuum subsystem includes a mechanical pump, a solenoid valve, and a molecular pump arranged on an exhaust pipeline, and the exhaust pipeline is connected to the gas mixing chamber through a plug-in valve; a cold gauge for measuring the vacuum degree is arranged on the exhaust pipeline.

[0013] Further, in a specific embodiment, the mass spectrometer ion source uses a trace gas mixing intake system as described above, wherein each of the sample intake subsystems includes an independent injection pipeline connected to a gas mixing chamber, and the injection pipeline is provided with a sample bottle, a manual switching valve, a pressure reducing valve, a shut-off valve and a flow control valve.

[0014] Furthermore, when the gas sample is a harmful gas, its corresponding sample air intake subsystem is arranged in the glove box, and a sample main gas cylinder is arranged in the glove box. The sample main gas cylinder is connected to the sample bottle through the pressure reducing valve and the flow control valve, thereby reducing the volume of the sample bottle containing the harmful gas and reducing the content of the harmful gas in the recovered residual gas sample.

[0015] Further, in a specific embodiment, the trace gas mixing intake system for the mass spectrometer ion source as described above, wherein the trace intake flow control subsystem includes an outlet pipeline arranged between the gas mixing chamber and the ion source, and a shut-off valve and a flow control valve are arranged on the outlet pipeline.

[0016] Further, in a specific embodiment, the trace gas mixed intake system for the mass spectrometer ion source as described above, wherein the recovery subsystem includes a recovery bottle, a manual switch valve and a stop valve arranged on the recovery pipeline.

[0017] Furthermore, when the gas sample contains harmful gases, the recovery subsystem is arranged in the glove box.

[0018] Further, in a specific embodiment, in the trace gas mixing intake system for the mass spectrometer ion source as described above, a resistance gauge for measuring the vacuum degree is provided on the gas mixing chamber.

[0019] A control method for the trace gas mixing intake system for the mass spectrometer ion source, comprising:

[0020] (1) Set the flow control valves of the sample air intake subsystem and the trace air intake flow control subsystem to fixed values, and close the inlet pipeline connecting the sample air intake subsystem and the gas mixing chamber, as well as the outlet pipeline connecting the gas mixing chamber and the ion source;

[0021] (2) Start the vacuum subsystem to evacuate the gas mixing chamber to a specified vacuum degree;

[0022] (3) opening each sample gas inlet subsystem in turn, allowing different gas samples to enter the gas mixing chamber at a set flow rate and be evenly mixed in the gas mixing chamber, and providing the mixed gas to the ion source through the micro-inlet flow control subsystem;

[0023] (4) Close the sample inlet pipeline connecting the sample inlet subsystem and the gas mixing chamber, and the gas outlet pipeline connecting the gas mixing chamber and the ion source, and open the recovery subsystem to recover the residual gas sample in the entire system.

[0024] Further, in the control method of the trace gas mixing intake system for the mass spectrometer ion source as described above, when two gas samples are mixed and one of the gas samples is a harmful gas, the specific operation of step (3) is as follows:

[0025] (3-1) After the sample main cylinder containing the harmful gas supplies the set amount of gas to the sample bottle connected to it through the pressure reducing valve and the flow control valve, the pressure reducing valve and the flow control valve are closed;

[0026] (3-2) supplying gas to the gas mixing chamber through the inlet pipeline of the non-hazardous gas sample to make the gas mixing chamber reach a specified pressure value, and then opening the outlet pipeline of the micro-inlet flow control subsystem to supply gas to the ion source, during which the pressure of the gas mixing chamber is maintained at the specified pressure value until the ion source starts arcing;

[0027] (3-3) Close the inlet line of the non-harmful gas sample and open the inlet line of the harmful gas, so that the two gas samples are fully mixed in the gas mixing chamber, and provide the mixed gas to the ion source through the outlet line of the trace inlet flow control subsystem.

[0028] The beneficial effects of the present invention are as follows: the present invention mixes two or more independently loaded gases through a pipeline under a vacuum state and then injects them into the ion source of a mass spectrometer, thereby solving the problem of quantitative and proportional mixing of multiple trace gases required by the mass spectrometer, ensuring the accuracy of measurement after gas mixing and the safety of toxic and harmful gas operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of a trace gas mixing intake system for a mass spectrometer ion source in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] The present invention provides a trace gas mixing intake system and control method for a mass spectrometer ion source. The whole system comprises a vacuum subsystem, at least two sample intake subsystems and a recovery subsystem respectively connected to a gas mixing chamber. The gas mixing chamber is connected to the ion source via a trace intake flow control subsystem.

[0032] The vacuum subsystem is used to make the gas mixing chamber in a vacuum state before the gas sample is introduced. Specifically, the vacuum subsystem includes a mechanical pump, a solenoid valve, and a molecular pump arranged on the exhaust pipeline, and the exhaust pipeline is connected to the gas mixing chamber through a plug valve; a cold gauge for measuring the vacuum degree is arranged on the exhaust pipeline, and a resistance gauge for measuring the vacuum degree is arranged on the gas mixing chamber.

[0033] The sample intake subsystem is used to pass different gas samples into the gas mixing chamber at a set flow rate and mix them evenly in the gas mixing chamber. Specifically, each sample intake subsystem includes an independent sampling pipeline connected to the gas mixing chamber, and the sampling pipeline is provided with a sample bottle, a manual switch valve, a pressure reducing valve, a stop valve and a flow control valve. When a certain gas sample is a harmful gas, its corresponding sample intake subsystem is arranged in a glove box, and a sample main gas cylinder of the harmful gas is arranged in the glove box, and the sample main gas cylinder is connected to the sample bottle through the pressure reducing valve and the flow control valve, thereby reducing the volume of the sample bottle containing the harmful gas and reducing the content of the harmful gas in the recovered residual gas sample.

[0034] The micro-intake flow control subsystem is used to deliver the mixed gas sample to the ion source at a set flow rate. Specifically, the micro-intake flow control subsystem includes an outlet pipeline arranged between the gas mixing chamber and the ion source, and a stop valve and a flow control valve are arranged on the outlet pipeline.

[0035] The recovery subsystem is used to recover the residual gas sample in the whole system. Specifically, the recovery subsystem includes a recovery bottle, a manual switch valve and a stop valve arranged on the recovery pipeline. When the gas sample contains harmful gases, the recovery subsystem should also be arranged in the glove box.

[0036] The control method of the trace gas mixing intake system for the mass spectrometer ion source comprises the following steps:

[0037] (1) Set the flow control valves of the sample air intake subsystem and the trace air intake flow control subsystem to fixed values, and close the inlet pipeline connecting the sample air intake subsystem and the gas mixing chamber, as well as the outlet pipeline connecting the gas mixing chamber and the ion source;

[0038] (2) Start the vacuum subsystem to evacuate the gas mixing chamber to a specified vacuum degree;

[0039] (3) opening each sample gas inlet subsystem in turn, allowing different gas samples to enter the gas mixing chamber at a set flow rate and be evenly mixed in the gas mixing chamber, and providing the mixed gas to the ion source through the micro-inlet flow control subsystem;

[0040] (4) Close the sample inlet pipeline connecting the sample inlet subsystem and the gas mixing chamber, and the gas outlet pipeline connecting the gas mixing chamber and the ion source, and open the recovery subsystem to recover the residual gas sample in the entire system.

[0041] Example

[0042] The following takes the mixing of two gas samples as an example, one of which is a harmful gas, to specifically illustrate the system and control method of the present invention.

[0043] The structure of the trace gas mixing inlet system for the mass spectrometer ion source of this embodiment is as follows: Figure 1 As shown, it includes a sample I air intake subsystem, a sample II air intake subsystem, a recovery subsystem, a vacuum subsystem, and a micro air intake flow control subsystem. The above subsystems are connected to the gas mixing chamber through pipelines.

[0044] The sample I air intake subsystem includes sample I bottle, manual switch valve I, pressure reducing valve I, stop valve I, and mass flow control valve I (trace). Each component is connected in sequence through a gas pipeline and finally connected to the mass flow control valve I (trace). The mass flow control valve I (trace) is connected to the gas mixing chamber through a gas pipeline.

[0045] In this embodiment, the gas sample II is a harmful gas, and the sample II intake subsystem is set in the glove box, including the sample II main gas cylinder, pressure reducing valve II, mass flow control valve III (micro), sample II bottle, manual switch valve II, and stop valve II. Each component is connected in turn through a gas pipeline, and the stop valve II is led out of the glove box through a gas pipeline and connected to the gas mixing chamber. The mass flow control valve III (micro) has a timing function, which can control the amount of gas in the sample II bottle by controlling the flow and time.

[0046] The recovery subsystem is also arranged in the glove box, including a recovery bottle, a manual switch valve III, and a stop valve III. The various components are connected in sequence through a gas pipeline. The stop valve III is led out of the glove box through a gas pipeline and connected to the gas mixing chamber.

[0047] The entire sample II air intake subsystem and recovery subsystem are installed in a glove box. The glove box is connected to the exhaust gas recovery device through a pipeline. The glove box is used to prevent the gas sample II from leaking into the atmosphere to protect the safety of the operator.

[0048] The vacuum subsystem includes a mechanical pump, a solenoid valve, a molecular pump, a cold gauge and a gate valve. The components are connected in sequence through gas pipelines and finally connected to the gate valve, which is connected to the gas mixing chamber through the gas pipeline.

[0049] A resistance gauge is arranged on the gas mixing chamber, and the gas mixing chamber, sample bottle II and the connecting pipe therebetween together constitute the total volume of the gas mixture.

[0050] The micro-intake flow control subsystem is connected to the gas mixing chamber and the ion source, and includes a stop valve IV and a mass flow control valve II (micro).

[0051] The whole system working process is divided into preparation process, pre-extraction process, air intake process and gas recovery process. The whole working process is as follows:

[0052] 1) Preparation process

[0053] Close all the stop valves of the air intake system in advance, close the gate valve, set the mass flow control valve Ⅰ, mass flow control valve Ⅱ, and mass flow control valve Ⅲ to a fixed value, with an optional set value of 5sccm, and then open the manual switch valves Ⅰ, Ⅱ, and Ⅲ of the sample bottle Ⅰ, sample bottle Ⅱ, and recovery bottle.

[0054] 2) Pre-extraction process

[0055] Open stop valve II, open the gate valve, turn on the molecular pump and mechanical pump, and pump until the pressure value displayed on the cold gauge is below 1E-3Pa. Close the gate valve, turn off the pump group, and close the stop valve II to complete the pre-pumping process.

[0056] 3) Intake process

[0057] (a) Open pressure reducing valve II, and supply gas from the main gas cylinder of sample II into sample bottle II. In order to save gas sample II, the volume of sample bottle II is small, and 10 ml can be selected. The time is calculated through the mass flow control valve III to ensure that the gas volume flowing into sample bottle II at 60 kPa is sufficient. Then close the mass flow control valve III and the pressure reducing valve II;

[0058] (b) Open stop valve I and keep other valves in their original state, so that the pressure value of the gas mixing chamber is maintained at 60KPa (just observe the resistance gauge), open stop valve IV to supply gas to the ion source, and keep the pressure value of the gas mixing chamber at 60KPa until the ion source starts arc discharge;

[0059] (c) Close stop valve I, keep other valves as they are, and open stop valve II to allow gas sample I and gas sample II to be fully mixed. It is expected that the gases will be evenly mixed within 30 seconds (when the gases are evenly mixed, the ratio of the mixed gases will be consistent as monitored at the mass spectrometer terminal). At the same time, the mixed gas is provided to the ion source.

[0060] 4) Gas recovery process

[0061] Mainly recover the residual gas sample II in the ion source intake system. Close the stop valve IV and stop valve I, open the stop valve II, and open the stop valve III. Recover the remaining sample II in the entire system pipeline and the sample II bottle through the recovery bottle. A recovery pump can also be added before the recovery bottle to provide power for gas recovery.

[0062] Those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. Thus, if these variations and use adaptations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and use adaptations.

[0063] The above embodiments are merely illustrative of the present invention, and the present invention may also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described embodiments should be considered illustrative rather than restrictive in any respect. The scope of protection of the present invention should be described by the claims, and any changes equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A trace gas mixing intake system for a mass spectrometer ion source, characterized in that: It includes a vacuum subsystem, at least two sample gas inlet subsystems and a recovery subsystem respectively connected to a gas mixing chamber, wherein the gas mixing chamber is connected to an ion source via a micro gas inlet flow control subsystem, The vacuum subsystem is used to put the gas mixing chamber into a vacuum state before the gas sample is introduced; The sample gas inlet subsystem is used to pass different gas samples into the gas mixing chamber according to a set flow rate and mix them evenly in the gas mixing chamber; The micro-intake flow control subsystem is used to deliver the mixed gas sample to the ion source at a set flow rate; The recovery subsystem is used to recover residual gas samples in the entire system.

2. The trace gas mixing intake system for a mass spectrometer ion source according to claim 1, characterized in that: The vacuum subsystem includes a mechanical pump, a solenoid valve, and a molecular pump arranged on a gas extraction pipeline, and the gas extraction pipeline is connected to a gas mixing chamber through a plug valve; a cold gauge for measuring vacuum degree is arranged on the gas extraction pipeline.

3. The trace gas mixing intake system for a mass spectrometer ion source according to claim 1, characterized in that: Each of the sample gas inlet subsystems comprises an independent sample inlet pipeline connected to the gas mixing chamber, and a sample bottle, a manual switch valve, a pressure reducing valve, a stop valve and a flow control valve are arranged on the sample inlet pipeline.

4. The trace gas mixing intake system for a mass spectrometer ion source according to claim 3, characterized in that: When the gas sample is a harmful gas, its corresponding sample air intake subsystem is arranged in the glove box, and a sample main gas cylinder is arranged in the glove box. The sample main gas cylinder is connected to the sample bottle through the pressure reducing valve and the flow control valve, thereby reducing the volume of the sample bottle containing the harmful gas and reducing the content of the harmful gas in the recovered residual gas sample.

5. The trace gas mixing intake system for a mass spectrometer ion source according to claim 1, characterized in that: The micro-intake flow control subsystem comprises an outlet pipeline arranged between the gas mixing chamber and the ion source, and a stop valve and a flow control valve are arranged on the outlet pipeline.

6. The trace gas mixing inlet system for a mass spectrometer ion source according to claim 1, characterized in that: The recovery subsystem comprises a recovery bottle, a manual switch valve and a stop valve arranged on the recovery pipeline.

7. The trace gas mixing inlet system for a mass spectrometer ion source according to claim 6, characterized in that: When the gas sample contains harmful gases, the recovery subsystem is arranged in the glove box.

8. The trace gas mixing inlet system for a mass spectrometer ion source according to claim 1, characterized in that: A resistance gauge for measuring the vacuum degree is arranged on the gas mixing chamber.

9. A method for controlling a trace gas mixing inlet system for a mass spectrometer ion source according to any one of claims 1 to 8, characterized in that: include: (1) Set the flow control valves of the sample air intake subsystem and the trace air intake flow control subsystem to fixed values, and close the inlet pipeline connecting the sample air intake subsystem and the gas mixing chamber, as well as the outlet pipeline connecting the gas mixing chamber and the ion source; (2) Start the vacuum subsystem to evacuate the gas mixing chamber to a specified vacuum degree; (3) opening each sample gas inlet subsystem in turn, allowing different gas samples to enter the gas mixing chamber at a set flow rate and be evenly mixed in the gas mixing chamber, and providing the mixed gas to the ion source through the micro-inlet flow control subsystem; (4) Close the sample inlet pipeline connecting the sample inlet subsystem and the gas mixing chamber, and the gas outlet pipeline connecting the gas mixing chamber and the ion source, and open the recovery subsystem to recover the residual gas sample in the entire system.

10. The control method of the trace gas mixing inlet system for the mass spectrometer ion source according to claim 9, characterized in that: When two gas samples are mixed and one of the gas samples is a harmful gas, the specific operation of step (3) is as follows: (3-1) After the sample main cylinder containing the harmful gas supplies the set amount of gas to the sample bottle connected to it through the pressure reducing valve and the flow control valve, the pressure reducing valve and the flow control valve are closed; (3-2) supplying gas to the gas mixing chamber through the inlet pipeline of the non-hazardous gas sample to make the gas mixing chamber reach a specified pressure value, and then opening the outlet pipeline of the micro-inlet flow control subsystem to supply gas to the ion source, during which the pressure of the gas mixing chamber is maintained at the specified pressure value until the ion source starts arcing; (3-3) Close the inlet line of the non-harmful gas sample and open the inlet line of the harmful gas, so that the two gas samples are fully mixed in the gas mixing chamber, and provide the mixed gas to the ion source through the outlet line of the trace inlet flow control subsystem.

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