An experimental system and method for high-vacuum gas micro-nano flow test

Abstract

This invention relates to an experimental system and method for testing micro / nano-scale gas flow in high vacuum, comprising a gas source and primary pressure regulation module, a flow rate setting and purging module, an upstream vacuum pressure stabilization microcontroller module, a sample clamping and testing section module, a front-end evacuation and pressure regulation module, a gas analysis and differential injection module, an analysis chamber vacuum module and an RGA / QMS detection module, and a data acquisition and control module. This invention achieves stable inlet pressure control by forming a closed-loop pressure stabilization circuit using a vacuum gauge, controller, and electromagnetic metering valve; it maintains the downstream high vacuum boundary and expands the Knudsen number coverage range by employing a dual vacuum subsystem and a throttling isolation sampling structure; and it achieves real-time identification and partial pressure verification of multi-component gases through online RGA / QMS integration. This invention solves the problems of unstable inlet boundaries, limited coverage of flow ranges, and lack of component partial pressure verification capabilities in existing technologies, significantly improving test repeatability and data traceability.

Description

Technical Field

[0001] This invention relates to the intersection of vacuum testing technology and micro / nano fluid dynamics. Specifically, it relates to an experimental system and method for testing high-vacuum gas micro / nano flow, which is suitable for high-precision quantitative characterization of rarefied gas transport characteristics in micron- to nano-scale channels or porous materials. Background Technology

[0002] For the study and quantitative characterization of gas transport within micro- and nano-scale channels, existing experimental setups typically follow a relatively unified overall approach: controllable gas supply and pressure stabilization are achieved upstream, using inlet pressure or inlet molar flow rate as boundary conditions; a high-vacuum / ultra-high-vacuum pumping system is configured downstream to establish a sufficiently large pressure ratio; and in many experiments, the outlet boundary is approximated as Pout→0 to cover typical rarefied gas flow ranges such as slip flow, transition flow, and even molecular flow. To ensure the traceability of boundary conditions and response quantities, the system often integrates high-sensitivity pressure measurement and component / partial pressure detection to achieve simultaneous monitoring of total pressure and partial pressure over a wide pressure range.

[0003] At the measurement and parameter inversion level, existing methods typically use loading-response strategies such as the equilibrium pressure method, pressure relaxation method, or constant flow loading method to map the obtained pressure-time response curve or steady-state pressure difference relationship into transport characterization quantities such as channel conductivity, flow rate, diffusion coefficient, or transport probability. These are then further combined with theoretical models to invert boundary effect parameters such as slip and TMAC. The resulting typical technical architecture can be summarized as a system of two-end gas storage / vacuum chambers – intermediate channel / sample – pumping and valve control – pressure and component measurement – ​​data inversion model. Differences between different studies mainly lie in key aspects such as vacuum level and pumping capacity, loading method, selection of measurement quantities, channel morphology and replaceability design, and calibration procedures and error control strategies.

[0004] The closest existing approach to this invention typically focuses on characterizing the pressure-driven transport of rarefied gases in microchannels or micropores. This approach employs a system architecture with a dual-chamber vacuum device, channel clamping components, a downstream turbomolecular pump for evacuation, an upstream pressure-stabilized intake, and multi-range pressure measurement. Such systems use two vacuum chambers as the supply chamber and the receiving chamber, or evacuation chamber, respectively. The channel or micropore to be tested is positioned between the two chambers, and pressure gauges are placed in each chamber to simultaneously acquire the pressure boundaries at the supply and receiving ends. The experimental procedure typically involves first evacuating the chambers to a low to medium vacuum level via a pre-evacuation pipeline, then using a turbomolecular pump to further evacuate the receiving chamber to a high or ultra-high vacuum level, thereby creating a boundary condition approximately Pout→0 downstream. On the supply side, gas is slowly introduced into the supply chamber via a gas cylinder, pressure regulator, and manual valve (or equivalent metering element) to set the inlet pressure and establish a pressure difference across the channel. Driven by this pressure difference, the system records the evolution of the receiving chamber pressure over time and acquires the steady-state or equilibrium pressure as the primary response quantity. The publicly available literature already contains relatively clear descriptions of engineering implementations, such as using a dual vacuum chamber of approximately 2L and pre-evacuating to... After mbar, the receiving cavity is further drawn to... mbar, the inert gas is controlled by a pressure regulator and a manual valve to enter the supply chamber, and a microchannel is placed between the two chambers and the transmission process is characterized by the pressure signal of the receiving chamber.

[0005] At the measurement and data processing level, such schemes often employ a multi-range combination of inlet absolute pressure and outlet high vacuum pressure. The supply chamber typically uses a capacitive diaphragm gauge for inlet pressure measurement to obtain a linear and calibrable absolute pressure; the receiving chamber commonly uses a hot cathode ionization gauge covering the high vacuum range to record the equilibrium pressure or pressure-time curves. For parameter solving, firstly, the condition of the receiving chamber reaching equilibrium pressure can be used to establish a conservation equilibrium relationship between the channel flux, pump speed, and the combined effects of system leakage and venting, thereby deriving the channel mass flow rate or equivalent conductance; secondly, in the slip-to-transition flow region, the Maxwell slip approximation or a more general rarefied flow model is often used to map the channel equivalent conductance and slip contribution, and the impact of boundary effects on transmission is discussed accordingly.

[0006] However, such solutions typically use a front-end pressure regulator in conjunction with a manual or needle valve for gas intake, clamping the sample (micro-nano channels or porous materials) in a vacuum pipeline. The rear end is equipped with only one vacuum pump unit (commonly a molecular pump and a backing pump) to maintain downstream vacuum. Operating condition control and result interpretation mainly rely on pressure gauge readings. The system generally does not integrate an RGA (Residual Gas Analyzer) or QMS (Quadrupole Mass Spectrometer), or uses it only briefly during leak detection rather than as an online monitoring and quantitative or partial pressure verification method. Based on the above setup, its main drawbacks can be summarized as follows: 1. Insufficient stability of front-end sample introduction and pressure stabilization, and uncertain inlet boundary conditions. This type of system typically uses a pressure regulator in conjunction with a manual valve or needle valve for gas introduction, lacking a closed-loop regulation mechanism based on pressure or flow signals. The relationship between valve opening and injection volume is nonlinear and exhibits mechanical hysteresis. Under conditions where the conductivity of micro-nano channels is low, these fluctuations are more easily amplified, making it difficult to maintain steady state or to unify steady-state criteria, thereby reducing repeatability and increasing the uncertainty in the inversion of parameters such as slip effect and transport probability.

[0007] 2. A single vacuum pump unit at the back end makes it difficult to maintain a high vacuum at the front end. Such systems typically use molecular pumps and backing pumps to maintain downstream vacuum. When the channel is micro- or nano-scale, they can only maintain a low vacuum at the front end, making it difficult to simulate the rarefied gas injection environment at the front end. Furthermore, maintaining vacuum often requires reducing the injection volume or narrowing the scan pressure range, thus limiting the Knudsen number range that can be covered.

[0008] 3. Lack of integrated RGA online monitoring, insufficient component and background verification, and inadequate verifiability of low-throughput data. These systems typically use total pressure as the primary criterion, failing to incorporate RGA or quadrupole mass spectrometry into routine testing procedures. This makes it impossible to distinguish the target gas from background components introduced by outgassing, adsorption / desorption, or microleakage in real time. In low-throughput testing, the background partial pressure and target signal may be on the same order of magnitude, and background drift is more likely to become the dominant error source when the steady-state settling time is long. In gas switching or multi-component conditions, the lack of partial pressure information also makes it difficult to identify memory effects and cross-contamination. Consequently, it is difficult to prove that the measurement signal originates from the target gas flux, abnormal operating conditions are not easily detected in a timely manner, and the lack of a partial pressure-to-flux verification and calibration link limits the traceability of quantitative results and the generalizability of the method. Summary of the Invention

[0009] To overcome the shortcomings of existing technologies, this invention provides an experimental system and method for testing micro / nano flow of high-vacuum gases, aiming to solve the following technical problems: To address the issues of insufficient front-end sample introduction stability and easy drift and difficulty in reproducing inlet boundary conditions in existing technologies, an automatic closed-loop stable control of upstream pressure or sample throughput is established. This is combined with controllable step and scanning condition generation and a unified steady-state criterion to ensure long-term stability and traceability of the inlet boundary under low-throughput conditions, thereby improving test repeatability and data comparability.

[0010] To address the problem that a single vacuum pump unit is difficult to maintain a medium-high vacuum at the inlet end for a long period of time and is easily affected by sample introduction disturbances, resulting in unstable operating conditions, a dual-pump pumping architecture is adopted in conjunction with flow path organization to achieve stable establishment and maintenance of a medium-high vacuum environment at the inlet end. This expands the pressure setting range without sacrificing vacuum boundary conditions, broadens the Knudsen number range that can be covered, and improves the consistency and repeatability of operating condition switching.

[0011] To address the lack of component and background verification in existing systems due to the absence of integrated online monitoring (RGA) or QMS, this paper proposes integrating RGA or QMS online into the downstream system. This enables real-time monitoring and recording of gas components and partial pressures, allowing for the identification and verification of interferences introduced by background gases, venting, and micro-leaks. Based on partial pressure information, the system supports micro-nano flow testing under mixed gas and multi-component switching conditions, enabling the differentiation and comparison of flux contributions from different components and improving the verifiability and traceability of multi-component experimental results.

[0012] To achieve the aforementioned objectives of the invention, the technical solution adopted to solve its technical problems is as follows: This invention discloses an experimental system for high-vacuum gas micro / nano flow testing, comprising a gas source and primary pressure regulation module, a flow rate setting and purging module, an upstream vacuum pressure stabilization microcontroller module, a sample clamping and testing section module, a front-end evacuation and pressure regulation module, a gas analysis and differential injection module, an analysis chamber vacuum module and RGA / QMS detection module, and a data acquisition and control module, wherein: The gas source and primary pressure regulating module includes a high-purity gas source, a pressure reducing valve / regulator, and an inlet pipeline, which are used to provide a stable gas source to the system and complete the primary pressure regulation. The flow setting and purging module includes a mass flow meter or an equivalent flow setting element, used to set the inlet flow rate and purge and replace residual gas in the pipeline; The upstream vacuum pressure stabilizing microcontroller module includes a full-range vacuum gauge, a controller, and an electromagnetic metering valve. The controller uses the upstream pressure measured by the full-range vacuum gauge as a feedback signal to drive the electromagnetic metering valve to automatically adjust the opening, thereby stabilizing the upstream pressure within a set range. The sample clamping and testing section module includes a sealing clamping structure and connectors for mounting the micro / nano channel sample or porous material sample to be tested, to ensure that gas can only be transmitted through the effective channel of the sample. The front-end evacuation and pressure regulation module includes an evacuation system consisting of a back pump and a turbomolecular pump, as well as at least two on / off valves and a throttle valve, for evacuating the test section and establishing a controllable upstream vacuum environment. The gas analysis and differential injection module includes a high-precision needle valve and its front-end connecting pipeline, which is used to extract trace amounts of gas from downstream of the sample and introduce them into the analysis system; the gas load entering the analysis chamber is controlled by adjusting the opening of the high-precision needle valve. The analysis chamber vacuum module and RGA / QMS detection module include an analysis chamber, a molecular pump + dry pump assembly for pumping the mass spectrometry analysis chamber to a high vacuum and maintaining stability; and an RGA / quadrupole mass spectrometer detector and its control software for online qualitative and quantitative detection of the gas entering the analysis chamber. The data acquisition and control module includes a data acquisition unit and a control program for acquiring vacuum gauge signals, valve opening, pump operating status and mass spectrometry signals; the control program at least realizes upstream pressure closed-loop control, operating condition scanning, steady state determination and data synchronous recording.

[0013] Furthermore, the high-purity gas source, mass flow meter, electromagnetic metering valve, and sample clamping device constitute the vacuum subsystem of the test section, which is evacuated / maintained by the front-end evacuation and pressure regulation module; wherein, the full-range vacuum gauge is installed downstream of the electromagnetic metering valve or at a key position in the test section, and feeds back the pressure signal to the controller, which drives the electromagnetic metering valve to form a closed-loop pressure stabilization.

[0014] Furthermore, the sample clamping device, high-precision needle valve, mass spectrometer chamber, and mass spectrometer constitute the vacuum subsystem of the analysis chamber; wherein, the analysis chamber maintains a high vacuum through an independent molecular pump + dry pump assembly; the high-precision needle valve is located between the test section and the analysis chamber, serving as a differential injection and throttling isolation element, so that changes in the operating conditions of the test section do not disrupt the vacuum of the analysis chamber.

[0015] Furthermore, the on / off valve is located on both sides of the evacuation path and / or sample in the test section, and is used to switch the flow path at different stages; the vacuum level on the left side of the sample can be finely adjusted by adjusting the opening degree of the on / off valve and / or the speed of the molecular pump.

[0016] Furthermore, in the upstream vacuum pressure stabilizing microcontroller module, the full-range vacuum gauge is installed on the upstream pressure stabilizing chamber or pressure stabilizing pipe section downstream of the electromagnetic metering valve. The controller uses the pressure at this location as a feedback signal to perform pressure stabilization control, thereby stabilizing the upstream pressure between 100 Pa and 10 Pa. -3 The set value within the Pa range.

[0017] Preferably, the sealing clamping structure adopts a KF16-1 / 4 ferrule connector or a quartz / glass ferrule structure.

[0018] This invention also discloses an experimental method for testing micro / nano flow of gas in high vacuum, which uses the above-mentioned experimental system and includes the following steps: Step 1: Sample clamping and system seal check Install the sample to be tested into the sample clamping module, lock the sealing interface, and ensure that the gas passage only passes through the effective structure of the sample; close the needle valve of the analysis chamber and prepare for evacuation. Step 2: Pre-evacuation of the test section and establishment of a vacuum environment Turn on the forepump and turbomolecular pump, open the on / off valve, and create a vacuum environment in the test section between the electromagnetic metering valve and the high-precision needle valve. Step 3: Pipeline purging / replacement The flow rate is set by a mass flow meter, and the upstream pipeline is purged to remove residual gas, followed by the pressure stabilization control stage. Step 4: Upstream voltage regulation setting and closed-loop control start-up Set the target pressure on the controller, and the controller will automatically adjust the opening of the electromagnetic metering valve based on the feedback from the full-range vacuum gauge to stabilize the upstream pressure at the set value Pset. Step 5: Evacuate the analysis chamber to a high vacuum and stabilize it. Start the independent pump unit of the analysis system to evacuate the analysis chamber to a high vacuum environment, and proceed to the sampling and detection stage after the baseline stabilizes; Step 6: Differential micro-injection and QMS online detection The high-precision needle valve is slowly opened to allow the downstream gas of the sample to enter the analysis chamber in a trace amount. The characteristic mass number signal / partial pressure signal of the QMS is recorded simultaneously to realize online monitoring and qualitative / quantitative analysis of gas composition and flux response. Step 7: Operating Condition Scan and Data Acquisition While maintaining the vacuum stability of the analysis chamber, the pressure setpoint or flow setpoint is changed sequentially to form multiple stable operating points. Data is recorded after each operating point meets the steady-state criterion. Step 8: End and Empty Close the electromagnetic metering valve and the high-precision needle valve, then close the relevant valves in sequence, and unload the sample.

[0019] Preferably, in step 4, the upstream pressure is stabilized at 100 Pa to 10 Pa. -3 Within the Pa range.

[0020] Preferably, in step 5, the analysis chamber is evacuated to a high vacuum environment of 10... -4 Pa level.

[0021] Preferably, in step 7, the steady-state criterion is that the pressure drift is less than a set threshold and the QMS signal enters the plateau region.

[0022] Furthermore, the method also includes calibration steps before and after the experiment: using standard leak calibration, known volume pressure rise calibration, or reference channel calibration, the QMS partial pressure signal or pressure change rate is converted into a traceable flux value.

[0023] Furthermore, the method also includes a blank baseline measurement step: recording the QMS background spectrum in the absence of sample injection or with the bypass closed, for subsequent signal subtraction. By employing the above technical solutions, this invention has the following advantages and positive effects compared with the prior art: 1. Improved stability and repeatability of inlet boundary conditions. This invention uses a vacuum gauge, controller, and electromagnetic metering valve to form a closed-loop pressure stabilization circuit, providing real-time feedback adjustment of the upstream pressure Pin or equivalent injection volume to maintain it stably near the set value. It also supports programmed switching between pressure stabilization and pressure sweeping modes. Compared to injection methods using a pressure regulator with a manual needle valve or leak valve, inlet pressure drift and jitter are significantly reduced, and different pressure points are more likely to repeatedly reach a consistent steady-state boundary, thereby improving the stability and data repeatability of throughput response measurements under low-throughput conditions.

[0024] 2. Expanding the Knudsen number range to cover molecular flow. Based on closed-loop pressure stabilization at the inlet, this invention maintains a high vacuum boundary downstream through a dual-vacuum subsystem and a throttling isolation sampling structure. This allows for stable setting and continuous scanning of the upstream pressure over a wider range, while maintaining a near-vacuum boundary at the outlet for an extended period. This enables a larger pressure ratio and pressure span, allowing the system to cover slip flow, transition flow, and extend to a wider Knudsen number range for molecular flow, thus improving its adaptability to various rarefied gas transport conditions.

[0025] 3. Achieve online component identification and partial pressure verification for multi-component gases. This invention integrates RGA or QMS online into the downstream analysis chamber. Through differential micro-sampling, the downstream gas of the sample is controlled and introduced into the analysis chamber, with real-time output of partial pressure or spectral peak signals. This allows for the differentiation of contributions from different components and verification of background components. Based on online partial pressure information, this invention supports micro-nano flow testing under mixed gas and gas switching conditions, improving the verifiability and traceability of multi-component experimental results.

[0026] 4. Expanding application scenarios and sample compatibility to meet the testing needs of channels, porous materials, and multi-gas applications. The sample clamping module of this invention can adapt to samples of different shapes, and the detection module can adapt to different gas systems. The upstream closed-loop voltage regulation and dual vacuum decoupling structure make the system independent of specific sample shapes or single gas conditions. Therefore, this invention can be used for various objects such as single micro / nano channel chips, nanoporous membranes, and porous bulk materials. It is also applicable to testing scenarios for inert gases, combustible gases, or multi-component gases. Under the premise of meeting safety and material compatibility requirements, it provides a general testing platform foundation for applications such as isotope separation, catalytic mass transfer, and analysis of nuclear material escape gases. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1This is a schematic diagram of the overall system structure of the present invention; Figure 2 This is a block diagram of the upstream voltage stabilization closed-loop control of the present invention; Figure 3 This is a schematic diagram of the differential micro-injection and RGA / QMS online detection of the present invention; Figure 4 This is a flowchart of the experimental method of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Example 1 like Figure 1-3 As shown, this invention discloses an experimental system for high-vacuum gas micro / nanoflow testing, including a gas source and primary pressure regulation module, a flow rate setting and purging module, an upstream vacuum pressure stabilization microcontroller module, a sample clamping and testing section module, a front-end evacuation and pressure regulation module, a gas analysis and differential injection module, an analysis chamber vacuum module and RGA / QMS detection module, and a data acquisition and control module, wherein: The gas source and primary pressure regulating module includes a high-purity gas source (8L gas cylinder), a pressure reducing valve / regulator, and an inlet pipeline, which are used to provide a stable gas source to the system and complete the primary pressure regulation. The flow setting and purging module includes a mass flow meter (range 0-100 sccm) or an equivalent flow setting element, used to set the inlet flow rate and purge and replace residual gas in the pipeline. The upstream vacuum pressure stabilizing microcontroller module includes a full-range vacuum gauge, a controller (which receives the vacuum gauge signal and drives the solenoid valve to form a closed loop), and an electromagnetic metering valve. The controller uses the upstream pressure measured by the full-range vacuum gauge as a feedback signal to drive the electromagnetic metering valve to automatically adjust the opening, thereby stabilizing the upstream pressure within the set range. The sample clamping and testing section module includes a sealed clamping structure and connectors for mounting the micro-nano channel sample or porous material sample to be tested, which ensures that gas can only be transmitted through the effective channel of the sample. The testing section pipeline is used to form a controlled upstream pressure zone and a pressure difference between the two ends of the sample. The front-end evacuation and pressure regulation module includes an evacuation system consisting of a back pump and a turbomolecular pump, as well as at least two on / off valves and a throttle valve, for evacuating the test section and establishing a controllable upstream vacuum environment. The gas analysis and differential injection module, such as Figure 3 As shown, it includes a high-precision needle valve (located between the test section and the analysis chamber, used for micro-sampling and throttling isolation) and its front-end connecting pipeline, used to extract trace amounts of gas from downstream of the sample and introduce them into the analysis system; the gas load entering the analysis chamber is controlled by adjusting the opening of the high-precision needle valve; The analysis chamber vacuum module and RGA / QMS detection module include an analysis chamber, a molecular pump + dry pump assembly for pumping the mass spectrometry analysis chamber to a high vacuum and maintaining stability; and an RGA / quadrupole mass spectrometer detector and its control software for online qualitative and quantitative detection of the gas entering the analysis chamber. The data acquisition and control module includes a data acquisition unit and a control program for acquiring vacuum gauge signals, valve opening, pump operating status and mass spectrometry signals; the control program at least realizes upstream pressure closed-loop control, operating condition scanning, steady state determination and data synchronous recording.

[0032] In this embodiment, the high-purity gas source, mass flow meter, electromagnetic metering valve, and sample clamping device constitute the vacuum subsystem of the test section, which is evacuated / maintained by the front-end evacuation and pressure regulation module; wherein, the full-range vacuum gauge is installed downstream of the electromagnetic metering valve or at a key position in the test section, and feeds back the pressure signal to the controller, and the controller drives the electromagnetic metering valve to form a closed-loop pressure stabilization.

[0033] In addition, the sample clamping device, high-precision needle valve, mass spectrometer chamber, and mass spectrometer constitute the vacuum subsystem of the analysis chamber; wherein, the analysis chamber maintains a high vacuum through an independent molecular pump + dry pump assembly; the high-precision needle valve is located between the test section and the analysis chamber, serving as a differential injection and throttling isolation element, so that changes in the operating conditions of the test section do not disrupt the vacuum of the analysis chamber.

[0034] refer to Figure 1 The on / off valves V2 and V3 are located on both sides of the evacuation path and / or sample in the test section, and are used to switch the flow path at different stages; the vacuum level on the left side of the sample (i.e., the upstream condition) can be finely adjusted by adjusting the opening degree of the on / off valves and / or the speed of the molecular pump.

[0035] Furthermore, in the upstream vacuum pressure stabilizing microcontroller module, the full-range vacuum gauge is installed on the upstream pressure stabilizing chamber or pressure stabilizing pipe section downstream of the electromagnetic metering valve. The controller uses the pressure at this location as a feedback signal to perform pressure stabilization control, thereby stabilizing the upstream pressure between 100 Pa and 10 Pa. -3 The set value within the Pa range.

[0036] Preferably, the sealing clamping structure adopts a KF16-1 / 4 ferrule connector or a quartz / glass adapter structure, which is compatible with micro / nano channel chips, porous blocks, glass tubes or flange samples.

[0037] System working principle: A closed-loop stable inlet vacuum pressure boundary is established upstream, and a high-vacuum analytical boundary maintained by an independent pump set is established downstream. The test section and analytical chamber are isolated by a high-precision needle valve. Gas passing through the sample is introduced into the analytical chamber using a micro-differential sampling method, and the partial pressure and composition are monitored online by RGA or QMS, enabling repeatable and quantitative characterization of the throughput and composition of micro / nanochannel or porous samples. Upstream, the inlet pressure Pin is acquired in real time by a vacuum gauge. The controller compares Pin with the set value Pset and drives the electromagnetic metering valve to continuously adjust the gas intake, ensuring the inlet pressure remains stable within the set range. This suppresses drift caused by gas source disturbances and valve nonlinearity, and ensures the reproducibility of pressure stabilization and pressure sweeping conditions. The vacuum in the test section and the vacuum in the analytical chamber are maintained independently by two separate pumping paths. The throttling isolation ensures that pressure changes in the test section are coupled to the analytical chamber only through controlled sampling, rather than through a direct gas load, ensuring long-term stability of the high vacuum in the analytical chamber during pressure sweeping and reducing systematic errors caused by boundary drift. RGA or QMS continuously outputs partial pressure or spectral peak signals under high vacuum conditions to distinguish target gas from background components and identify micro-leakage and abnormal gas release. It can also be combined with standard leak or volume pressure rise calibration to establish the conversion relationship between partial pressure signal and flux, realizing quantitative verification and drift correction in the low flux range.

[0038] Example 2 like Figure 4As shown, this invention also discloses an experimental method for testing micro / nano flow of high-vacuum gas, which uses the above-mentioned experimental system and includes the following steps: Step 1: Sample clamping and system seal check Install the sample to be tested into the sample clamping module, lock the sealing interface, and ensure that the gas passage only passes through the effective structure of the sample; close the needle valve of the analysis chamber and prepare for evacuation. Step 2: Pre-evacuation of the test section and establishment of a vacuum environment Turn on the forepump and turbomolecular pump, and open the on / off valves V2 and V3 to create a vacuum environment in the test section between the electromagnetic metering valve and the high-precision needle valve; when the sample is well sealed, the pressure in the test section can cover atmospheric pressure to... .

[0039] Step 3: Pipeline purging / replacement The flow rate is set by a mass flow meter, and the upstream pipeline is purged to remove residual gas, followed by the pressure stabilization control stage. Step 4: Upstream voltage regulation setting and closed-loop control start-up Set the target pressure on the controller, and the controller will automatically adjust the opening of the electromagnetic metering valve based on the feedback from the full-range vacuum gauge to stabilize the upstream pressure at the set value Pset. Step 5: Evacuate the analysis chamber to a high vacuum and stabilize it. Start the independent pump unit of the analysis system to evacuate the analysis chamber to a high vacuum environment, and proceed to the sampling and detection stage after the baseline stabilizes; Step 6: Differential micro-injection and QMS online detection The high-precision needle valve is slowly opened to allow the downstream gas of the sample to enter the analysis chamber in a trace amount. The characteristic mass number signal / partial pressure signal of the QMS is recorded simultaneously to realize online monitoring and qualitative / quantitative analysis of gas composition and flux response. Step 7: Operating Condition Scan and Data Acquisition While maintaining the vacuum stability of the analysis chamber, the pressure setpoint or flow setpoint is changed sequentially to form multiple stable operating points. Data is recorded after each operating point meets the steady-state criterion. Step 8: End and Empty Close the electromagnetic metering valve and the high-precision needle valve, and then close the relevant valves in sequence. If necessary, backflush / replace with inert gas and safely remove the sample.

[0040] Preferably, in step 4, the upstream pressure is stabilized at 100 Pa to 10 Pa. -3 Within the Pa range.

[0041] Preferably, in step 5, the analysis chamber is evacuated to a high vacuum environment of 10... -4 Pa level.

[0042] Preferably, in step 7, the steady-state criterion is that the pressure drift is less than a set threshold and the QMS signal enters the plateau region.

[0043] Furthermore, the method also includes calibration steps before and after the experiment: using standard leak calibration, known volume pressure rise calibration, or reference channel calibration, the QMS partial pressure signal or pressure change rate is converted into a traceable flux value.

[0044] Furthermore, the method also includes a blank baseline measurement step: recording the QMS background spectrum in the absence of sample injection or with the bypass closed, for subsequent signal subtraction.

[0045] Variation Example This invention can be modified in various ways without departing from its core idea. Several typical examples of modifications are listed below: Variation Example 1: Alternative Combination of Mass Flow Meter (MFC) and Injection Valve The MFC used in the embodiments can be replaced by: a mass flow controller (MFC with closed loop), a mass flow meter (MFM) + proportional valve combination, a critical flow nozzle / capillary restrictor, or a standard orifice as a quantitative injection element. When using a standard orifice or capillary restrictor, the MFC can be omitted, but pressure stabilization feedback or equivalent upstream pressure control / monitoring should be retained to maintain inlet boundary stability.

[0046] Variation Example 2: Substitution of Gas Source and Pressure Stabilizing Structure The gas source can be replaced by a high-pressure gas cylinder, a gas generator, a gas mixer, or a multi-source gas switching manifold; the primary pressure regulator can be replaced by a two-stage pressure regulator or an electronic pressure regulator to improve the stability and safety of the inlet pressure; a purifier / molecular sieve / water and oxygen removal module can be added to the gas supply side to reduce background impurities.

[0047] Variation Example 3: Replacement of Pressure Sensor and Feedback Loop The full-range vacuum gauge can be replaced with a capacitive thin-film gauge, Pirani, cold cathode / hot cathode ionization gauge or a combination gauge, and wide-range pressure measurement can be achieved by splicing the ranges; the pressure feedback point can be moved from "downstream of the electromagnetic metering valve" to "near the sample inlet" or "pressure stabilizing chamber" to reduce control deviations caused by pipeline pressure drop.

[0048] Variation Example 4: Actuator Replacement (Solenoid Metering Valve / Proportional Valve / Throttle Valve) The electromagnetic metering valve can be replaced by a proportional valve, a stepper motor needle valve, a piezoelectric valve, or other valves with continuously adjustable opening; the controller can realize PID, feedforward + feedback composite control, adaptive control, or segmented control (different parameters are used for different pressure ranges).

[0049] Variation Example 5: Adding an upstream buffer chamber / voltage stabilizing chamber A controllable volume buffer chamber (pressure stabilizer) is added between the injection valve and the sample to reduce high-frequency fluctuations in the inlet pressure and improve stability under extremely low throughput conditions; the buffer chamber can be equipped with an independent pressure gauge to form a "dual-point pressure measurement + compensation" control strategy.

[0050] Variation Example 6: Replacement of the air extraction configuration The test section pump set can be replaced by "molecular pump + backing pump" with: molecular pump + dry pump, turbomolecular pump + Roots pump, cryogenic pump, ion pump (for higher vacuum), etc.; the molecular pump can be equipped with a throttle valve or bypass valve to adjust the effective pumping speed; a second set of pumping branches can be added to form differential pumping, achieving stronger upstream and downstream pressure isolation.

[0051] Variation Example 7: Changes in Valve Network and Connection Relationships The positions of on / off valves V2 and V3 can be changed: for example, on / off valve V2 can be placed in the upstream evacuation branch of the sample, and on / off valve V3 can be placed in the downstream evacuation branch of the sample, or a three-way valve can be used to achieve the three-state switching of "evacuation / testing / isolation"; the on / off valves can be replaced with angle valves, diaphragm valves, gate valves or needle valves; bypass short-circuit channels can be added on both sides of the sample for system leak detection, evacuation acceleration or calibration (the bypass is closed during testing).

[0052] Variation Example 8: Detector Replacement and Parallel Connection RGA / QMS can be replaced by TOF mass spectrometry, ion trap mass spectrometry or other residual gas analysis devices; a pressure gauge and QMS can be connected in parallel in the analysis chamber to record total pressure and partial pressure simultaneously to improve traceability; a reference gas path (bypass) can be added for QMS online calibration or sensitivity drift correction.

[0053] Example of Change 9: Changes in RGA Usage (Online vs. Offline) The "online real-time monitoring" mode (preferred) or the "intermittent sampling monitoring" mode can be used: that is, the sampling valve is opened during the steady-state phase and then closed after a period of detection to further protect the vacuum of the analysis chamber and reduce the background. In some scenarios where only the total throughput is required, RGA / QMS can be omitted and the throughput can be estimated by pressure-time method alone.

[0054] Variation Example 10: Sample Type Expansion Samples can be: single micro / nano channel chips, nanopore / microporous membranes, porous bulk materials, sintered porous bodies, micro-machined slits / capillaries, etc.; for fragile samples, flexible gaskets or metal sealing rings can be used; for ultra-high vacuum, an all-metal sealing structure can be used.

[0055] Variation Example 11: Clamping Structure Changes and Bypass Suppression The clamping module can be replaced by a VCR connector, ferrule connector, or custom miniature vacuum interface from the KF / CF flange system; a "ring clamping + limiting" structure can be added to avoid micro-cracks caused by clamping stress; an independent bypass leak detection branch (such as a He leak detection interface) can be added to quickly determine the sealing quality before each test.

[0056] Variation Example 12: Adjustment of Step Sequence In the embodiments, the test section and analysis chamber are usually evacuated first, and then the pressure is stabilized before injection. In the variant, the analysis chamber can be evacuated and the baseline stabilized first, and then the test section can be evacuated and the pressure stabilized to shorten the QMS baseline recovery time. In the pressure sweep experiment, the order of "from low pressure to high pressure" or "from high pressure to low pressure" can be adopted. A brief evacuation recovery phase can be added between each pressure point.

[0057] Variation Example 13: Add pretreatment / baking / baseline correction steps The pre-evacuation time of the sample and tubing, the baking step, or the plasma cleaning step can be increased to reduce outgassing and memory effects; a "blank baseline measurement" can be added: the QMS background spectrum is recorded when there is no sample injection or the bypass is closed, for subsequent subtraction.

[0058] Variation Example 14: Add calibration steps Standard leak calibration, known volume pressure rise calibration, or reference channel calibration can be added before and after the experiment to convert the QMS partial pressure signal or pressure change rate into a traceable flux value. The calibration can be performed under the same gas and same analysis chamber pumping speed conditions to reduce systematic errors.

[0059] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An experimental system for testing micro / nano flow of gas in high vacuum, characterized in that, It includes a gas source and primary pressure regulation module, a flow rate setting and purging module, an upstream vacuum pressure stabilization microcontroller module, a sample clamping and testing section module, a front-end evacuation and pressure regulation module, a gas analysis and differential injection module, an analysis chamber vacuum module and RGA / QMS detection module, and a data acquisition and control module, among which: The gas source and primary pressure regulating module includes a high-purity gas source, a pressure reducing valve / regulator, and an inlet pipeline, which are used to provide a stable gas source to the system and complete the primary pressure regulation. The flow setting and purging module includes a mass flow meter or an equivalent flow setting element, used to set the inlet flow rate and purge and replace residual gas in the pipeline; The upstream vacuum pressure stabilizing microcontroller module includes a full-range vacuum gauge, a controller, and an electromagnetic metering valve. The controller uses the upstream pressure measured by the full-range vacuum gauge as a feedback signal to drive the electromagnetic metering valve to automatically adjust the opening, thereby stabilizing the upstream pressure within a set range. The sample clamping and testing section module includes a sealing clamping structure and connectors for mounting the micro / nano channel sample or porous material sample to be tested, to ensure that gas can only be transmitted through the effective channel of the sample. The front-end evacuation and pressure regulation module includes an evacuation system consisting of a back pump and a turbomolecular pump, as well as at least two on / off valves and a throttle valve, for evacuating the test section and establishing a controllable upstream vacuum environment. The gas analysis and differential injection module includes a high-precision needle valve and its front-end connecting pipeline, which is used to extract trace amounts of gas from downstream of the sample and introduce them into the analysis system; the gas load entering the analysis chamber is controlled by adjusting the opening of the high-precision needle valve. The analysis chamber vacuum module and RGA / QMS detection module include an analysis chamber, a molecular pump + dry pump assembly for pumping the mass spectrometry analysis chamber to a high vacuum and maintaining stability; and an RGA / quadrupole mass spectrometer detector and its control software for online qualitative and quantitative detection of the gas entering the analysis chamber. The data acquisition and control module includes a data acquisition unit and a control program for acquiring vacuum gauge signals, valve opening, pump operating status and mass spectrometry signals; the control program at least realizes upstream pressure closed-loop control, operating condition scanning, steady state determination and data synchronous recording.

2. The experimental system for testing micro / nano flow of gas in high vacuum according to claim 1, characterized in that, The high-purity gas source, mass flow meter, electromagnetic metering valve, and sample clamping device constitute the vacuum subsystem of the test section, which is evacuated / maintained by the front-end evacuation and pressure regulation module. The full-range vacuum gauge is installed downstream of the electromagnetic metering valve or at a key position in the test section and feeds back the pressure signal to the controller. The controller drives the electromagnetic metering valve to form a closed-loop pressure stabilization.

3. The experimental system for testing high-vacuum gas micro / nano flow according to claim 1, characterized in that, The sample clamping device, high-precision needle valve, mass spectrometer chamber, and mass spectrometer constitute the vacuum subsystem of the analysis chamber. The analysis chamber maintains a high vacuum through an independent molecular pump and dry pump assembly. The high-precision needle valve is located between the test section and the analysis chamber, serving as a differential injection and throttling isolation element to prevent changes in the test section's operating conditions from disrupting the vacuum of the analysis chamber.

4. The experimental system for testing high-vacuum gas micro / nano flow according to claim 1, characterized in that, The on / off valve is located on both sides of the evacuation path and / or sample in the test section, and is used to switch the flow path at different stages; the vacuum level on the left side of the sample can be finely adjusted by adjusting the opening degree of the on / off valve and / or the speed of the molecular pump.

5. The experimental system for testing micro / nano flow of gas in high vacuum according to claim 1, characterized in that, In the upstream vacuum pressure stabilizing microcontroller module, the full-range vacuum gauge is installed on the upstream pressure stabilizing chamber or pressure stabilizing pipe section downstream of the electromagnetic metering valve. The controller uses the pressure at this location as a feedback signal to perform pressure stabilization control, keeping the upstream pressure stable between 100 Pa and 10 Pa. -3 The set value within the Pa range.

6. The experimental system for testing micro / nano flow of gas in high vacuum according to claim 1, characterized in that, The sealing clamping structure adopts a KF16-1 / 4 ferrule connector or a quartz / glass ferrule structure.

7. An experimental method for testing micro / nano flow of gas in high vacuum, characterized in that, The experiment, conducted using the experimental system described in any one of claims 1-6, includes the following steps: Step 1: Sample clamping and system seal check Install the sample to be tested into the sample clamping module, lock the sealing interface, and ensure that the gas passage only passes through the effective structure of the sample; close the needle valve of the analysis chamber and prepare for evacuation. Step 2: Pre-evacuation of the test section and establishment of a vacuum environment Turn on the forepump and turbomolecular pump, open the on / off valve, and create a vacuum environment in the test section between the electromagnetic metering valve and the high-precision needle valve. Step 3: Pipeline purging / replacement The flow rate is set by a mass flow meter, and the upstream pipeline is purged to remove residual gas, followed by the pressure stabilization control stage. Step 4: Upstream voltage regulation setting and closed-loop control start-up Set the target pressure on the controller, and the controller will automatically adjust the opening of the electromagnetic metering valve based on the feedback from the full-range vacuum gauge to stabilize the upstream pressure at the set value Pset. Step 5: Evacuate the analysis chamber to a high vacuum and stabilize it. Start the independent pump unit of the analysis system to evacuate the analysis chamber to a high vacuum environment, and proceed to the sampling and detection stage after the baseline stabilizes; Step 6: Differential micro-injection and QMS online detection The high-precision needle valve is slowly opened to allow the downstream gas of the sample to enter the analysis chamber in a trace amount. The characteristic mass number signal / partial pressure signal of the QMS is recorded simultaneously to realize online monitoring and qualitative / quantitative analysis of gas composition and flux response. Step 7: Operating Condition Scan and Data Acquisition While maintaining the vacuum stability of the analysis chamber, the pressure setpoint or flow setpoint is changed sequentially to form multiple stable operating points. Data is recorded after each operating point meets the steady-state criterion. Step 8: End and Empty Close the electromagnetic metering valve and the high-precision needle valve, then close the relevant valves in sequence, and unload the sample.

8. The experimental method for testing high-vacuum gas micro / nano flow according to claim 7, characterized in that, In step 4, the upstream pressure is stabilized at 100 Pa to 10 Pa. -3 Within the Pa range.

9. The experimental method for testing high-vacuum gas micro / nano flow according to claim 7, characterized in that, In step 5, the analysis chamber is evacuated to a high vacuum environment of 10. -4 Pa level.

10. The experimental method for testing high-vacuum gas micro / nano flow according to claim 7, characterized in that, In step 7, the steady-state criterion is that the pressure drift is less than a set threshold and the QMS signal enters the plateau region.

11. The experimental method for testing high-vacuum gas micro / nano flow according to claim 7, characterized in that, The method also includes calibration steps before and after the experiment: using standard leak calibration, known volume pressure rise calibration, or reference channel calibration, the QMS partial pressure signal or pressure change rate is converted into a traceable flux value.

12. The experimental method for testing high-vacuum gas micro / nano flow according to claim 7, characterized in that, The method also includes a blank baseline measurement step: recording the QMS background spectrum in the absence of sample injection or with the bypass closed, for subsequent signal subtraction.

Images