Method for in-situ detection of gas tightness of a detector interface in an icp-oes system

Abstract

The present application relates to the field of air tightness detection, in particular to a kind of air tightness in-situ detection method of detector interface in ICP-OES system, including in the stable stage of ICP-OES system plasma torch flame and no sample introduction carrier gas, control DMD micromirror array switches between full open state and full off state;The photon counting value of MCP single-photon counting detector is recorded in the two states of DMD micromirror array respectively, and the difference of the photon counting value in the two states is used as effective light flux reference;Periodically measure the difference of photon number, and calculate the decay rate according to the difference of photon number, when the decay rate exceeds the preset threshold, determine that the interface air tightness is abnormal.The present application solves the pain points of offline, qualitative, lag in the prior art, guarantees the detection accuracy and operation stability of ICP-OES system, reduces operating cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of air tightness detection, and particularly relates to an air tightness in-situ detection method for a detector interface in an ICP-OES system. BACKGROUND

[0002] Inductively coupled plasma atomic emission spectrometer (ICP-OES) as a core means of trace analysis of inorganic elements plays a crucial role in the fields of environmental monitoring, food safety, geological exploration and material science. Its working principle is to gasify and excite atoms of sample solution through a high-temperature plasma torch maintained by argon, and to realize quantitative analysis by measuring the emission intensity of element characteristic spectrum. With the increasing requirements of analytical science on detection sensitivity, dynamic range and long-term stability of the instrument, the performance of the detection system has become one of the key factors restricting the development of ICP-OES technology.

[0003] Traditional ICP-OES systems generally use deep-cooled charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) image sensors based on semiconductor technology as spectral detectors. Such detectors need to work in a deep cooling (usually below -70°C) environment to suppress dark current noise. However, in the deep ultraviolet band (especially below 200 nm), due to the intrinsic absorption effect of semiconductor materials, the quantum efficiency decays sharply, resulting in limited detection capability of the system in this important spectral region and narrow dynamic range.

[0004] To break through the above bottleneck, in recent years, a new type of detection architecture combining micro-channel plate (MCP) single-photon counting imaging detector and digital micro-mirror device (DMD) spatial light modulator has emerged. MCP detector has extremely high sensitivity and dynamic range, and can realize extremely low dark count rate (such as below 0.5 counts / (s·cm 2 ) ) at room temperature without complex deep cooling system. DMD as a programmable digital spatial grating can realize selective passing or blocking of specific spectral components through rapid flipping of micro-mirror array. The two work together to build an innovative model of "cold optics + room temperature detection", which can avoid the inherent defects of deep-cooled detectors in principle and is expected to significantly improve the performance of the system in the ultraviolet band.

[0005] However, when such high-performance UV imaging detectors (e.g. DMD-MCP system) are integrated into existing ICP-OES systems, serious technical adaptation challenges are encountered. The original system is usually designed with a highly integrated interface that matches a specific vendor's (e.g. E2V, UK) cryogenic camera, with the mechanical coaxiality, vacuum sealing level, and focusing mechanism being coupled with each other. The new detector, due to the introduction of DMD light path folding and the corresponding coupling optical system, has significantly increased physical size and structural complexity (volume increase can exceed 400%), which cannot be directly compatible with the original interface. The mismatch of the interface makes it extremely difficult to seal, and it is difficult to achieve complete sealing, resulting in continuous leakage of a small amount of argon during system operation.

[0006] This micro-leakage is usually discovered and located by offline helium mass spectrometry leak detection in the traditional maintenance mode, which is usually quarterly or annual. However, there is a lack of effective in-situ monitoring means during the online operation of the ICP-OES system. Argon leakage will cause instability of the plasma torch flame chamber pressure and introduce impurity gases such as oxygen and water vapor in the air. Oxygen has strong absorption characteristics in the deep ultraviolet region below 190 nm, and even a small amount of oxygen will cause the spectral signal intensity in this wavelength band to decay. At the same time, the introduction of impurity gases will change the impedance and stability of the plasma, causing the torch flame to drift, the signal-to-noise ratio to decrease, and the analysis results to be less reproducible. In order to temporarily suppress the effects of leakage, the current engineering solution is often forced to use a continuous high flow of argon for purging (e.g. increasing the purge flow from the conventional 1 L / min to 5 L / min). Although this method can dilute the leaked gas, it has significant drawbacks: first, the argon consumption is doubled, significantly increasing the operating cost; second, the thermal disturbance and turbulent noise introduced by the high flow of gas will exacerbate the baseline drift; third, the increased load on the vacuum exhaust system may frequently trigger safety interlocks, causing unplanned downtime, affecting equipment availability and analysis efficiency.

[0007] Therefore, in view of the interface air tightness monitoring problem in the integration of the new DMD-MCP ultraviolet imaging detector and the ICP-OES system, it is urgent to develop an in-situ detection method for the interface air tightness that can be monitored online in real time without disturbing the normal analysis, without the need for additional complex sensors, and can be quantitatively evaluated to ensure the stable performance of the instrument and reduce the operating and maintenance costs. SUMMARY

[0008] Therefore, in view of the interface air tightness monitoring problem in the integration of the new DMD-MCP ultraviolet imaging detector and the ICP-OES system, it is urgent to develop an in-situ detection method for the interface air tightness that can be monitored online in real time without disturbing the normal analysis, without the need for additional complex sensors, and can be quantitatively evaluated to ensure the stable performance of the instrument and reduce the operating and maintenance costs.

[0009] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0010] An in-situ method for airtightness testing of a detector interface in an ICP-OES system includes the following steps:

[0011] S1: During the carrier gas stabilization phase when the plasma torch is ignited in the ICP-OES system and no sample is introduced, control the DMD micromirror array to switch between fully open and fully closed states.

[0012] S2: Record the photon count N collected by the MCP single-photon counting detector when the DMD micromirror array is fully open. open And the dark count N acquired when the DMD micromirror array was in the fully off state. close Count the number of photons N open With dark count N close The photon number difference ΔN is used as the effective luminous flux reference.

[0013] S3: Periodically measure the photon number difference ΔN, and calculate the attenuation rate η based on the photon number difference ΔN. When the attenuation rate η exceeds a preset threshold, the interface airtightness of the DMD-MCP ultraviolet imaging detector is determined to be abnormal. The formula for calculating the attenuation rate η is η=(ΔN0-ΔN). t ) / ΔN0×100%, where ΔN0 represents the initial reference photon number difference, ΔN t This represents the difference in the number of photons obtained from the t-th monitoring.

[0014] Furthermore, the initial reference photon number difference ΔN0 is calculated as follows:

[0015] Based on multiple measurements, a photon number difference sequence {ΔN1, ΔN2, ..., ΔN} was obtained. t}, take the photon number difference sequence {ΔN1, ΔN2, ..., ΔN t The arithmetic mean of the values ​​is used as the initial reference photon number difference ΔN0.

[0016] Furthermore, before each measurement of the photon number difference ΔN, image data of the DMD micromirror array in a fully off state for a preset number of frames is acquired to obtain an image dataset, and the average dark count N of the image dataset is calculated. close_base This serves as the baseline for the current measurement cycle; when measuring the photon number difference ΔN, the collected dark count N will be used as the baseline. close With average dark count N close_base Subtract to obtain the dark count after deducting baseline drift, then add the collected photon count N. open Subtracting the dark count after deducting baseline drift yields the photon number difference ΔN.

[0017] Furthermore, following step S3, the following steps are also included:

[0018] S4: by standard argon concentration calibration experiment, pre-establishing the quantitative relationship between the decay rate η and the equivalent air leakage rate Q, Q=k·η, wherein k is the calibration coefficient;

[0019] S5: in the actual operation of the ICP-OES system, the real-time measured decay rate η is substituted into the quantitative relationship Q=k·η, the equivalent air leakage rate Q is calculated, and the alarm is graded according to the numerical range of the equivalent air leakage rate Q.

[0020] Further, the calculation method of the calibration coefficient k is:

[0021] Different known purity argon is used as carrier gas, and the corresponding decay rate η is measured under the standard working condition of the ICP-OES system.

[0022] According to the equivalent air leakage rate Q corresponding to each known purity argon and the measured decay rate η, the calibration coefficient k is determined by linear fitting.

[0023] Further, the graded alarm mechanism is as follows:

[0024] When Q

[0025] When a≤Q

[0026] When Q≥b, trigger high-level warning, stop the operation of the ICP-OES system.

[0027] Wherein, a, b are threshold values set according to the noise level and detection accuracy requirements of the ICP-OES system, and b>a.

[0028] Compared with the prior art, the present application can achieve the following beneficial effects:

[0029] 1, the present application does not need to stop, does not need to introduce external tracer gas, directly uses the light source and detector of ICP-OES system, and can complete the interface air tightness detection during the normal operation of ICP-OES system.

[0030] 2, the present application uses the photon counting difference ΔN generated by DMD modulation as the detection parameter, which is extremely sensitive to the concentration change of light-absorbing impurity gas (such as oxygen) in the optical path. Based on the Beer-Lambert law, the present application can detect the change of light-absorbing impurity gas concentration caused by small leakage, and its sensitivity is much higher than that of the traditional pressure decay method, especially suitable for the air tightness detection of DMD-MCP ultraviolet imaging detector interface, which provides a key technical support for the normal operation of ICP-OES system.

[0031] 3、The application quantitatively correlates the decay rate η obtained by monitoring with the equivalent air leakage rate Q through pre-calibration, which enables the ICP-OES system not only to alarm whether there is leakage, but also to accurately assess the degree of leakage and achieve graded early warning accordingly. This provides a scientific basis for predictive maintenance, and users can reasonably arrange maintenance time according to the quantitative results to avoid excessive maintenance or untimely maintenance, significantly improving the fine and intelligent level of equipment management.

[0032] 4、Through real-time interface airtightness monitoring, the application enables the ICP-OES system to no longer rely on continuous high-flow argon purge to cover up the leakage problem. Actual measurement and application show that a single set of ICP-OES system can reduce argon consumption by more than 60%, and annual operating cost can save 20-30 thousand yuan RMB. At the same time, it reduces the analysis interruption caused by blind maintenance and unscheduled downtime, improves the equipment availability, and reduces the wear of components such as vacuum pumps, with outstanding comprehensive economic benefits.

[0033] 5、The application does not need to add any additional gas sensor or detection hardware, completely reuses the existing DMD and MCP detectors of the ICP-OES system as sensing units, and only realizes new functions through software algorithm innovation. This scheme does not change the core optical machine structure, does not introduce new fault points, has low implementation cost, high stability, is very convenient for upgrading and modification on existing spectral instruments equipped with DMD-MCP detectors, has wide applicability and good popularization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the application, and their

[0035] Figure 1 The flowchart of the method for in-situ detection of the airtightness of the detector interface in the ICP-OES system according to the embodiments of the application is shown.

[0036] Figure 2 The curve diagram of ΔN changing with time in the case of argon leakage according to the embodiments of the application is shown.

[0037] Figure 3 The linear fitting diagram between the decay rate η and the equivalent air leakage rate Q according to the embodiments of the application is shown. DETAILED DESCRIPTION

[0038] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and do not constitute a limitation on the present application.

[0039] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified and limited, the terms "assemble", "connect", "connect" should be understood broadly, for example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0041] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "assemble", "connect", "connect" should be understood broadly, for example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0042] The present application will be described in detail below with reference to the drawings and embodiments.

[0043] The application provides a method for detecting the gas tightness of a detector interface in an ICP-OES system. The core principle of the method is that, in a pure carrier gas mode with the sample carrier gas turned off, the difference ΔN in the number of photons collected by a MCP single photon counting detector when the DMD micro-mirror array is in two extreme states of full opening and full closing is only related to the intrinsic emission intensity of argon plasma. According to the Beer-Lambert law, when the argon concentration in the optical path is constant and no absorbing impurity gas invades, ΔN should remain stable for a long time. When the argon leakage rate is constant, the oxygen concentration c(t) in the chamber increases linearly with time, and according to the Beer-Lambert law, the absorbance A = σ·L·c(t) also increases linearly with time, where σ represents the molar absorption coefficient and L represents the optical path length. Therefore, ΔN(t) = ΔN0·e^ (L is a constant), that is, ΔN decreases exponentially with time t, and the curve of the change of ΔN with time is as shown in Figure 1 .

[0044] Therefore, by periodically repeating the measurement of ΔN and calculating the moving average, an initial reference value ΔN0 is established, and if the deviation of the subsequent monitoring value ΔN t from ΔN0 (i.e., the decay rate η of ΔN t relative to the initial reference ΔN0) exceeds a preset threshold (such as 3%), it can be determined that the interface gas tightness of the DMD-MCP ultraviolet imaging detector (composed of a DMD micro-mirror array and a MCP single photon counting detector) is deteriorated and a warning is triggered, thereby realizing the in-situ detection of the gas tightness of the DMD-MCP ultraviolet imaging detector interface. In an embodiment, "ΔN decreases by 5% relative to the initial value" is taken as an example threshold for gas tightness warning. This value is derived from the theoretical estimation of the application example above and is only used to demonstrate the principle of the application; in actual application, the user should establish a threshold value specific to the instrument after installation, in the absence of a sample. In the above example, a change of 3% in the ΔN value corresponds to a change of 1.05×10 -2 in the absorbance A, which is about 9 times the equivalent noise absorbance (NEA = 1.5×10 -3 ) of the instrument, at which point the instrument will not be able to accurately detect.

[0045] The process of the method for detecting the gas tightness of a detector interface in an ICP-OES system will be described in detail below.

[0046] As shown in Figure 2 , the method for detecting the gas tightness of a detector interface in an ICP-OES system comprises the following steps:

[0047] S1: In the ICP-OES system, ignite the plasma torch flame and stabilize the carrier gas without sample introduction, and control the DMD micro-mirror array to switch between the fully open state and the fully closed state.

[0048] DMD (Digital Micromirror Device) as a programmable spatial light modulator, its micro-mirror array can flip at an extremely high speed between two main working attitudes. In the fully open state, all the effective micro-mirrors are in the direction of reflecting the incident light to the detection light path, so that the ultraviolet continuous spectrum light emitted by the plasma torch flame is projected as completely as possible to the MCP single photon counting detector; in the fully closed state, the micro-mirror array is flipped as a whole to the direction of guiding the incident light to the light trap, almost all the light flux is absorbed, and only a small amount of stray light may reach the MCP single photon counting detector.

[0049] In an embodiment, the switching period is set to 60-120 seconds for each full opening collection of the DMD micro-mirror array, and then immediately switched to the fully closed state and kept for the same length of time, forming a complete differential measurement period. The switching action itself takes very short time, usually in the order of 50 microseconds, which can be ignored in the collection integration time.

[0050] It should be noted that step S1 requires that the plasma torch flame has reached a thermodynamic steady state, i.e. the radio frequency power, the carrier gas flow rate, and the auxiliary gas flow rate are kept constant for at least 5 minutes or more, and no solid or liquid sample enters the plasma region through a peristaltic pump or an atomizer. At this time, the light emitted by the plasma torch flame is mainly the intrinsic continuous background radiation of the high-purity argon plasma and the characteristic spectrum lines of a very small amount of impurity elements.

[0051] S2: record the photon counts N open and the dark counts N close collected by the MCP single photon counting detector when the DMD micro-mirror array is in the fully open state and the fully closed state respectively. open close The difference ΔN = N open -N close between the photon counts N open and the dark counts N close is taken as the effective light flux reference.

[0052] The MCP single photon counting detector uses a combination of microchannel plate gain and position-sensitive anode readout, which can count each ultraviolet photon event that reaches its effective area and give spatial position information. In this invention, only the total count rate is usually used without considering the spatial distribution information, i.e. the photon events of all effective pixels in the entire effective detection area within the integration time period are accumulated to obtain the total count.

[0053] In one possible implementation, to improve the measurement accuracy, the DMD micromirror array has an acquisition time of no less than 60 seconds in each full-on or full-off state, preferably 90 to 120 seconds, to ensure that the number of photons accumulated in a single measurement period is sufficient, so that the statistical fluctuation relative error is controlled at a low level. For example, under the typical working condition of a plasma power of 1.2 kW and an argon total flow rate of 15 liters per minute, a single integration time of 100 seconds in the full-on state can accumulate about 1100 to 1200 counts, while in the full-off state, the main is the dark count of the detector background, usually only 2 to 5 counts, so the photon number difference ΔN has a high signal-to-noise ratio.

[0054] It can be understood that the photon number difference ΔN essentially represents the pure argon plasma radiation photon flux that can effectively pass through the optical system of the ICP-OES system and finally reach the MCP single-photon counting detector under the current optical path geometry configuration, plasma excitation condition and argon purity condition. This value is extremely sensitive to the concentration of absorbing gas in the optical path and is the core observation physical quantity for subsequent airtightness detection.

[0055] To reduce the interference of the dark count rate drift of the MCP single-photon counting detector with time on the ΔN measurement, the following operations are performed before each measurement of ΔN:

[0056] First, image data of the DMD micromirror array in the full-off state is collected for a preset number of frames to obtain an image data set, and the average dark count N close_base of the image data set is calculated as the baseline of the current measurement period.

[0057] For example, 5 frames of image data in the full-off state, each with an integration time of 10 seconds, the average dark count N close_base of the 5 frames of image data is calculated as the baseline of the dark count of the current measurement period.

[0058] Subsequently, when measuring ΔN, the collected dark count N close is subtracted from the average dark count N close_base to obtain the dark count after deducting the baseline drift, and the collected photon count N open is subtracted from the dark count after deducting the baseline drift to obtain a more accurate photon number difference ΔN0.

[0059] The application eliminates the influence of MCP single photon counting detector aging by dynamically updating the baseline of dark count. The updating frequency of the baseline can be adjusted according to the running time of the ICP-OES system and the service life of the MCP single photon counting detector. For example, at the beginning of the ICP-OES system operation, the performance of the MCP single photon counting detector is relatively stable, and the baseline can be updated once every 3 days; and after the ICP-OES system has been operated for more than 6 months, the aging effect of the MCP single photon counting detector gradually appears, and the baseline can be updated once a day to ensure the long-term stability of the ΔN measurement.

[0060] S3: periodically measure the photon number difference ΔN, and calculate the decay rate η according to the photon number difference ΔN, when the decay rate η exceeds the preset threshold, it is determined that the interface airtightness of the DMD-MCP ultraviolet imaging detector is abnormal.

[0061] A sequence of photon number differences {ΔN0, ΔN1, ΔN2,..., ΔN t} varying with time is established, and a sliding average algorithm is used to extract the trend item, when the photon number difference ΔN t t obtained by the tth monitoring exceeds the preset threshold (such as 5%) relative to the initial reference photon number difference ΔN0, it is determined that the interface airtightness of the DMD-MCP ultraviolet imaging detector is abnormal.

[0062] The calculation formula of the decay rate η is:

[0063] η=(ΔN0-ΔN t ) / ΔN0×100%.

[0064] The calculation method of the initial reference photon number difference ΔN0 is:

[0065] Based on the sequence of photon number differences {ΔN1, ΔN2,..., ΔN t} obtained by multiple measurements, the arithmetic mean of the sequence of photon number differences {ΔN1, ΔN2,..., ΔN t} is taken as the initial reference photon number difference ΔN0.

[0066] For example: after the installation and debugging of the ICP-OES system, perform 3 complete differential measurement cycles every day within the first 3 days at a fixed time (such as 10:00 am); each cycle includes three sub-stages of DMD micromirror array full-on 100s→ full-off 100s→ full-on 100s, and the corresponding photon counts and dark counts are received on the MCP single photon counting detector, the single ΔN is calculated, 3 ΔN single measurement values are obtained, and then the arithmetic mean of the 9 measurement results in the three days is taken as the initial reference photon number difference ΔN0 for long-term monitoring.

[0067] In the actual long-term operation of the ICP-OES system, a rapid diagnosis program is triggered automatically once a day, which is usually performed in the unattended period at night or before the daily routine maintenance, and the acquisition period can be appropriately shortened to 60 seconds of full opening of the DMD micro-mirror array + 60 seconds of full closing to reduce the occupation time of the normal analysis work. The current ΔN is calculated immediately after the end of each rapid diagnosis t , and the current decay rate η is further calculated t = (ΔN0- ΔN t ) / ΔN0×100%.

[0068] So far, the core processes of data acquisition, photon count difference calculation, and online monitoring in the in-situ detection method for the interface airtightness of the DMD-MCP ultraviolet imaging detector have been completed. Subsequent contents such as quantitative evaluation of the leakage degree, early warning classification, and establishment of the calibration relationship will be further elaborated.

[0069] After step S3, the following steps are further included:

[0070] S4: Through a standard argon concentration calibration experiment, a quantitative relationship Q=k·η between the decay rate η and the equivalent air leakage rate Q is established in advance, where k is a calibration coefficient.

[0071] The calculation method of the calibration coefficient k is:

[0072] Different known purities of argon are used as carrier gas, and the corresponding decay rates η are measured under the standard working conditions of the ICP-OES system.

[0073] According to the equivalent air leakage rates Q corresponding to each known purity of argon and the measured decay rates η, the calibration coefficient k is determined by linear fitting of the two.

[0074] The quantitative corresponding relationship between the decay rate η and the equivalent air leakage rate Q is established through the pre-calibration experiment, so as to calculate the leakage degree of argon according to the real-time measured decay rate η in the actual operation of the ICP-OES system.

[0075] The calibration experiment needs to be performed after the installation and debugging of the instrument are completed and before the formal analysis task is put into operation, the purpose is to determine the linear or approximately linear relationship between the decay rate η and the equivalent air leakage rate Q. During the experiment, a series of argon with known purity is used as carrier gas, and the proportion of air impurities is gradually changed to simulate different degrees of leakage. Each experiment is performed under standard conditions, that is, the inductively coupled plasma torch power is kept at 1.2 kW, the total argon flow is 15 liters per minute, the auxiliary gas flow is 0.5 liters per minute, and the torch flame stabilizing time is not less than 5 minutes.

[0076] In one embodiment, at least eight argon gas concentration points with different purities are selected, for example, purities of 100%, 99.8%, 99.5%, 99.2%, 99.0%, 98.5%, 98.0%, and 97.0%, corresponding to equivalent air leakage rates Q of 0%, 0.2%, 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, and 3.0%, respectively. The linear fitting results between the attenuation rate η and the equivalent air leakage rate Q are as follows: Figure 3 As shown. For each concentration point, three complete differential measurement cycles were performed, each cycle including 100 seconds of the DMD micromirror array being fully on and 100 seconds of being fully off. The ΔN value was calculated for each cycle and averaged to obtain the attenuation rate η corresponding to that concentration point. Finally, a calibration coefficient k between the attenuation rate η and the equivalent air leakage rate Q was determined using a linear fitting method, such that the two satisfy the approximate relationship Q = k·η.

[0077] For example, at the concentration points mentioned above, when the argon purity is 99.5%, the equivalent air leakage rate Q is 0.5%, and the measured attenuation rate η is approximately 0.577%. By fitting and analyzing the data from all concentration points, the specific value of the calibration coefficient k can be obtained. This coefficient is closely related to the inherent parameters of the instrument, such as the optical path length, detector sensitivity, and cavity volume, and usually varies slightly between different individual instruments.

[0078] It should be noted that calibration experiments should be conducted in a stable laboratory environment without sample injection to ensure that the measurement results are not affected by external factors. The purity of the argon gas used in the experiment must be verified by an independent gas analysis instrument to ensure the accuracy of the calibration data. In addition, calibration results should be reviewed periodically, especially after the instrument has undergone major maintenance or interface components have been replaced, in which case the calibration procedure must be repeated to update the calibration coefficients.

[0079] S5: In the actual operation of the ICP-OES system, the real-time measured attenuation rate η is substituted into the quantization relationship Q=k·η to calculate the equivalent air leakage rate Q, and alarms are classified according to the numerical range of the equivalent air leakage rate Q.

[0080] After each quick diagnostic procedure is completed, the system automatically calculates the current attenuation rate η. t And using the calibration coefficient k determined in step S4, the current attenuation rate η is calculated. t The corresponding equivalent air leakage rate Q t =k·η t Subsequently, according to Q t The specific numerical values ​​are used to classify the leakage level into different grades and trigger corresponding alarm mechanisms. The threshold settings for graded alarms are based on the noise level of the ICP-OES system's measurement accuracy and the data reliability requirements in practical applications.

[0081] The tiered alarm mechanism is as follows:

[0082] When Q t When a < Q

[0083] When a < Q t When a < Q

[0084] When Q t When Q

[0085] Wherein, a and b are threshold values set according to the noise level of ICP-OES system and the requirement of detection accuracy, and b > a.

[0086] For example, the threshold value a of low-level warning is set as 0.863%, and when Q t is less than 0.863%, the current attenuation rate η is about 1.0%, and the signal attenuation amplitude is about 3 times the instrument noise level, which is still within the measurement error range, allowing the ICP-OES system to continue to perform high-sensitivity analysis tasks.

[0087] The threshold value a of medium-level warning is set as 0.863% and b is set as 2.58%, and when Q t is between 0.863% and 2.58%, the current attenuation rate η is about 1.0% to 3.0%, and the signal attenuation amplitude reaches 3 to 9 times the instrument noise level, the measurement accuracy decreases, and the ICP-OES system will issue a warning to limit high-sensitivity analysis tasks, suggesting users to avoid trace element detection.

[0088] The threshold value b of high-level warning is set as 2.58%, and when Q t is greater than or equal to 2.58%, the current attenuation rate η exceeds 3.0%, and the signal attenuation amplitude has exceeded 9 times the instrument noise level, and the data reliability cannot be guaranteed, and the ICP-OES system will immediately trigger a stop and leak detection instruction, and lock the sample injection function to prevent further operation from causing equipment damage or data distortion.

[0089] Preferably, the alarm information will prompt the user through the instrument control panel with different colors and sounds, for example, low-level warning displays a yellow icon and is accompanied by a short prompt sound, medium-level warning displays an orange icon and is accompanied by intermittent prompt sound, and high-level warning displays a red icon and is accompanied by a continuous alarm sound. At the same time, the system will automatically record the occurrence time, attenuation rate value and equivalent leakage rate of each alarm, which is convenient for subsequent maintenance personnel to trace the root cause of the problem.

[0090] For different levels of leakage alarm, corresponding processing measures are taken to protect the instrument and restore the airtightness.

[0091] Specifically, when a low-level warning is triggered, the system allows continuous operation but suggests that the user check the interface sealing components, such as O-rings, gaskets, or the fastening state of connecting bolts, at the next routine maintenance, and records the current operating parameters for subsequent comparative analysis. When a medium-level warning is triggered, the system restricts high-sensitivity analysis tasks and only allows the execution of element detection within a conventional concentration range, while suggesting that the user arrange an interface airtightness special inspection as soon as possible, and temporarily increase the argon purge flow to 2 liters per minute if necessary, to slow down the impact of leaked gas on the signal.

[0092] When a high-level warning is triggered, the system immediately executes a protective shutdown procedure, first shutting down the sample injection pump and the atomizer, gradually reducing the radio frequency power to the standby state, then cutting off the torch ignition power to ensure that the plasma is extinguished before entering the safety mode. At the same time, the system locks all analysis functions until the maintenance personnel complete the leak detection and repair work and manually reset the alarm state. During shutdown, it is recommended that the maintenance personnel use a portable gas detection device to conduct preliminary investigation around the interface, focusing on checking the sealing condition of the connection between the digital micromirror device and the coupling optical system, and disassembling and replacing damaged sealing elements if necessary.

[0093] For example, in a certain actual operation, the system triggered a three-level emergency alarm on the 30th day of operation, with a decay rate η of 3.2%, corresponding to an equivalent leakage rate Q t of 2.77%. The maintenance personnel immediately executed the shutdown procedure, and found a small crack in the interface flange connection that caused the seal to fail. After replacing the new gasket and re-tightening the bolts, the system returned to normal operation, with the decay rate η reduced to below 0.5%, re-entering the safe operating range.

[0094] The present application changes the traditional standby continuous purge mode to a small flow purge, for example, the original standby purge flow is 2L / min, according to 300h of purge work per year, 36000L of argon is obtained, according to the unit price of 1.25 yuan / L, 45000 yuan needs to be spent, the present application can reduce the purge flow to 0.5L / min, more than 70% of argon can be reduced, the annual operating cost is greatly reduced.

[0095] In addition to realizing the interface airtightness monitoring, the present application can also use the differential measurement data to assist in diagnosing the operating state of other key components of the instrument. For example, by long-term monitoring of the change trend of the photon count N open under full opening state, the transmittance attenuation of the optical elements such as window lenses and mirrors in the deep ultraviolet light path can be reflected. When N open drops by more than 10% relative to the initial value, the system prompts the user to check whether there is contamination or aging phenomenon on the surface of the optical elements, and clean or replace them if necessary, to avoid systematic deviation in quantitative analysis results.

[0096] In one embodiment, the stability of the plasma torch flame can also be evaluated by analyzing the fluctuation amplitude of ΔN in a short time. For example, the standard deviation of ΔN in the last 10 fast diagnoses is calculated, and if the value significantly increases, for example, more than 5% of the initial baseline value, it can indicate that the torch flame has problems such as turbulence, poor impedance matching, or contamination of the inner wall of the quartz torch tube. At this time, the system will suggest that the user check the stability of the radio frequency power supply output, whether the carrier gas flow control valve is normal, or clean and maintain the torch tube.

[0097] For example, in one operation, the system detected that the standard deviation of ΔN increased from the initial 2.5 counts / s to 6.8 counts / s for 3 consecutive days, and combined with the analysis of other operating parameters, it was confirmed that the torch flame was unstable due to a slight blockage of the auxiliary gas flow control valve. The user then cleaned the valve and adjusted the flow to the standard value of 0.5 liters per minute, and the fluctuation amplitude of ΔN returned to the normal range, and the accuracy of the instrument analysis was maintained.

[0098] In another embodiment, it can also be extended to real-time monitoring of the purity of high-purity carrier gases such as argon, helium, and nitrogen. The gas pipeline is connected to a spectral pure reference sample (such as a mercury lamp), the intensity of the characteristic spectral line is measured, and the concentration of impurity gases (O2, H2O, CO2) in the carrier gas is detected using the same principle. It is suitable for instruments and systems that require ultra-high purity carrier gas, such as gas chromatography-mass spectrometry (GC-MS) and inductively coupled plasma mass spectrometry (ICP-MS).

[0099] It should be noted that the above-mentioned extended functions make full use of the multi-dimensional information contained in the differential measurement data, and are not limited to gas tightness judgment, but can also provide support for long-term monitoring of the overall performance of the instrument. By regularly recording and analyzing the trend data of N open , N close and ΔN, the user can discover potential problems in advance and take preventive maintenance measures, thereby prolonging the service life of the instrument and ensuring data quality.

[0100] It should be understood that the various forms of flow shown above can be reordered, added to, or steps deleted. For example, the steps described in the present disclosure can be executed in parallel, in sequence, or in a different order, as long as the desired results of the technical solutions of the present disclosure can be achieved, which is not limited herein.

[0101] The above detailed description does not constitute a limitation on the scope of protection of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for in-situ testing the airtightness of a detector interface in an ICP-OES system, characterized in that, It includes the following steps: S1: During the carrier gas stabilization stage when the plasma torch flame is ignited and no sample is injected in the ICP-OES system, control the DMD micro-mirror array to switch between the fully open state and the fully closed state; S2: Record the photon count N collected by the MCP single-photon counting detector when the DMD micromirror array is fully open. open And the dark count N acquired when the DMD micromirror array was in the fully off state. close Count the number of photons N open With dark count N close The photon number difference ΔN is used as the effective luminous flux reference. S3: Periodically measure the photon number difference ΔN, and calculate the attenuation rate η based on the photon number difference ΔN. When the attenuation rate η exceeds a preset threshold, the interface airtightness of the DMD-MCP ultraviolet imaging detector is determined to be abnormal. The formula for calculating the attenuation rate η is η=(ΔN0-ΔN). t ) / ΔN0×100%, where ΔN0 represents the initial reference photon number difference, ΔN t This represents the difference in the number of photons obtained from the t-th monitoring.

2. The in-situ airtightness detection method for the detector interface in the ICP-OES system according to claim 1, characterized in that, The calculation method of the initial reference photon number difference ΔN0 is as follows: Based on multiple measurements, a photon number difference sequence {ΔN1, ΔN2, ..., ΔN} was obtained. t }, take the photon number difference sequence {ΔN1, ΔN2, ..., ΔN t The arithmetic mean of the values ​​is used as the initial reference photon number difference ΔN0.

3. The in-situ airtightness detection method for the detector interface in the ICP-OES system according to claim 1, characterized in that, Before each measurement of the photon number difference ΔN, image data of the DMD micromirror array in a fully off state for a preset number of frames is acquired to obtain an image dataset. The average dark count N of the image dataset is then calculated. close_base This serves as the baseline for the current measurement cycle; when measuring the photon number difference ΔN, the collected dark count N will be used as the baseline. close With average dark count N close_base Subtract to obtain the dark count after deducting baseline drift, then add the collected photon count N. open Subtracting the dark count after deducting baseline drift yields the photon number difference ΔN.

4. The in-situ airtightness detection method for the detector interface in the ICP-OES system according to claim 3, characterized in that, After step S3, the following steps are further included: S4: Through a standard argon concentration calibration experiment, pre-establish the quantitative relationship Q = k·η between the attenuation rate η and the equivalent air leakage rate Q, where k is the calibration coefficient; S5: During the actual operation of the ICP-OES system, substitute the measured attenuation rate η into the quantitative relationship Q = k·η, calculate the equivalent air leakage rate Q, and classify and alarm according to the numerical range of the equivalent air leakage rate Q.

5. The in-situ airtightness detection method for the detector interface in the ICP-OES system according to claim 4, characterized in that, The calculation method of the calibration coefficient k is as follows: Use argon with different known purities as the carrier gas, and measure the corresponding attenuation rate η respectively under the standard working conditions of the ICP-OES system; According to the equivalent air leakage rate Q and the measured attenuation rate η corresponding to each argon with known purity, determine the calibration coefficient k by performing linear fitting on the two.

6. The in-situ airtightness detection method for the detector interface in the ICP-OES system according to claim 4, characterized in that, The classification and alarm mechanism is as follows: When Q < a, trigger a low-level warning, and allow the ICP-OES system to continue high-sensitivity analysis; When a ≤ Q < b, trigger a medium-level warning, and limit the ICP-OES system to perform high-sensitivity analysis; When Q ≥ b, trigger a high-level warning, and stop the operation of the ICP-OES system; where a and b are thresholds set according to the noise level and detection accuracy requirements of the ICP-OES system, and b > a.

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