Method and system for screening ions in a mass spectrometer, high voltage pulse circuit and selection circuit - Patent Application 20070122997

Abstract

The present invention discloses a method and system for screening ions in a mass spectrometer. A deflection conductor is disposed in the mass spectrometer. The screening method includes connecting a first voltage signal to the deflection conductor before a laser synchronization pulse signal is output to generate a deflection field for deflecting the flight direction of non-target ions, applying a second voltage signal to the deflection conductor to allow the target ions to reach an ion detector when the target ions fly out of the acceleration field, and connecting the first voltage signal to the deflection conductor when all the target ions have passed the deflection conductor. According to the present invention, the service life of the detector is extended and the interference of non-target ions is reduced. The high voltage pulse circuit and the ion selection circuit include a circuit consisting of a first voltage source, a second voltage source, a pulse circuit, and an RC series circuit, and the voltage difference between the voltage output from the first voltage source and the voltage output from the second voltage source is equal to or greater than a predetermined voltage, and the transistor switch can switch between on and off to realize switching between high and low levels. According to the present invention, the buffer time for switching between high and low levels in the high voltage pulse signal is shortened.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority based on a Chinese patent application filed with the China Patent Office on November 18, 2021, bearing application number 202111370623.4 and entitled "Method and system for screening ions in a mass spectrometer," and a Chinese patent application filed with the China Patent Office on November 18, 2021, bearing application number 202122831001.9 and entitled "High-voltage pulse circuit and ion selection circuit," the disclosures of which are incorporated herein in their entireties.

[0002] The present invention relates to the technical field of ion detection, and in particular to a method and system for screening ions in a mass spectrometer, a high voltage pulse circuit and an ion selection circuit. [Background technology]

[0003] Figure 1 shows a schematic diagram of a commonly used mass spectrometer. A laser pulse source irradiates a sample with an excitation laser, generating ions from the ion source sample. The ions are accelerated by an acceleration field, enter a field-free drift tube, and fly toward an ion detector at a constant speed. In reality, not all ions generated by excitation in the ion source sample are target ions that require detection. Only target ions with molecular weights within a specific range are targeted for detection and analysis. However, in current conventional mass spectrometers, all ions generated by excitation in the ion source sample fly toward the ion detector and are ultimately received by the ion detector. The ion detector can only receive and detect a limited number of ions, and after a certain period of use, it becomes unusable once the number of detected ions reaches a limit. Therefore, the ions received and detected by the ion detector contain a large number of useless non-target ions, which shortens the detector's lifespan to a certain extent. Therefore, if we can prevent non-target ions generated from the ion source sample from being received by the ion detector, the detector's lifespan can be significantly extended.

[0004] Pulse signals are commonly used in various electronic and electrical devices. For example, rectangular pulse signals can be used as control signals for relay switches. An ideal rectangular pulse signal would have no buffering delay when it falls from a high level to a low level or rises from a low level to a high level. However, in reality, it is impossible to achieve zero delay when it falls from a high level to a low level or rises from a low level to a high level. While low-voltage pulse signals currently have negligible delays when falling from a high level to a low level and rising from a low level to a high level, it is still difficult to reduce such buffering delays satisfactorily for high-voltage pulse signals. Therefore, when using high-voltage pulse signals for control, the achievable precision is limited, which limits the application of high-voltage pulse signals. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a method and system for screening ions in a mass spectrometer, thereby measurably reducing the number of non-target ions reaching a detector, thereby extending the life of the detector in the mass spectrometer. The present invention also provides a high-voltage pulse circuit and an ion selection circuit, measurably reducing the delay between the rising and falling edges of the high-voltage pulse signal, thereby improving the control accuracy of the high-voltage pulse signal. [Means for solving the problem]

[0006] In order to solve the above technical problems, the present invention provides a method for screening ions in a mass spectrometer. According to an embodiment of the present invention, a deflection conductor is arranged on the ion flight path side between an accelerating field and a detector in the mass spectrometer, and the screening method includes: applying a first voltage to a deflection conductor to generate a deflection electric field in the deflection conductor and to deflect the flight direction of the ions as they fly through the deflection electric field so that they do not reach the ion detector; In response to detecting that a pulse synchronized with the laser is output, among the ions ejected from the accelerating electric field, Non maintaining a first voltage applied to the deflection conductor to deflect target ions; applying a second voltage to the deflection conductor when the target ions are ejected from the accelerating field to prevent a deflection field from being generated that deflects the target ions, allowing the target ions to reach the ion detector; applying the first voltage to the deflection conductor when all of the target ions pass through the deflection conductor.

[0007] In one alternative embodiment of the present invention, the deflection conductor includes at least one pair of conductive plates arranged on both sides of the ion flight path, each of the at least one pair of deflection conductive plates includes a first conductive plate and a second conductive plate, and the first conductive plate is grounded; The step of applying a first voltage to the deflection conductor includes: applying a high voltage higher than a ground voltage to the second conductor plate; Alternatively, the method includes applying a negative high voltage lower than a ground voltage to the second conductor plate, The step of applying a second voltage to the deflection conductor includes: The method includes applying a voltage equal to the ground voltage to the second conductive plate.

[0008] In an alternative embodiment of the present invention, the deflection conductor is a focusing electrode disposed in the mass spectrometer or a metal tubular shell disposed in a field-free region of the mass spectrometer; The step of applying a first voltage to the deflection conductor includes: applying a high voltage of opposite polarity to the ions to the deflection conductor; The step of applying a second voltage to the deflection conductor includes: the deflection conductor to Applying a high voltage of the same polarity as the ions.

[0009] In an alternative embodiment of the present invention, the method further comprises the step of alternately applying the first voltage and the second voltage to the deflection conductor for a plurality of cycles; Here, in each of the multiple cycles, the duration for applying the first voltage and the duration for applying the second voltage are determined by the molecular weights of the non-target ions to be deflected and the target ions that are not deflected.

[0010] The system for screening ions in a mass spectrometer provided by the present invention comprises: a controller having an input terminal connected to a laser pulse source for outputting laser pulses; an ion selection circuit having an output terminal connected to a deflection conductor disposed in the mass spectrometer and an input terminal connected to the controller; To perform the steps of any of the above methods for screening ions in a mass spectrometer, the controller controls the ion selection circuit to output a voltage to the deflection conductor that switches between a first voltage and a second voltage.

[0011] In one alternative embodiment of the present invention, the deflection conductor includes at least one pair of conductive plates arranged on both sides of the ion flight path, each of the at least one pair of deflection conductive plates includes a first conductive plate and a second conductive plate, and the first conductive plate is grounded; the second conductor plate is connected to an output terminal of the ion selection circuit, the ion selection circuit including a high voltage power supply, a pulse circuit, and an RC series circuit; the pulse circuit includes a voltage divider and a transistor switch connected in series, one end of the pulse circuit is connected to the output terminal of the high voltage power supply and the other end of the pulse circuit is grounded, a node where the voltage divider and the transistor switch are connected functions as an output terminal of the ion selection circuit, a first terminal of the RC series circuit is connected to the output terminal of the ion selection circuit and a second terminal of the RC series circuit is grounded; The controller is connected to a control terminal of the transistor switch, the controller being configured to switch the transistor switch on and off.

[0012] In an alternative embodiment of the present invention, a first terminal of the voltage divider is connected to a high voltage power supply, a second terminal is connected to a first terminal of the transistor switch, and a second terminal of the transistor switch is grounded; in response to the controller outputting an electrical level, the first terminal and the second terminal of the transistor switch are electrically disconnected; In response to the controller outputting another electrical level higher than the electrical level, the first terminal and the second terminal of the transistor switch are electrically connected.

[0013] In an alternative embodiment of the present invention, a first terminal of the transistor switch is connected to a high voltage power supply, a second terminal of the transistor switch is connected to a first terminal of a voltage divider, and a second terminal of the voltage divider is connected to ground; In response to the controller outputting the electrical level, the first terminal and the second terminal of the transistor switch are electrically disconnected; In response to the controller outputting another electrical level higher than the electrical level, the first terminal and the second terminal of the transistor switch are electrically connected.

[0014] In one alternative embodiment of the present invention, the ion selection circuit further includes an RC parallel circuit, and a control terminal of the transistor switch is connected to the controller via the RC parallel circuit.

[0015] The present invention provides a method for screening ions in a mass spectrometer, wherein a deflection conductor is disposed on the ion flight path side between an acceleration field and a detector in the mass spectrometer, and the screening method includes the steps of applying a first voltage to the deflection conductor to generate a deflection field in the deflection conductor, thereby deflecting the flight direction of ions as they fly through the deflection field so as not to reach the ion detector, and maintaining the first voltage applied to the deflection conductor in response to detecting that a pulse synchronized with a laser has been output, in order to deflect target ions among ions ejected from the acceleration field. applying a second voltage to the deflection conductor when the target ions are ejected from the accelerating field to prevent a deflection field from being generated that deflects the target ions, allowing the target ions to reach the ion detector; applying the first voltage to the deflection conductor when all of the target ions pass through the deflection conductor.

[0016] The present invention employs the principle that ions with different molecular weights pass through the field-free region of a mass spectrometer at different times as they fly toward the detector. Before the laser pulse source is activated, a first voltage is applied to a deflection conductor in the mass spectrometer. When the laser pulse source is activated, the deflection field generated by the deflection conductor can deflect non-target ions. When target ions begin to fly, a second voltage signal is applied to the deflection conductor, causing the deflection conductor to no longer generate a deflecting field. After all target ions have passed through the field-free region, the first voltage is again applied to the deflection conductor. This ensures that the field generated by the deflection conductor can deflect both ions larger than and smaller than the target ion molecular weight to prevent them from reaching the detector. Furthermore, the ion detector presents results based on the detection of only target ions, thereby avoiding interference from non-target ions in the detection of target ions to some extent.

[0017] The present invention further provides a system for screening ions in a mass spectrometer, which also has the above beneficial effects.

[0018] The high-voltage pulse circuit provided by the present invention includes a first voltage source, a second voltage source, a pulse circuit, and an RC series circuit, and the voltage difference between the voltage output by the first voltage source and the voltage output by the second voltage source is equal to or greater than a predetermined voltage. wherein the pulse circuit includes a voltage divider and a transistor switch connected in series, one end of the pulse circuit is connected to the first voltage source, the other end of the pulse circuit is connected to the second voltage source, and a node where the voltage divider and the transistor switch are connected is an output terminal of the high-voltage pulse circuit; a first terminal of the RC series circuit is connected to an output terminal of the high voltage pulse circuit, and a second terminal of the RC series circuit is connected to the second voltage source; The transistor switch is configured to switch between on and off according to a switch control signal received by a control terminal of the transistor switch.

[0019] In an alternative embodiment of the present invention, a first terminal of the voltage divider is connected to a first voltage source, a second terminal of the voltage divider is connected to a first terminal of the transistor switch, and a second terminal of the transistor switch is connected to the second voltage source; in response to the switch control signal being a high level signal, the first terminal and the second terminal of the transistor switch are electrically connected; In response to the switch control signal being at another electrical level lower than the electrical level, the first terminal and the second terminal of the transistor switch are electrically disconnected.

[0020] In an alternative embodiment of the present invention, a first terminal of the transistor switch is connected to the first voltage source, a second terminal is connected to a first terminal of the voltage divider, and a second terminal of the voltage divider is connected to the second voltage source; in response to the switch control signal, the first terminal and the second terminal of the transistor switch are electrically connected; In response to the switch control signal being at another electrical level lower than the electrical level, the first terminal and the second terminal of the transistor switch are electrically disconnected.

[0021] In one alternative embodiment of the present invention, the first voltage source is a power supply that outputs a positive voltage, and the voltage output by the second voltage source is a ground voltage; Alternatively, the first voltage source is a power supply that outputs a positive voltage, and the second voltage source is a power supply that outputs a negative high voltage, Alternatively, the voltage output by the first voltage source is a ground voltage, and the second voltage source is a power supply that outputs a negative high voltage.

[0022] In one alternative embodiment of the present invention, the switch further includes an RC parallel circuit connected to a control terminal of the transistor switch, the control terminal of the transistor switch receiving the switch control signal via the RC parallel circuit.

[0023] The ion selection circuit is applied to a mass spectrometer, wherein the mass spectrometer includes a conductor for deflecting non-target ions; the ion selection circuit, the controller, and the high voltage pulse circuit; an output terminal of the high voltage pulse circuit connected to the conductor, and an output terminal of the controller connected to a control terminal of the transistor switch on the high voltage pulse circuit; Here, the controller outputs a switch control signal to the high-voltage pulse circuit to switch the high-voltage pulse signal output by the high-voltage pulse circuit between two different voltages, and switches the switch control signal between two different levels.

[0024] The present invention provides a high-voltage pulse circuit comprising a first voltage source, a second voltage source, a pulse circuit, and an RC series circuit, wherein a voltage difference between a voltage output by the first voltage source and a voltage output by the second voltage source is equal to or greater than a predetermined voltage, wherein the pulse circuit comprises a voltage divider and a transistor switch connected in series, wherein one end of the pulse circuit is connected to the first voltage source and the other end is connected to the second voltage source, a node where the voltage divider and the transistor switch are connected is an output terminal of the high-voltage pulse circuit, a first terminal of the RC series circuit is connected to the output terminal of the high-voltage pulse circuit, and a second terminal of the RC series circuit is connected to the second voltage source, and the transistor switch is configured to switch between on and off according to a switch control signal received by a control terminal of the transistor switch. [Effects of the Invention]

[0025] According to the present invention, a transistor switch and a voltage divider are connected in series and function as a pulse circuit between a first voltage source and a second voltage source. The transistor switch switches between on and off so that a high-voltage pulse circuit generates a high-voltage pulse at a node between the transistor and the voltage divider. The voltage output by the first voltage source becomes the high voltage of the high-voltage pulse signal, and the voltage output by the second voltage source becomes the low voltage of the high-voltage pulse signal. The transistor switch and the voltage divider form an equivalent RC circuit, which introduces a delay in switching between the high voltage and the low voltage. Here, the RC series circuit is further connected in parallel between the output terminal of the high-voltage pulse circuit and the second voltage source. The RC series circuit can charge and discharge the junction capacitor within the transistor switch, thereby shortening the time required to turn the transistor switch on and off based on the control signal and reducing the delay in switching between the high voltage and the low voltage in the high-voltage pulse signal. As a result, the output high-voltage pulse signal can switch between high and low voltages in a matter of nanoseconds, facilitating a wide range of applications for high-voltage pulse signals.

[0026] According to an embodiment of the invention, there is further provided an ion selection circuit, which also has the above beneficial effects.

[0027] In order to more clearly describe the embodiments of the present invention or the technical solutions of the prior art, the following briefly describes drawings applicable to the embodiments of the present invention or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on the provided drawings without creative efforts. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic structural diagram of a conventional mass spectrometer. [Figure 2] 1 is a flowchart of a method for screening ions in a mass spectrometer provided by an embodiment of the present invention. [Figure 3] 1 is a schematic structural diagram of a mass spectrometer provided by an embodiment of the present invention; [Figure 4] This is a mass spectrum obtained at the detector without screening for target and non-target ions. [Figure 5] A mass spectrum obtained by a detector by screening target ions with molecular weights within a range. [Figure 6] A mass spectrum obtained by a detector by screening target ions with molecular weights within multiple ranges. [Figure 7] FIG. 2 is a schematic structural diagram of an ion selection circuit provided by an embodiment of the present invention. [Figure 8] FIG. 10 is a schematic structural diagram of another ion selection circuit provided by an embodiment of the present invention. [Figure 9] 1 is a schematic structural diagram of a high-voltage pulse circuit provided by an embodiment of the present invention; [Figure 10] FIG. 10 is a schematic structural diagram of another high-voltage pulse circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] 1, in a mass spectrometer, ions of different molecular weights in an ion source sample 01 are excited by the laser output of a laser pulse source 2a and are accelerated to different velocities in an accelerating electric field U, with the acceleration velocity of the ion in the accelerating electric field U increasing as the molecular weight decreases, and decreasing as the molecular weight increases. Ions with smaller molecular weights emerge first from the accelerating electric field U, enter a field-free region, and fly toward the detector 1, while ions with larger molecular weights emerge later from the accelerating electric field U, pass through the field-free region, and fly toward the detector 1.

[0030] Generally, in actual ion detection, only target ions with molecular weights within a certain range are ions that need to be detected, and ions with molecular weights within other ranges are non-target ions. If the non-target ions reach and are detected by the ion detector 1, not only will the life of the ion detector 1 be shortened, but the detection results of the target ions will also be blurred.

[0031] To solve the above problems, the present invention utilizes the fact that the difference in mass between target ions and non-target ions leads to a difference in the time it takes for target ions and non-target ions to pass through the field-free region, to screen target ions and non-target ions, and when non-target ions pass through the field-free region, they are prevented from flying toward the ion detector 1. As a result, non-target ions cannot reach the ion detector 1, and only target ions ultimately reach and are detected by the ion detector 1, thereby extending the life of the ion detector and improving the clarity of the detection results.

[0032] In order to allow those skilled in the art to better understand the solution of the present invention, the present invention will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0033] As shown in FIGS. 2 and 3, FIG. 2 is a flowchart of a method for screening ions in a mass spectrometer provided by an embodiment of the present invention. FIG. 3 is a schematic structural diagram of a mass spectrometer provided by an embodiment of the present invention. In order to implement the method for screening ions in a mass spectrometer according to the present invention, a deflection conductor is arranged on the side of the ion flight path in a field-free region between the accelerating field and the detector in the mass spectrometer. Take the mass spectrometer shown in FIG. 3 as an example. The deflection conductor may be a flat conductor arranged in the field-free region. Based on this, the method for screening ions in a mass spectrometer according to the present invention includes the following steps S11 to S14.

[0034] S11: A first voltage is applied to the deflection conductor to generate a deflection electric field in the deflection conductor, and when ions fly through the deflection electric field, the flight direction of the ions is deflected so that they do not reach the ion detector.

[0035] The flight direction of ions flying through the field-free region is straight, i.e., the direction in which the exit of the accelerating field U faces the detector 1 in Figure 3. In the field-free region, there is no external force, so ions continue to fly at the same speed and direction. As soon as a first voltage is applied to the deflecting conductor, an electric field is generated around the deflecting conductor. As the ions pass through the spatial region occupied by the electric field, their flight direction is deflected under the electric field, and they are unable to reach the ion detector 1.

[0036] In S12, a laser synchronization pulse signal is detected, and after the laser synchronization pulse signal is output, the first voltage applied to the deflection conductor is maintained as it is, thereby deflecting the flight direction of non-target ions emerging from the accelerating electric field.

[0037] The laser synchronization pulse signal also signals the laser pulse source to initiate laser irradiation of the ion source sample 01. Generally, a first voltage is applied to the deflection conductor synchronously with the start of output of the laser synchronization pulse signal. However, in this embodiment, it is difficult to synchronize the deflection conductor so that the first voltage is applied immediately after detecting the output of the laser synchronization pulse signal. As a result, there is a delay between the start of the laser synchronization pulse output and the start of application of the first voltage to the deflection conductor. During this delay, some non-target ions may be generated from excitation and reach the detector. In consideration of the above problem, in this embodiment of the present invention, to improve the accuracy of screening for non-target ions, the first voltage is applied to the deflection conductor before the laser synchronization pulse activates the laser source 2. This allows the deflection conductor to deflect non-target ions as long as they are generated, preventing them from reaching the detector 1.

[0038] Furthermore, to ensure that the strength of the electric field generated by the deflection conductor can exert a sufficient deflection force on non-target ions, the amplitude of the first voltage should meet certain requirements. The first voltage is preferably a high voltage.

[0039] In S13, in response to the target ions being ejected from the accelerating field, a second voltage signal is applied to the deflection conductor to stop the generation of the deflection field and to allow the target ions among the ions to reach the detector.

[0040] The specific form of the second voltage depends strongly on the type of deflection conductor.

[0041] In an alternative embodiment of the present invention, the deflection conductor may be at least one pair of deflection conductor plates disposed on either side of the ion flight path, each pair of plates including a first conductor plate and a second conductor plate, the first conductor plate being grounded.

[0042] The step of applying a first voltage to the deflection conductor includes a step of applying a high voltage higher than the ground voltage to the second conductor plate, or a step of applying a negative high voltage lower than the ground voltage to the second conductor plate.

[0043] Applying a second voltage signal to the deflection conductor includes applying a voltage equal to ground to the second conductor plate.

[0044] 3, the deflection conductor is implemented as a pair of conductive plates. A first conductive plate 31 is grounded, and a high voltage is applied to a second conductive plate 32, thereby forming a deflection electric field between the first conductive plate 31 and the second conductive plate 32. As a result, charged non-target ions are deflected by the deflection electric field when flying between the first conductive plate 31 and the second conductive plate 32.

[0045] Based on this, it is clear that an electric field cannot be generated to deflect the target ions once they begin to enter the region between the first conductive plate 31 and the second conductive plate 32. In this case, a ground voltage may be applied to the second conductive plate 32 so that no electric field exists between the first conductive plate 31 and the second conductive plate 32. The target ions are not deflected as they fly through the region between the first conductive plate 31 and the second conductive plate 32, and can reach the ion detector 1.

[0046] However, in practical applications, the deflection conductors on both sides of the ion flight path do not necessarily need to be a pair of conductor plates. Even if there is only one conductor, non-target ions may be deflected when a high voltage is applied to the conductor component to form an electric field in the conductor component. When a target ion flies, the high voltage applied to the conductor component is switched to ground voltage, eliminating the electric field around the conductor component and allowing the target ion to reach the detector 1.

[0047] In another alternative embodiment of the present invention, the deflection conductor may be a focusing electrode 4 located in the mass spectrometer, or may be a metal tubular shell located in the field-free region of the mass spectrometer.

[0048] Applying a first voltage to the deflection conductor includes applying a high voltage to the deflection conductor, the high voltage having a polarity opposite to that of the ions.

[0049] Applying a second voltage signal to the deflection conductor includes applying a high voltage to the deflection conductor that has the same electrical polarity as the ions.

[0050] The focusing electrode 4 is an example of a deflection conductor. The focusing electrode 4 of a mass spectrometer is a metal tube located at the exit of the accelerating electric field U. In conventional mass spectrometers, it is not possible to guarantee that all ions generated by the excitation of the ion source sample 01 after acceleration by the accelerating electric field U will fly toward the ion detector 1; some ions may fly at a specific deflection angle. This is why the focusing electrode 4 is necessary within the mass spectrometer. If all ions generated by the laser exciting the ion source sample 01 are positive ions, a positive voltage is applied to the focusing electrode 4. This generates an electric field in the metal tube of the focusing electrode 4, with the electric field lines converging on the central axis of the metal tube. If ions fly in a direction away from the central axis of the focusing electrode 4, the flight trajectory of the ions driven by the electric field will be close to the central axis of the focusing electrode 4, and the final flight trajectory of the ions will approximately coincide with the line on which the central axis of the focusing electrode 4 is located. Similarly, if all ions generated by excitation are negative ions, a negative voltage is applied to the focusing electrode 4, and the direction of the electric field lines generated within the cylinder of the focusing electrode 4 is from the central axis of the focusing electrode 4 toward the inner wall of the focusing electrode 4.

[0051] It should be noted that target and non-target ions generated by laser excitation on the same sample and emerging from the accelerating field U have the same electrical polarity.

[0052] Therefore, the present invention applies different voltage signals to the focusing electrode 4 when the target ions and non-target ions pass through the focusing electrode 4, thereby screening the target ions and non-target ions.

[0053] For example, both the target ions and the non-target ions are positively charged ions. When the non-target ions pass through the focusing electrode 4, the first voltage signal applied to the focusing electrode 4 is a negative voltage less than 0 V, and the focusing electrode 4 attracts the ions. As a result, the flight trajectory of the non-target ions deviates from the central axis of the focusing electrode 4 and is deflected toward the side wall of the focusing electrode 4, preventing them from reaching the ion detector 1.

[0054] When the target ions pass through the cylindrical interior of the focusing electrode 4, the second voltage applied to the focusing electrode 4 can be regarded as a positive voltage greater than 0 V. At this time, the force exerted on the ions by the focusing electrode 4 becomes a repulsive force, and the flight trajectory of the target ions approaches the central axis of the focusing electrode 4, allowing them to reach the ion detector 1 more smoothly.

[0055] Similarly, if both the target ions and the non-target ions are negatively charged ions, the first voltage signal is a positive voltage greater than 0V, and the second voltage signal is a negative voltage less than 0V.

[0056] When the metal tubular shell 5 placed in the field-free region of the mass spectrometer is used as a deflection conductor, its operating method and principle are the same as those of the focusing electrode 4 as a deflection conductor, except that the first voltage is opposite to the electric polarity of the ions and the second voltage is the same as the electric polarity of the ions. Details will not be repeated here.

[0057] S14: When all the target ions have passed through the deflection conductor, a first voltage is applied to the deflection conductor.

[0058] Generally, among the ions generated by exciting the ion source sample 01, some non-target ions have larger molecular weights than the target ions, while others have smaller molecular weights. Naturally, non-target ions with larger molecular weights than the target ions travel slower than the target ions. Therefore, even after the target ions reach the ion detector 1, some non-target ions with larger molecular weights than the target ions may still be traveling toward the ion detector. To minimize the risk of non-target ions reaching the ion detector 1, a first voltage is applied to the deflection conductor after the target ions pass through the field-free region. Deflecting non-target ions with larger molecular weights than the target ions ensures that only the target ions ultimately reach the ion detector 1 smoothly.

[0059] Furthermore, target ions that need to be detected may be distributed in multiple discontinuous and disconnected molecular weight ion regions, for example, (0, a1], (a1, a2], (a2, a3], (a3, a4], (a4, a5]. Here, ions with molecular weights within two molecular weight ion regions (a1, a2] and (a3, a4]) are target ions. Ions with molecular weights within three molecular weight ion regions (0, a1], (a2, a3], (a4, a5]) are non-target ions. During ion screening, a first voltage and The second voltage can be applied repeatedly and alternately. The time for applying the first voltage and the time for applying the second voltage are determined depending on the molecular weight of the non-target ions to be deflected and the target ions not to be deflected. When non-target ions with molecular weights within the three molecular weight ion regions (0, a1), (a2, a3), and (a4, a5) pass through the field-free region, the first voltage is applied to the deflection conductor. For target ions with molecular weights within the two molecular weight ion regions (a1, a2) and (a3, a4), the second voltage is applied to the deflection conductor.

[0060] Referring to Figures 4 to 6, Figure 4 shows a mass spectrum obtained by a detector without screening target ions from non-target ions. Figure 5 shows a mass spectrum obtained by a detector by screening target ions with molecular weights within one range. Figure 6 shows a mass spectrum obtained by a detector by screening target ions with molecular weights within multiple ranges. Comparing Figures 4 and 5, the spectral peaks of low-molecular-weight matrix molecules in the mass spectrum in the figure contain many low-molecular-weight matrix peaks. This shortens the life of the ion detector. Furthermore, the spectral peaks of low-molecular-weight matrix molecule ions become noise peaks, reducing the signal-to-noise ratio of the mass spectrum and making the instrument calculations more complex. In Figure 5, target ions with molecular weights within one predetermined molecular weight range are selected to reach the detector, while non-target ions within the remaining ranges are deflected so that they cannot reach the detector. In Figure 6, target ions with molecular weights within two predetermined molecular weight ranges are selected to reach the detector, and an ion mass spectrum is obtained. Only target ions with molecular weights within the target molecular weight ranges are screened to reach the ion detector, and unwanted non-target ions are removed by screening. This significantly reduces losses in the ion detector, extending its useful life, and also reduces noise in the mass spectrum, significantly improving the signal-to-noise ratio. Therefore, by only analyzing and processing the mass spectra of ions with molecular weights within the target molecular weight range, subsequent instrument calculations are simplified and efficiency is improved.

[0061] In summary, in the present invention, a deflection conductor is placed in a field-free region in a mass spectrometer where ions fly around, and a voltage is applied to the deflection conductor to generate a deflection field before the laser pulse source is activated. All non-target ions that initially enter the field-free region are deflected and prevented from reaching the ion detector. When target ions enter the field-free region, the voltage applied to the deflection conductor is switched so that the target ions are not deflected by the deflection conductor. Furthermore, the deflection conductor deflects non-target ions with larger molecular weights than the target ions. This maximizes deflection of non-target ions, minimizing the number of non-target ions that reach the ion detector, slowing wear on the ion detector, and extending its useful life.

[0062] The present invention further provides an embodiment of a system for screening ions in a mass spectrometer, the system for screening ions comprising: a controller having an input terminal connected to a laser pulse source for outputting laser pulses; an ion selection circuit having an output terminal connected to a deflection conductor disposed within the mass spectrometer and an input terminal connected to the controller;

[0063] The controller is used to control the ion selection circuit to output the first voltage and the second voltage to the deflection conductors to carry out the steps of the method for screening ions in a mass spectrometer according to any one of the above.

[0064] Based on the above-described method for screening ions in a mass spectrometer, the voltage applied to the deflection conductor is switched between two different constant voltages so that the deflection conductor can screen for target ions and non-target ions. Therefore, the voltage applied to the deflection conductor can be regarded as a square-wave pulse, and the ion selection circuit can actually adopt a structure that outputs a square-wave pulse. To meet the requirements for the electric field generated by the deflection conductor to deflect non-target ions, the voltage difference between the high and low voltages in the square-wave pulse must be equal to or greater than a certain value. That is, the pulse voltage signal output from the ion selection circuit must be a high-voltage pulse.

[0065] Theoretically, a square-wave pulse signal switches instantly between high and low voltages at its rising and falling edges. In reality, however, there is a delay from both the rising and falling edges. Especially for high-voltage pulses with a large voltage difference between the high and low voltages, it is difficult to achieve a rapid rise and fall in voltage when switching between the high and low voltages. The time difference between when target ions pass through the mass spectrometer and when non-target ions pass through the mass spectrometer is short, on the order of a few nanoseconds. Therefore, when the ion-selection circuit switches between one voltage output and another, a fast rise and fall between the high and low voltages is required to ensure accurate screening of non-target and target ions.

[0066] For example, there may be at least one pair of deflection conductor plates, with the deflection conductors arranged on both sides of the ion flight path. Each pair of conductor plates is composed of a first conductor plate and a second conductor plate, where the first conductor plate is grounded and the second conductor plate is connected to an ion selection circuit. Referring to Figures 7 and 8, Figure 7 is a schematic structural diagram of an ion selection circuit provided by an embodiment of the present invention. Figure 8 is a schematic structural diagram of another ion selection circuit provided by an embodiment of the present invention.

[0067] In an alternative embodiment of the present invention, the ion selection circuit includes a high-voltage power supply HV, a pulse circuit, and an RC series circuit. As shown in Figures 7 and 8, the RC series circuit is composed of a high-voltage capacitor C2 and a high-voltage resistor R3 connected in series. Since a large amount of power is supplied to the high-voltage resistor R3, its resistance is smaller than the resistance of the voltage divider R2.

[0068] The pulse circuit includes a voltage divider R2 and a transistor switch Q connected in series.

[0069] One end of the pulse circuit is connected to the output terminal of the high voltage power supply HV, and the other end of the pulse circuit is grounded.

[0070] The node where the voltage divider R2 and the transistor switch Q are connected functions as the output terminal OUT of the ion selection circuit.

[0071] One end of the RC series circuit is connected to the output terminal OUT of the ion selection circuit, and the other end of the RC series circuit is grounded.

[0072] The controller is connected to the control terminal of the transistor switch Q, the controller being configured to switch the transistor switch on and off.

[0073] Optionally, an RC parallel circuit is further disposed between the controller and the control terminal of the transistor switch Q. In the RC parallel circuit, a resistor R1 and a capacitor C1 are connected in parallel.

[0074] According to this embodiment, the output of a high-voltage pulse is realized by a pulse circuit mainly composed of a voltage divider R2 and a transistor switch Q. One end of the pulse circuit is connected to the output terminal of the high-voltage power supply HV, and the other end of the pulse circuit is grounded. Furthermore, the control terminal of the transistor switch Q is connected to the output terminal of the controller via an RC parallel circuit, and the controller outputs a control signal to switch the transistor switch Q on and off. The on / off state of the transistor switch Q determines whether the voltage at the node between the transistor switch Q and the voltage divider R2 is ground or the output voltage of the high-voltage power supply HV. As a result, the voltage output by the pulse circuit switches between high voltage and ground.

[0075] In the pulse circuit composed of the voltage divider R2 and the transistor switch Q, the voltage divider R2 may be a voltage dividing resistor or other voltage divider with a certain resistance, and the transistor switch Q may be a semiconductor switch such as a triode or a MOS transistor, but is not limited to these in the present invention.

[0076] As mentioned above, the controller can control the on and off of the transistor switch Q. Based on the basic operating characteristics of the transistor switch Q, the control signal used by the controller to control the transistor switch Q can be a pulse signal that switches between high and low levels. Unlike the high-voltage pulse signal applied to the deflection conductor, the controller only needs to output a low-voltage pulse signal to the control terminal of the transistor switch Q.

[0077] Furthermore, the pulse circuit consisting of voltage divider R2 and transistor switch Q can be regarded as another RC series circuit. The transistor switch Q resembles a capacitor in the process of charging and discharging, and the junction capacitor of transistor switch Q and voltage divider R2 form an equivalent RC series circuit. The junction capacitor of transistor switch Q introduces a delay when switching transistor switch Q on and off, which results in longer rising and falling edges of the final output pulse signal.

[0078] In order to reduce the delay at the rising and falling edges when the output of the ion selection circuit switches between high and low voltages, the ion selection circuit of this embodiment further includes an RC series circuit connected in parallel between the signal output terminal OUT and the ground terminal.

[0079] During the transition of the high-voltage pulse signal, the RC series circuit consisting of high-voltage capacitor C2 and high-voltage resistor R3 forms a charging / discharging circuit for filtering. The high-voltage capacitor C2 in the RC series circuit charges transistor switch Q when it is on and discharges it when it is off. This shortens the buffering delay of the rising and falling edges of the output high-voltage pulse, enabling fast switching between high and low voltages. The rapid rise and fall of the high-voltage pulse signal is extremely short, on the order of a few nanoseconds, ensuring accurate switching between high and low voltages. Furthermore, the new RC circuit forms a filter that can remove high-order harmonics, resulting in a uniform waveform for the high-voltage pulse.

[0080] Furthermore, the controller is connected via an RC parallel circuit to the control terminal of the transistor switch Q. The capacitor C1 in the RC parallel circuit can be charged and discharged, allowing the transistor switch Q to be switched on and off more quickly under the control of the switch control signal.

[0081] In the high-voltage pulse signal output from the ion selection circuit, when switching between high and low voltages, the delay between the rising edge and the falling edge can be reduced to a few nanometers, that is, the delay between the rising edge and the falling edge can be significantly reduced. When the ion selection circuit is applied to various control systems, the control precision of the system can be improved.

[0082] The elements in the pulse circuit can be connected in a variety of configurations.

[0083] As shown in FIG. 7, in one alternative embodiment of the present invention, the pulse circuitry can be configured as follows.

[0084] The first terminal of the voltage divider R2 is connected to the high voltage power supply HV, and the second terminal is connected to the first terminal of the transistor switch Q. The second terminal of the transistor switch Q is grounded, and the control terminal of the transistor switch Q is connected to the controller via an RC parallel circuit.

[0085] In response to the output of the controller, when at a high level, the first and second terminal conductors of the transistor switch Q are electrically connected.

[0086] In response to the output of the controller, when at a low level, the first and second terminals of the transistor switch Q are electrically disconnected.

[0087] As shown in Figure 7, the first terminal of transistor switch Q is connected to the output terminal of the high-voltage power supply HV via voltage divider R2. The second terminal of transistor switch Q is grounded and connected in parallel to transistor switch Q in an RC series circuit. Taking transistor switch Q in Figure 7 as an NPN transistor, the controller outputs a low level to the base of transistor switch Q via an RC parallel circuit, electrically disconnecting the collector and emitter of transistor switch Q. The collector of transistor switch Q is connected to voltage divider R2 and functions as the output terminal of the pulse circuit. The output terminal of the pulse circuit outputs a high voltage. When the controller outputs a high level to the base of transistor switch Q, the collector and emitter of transistor switch Q are electrically connected. The collector of transistor switch Q is connected to the high-voltage power supply HV via voltage divider R2, and the collector of transistor switch Q functions as the output terminal of the pulse circuit and outputs ground, or 0V. This allows the voltage output from the ion selection circuit to be switched between high voltage and ground.

[0088] As shown in FIG. 8, in another alternative embodiment of the present invention, the pulse circuit may be configured as follows.

[0089] The first terminal of transistor switch Q is connected to the high-voltage power supply HV, the second terminal is connected to the first terminal of voltage divider R2, and the control terminal of transistor switch Q is connected to the second terminal of the RC parallel circuit, the second terminal of which is grounded.

[0090] In response to the controller output, when it is at a low level, the first and second terminals of the transistor switch Q are electrically connected, and when it is at a high level, the first and second terminals of the transistor switch Q are electrically disconnected.

[0091] Consider an example where the transistor switch Q is a PNP transistor, as shown in Figure 8. The terminal of the transistor switch Q is connected to the voltage divider R2 and functions as the emitter of the transistor switch Q. That is, the emitter voltage of the transistor switch Q is the output voltage of the pulse circuit. The RC series circuit is connected in parallel with the voltage divider R2. Similar to the principle of Figure 7, when the controller outputs a high level to the base of the transistor switch Q through the RC parallel circuit, the collector and emitter of the transistor switch Q are electrically disconnected. At this time, the emitter of the transistor switch Q is connected to the ground terminal through the voltage divider R2, and the voltage output from the pulse circuit is the voltage of the ground terminal.

[0092] On the other hand, when the controller outputs a low-level signal to the base of transistor switch Q, the collector and emitter of the transistor are electrically connected. The emitter of transistor switch Q can be considered to be directly connected to the high-voltage power supply HV. Naturally, at this time, the voltage at the emitter of transistor switch Q is equal to the high voltage. As a result, the voltage output from the pulse circuit switches between the high voltage and ground (0V), generating a high-voltage pulse.

[0093] The embodiments of Figures 7 and 8 illustrate an example in which the high voltage is higher than the ground voltage at an electrical level. In practice, the high voltage pulse output from the ion selection circuit may be generated from a ground voltage having a higher level and a negative high voltage having a lower level (i.e., lower or greater than the ground voltage). In such a case, the power supply HV in Figures 7 and 8 can be replaced with a ground voltage, and the ground terminal in Figures 7 and 8 can be replaced with a voltage source that outputs a negative high voltage.

[0094] Furthermore, the high voltage pulse output by the ion selection circuit may be generated from a high voltage having a higher level and a negative high voltage having a lower level. In this case, the ground terminal in Figures 7 and 8 can be replaced with a voltage source outputting a negative high voltage. Naturally, the ion selection circuit corresponding to this embodiment is also applicable to an embodiment in which the deflection conductor is the focusing electrode 4 or the metal tubular shell 5.

[0095] Take Figure 8 as an example. When the controller outputs a high level to the control terminal of transistor switch Q, transistor switch Q turns on. When the controller outputs a low level to the control terminal of transistor switch Q, transistor switch Q turns off. A high-voltage power supply HV supplies a voltage ranging from several tens of volts to 1,000 volts, which is applied to the first terminal of voltage divider R2 via transistor switch Q. The node connecting voltage divider R2 and transistor switch Q is connected to the first terminal of high-voltage capacitor C2. The second terminal of high-voltage capacitor C2 is connected to the first terminal of high-voltage resistor R3. This high-voltage resistor R3 may be equivalent to a filter and may also have high power durability. The resistance of high-voltage resistor R3 is much smaller than the resistance of voltage divider R2. The second terminal of high-voltage resistor R3 is grounded. The second terminal of voltage divider R2 is also grounded. The common terminal connecting voltage divider R2, transistor switch Q, and high-voltage capacitor C2 serves as the output terminal of the ion selection circuit.

[0096] When the controller outputs a high-level signal to the control terminal of transistor switch Q, transistor switch Q turns on, forming an electrical path. The high-voltage power supply HV is directly grounded via transistor switch Q and voltage divider R2. The terminal of transistor switch Q connected to voltage divider R2 and high-voltage capacitor C2 becomes the output terminal OUT of the ion selection circuit, and outputs a high voltage.

[0097] When the controller outputs a low-level signal to the control terminal of transistor switch Q, transistor switch Q turns off, cutting the electrical path. The output terminal of the ion selection circuit is grounded via voltage divider R2 and outputs a low voltage. The RC series circuit consisting of high-voltage capacitor C1 and high-voltage resistor R3 can charge, discharge, and filter when the voltage of the high-voltage pulse signal changes, so the output high-voltage pulse signal rises and falls sharply on the scale of a few nanoseconds, ensuring the accuracy of switching between high and low voltage in the high-voltage pulse signal.

[0098] As described above, the controller outputs a low-voltage pulse signal to switch the transistor on and off, thereby controlling the high-voltage pulse signal output by the ion selection circuit. That is, in the present invention, the low-voltage pulse signal output by the controller controls the high-voltage pulse signal output. To ensure the safety of the circuit, an isolation circuit is further provided between the controller and the control terminal of the transistor. In a specific embodiment, an isolation chip can be connected between the controller and the RC parallel circuit to prevent interference with the controller caused by the high-voltage pulse.

[0099] The high-voltage pulse circuit of the present invention refers to a circuit configured to output a square-wave pulse signal that switches between a high voltage and a low voltage, where there is a large voltage difference between the high voltage and the low voltage. In theory, the switching between the high voltage and the low voltage is performed instantaneously at the rising edge and the falling edge. In practice, such instantaneous switching between the rising edge and the falling edge is difficult, and a certain delay occurs between the rising edge and the falling edge. The larger the voltage difference between the high voltage and the low voltage, the longer the delay.

[0100] Therefore, according to one embodiment of the present invention, a high-voltage pulse circuit is provided, in which a high-voltage pulse having a large voltage difference between the output high voltage and the output low voltage has a short delay between the rising edge and the falling edge.

[0101] In order to facilitate the understanding of those skilled in the art, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the examples of the present invention. It is clear that the described examples are only a part of the embodiments of the present invention, and are not all of the embodiments. Other examples obtained by those skilled in the art based on the examples of the present invention without any creative efforts are included in the protection scope of the present invention.

[0102] 9 and 10, Fig. 9 is a schematic structural diagram of a high-voltage pulse circuit provided by an embodiment of the present invention, and Fig. 10 is a schematic structural diagram of another high-voltage pulse circuit provided by an embodiment of the present invention, which includes a first voltage source HV+ and a second voltage source HV-.

[0103] Because there is a large voltage difference between the high voltage and the low voltage output from the high-voltage pulse circuit, the voltage difference between the voltage output from the first voltage source HV+ and the voltage output from the second voltage source HV- in this embodiment is equal to or greater than a predetermined voltage difference. In other words, there is also a large voltage difference between the voltage output from the first voltage source HV+ and the voltage output from the second voltage source HV-. The specific amplitude of this voltage difference is proportional to the required voltage difference between the high voltage and the low voltage in the high-voltage pulse signal output from the high-voltage pulse circuit.

[0104] Optionally, the first voltage source HV+ is a high voltage power supply, and the voltage output from the second voltage source HV- is a ground voltage.

[0105] Alternatively, the first voltage source HV+ is a high voltage power supply and the second voltage source HV- is a negative high voltage power supply.

[0106] Alternatively, the voltage output from the first voltage source HV+ is a ground voltage, and the second voltage source HV- is a negative high voltage power supply.

[0107] The high voltage power supply in this embodiment refers to a voltage ranging from several tens of volts to several thousand volts. Similarly, the negative high voltage power supply refers to a negative voltage having an amplitude ranging from several tens of volts to several thousand volts.

[0108] The high voltage pulse circuit further includes a pulse circuit and an RC series circuit.

[0109] Here, the pulse circuit includes a voltage divider R2 and a transistor switch Q connected in series.

[0110] One end of the pulse circuit is connected to a first voltage source HV+, and the other end of the pulse circuit is connected to a second voltage source HV-. The node connecting the voltage divider R2 and the transistor switch Q is the output terminal OUT of the high-voltage pulse circuit. The control terminal of the transistor switch Q is configured to receive a switch control signal and controls the on and off of the transistor switch Q in response to the switch control signal.

[0111] A first terminal of the RC series circuit is connected to the output terminal OUT of the high voltage pulse circuit, and a second terminal of the RC series circuit is connected to a second voltage source HV-.

[0112] Optionally, the control terminal of the transistor switch Q may be connected in series with an RC parallel circuit, a first terminal of which is configured to receive a switch control signal and a second terminal of which is connected to the control terminal of the transistor switch Q. The switch control signal is used to switch the transistor switch Q on and off.

[0113] As shown in FIGS. 9 and 10, the RC parallel circuit may include a resistor R1 and a capacitor C1 connected in parallel.

[0114] The voltage divider R2 in the pulse circuit can be a voltage dividing resistor or other circuit component with a fixed resistance. The transistor switch Q can be a semiconductor switching element such as a triode or MOS transistor.

[0115] The pulse circuit is a series branch circuit connected between the first voltage source HV+ and the second voltage source HV-, and functions as the main circuit that outputs the high-voltage pulse. Furthermore, the voltage divider R2 and the transistor switch Q in the pulse circuit can be connected in series between the first voltage source HV+ and the second voltage source HV- in two different configurations.

[0116] 9, in one alternative embodiment, a first terminal of voltage divider R2 is connected to a first voltage source, and a second terminal is connected to a first terminal of transistor switch Q. A second terminal of transistor switch Q is connected to a second voltage source. A control terminal of transistor switch Q is connected to the second terminal of the RC parallel circuit.

[0117] The control terminal of the transistor switch Q in the pulse circuit receives a switch control signal via an RC parallel circuit. The switch control signal may be a low-voltage pulse signal generated by a controller or other pulse source. As shown in Figure 9, the first voltage source HV+ is a high-voltage power supply, the second voltage source HV- is a ground voltage supply, and the transistor switch QQ is an NPN transistor. The control terminal of the transistor switch Q is the base of the NPN transistor, the first terminal is the collector of the NPN transistor, and the second terminal is the emitter of the NPN transistor.

[0118] When a low-level voltage is applied to the control terminal of transistor switch Q, the first and second terminals of transistor switch Q are electrically disconnected from each other. The voltage divider R2, connected to the first terminal of transistor switch Q, is electrically disconnected from the second voltage source HV-, connected to the second terminal of transistor switch Q. In this case, the first terminal of voltage divider R2 can be considered to be connected to a high-voltage power supply, and the second terminal functions as the output terminal of the high-voltage pulse circuit. In this case, the voltage at the second terminal of voltage divider R2 is the voltage signal output by the high-voltage power supply, and a high voltage is output.

[0119] When a high voltage is applied to the control terminal of transistor switch Q, the first and second terminals of transistor switch Q are electrically connected to each other. The voltage divider R2, connected to the first terminal of transistor switch Q, is connected to a second voltage source, connected to the second terminal of transistor switch Q. Naturally, the first terminal of voltage divider R2 is connected to the first voltage source HV+, and the second terminal is connected to the second voltage source HV-. The second terminal of voltage divider R2 functions as the output terminal of the high-voltage pulse circuit. The voltage at the second terminal of voltage divider R2 is equal to or greater than the voltage output from the second voltage source HV-. The second voltage source HV- is a ground voltage source. The voltage signal output from the output terminal of the high-voltage pulse circuit is ground, i.e., 0V.

[0120] As a result, when the control signal switches between a high level and a low level, the voltage output by the high voltage pulse circuit switches between the first voltage output by the first voltage source and the second voltage output by the second voltage source, generating a high voltage pulse.

[0121] 10, in another alternative embodiment of the present invention, the first terminal of the transistor switch Q is connected to the first voltage source HV+, the second terminal is connected to the first terminal of the voltage divider R2, and the control terminal of the transistor switch Q is connected to the second terminal of the RC parallel circuit. The second terminal of the voltage divider R2 is connected to the second voltage source HV−.

[0122] As shown in Figure 10, the first voltage source HV+ is a high-voltage power supply, the second voltage source HV- is a ground voltage source, and the transistor switch Q is a PNP transistor. Similarly, the control terminal of the transistor switch Q is the base of the PNP transistor, the first terminal of the transistor switch Q is the collector of the PNP transistor, and the second terminal is the emitter of the PNP transistor. Similar to the operating principle of the circuit configuration shown in Figure 9, when the switch control signal is at a high level, the first and second terminals of the transistor Q are electrically isolated, and when the switch control signal is at a low level, the first and second terminals of the transistor Q are electrically connected.

[0123] In both the embodiments shown in Figures 9 and 10, the pulse circuit of the present invention is a series branch connected between a first voltage source HV+ and a second voltage source HV-, and is the main part of the high-voltage pulse circuit for outputting a high-voltage pulse. The voltage output from the output terminal OUT of the high-voltage pulse circuit is the voltage at the node where the transistor switch Q and the voltage divider R2 in the pulse circuit are connected.

[0124] Regardless of the order of the voltage divider R2 and transistor switch Q in the series branch, the pulse circuit connected in series between the first voltage source HV+ and the second voltage source HV- can be viewed as an RC series circuit formed by the junction capacitor of transistor switch Q and voltage divider R2. The junction capacitor of transistor switch Q introduces a delay when transistor switch Q switches on and off, and therefore a delay in the rising and falling edges of the final output high-voltage pulse.

[0125] To reduce the delay in rising and falling edges when the ion selection circuit switches between high and low voltages, the RC series circuit of this embodiment may be provided as a parallel branch in the ion selection circuit connected between the output terminal OUT and the second power supply HV−.

[0126] The RC series circuit includes a high-voltage capacitor C2 and a high-voltage resistor R3 connected in series. Because high power is applied to the high-voltage resistor R3, its resistance must be smaller than that of the voltage divider. The RC series circuit consisting of the high-voltage capacitor C2 and the high-voltage resistor R3 forms a charging / discharging path and performs filtering when the voltage of the high-voltage pulse signal changes. The high-voltage capacitor C2 in the RC series circuit charges the transistor switch Q when it is on and discharges it when it is off. This reduces the delay in the rising and falling edges of the output high-voltage pulse signal, enabling fast switching between high and low voltages. The rising and falling times of the output high-voltage pulse signal can be achieved in extremely short times, on the order of a few nanoseconds. This allows for more accurate switching between high and low voltages in the high-voltage pulse signal. Furthermore, the RC circuit provides filtering, eliminating high-order harmonics and regularizing the waveform of the high-voltage pulse signal.

[0127] In addition, the switch control signal is further input to the control terminal of the transistor switch Q via the RC parallel circuit, and the charging and discharging function of the capacitor C1 in the RC parallel circuit reduces the time it takes for the transistor Q to turn on and off in response to the switch control signal.

[0128] The high-voltage pulse signal output from the high-voltage pulse circuit can reduce the delay between the rising and falling edges to a few nanometers when switching between high and low voltages. This significantly reduces the delay between the rising and falling edges. Applying this high-voltage pulse circuit to various control systems can improve the control precision of the system.

[0129] In summary, the high-voltage pulse circuit provided by this invention utilizes a voltage divider and a transistor connected in series between two voltage sources, where a large difference exists between the voltages supplied by the two voltage sources. A switch control signal input to the control terminal of the receiving transistor controls the transistor's on / off state. The output high-voltage pulse signal switches between a high voltage and a low voltage in response to the level-switching switch control signal. An RC parallel circuit is further connected to the control terminal of the transistor switch, significantly reducing the delay in the rising and falling edges when switching between high and low voltages. This facilitates the wide application of high-voltage pulse signals and improves the control precision of high-voltage pulse circuits used in various devices.

[0130] Based on the above embodiment, the aforementioned high-voltage pulse circuit is applied to a mass spectrometer to screen target ions and non-target ions as follows: According to a specific embodiment of the present invention, the present invention further provides an ion selection circuit applied to a mass spectrometer, in which a conductor for deflecting non-target ions is arranged, the ion selection circuit including a controller and the aforementioned high-voltage pulse circuit, an output terminal of the high-voltage pulse circuit connected to the conductor, and an output terminal of the controller connected to a control terminal of a transistor switch of the high-voltage pulse circuit.

[0131] Here, the controller is configured to output a switch control signal and switch the switch control signal between two different levels so that the high-voltage pulse signal output by the high-voltage pulse circuit switches between two different voltages.

[0132] Referring to the above-described embodiment of the high-voltage pulse circuit, the switch control signal output from the controller according to this embodiment, which can be switched between two different levels, is a switch control signal having two different states and input to the control terminal of the transistor switch in the high-voltage pulse circuit. Take the case where the switch control signal output from the controller is a low-voltage pulse signal as an example. The switch control signal having two different levels may be a low-voltage pulse signal having a low level and a high level. When the controller outputs one level to the high-voltage pulse circuit, the high-voltage pulse circuit outputs a corresponding voltage as a pulse signal. For example, when the controller inputs a low level to the control terminal of the transistor switch in the high-voltage pulse circuit, the high-voltage pulse circuit outputs a high voltage of the high-voltage pulse signal. On the other hand, when the controller inputs a high level to the control terminal of the transistor switch in the high-voltage pulse circuit, the high-voltage pulse circuit outputs a low voltage of the high-voltage pulse signal. That is, the voltage applied to the conductor by the high voltage pulse circuitry enables the conductor to generate an electric field that deflects non-target ions when the controller outputs one level of the switch control signal, and the voltage applied to the conductor by the high voltage pulse circuitry disables the conductor from generating an electric field that deflects target ions when the controller outputs another level of the switch control signal.

[0133] After the controller outputs high and low levels of the switch control signal, the operation of the high voltage pulse circuit that outputs corresponding voltages in the high voltage pulse signal can be referred to the above-mentioned embodiment of the high voltage pulse circuit, and the details will not be repeated here.

[0134] Optionally, the controller is also connected to the pulse circuit via an isolation circuit.

[0135] As shown in FIG. 3, this is a schematic structural diagram showing a cross section of a mass spectrometer provided by an embodiment of the present invention. In the mass spectrometer, a pulsed laser emitted from a laser source 2a excites a sample 01, which is an ion source, to generate ions with different molecular weights. The ions with different molecular weights are accelerated to different velocities within an accelerating electric field U. Ions with smaller molecular weights are accelerated to higher velocities, so they leave the accelerating electric field U earlier, enter the field-free region earlier, and fly toward the ion detector 1. Conversely, ions with larger molecular weights are accelerated to lower velocities, leave the accelerating electric field U later, enter the field-free region later, and fly toward the ion detector 1.

[0136] Generally, in actual ion detection, it is necessary to detect only target ions with molecular weights within a specific range. Ions with other molecular weights are called non-target ions. If such non-target ions reach and are detected by the ion detector 1, not only will the life of the ion detector 1 be shortened, but the detection results of the target ions will also be blurred.

[0137] The difference in mass between target ions and non-target ions results in a difference in the time it takes for the target ions and non-target ions to pass through the field-free region, which is utilized herein for screening between target ions and non-target ions. A conductor is placed in the field-free region of the mass spectrometer. Different electrical signals are applied to the target ions and non-target ions as they pass through the field-free region, and the conductor generates different electric fields for the target ions and non-target ions as they pass through the field-free region. If the target ions are close to the conductor, their flight direction remains unchanged, and the target ions continue to fly toward the ion detector. If non-target ions approach the conductor, they are deflected by the electric field generated by the conductor and cannot reach the ion detector. This allows screening between target ions and non-target ions.

[0138] For example, if the conductor includes a first conductive plate 31 and a second conductive plate 32, the two conductive plates are disposed on either side of the ion flight path, respectively. The first conductive plate 31 is grounded, and the second conductive plate 32 is connected to the output terminal of the ion selection circuit.

[0139] When the target ions pass through the field-free region, the controller can control the ion selection circuit to output a ground voltage, so that no electric field exists between the first conductive plate 31 and the second conductive plate 32, allowing the target ions to pass through the field-free region and reach the ion detector 1 without interference.

[0140] When non-target ions fly through the electric field-free region, the controller can control the high-voltage pulse circuit to output a high voltage. In this case, an electric field is generated between the first conductive plate 31 and the second conductive plate 32, and the direction of the electric field lines of the electric field is perpendicular to the flight direction of the non-target ions. As a result, when passing through the electric field, the flight of the non-target ions is deflected and cannot reach the ion detector 1, thereby screening the target ions from the non-target ions.

[0141] In practice, the conductors do not need to be two conductor plates, but can be implemented as a metal tube. Ions flow through the metal tube in a direction parallel to the central axis of the metal tube. In this case, the first voltage source HV+ of the high-voltage pulse circuit that needs to be used can be a high-voltage voltage source, and the second voltage source HV+ can be a voltage source that outputs a negative high voltage. The high voltage and negative high voltage can respectively induce the high voltage and low voltage output by the high-voltage pulse circuit.

[0142] Take positive ions as an example. When target ions fly through the metal tube, the controller controls the high-voltage pulse circuit to apply a high voltage to the metal tube. The electric field inside the metal tube adjusts the flight trajectory of the flying target ions, converging them toward the central axis of the metal tube and allowing the target ions to reach the ion detector 1. When non-target ions fly through the metal tube, the controller controls the high-voltage pulse circuit to apply a low voltage to the metal tube. The electric field inside the metal tube deflects the flight trajectory of the non-target ions toward the wall of the metal tube. Therefore, the non-target ions cannot reach the detector. This allows screening of target ions and non-target ions. For negative ions, a low voltage is applied to the metal tube when target ions fly through the metal tube, and a high voltage is applied to the metal tube when non-target ions fly through the metal tube.

[0143] Target ions and non-target ions pass through the field-free region at different times, with the specific order depending on the molecular weights of the target ions and non-target ions. Because the time difference between the time it takes for target ions to pass through the field-free region and the time it takes for non-target ions to pass through the field-free region is relatively small, it is necessary to accommodate the rapid rise and fall of voltage when two different voltages applied to the conductor are switched. The high-voltage pulse circuit provided by the present invention can significantly reduce the delay when switching between high and low voltages, thereby meeting the requirement of a small delay when switching between two voltages for screening target ions and non-target ions. This improves the accuracy of ion screening in mass spectrometers, extends the service life of ion detectors, and improves the clarity of detection results.

[0144] It should be noted that in the present specification, relational terms such as "first" and "second" are used only to distinguish the operation of one entity from the operation of another entity, and do not necessarily require or imply that these entities or operations actually have a relationship or order between them. Furthermore, the terms "comprise" and "comprises," and variations thereof, are intended to cover a non-exclusive inclusion, such as when a process, method, article, or apparatus includes a range of elements inherent in the process, method, or apparatus. Without further limitation, an element defined by a statement "comprises" does not exclude the existence of additional identical elements in a process, method, article, or apparatus that includes the described element. Furthermore, among the above technical solutions provided by the embodiments of the present invention, those parts that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid undue redundancy.

[0145] In the specification of the present invention, this article uses specific examples to explain the principle and implementation of the present invention. The above description of the embodiments is only used to understand the method of the present invention and its core concept. It should be noted that those skilled in the art can make some improvements and modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. 1. A method for screening ions in a mass spectrometer, wherein a deflection conductor is positioned in the ion flight path between an accelerating field in the mass spectrometer and an ion detector, comprising: applying a first voltage to the deflection conductor to generate a deflection electric field in the deflection conductor and to deflect the flight direction of the ions as they fly through the deflection electric field so that they do not reach the ion detector; maintaining a first voltage applied to the deflection conductor in response to detecting that a pulse synchronized with the laser has been output, to deflect non-target ions among ions emerging from the accelerating field; applying a second voltage to the deflection conductor when the target ions are ejected from the accelerating field to prevent a deflection field from being generated that deflects the target ions, allowing the target ions to reach the ion detector; applying the first voltage to the deflection conductor when non-target ions pass after all of the target ions have passed through the deflection conductor; applying the first voltage and the second voltage alternately to the deflection conductor for a plurality of cycles; 1. A method for screening ions in a mass spectrometer, comprising: applying a first voltage for a duration of time and a second voltage for a duration of time in each of a plurality of cycles; and determining the duration of time for which the first voltage is applied and the second voltage for a duration of time in each of a plurality of cycles based on the molecular weights of non-target ions to be deflected and target ions that are not deflected.

2. the deflection conductor includes at least one pair of conductive plates arranged on either side of the ion flight path, each of the at least one pair of conductive plates including a first conductive plate and a second conductive plate, the first conductive plate being grounded; The step of applying a first voltage to the deflection conductor includes: applying a voltage higher than ground voltage to the second conductor plate; Alternatively, applying a voltage lower than a ground voltage to the second conductor plate, The step of applying a second voltage to the deflection conductor includes:

2. A method for screening ions in a mass spectrometer as recited in claim 1, including the step of applying a voltage to said second conductive plate equal to ground voltage.

3. the deflection conductor is a focusing electrode disposed in the mass spectrometer or a metal tubular shell disposed in a field-free region of the mass spectrometer; The step of applying a first voltage to the deflection conductor includes: applying a voltage to the deflection conductor that has a polarity opposite to that of the ions; The step of applying a second voltage to the deflection conductor includes:

2. A method for screening ions in a mass spectrometer as recited in claim 1, including the step of applying a voltage to said deflection conductor of the same polarity as said ions.

4. 1. A system for screening ions in a mass spectrometer, comprising: a controller having an input terminal connected to a laser pulse source for outputting laser pulses; an ion selection circuit having an output terminal connected to a deflection conductor disposed in the mass spectrometer and an input terminal connected to the controller; 4. A system for screening ions in a mass spectrometer, characterized in that the controller is configured to control the ion selection circuit to output the first voltage and the second voltage alternately to the deflection conductor, in order to perform the method for screening ions in a mass spectrometer described in any one of claims 1 to 3.

5. the deflection conductor includes at least one pair of conductive plates arranged on either side of the ion flight path, each of the at least one pair of conductive plates including a first conductive plate and a second conductive plate, the first conductive plate being grounded; the second conductor plate is connected to an output terminal of the ion selection circuit, the ion selection circuit including a power supply, a pulse circuit, and an RC series circuit; the pulse circuit includes a voltage divider and a transistor switch connected in series, one end of the pulse circuit is connected to the output terminal of the power supply and the other end of the pulse circuit is grounded, a node where the voltage divider and the transistor switch are connected functions as an output terminal of the ion selection circuit, a first terminal of the RC series circuit is connected to the output terminal of the ion selection circuit and a second terminal of the RC series circuit is grounded; 5. The system for screening ions in a mass spectrometer of claim 4, wherein the controller is connected to a control terminal of the transistor switch, the controller being configured to switch the transistor switch on and off.

6. a first terminal of the voltage divider connected to the power supply, a second terminal of the voltage divider connected to a first terminal of the transistor switch, and a second terminal of the transistor switch connected to ground; in response to the controller outputting an electrical level, the first terminal and the second terminal of the transistor switch are electrically disconnected; 6. The system for screening ions in a mass spectrometer of claim 5, wherein the first terminal and the second terminal of the transistor switch are electrically connected in response to the controller outputting another electrical level.

7. a first terminal of the transistor switch connected to the power supply, a second terminal of the transistor switch connected to a first terminal of the voltage divider, and a second terminal of the voltage divider connected to ground; in response to the controller outputting an electrical level, the first terminal and the second terminal of the transistor switch are electrically disconnected; 6. The system for screening ions in a mass spectrometer of claim 5, wherein the first terminal and the second terminal of the transistor switch are electrically connected in response to the controller outputting another electrical level.

8. 6. The system for screening ions in a mass spectrometer of claim 5, wherein the ion selection circuit further comprises an RC parallel circuit, and a control terminal of the transistor switch is connected to the controller via the RC parallel circuit.

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