Flight tube temperature compensation circuit and mass spectrometer

Abstract

The utility model discloses a flight tube temperature compensation circuit and a mass spectrometer. The flight tube temperature compensation circuit comprises an input end, a voltage regulation circuit and an output end. Temperature compensation is carried out through a voltage adjusting circuit arranged in the same temperature field as the flight tube, and the length variation of the flight tube in the temperature field is converted into temperature compensation voltage used for adjusting temperature applied to an electrode plate. Therefore, the deviation of the flight time caused by the change of the length of the flight tube by the temperature is eliminated; and the flight time of ions in the flight tube at different temperatures is kept unchanged. According to the circuit, by adjusting the output of the target high voltage, the mass axis offset of the instrument caused by the temperature change is reduced, so that the instrument identification is more accurate.

Description

Technical Field

[0001] This utility model relates to the field of mass spectrometry analysis technology, and in particular to a flight tube temperature compensation circuit and a mass spectrometer. Background Technology

[0002] Time-of-flight mass spectrometry (TOFMS) is a commonly used mass spectrometry technique. It's a mass spectrometer that creates a mass spectrum by detecting ions arriving at a detector at different times within a vacuum field-free region at varying mass-to-charge ratios. Alternatively, electrons emitted from an ion source break down the gas molecules of the analyte into fragment ions. These fragment ions need to be accelerated by an electric field to travel within the vacuum chamber, allowing for the calculation of the mass-to-charge ratio.

[0003] However, the mass axis of existing mass spectrometers is affected by temperature changes. For example, as the temperature changes from 5°C to 35°C, the temperature affects the length of the flight tube, and the mass axis of the mass spectrometer can shift by about 1500 ppm. This affects the time it takes for ions to travel from the ion source to the detector, resulting in different mass-to-charge ratios for the same ions at different temperatures. It is evident that temperature has a significant impact on the thermal expansion and contraction of the flight tube. However, since the test time is short, the temperature will not change drastically in a short period of time. This can be addressed by calibrating the mass axis each time during the test. Alternatively, the influence of temperature can be reduced by changing the material of the flight tube.

[0004] Therefore, there is an urgent need for a temperature compensation device that can correct for changes in flight time caused by thermal expansion and contraction of the flight tube. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a flight tube temperature compensation circuit and a mass spectrometer, which eliminates the influence of ion flight time deviation in the flight tube through a temperature compensation device.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] The flight tube temperature compensation circuit provided by this utility model includes an input terminal, a voltage regulation circuit, and an output terminal;

[0008] The input terminal is used to receive an external input voltage and apply the input voltage to the voltage regulation circuit;

[0009] The voltage regulation circuit includes at least one feedback resistor, which is located in the same temperature field as the flight tube. The voltage regulation circuit is used to adjust the received input voltage to a temperature-compensated voltage.

[0010] The output terminal outputs an output voltage that is applied to the flight tube electrode plate according to the temperature compensation voltage adjusted by the voltage regulation circuit.

[0011] The feedback resistor has a temperature drift coefficient r, which is within a critical range. When the temperature drift coefficient r of the feedback resistor is within this critical range, after the temperature compensation voltage regulated by the voltage regulation circuit is applied to the electrode plate of the mass spectrometer, the offset of the mass axis of the mass spectrometer relative to the mass axis calibrated by the standard substance during the analysis process is ≤500ppm.

[0012] Furthermore, the temperature drift coefficient r of the feedback resistor satisfies:

[0013] 1.4b-α≤r≤2.7b+α;

[0014] Where b is the temperature drift coefficient of the flight tube, and α is the offset.

[0015] Furthermore, the temperature drift coefficient r of the feedback resistor satisfies:

[0016] 1.5b≤r≤2.6b.

[0017] Furthermore, the temperature drift coefficient r of the feedback resistor satisfies:

[0018] 1.5b ≤ r < 1.7b, or,

[0019] 1.7b≤r<1.9b, or,

[0020] 1.9b≤r<2b, or,

[0021] 2b≤r<2.1b, or,

[0022] 2.1b ≤ r < 2.2b, or,

[0023] 2.2b≤r<2.3b, or,

[0024] 2.3b≤r≤2.6b.

[0025] Furthermore, the voltage regulation circuit includes an operational amplifier and a feedback branch;

[0026] The feedback resistor is located in the feedback branch.

[0027] The feedback branch is located between the input and output terminals of the operational amplifier.

[0028] The feedback branch responds to the temperature change of the feedback resistor and generates a feedback signal, which is input to the operational amplifier and generates a temperature compensation voltage acting on the electrode plate.

[0029] Furthermore, the voltage regulation circuit also includes a voltage divider resistor connected to the inverting input terminal of the operational amplifier. The value of the feedback resistor is greater than or equal to 50 times the value of the voltage divider resistor, or greater than or equal to 60 times the value of the voltage divider resistor, or greater than or equal to 70 times the value of the voltage divider resistor, or greater than or equal to 80 times the value of the voltage divider resistor, or greater than or equal to 90 times the value of the voltage divider resistor, or greater than or equal to 100 times the value of the voltage divider resistor.

[0030] Furthermore, the voltage regulation circuit adopts a non-inverting proportional voltage compensation circuit.

[0031] Furthermore, the voltage regulation circuit employs an inverting proportional voltage compensation circuit.

[0032] This utility model provides a mass spectrometer, including a flight tube and an electrode plate, characterized in that it further includes the aforementioned flight tube temperature compensation circuit;

[0033] The feedback resistor in the flight tube temperature compensation circuit is set in the same temperature field as the flight tube. The output terminal of the flight tube temperature compensation circuit is connected to the electrode plate and is used to input the temperature compensation voltage caused by the length change of the flight tube in the temperature field to the electrode plate.

[0034] Furthermore, the flight tube is also provided with a feedback resistor mounting position, and the feedback resistor is mounted on the mounting position.

[0035] The beneficial effects of this utility model are as follows:

[0036] This invention provides a flight tube temperature compensation circuit and a mass spectrometer. The flight tube temperature compensation circuit performs temperature compensation through a voltage regulation circuit located in the same temperature field as the flight tube. It converts the change in the length of the flight tube in the temperature field into a temperature compensation voltage applied to the electrode plates, thereby eliminating the deviation in flight time caused by temperature changes in the flight tube length and ensuring that the flight time of ions in the flight tube remains constant at different temperatures. This circuit also reduces the mass axis offset caused by temperature changes by adjusting the output of the target high voltage, resulting in more accurate instrument identification.

[0037] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description

[0038] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the following drawings are provided for illustration.

[0039] Figure 1 This is a block diagram of a voltage regulation circuit.

[0040] Figure 2 This is a circuit diagram for an inverting proportional voltage regulator.

[0041] Figure 3 This is a circuit diagram for a non-inverting proportional voltage regulator.

[0042] Figure 4 This is a diagram showing the connection relationship between the in-phase proportional circuit and the original circuit.

[0043] Figure 5 This is a diagram showing the connection relationship between the inverting proportional circuit and the original circuit.

[0044] Figure 6 Different temperature drift deviations correspond to different r / b values.

[0045] Figure 7 The accuracy of mass spectrometry identification corresponding to different offsets. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0047] Example 1

[0048] like Figure 1 As shown, the flight tube temperature compensation circuit provided in this embodiment includes an input terminal, a voltage regulation circuit, and an output terminal;

[0049] The input terminal is used to receive an external input voltage and apply the input voltage to the voltage regulation circuit.

[0050] The voltage regulation circuit includes at least one feedback resistor, which is located in the same temperature field as the flight tube; the voltage regulation circuit is used to adjust the received input voltage to a temperature-compensated voltage.

[0051] The output terminal outputs an output voltage that is applied to the flight tube electrode plate according to the temperature compensation voltage adjusted by the voltage regulation circuit.

[0052] In this embodiment, the flight time variation caused by the change in flight tube length is adjusted by temperature compensation voltage, so that the flight time remains constant under different temperatures; the temperature compensation voltage is used to compensate for the flight time variation caused by the change in flight tube length.

[0053] In this embodiment, different temperature fields have different effects on the flight tube, and the length of the flight tube changes due to thermal expansion and contraction; since the feedback resistor and the flight tube are in the same temperature field, the temperature change is the same.

[0054] The temperature compensation voltage of the voltage regulation circuit is applied to the electrode plate through the output terminal, so that the flight time of ions in the flight tube remains constant.

[0055] The following is the derivation process based on the principle that the flight time of the flight tube remains constant in different temperature fields:

[0056] The input voltage in the voltage regulation circuit remains constant. When the temperature field changes, the output voltage and the change in the length of the flight tube satisfy the following relationship:

[0057]

[0058] Where E1 represents the input voltage in the first temperature field, i.e., the voltage of the electrode plate in the first temperature field; E2 represents the voltage of the electrode plate in the second temperature field; L1 represents the length of the flight tube in the first temperature field; ΔL represents the length of the flight tube in the second temperature field.

[0059] In this embodiment, E1 or E2 refers to the voltage on the electrode plate;

[0060] The derivation process of the relationship between the output voltage and the change in flight tube length in this embodiment is as follows:

[0061] Based on the principle of time-of-flight mass spectrometry:

[0062]

[0063] Where V is the velocity of the ions; E K M is the kinetic energy of the ion; E is the mass of the ion; and E is the accelerating voltage of the ion.

[0064] Formula for calculating flight time under the first temperature field:

[0065] Formula for calculating flight time under the second temperature field:

[0066] If the flight time is kept the same under the first and second temperature fields, then the following formula is satisfied:

[0067]

[0068]

[0069] After expanding the formula, since the change in flight tube length is relatively small, we can neglect the quadratic term and obtain the following formula:

[0070]

[0071] Approximately equal to:

[0072] Where ΔE represents the voltage applied to the electrode plates in the second temperature field.

[0073] Based on the above derivation, it can be concluded that the ratio of the voltage change on the electrode plate to the length change of the flight tube is approximately twice the ratio of the initial voltage on the electrode plate to the initial length of the flight tube.

[0074] The voltage regulation circuit in this embodiment includes an operational amplifier and a feedback circuit. The feedback circuit is located between the input and output terminals of the operational amplifier and is situated in the same temperature field as the flight tube. The feedback circuit generates a feedback signal based on the length change of the flight tube in the temperature field. The feedback signal is input to the operational amplifier and generates a temperature compensation voltage for adjusting the voltage on the electrode plate.

[0075] In this embodiment, the temperature compensation voltage refers to the voltage output by the operational amplifier in the voltage regulation circuit after a temperature change; this voltage is equal to the voltage change on the electrode plate.

[0076] The voltage regulation circuit in this embodiment can be an inverting proportional voltage compensation circuit or a non-inverting proportional voltage compensation circuit.

[0077] In this embodiment, the basic amplifier of the inverting proportional voltage compensation circuit is an operational amplifier, and the operational amplifier and the feedback circuit constitute an inverting proportional operational circuit.

[0078] The non-inverting input of the operational amplifier is grounded through a resistor;

[0079] The inverting input terminal of the operational amplifier is used to input the control voltage of the control electrode plate;

[0080] The inverting input terminal of the operational amplifier is connected to an input resistor, and the other end of the input resistor is grounded; a feedback resistor is provided between the inverting input terminal and the output terminal of the operational amplifier, and the feedback resistor is set in the same temperature field as the flight tube; the output terminal of the operational amplifier is used to output an adjusted temperature compensation voltage.

[0081] like Figure 2 As shown, Figure 2 For an inverting proportional operational circuit, the output voltage and input voltage satisfy the following formula:

[0082]

[0083] Among them, Eout E0 represents the output voltage after passing through the voltage regulation circuit, i.e., the temperature-compensated voltage; R1 represents the input voltage of the voltage regulation circuit; R f This indicates that a feedback resistor is set to be in the same temperature field as the flight tube;

[0084] The feedback resistor satisfies the following relationship:

[0085] r = 2b;

[0086] Where b is the temperature drift coefficient of the flight tube; r represents the temperature drift coefficient of the feedback resistor;

[0087] The flight tube in this embodiment is made of materials such as stainless steel and titanium alloy; the temperature drift coefficient of the stainless steel or titanium alloy can be found in existing technical manuals. This application will use a stainless steel flight tube as an example for explanation.

[0088] The relationship between the feedback resistor and the temperature drift coefficient of the flight tube in this embodiment can be derived as follows, when the following conditions are met:

[0089] When the temperature remains unchanged:

[0090] After temperature change:

[0091] ΔE = rΔTE1;

[0092] ΔL=bΔTL1;

[0093]

[0094] We can obtain: r = 2b;

[0095] In this embodiment, the temperature drift coefficient of the feedback resistor is twice that of the flight tube material.

[0096] The voltage regulation circuit in this embodiment adopts a non-inverting proportional voltage compensation circuit, which includes an operational amplifier, a feedback resistor, and a voltage divider resistor.

[0097] The non-inverting input of the operational amplifier is used to input the control voltage of the control electrode plate; the inverting input of the operational amplifier is connected to a voltage divider resistor, the other end of which is grounded; a feedback resistor is connected between the inverting input and the output of the operational amplifier; the input of the operational amplifier is used to output the adjusted temperature compensation voltage; the feedback resistor is positioned in the same temperature field as the flight tube.

[0098] The temperature drift coefficient of the feedback resistor is derived according to the following process:

[0099] according to Figure 3 From the circuit shown, it can be seen that the output voltage and input voltage satisfy the following formula:

[0100] E out =k*E0*(R1+R + ) / R1 (2)

[0101] Where R1 is the low temperature drift resistor, R + For a resistor set within the same temperature field range as the flight tube, E0 is the input voltage, and k is the coefficient of the control voltage; E out This refers to the output voltage.

[0102] If the temperature of the flight tube changes from T1 to T2, then the following formula applies:

[0103] L2=L1*(1+b(T2-T1))= L1*(1+b△T) (3)

[0104] E2=E1*(1+r(T2-T1))= E1*(1+r△T) (4)

[0105] Feedback resistor temperature drift formula: R +2 =R +1 *(1+r)ΔT;

[0106] When the temperature remains unchanged: E1=k*E0*(1+R) +1 / R1);

[0107] After the temperature change: E2=k*E0*(1+R) +2 / R1);

[0108]

[0109] When R +1 When the value is much greater than R1, the following formula is satisfied:

[0110] E2=E1*(1+rΔT);

[0111] Where L1 is the initial length of the flight tube, L2 is the length of the flight tube at the new temperature; T1 is the initial temperature of the flight tube, T2 is the new temperature of the stainless steel flight tube; ΔT represents the temperature change of the stainless steel flight tube; b is the temperature drift coefficient of the flight tube.

[0112] Where E1 represents the initial voltage applied across the flight tube; E2 represents the voltage applied to the flight tube at the new temperature; T1 represents the initial temperature; T2 represents the new temperature; and r represents the feedback resistor R. + Temperature drift coefficient;

[0113] It is derived from formula (2):

[0114] T2 2 =M*L1 2 (1+b△T) 2 / 2qE1(1+r△T);

[0115] Since the masses M, q, L1, and E1 all remain constant, to keep the flight time t2 constant, then:

[0116] (1+b△T) 2 / (1+r△T)=1

[0117] That is, 1 + 2b△T + b 2 △T 2 =1+r△T

[0118] Because the temperature drift coefficient is very small, therefore b 2 △T 2 Approximately equal to 0;

[0119] Therefore, r = 2b;

[0120] Again R +2 =R +1 (1+r△T)(5)

[0121] Combining formulas 4, 5, and 1, we can deduce that E2 - E1 = E1 * r * △T;

[0122] E1=K*DA*(R +1 +R1) / R1;

[0123] E2=K*DA*(R +2 +R1) / R1; Launch

[0124] E1=K*DA*R +1 / R1;

[0125] The condition for Formula 1 to hold is: R + >>R1;

[0126] R + The coefficient of resistance drift with temperature is twice that of stainless steel tube.

[0127] The effect of temperature on flight time T can be directly compensated for by an electric field.

[0128] In this embodiment, the feedback resistor is much larger than the voltage divider resistor. In this embodiment, when R + When R1*50 is greater than or equal to R1, it can be considered that the feedback resistance is much larger than the voltage divider resistance. Preferably, R can also be limited. +When the value is 60, 70, 80, 90, 100 or more times greater than R1, it is considered that the feedback resistance is much greater than the voltage divider resistance.

[0129] In this embodiment, the operational amplifier forming the inverting proportional voltage compensation circuit or the non-inverting proportional voltage compensation circuit also needs to be connected to a power supply at the power supply terminal to ensure the normal operation of the operational amplifier circuit.

[0130] Example 2

[0131] This embodiment also provides a mass spectrometer using the above-described flight tube temperature compensation circuit, the mass spectrometer including a flight tube, an electrode plate, and a flight tube temperature compensation circuit;

[0132] The feedback resistor in the flight tube temperature compensation circuit is set in the same temperature field as the flight tube. The output terminal of the flight tube temperature compensation circuit is connected to the electrode plate and is used to input the temperature compensation voltage caused by the length change of the flight tube in the temperature field to the electrode plate.

[0133] The feedback resistor in the flight tube temperature compensation circuit is located inside the flight tube, in close contact with the flight tube, or in a dedicated feedback resistor mounting position, so that the feedback resistor is located in the same temperature field as the flight tube, so as to avoid the heat generated by the power supply, circuit or motor affecting the temperature feedback.

[0134] like Figure 4 As shown, Figure 4 The diagram shows the connection relationship between the in-phase proportional voltage compensation circuit and the original circuit. The voltage regulation circuit in the flight tube temperature compensation circuit adopts an in-phase proportional voltage compensation circuit, which includes an operational amplifier, a feedback resistor, and a voltage divider resistor.

[0135] The non-inverting input of the operational amplifier is used to receive the input voltage from the external input; the inverting input of the operational amplifier is connected to a voltage divider resistor, the other end of which is grounded; a feedback resistor is connected between the inverting input and the output of the operational amplifier; and the output of the operational amplifier is used to output a temperature compensation voltage, which is applied to the electrode plate to keep the flight time of ions in the flight tube constant.

[0136] The voltage regulation circuit in the flight tube temperature compensation circuit provided in this embodiment compensates for the effect of temperature on the flight time of the mass spectrometer, so that the flight time of the mass spectrometer test remains unchanged, thereby keeping the mass-to-charge ratio of the mass spectrometer test unchanged and avoiding a decrease in the mass accuracy of the mass spectrometer.

[0137] This embodiment compensates for the impact of flight tube length variation on flight time by using a voltage regulation circuit located in the same temperature influence zone as the flight tube. In other words, the circuit adjusts the output voltage according to temperature changes, thereby compensating for the effect of temperature on the thermal expansion and contraction of the flight tube.

[0138] In this embodiment, it is necessary to determine the coefficient of linear expansion of the flight tube. The coefficient of linear expansion is a physical quantity that describes the length change characteristics of a material when the temperature changes. It means the ratio of the length change caused by a unit temperature change to the original length, and can be determined by consulting the material used to manufacture the flight tube.

[0139] In this embodiment, it is necessary to determine the temperature drift coefficient of the feedback resistor placed in the temperature field of the flight tube. The temperature drift coefficient (TCR) of the resistor refers to the rate at which the resistance value changes with temperature, usually expressed as parts per million (ppm / °C). The TCR can be used to quantify the degree of resistance change at different temperatures. A suitable feedback resistor can be determined by consulting a resistor manual, and a resistor with a temperature drift coefficient twice that of stainless steel is selected.

[0140] like Figure 5 As shown, Figure 5 The diagram shows the connection relationship between the inverting proportional voltage compensation circuit and the original circuit. The flight tube temperature compensation circuit includes a first inverting proportional voltage compensation circuit and a second inverting proportional voltage compensation circuit. The output terminal of the first inverting proportional voltage compensation circuit is connected to the input terminal of the second inverting proportional voltage compensation circuit, and the output terminal of the second inverting proportional voltage compensation circuit is connected to the electrode plate.

[0141] If the voltage regulation circuit in this embodiment adopts an inverting proportional voltage compensation circuit, it is composed of two inverting proportional operational amplifier circuits connected in series; the feedback resistors in the first and second inverting proportional voltage compensation circuits are respectively set in the same temperature range of the flight tube.

[0142] The ratio of the voltage change on the electrode plate to the length change of the flight tube is approximately equal to twice the initial voltage of the electrode plate to the initial length of the flight tube; the length change ΔL of the flight tube is linearly related to the temperature drift coefficient of the flight tube material; and the voltage change on the electrode plate is linearly related to the temperature drift coefficient of the feedback resistor.

[0143] Therefore, by selecting a flight tube with an appropriate temperature drift coefficient and a feedback resistor with a matching temperature drift coefficient, the temperature-compensated voltage on the electrode plate can be adjusted by a voltage regulation circuit to obtain the output voltage applied to the electrode plate.

[0144] like Figure 6 and Figure 7 As shown, Figure 6 For different r / b values, there are different temperature drift deviations. Figure 7 This represents the accuracy of mass spectrometry identification corresponding to different offsets; it is used to represent the relationship between the mass axis offset and the temperature drift coefficient after mass spectrometer calibration. The feedback resistor has a temperature drift coefficient r, which is within a critical range. When the temperature drift coefficient r of the feedback resistor is within this critical range, after the temperature compensation voltage adjusted by the voltage regulation circuit is applied to the electrode plates of the mass spectrometer, the offset of the mass axis of the mass spectrometer relative to the mass axis after calibration with the standard substance during the mass spectrometer analysis process is such that, if the offset needs to be ≤500ppm, then the temperature drift coefficient r of the feedback resistor satisfies:

[0145] 1.4b-α≤r≤2.7b+α;

[0146] Where b is the temperature drift coefficient of the flight tube, and α is the offset. In this embodiment, the offset is adjusted appropriately according to the selection of the flight tube. For example, the value of α can be in the range of 0 to 0.1b, so that the corresponding resistor can be selected more easily when selecting a fixed temperature drift resistor.

[0147] In this embodiment, the relationship between the temperature drift coefficient r of the feedback resistor and the temperature drift coefficient b of the flight tube can be set according to actual conditions, specifically satisfying any of the following conditions:

[0148] 1.5b≤r≤2.6b; or,

[0149] 1.5b ≤ r < 1.7b, or,

[0150] 1.7b≤r<1.9b, or,

[0151] 1.9b≤r<2b, or,

[0152] 2b≤r<2.1b, or,

[0153] 2.1b ≤ r < 2.2b, or,

[0154] 2.2b≤r<2.3b, or,

[0155] 2.3b≤r≤2.6b.

[0156] This embodiment Figure 6 The curve in the middle shows the impact of offset identification accuracy. After circuit compensation, the actual mass axis offset can achieve a good accuracy within 500 by adjusting the circuit provided in this embodiment.

[0157] In this embodiment, the change in the length of the flight tube is achieved by using a feedback resistor that is related to the temperature drift coefficient of the flight tube and is placed in the same temperature field as the flight tube. The feedback signal on the feedback resistor is input into the operational amplifier circuit and generates a temperature compensation voltage applied to the electrode plate. This ensures that the flight time inconsistency caused by the change in the length of the flight tube due to temperature changes is eliminated, thus guaranteeing the accuracy of the mass spectrometer detection.

[0158] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A flight tube temperature compensation circuit, comprising an input terminal, a voltage regulation circuit, and an output terminal, characterized in that: The input terminal is used to receive an external input voltage and apply the input voltage to the voltage regulation circuit; The voltage regulation circuit includes at least one feedback resistor, which is located in the same temperature field as the flight tube. The voltage regulation circuit is used to adjust the received input voltage to a temperature-compensated voltage. The output terminal outputs an output voltage that is applied to the flight tube electrode plate according to the temperature compensation voltage adjusted by the voltage regulation circuit. The feedback resistor has a temperature drift coefficient r, which is within a critical range. When the temperature drift coefficient r of the feedback resistor is within this critical range, after the temperature compensation voltage regulated by the voltage regulation circuit is applied to the electrode plate of the mass spectrometer, the offset of the mass axis of the mass spectrometer relative to the mass axis calibrated by the standard substance during the analysis process is ≤500ppm.

2. The flight tube temperature compensation circuit of claim 1, wherein: The temperature drift coefficient r of the feedback resistor satisfies: 1.4b-α≤r≤2.7b+α; Where b is the temperature drift coefficient of the flight tube, α is the offset, and 0 < α < 0.1b.

3. The flight tube temperature compensation circuit of claim 2, wherein: The temperature drift coefficient r of the feedback resistor satisfies: 1.5b≤r≤2.6b.

4. The flight tube temperature compensation circuit of claim 2, wherein: The temperature drift coefficient r of the feedback resistor satisfies: 1.5b ≤ r < 1.7b, or, 1.7b≤r<1.9b, or, 1.9b≤r<2b, or, 2b≤r<2.1b, or, 2.1b ≤ r < 2.2b, or, 2.2b≤r<2.3b, or, 2.3b≤r≤2.6b.

5. The flight tube temperature compensation circuit of any one of claims 1 to 4, wherein: The voltage regulation circuit includes an operational amplifier and a feedback branch; The feedback resistor is located in the feedback branch. The feedback branch is located between the input and output terminals of the operational amplifier. The feedback branch responds to the temperature change of the feedback resistor and generates a feedback signal, which is input to the operational amplifier and generates a temperature compensation voltage acting on the electrode plate.

6. The flight tube temperature compensation circuit of claim 5, wherein: The voltage regulation circuit further includes a voltage divider resistor connected to the inverting input terminal of the operational amplifier. The value of the feedback resistor is greater than or equal to 50 times the value of the voltage divider resistor, or greater than or equal to 60 times the value of the voltage divider resistor, or greater than or equal to 70 times the value of the voltage divider resistor, or greater than or equal to 80 times the value of the voltage divider resistor, or greater than or equal to 90 times the value of the voltage divider resistor, or greater than or equal to 100 times the value of the voltage divider resistor.

7. The flight tube temperature compensation circuit of claim 5, wherein: The voltage regulation circuit adopts an in-phase proportional voltage compensation circuit.

8. The flight tube temperature compensation circuit of claim 5, wherein: The voltage regulation circuit adopts an inverting proportional voltage compensation circuit.

9. A mass spectrometer comprising a flight tube, an electrode plate, characterised in that: It also includes the flight tube temperature compensation circuit as described in any one of claims 1-8; The feedback resistor in the flight tube temperature compensation circuit is set in the same temperature field as the flight tube. The output terminal of the flight tube temperature compensation circuit is connected to the electrode plate and is used to input the temperature compensation voltage caused by the length change of the flight tube in the temperature field to the electrode plate.

10. The mass spectrometer of claim 9, wherein: The flight pipe is also provided with a feedback resistor mounting position, and the feedback resistor is arranged on the mounting position.

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