Ground calibration apparatus and method for space pressure sensors

Abstract

The application relates to a ground calibration device and method for a space pressure sensor, and the calibration device comprises a gas supply module for providing a stable flow of working gas; a high-speed directional flow generation module connected with a gas outlet end of the gas supply module and used for outputting a high-speed directional flow; and an ultrahigh vacuum module comprising a calibration chamber and a first ultrahigh vacuum pump set, wherein a gas inlet of the calibration chamber is connected with an output end of the high-speed directional flow generation module, and a space pressure sensor to be calibrated is arranged in the calibration chamber and coaxially arranged with the gas inlet of the calibration chamber and the first ultrahigh vacuum pump set. According to the application, the high-speed directional flow generation module generates a high-speed directional flow with a standard pressure as a standard for calibrating the space pressure sensor, the low-speed directional flow output defect of a traditional directional flow pressure calibration device is overcome, the high-speed directional flow environment faced by a spacecraft during on-orbit operation can be more accurately simulated on the ground, and the reliability and accuracy of a measurement value of the space pressure sensor are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of space vacuum metrology, and in particular to a ground calibration device and method for a space pressure sensor. BACKGROUND

[0002] The obtaining of pressure data on the outer surface of a spacecraft is of great significance to the orbit life of the spacecraft and the study of planetary atmospheres. At present, pressure sensors are generally carried on spacecraft to measure the pressure in the space environment.

[0003] Unlike conventional pressure measurement, when a spacecraft is in orbit, it moves at high speed relative to the surrounding gas molecules, and the gas molecules in space are low in density and in a molecular flow state, so the pressure sensor is faced with a high-speed directional molecular flow, simply referred to as directional flow. Directional flow is a kind of steady-state non-equilibrium gas, which is characterized by non-uniform spatial distribution but does not change with time. The physical parameters are anisotropic, and the gas laws used to study equilibrium gases are not applicable. Most importantly, directional flow has strong directionality, and its pressure manifestation is different from that of equilibrium gases. Therefore, the pressure of directional flow cannot be measured by a conventional vacuum gauge.

[0004] The most commonly used directional flow pressure measurement sensor is a converter type directional gauge, whose measurement principle is to convert the non-equilibrium directional flow into equilibrium gas, and then measure the equilibrium gas to obtain pressure data. However, this method is an indirect measurement, and the converter type directional gauge needs to be calibrated to ensure the accuracy of the measurement results. However, there is currently a lack of quantitative simulation means for high-speed directional flow, and the calibration theory for high-speed directional flow pressure measurement is not perfect.

[0005] For a spacecraft, its in-orbit running speed is generally 3km / s to 43km / s, and the pressure level range that may affect its orbit life is about (10 -7 ~1) Pa. Generally, the calibration system for directional flow pressure measurement sensors is based on molecular beam method, pressure decay method or refrigeration pumping technology, such as the UHV / XHV calibration system of NASA, the CASYMIR system of ESA, and the directional flow calibration device of the Lanzhou Institute of Space Technology. The speed of the standard directional flow generated based on the above principles is below 7km / s, which is far from the speed of the directional flow that most spacecrafts actually face, and cannot accurately simulate the real space environment that the spacecrafts face in orbit. Therefore, the reliability and accuracy of the measurement values of the calibrated space pressure sensor in the actual in-orbit running process are uncertain. SUMMARY

[0006] To address the technical problems existing in the prior art, the present invention aims to provide a ground calibration device and calibration method for a space pressure sensor, which quantitatively simulates the high-speed directional flow faced by a spacecraft in orbit on the ground, so as to accurately calibrate the space pressure sensor and ensure that its measurement values ​​are accurate and reliable in actual use.

[0007] To achieve the above-mentioned objectives, the present invention provides a ground calibration device for a space pressure sensor, comprising:

[0008] The gas supply module is used to provide a stable flow of working gas;

[0009] A high-speed directional flow generating module is connected to the outlet end of the gas supply module and is used to output a high-speed directional flow.

[0010] The ultra-high vacuum module includes a calibration chamber and a first ultra-high vacuum pump group. The air inlet of the calibration chamber is connected to the output end of the high-speed directional flow generation module. The pressure sensor of the space to be calibrated is set in the calibration chamber and is coaxially arranged with the air inlet of the calibration chamber and the first ultra-high vacuum pump group.

[0011] The high-speed directional flow generation module includes a first chamber, a second chamber, an ion energy screening device, a charged particle stripping device, and a second ultra-high vacuum pump group.

[0012] The first chamber is equipped with a plasma source, an ion acceleration extraction device and a first ion beam collimation device arranged in sequence and coaxially. The first ion beam collimation device is coaxially arranged with the gas outlet of the first chamber.

[0013] The second chamber is equipped with a second ion beam collimation device, an ion beam deceleration device, an ion beam current measurement device and an ion neutralization device arranged in sequence. The second ion beam collimation device, the ion beam deceleration device and the ion neutralization device are coaxially arranged with the air inlet and air outlet of the second chamber.

[0014] The air inlet and outlet of the ion energy screening device are respectively connected to the air outlet of the first chamber and the air inlet of the second chamber.

[0015] The charged particle stripping device is installed at the air outlet of the second chamber;

[0016] The second ultra-high vacuum pump unit is connected to the interior of the first chamber and the second chamber, and is used to maintain the interior of the first chamber and the second chamber under vacuum.

[0017] According to one technical solution of the present invention, the gas supply module includes a gas source, an inlet valve and a mass flow meter connected in sequence, and the output end of the mass flow meter is connected to the input end of the high-speed directional flow generation module.

[0018] According to one technical solution of the present invention, the position of the ion beam measuring device on the axis of the second chamber is the ion beam measuring position, and the ion beam measuring position is coaxially arranged with the gas outlet of the second chamber;

[0019] The ion beam measuring device is provided with a first transmission mechanism for driving the ion beam measuring device to or from the ion beam measuring position;

[0020] A second transmission mechanism is provided between the ion neutralization device and the outlet of the second chamber. The second transmission mechanism is used to drive the ion neutralization device to move axially along the second chamber to or away from the ion beam measurement position.

[0021] According to one technical solution of the present invention, the ultra-high vacuum module further includes:

[0022] A position and posture control device is installed in the calibration chamber to fix the pressure sensor of the space to be calibrated and to adjust its position and azimuth angle.

[0023] According to one technical solution of the present invention, the posture control device has at least the degrees of freedom in the horizontal axis, horizontal radial direction, vertical diameter direction and horizontal circumferential direction.

[0024] According to one technical solution of the present invention, the plasma source is an ECR plasma source or a laser plasma source.

[0025] According to one technical solution of the present invention, the measuring area of ​​the ion beam measuring device is the same as the effective neutralization area of ​​the ion neutralization device.

[0026] According to one technical solution of the present invention, the expanded uncertainty of the ground calibration device is 4.2%.

[0027] According to one aspect of the present invention, a calibration method for a ground calibration device for a space pressure sensor as described in any of the preceding claims is provided, comprising the following steps:

[0028] Step S1: Fix the pressure sensor to be calibrated in the calibration chamber, so that the pressure sensor to be calibrated is coaxial with the air inlet of the calibration chamber;

[0029] Step S2: Start the first ultra-high vacuum pump group and the second ultra-high vacuum pump group to evacuate the first chamber, the second chamber, and the calibration chamber, and record the pressure value P2 of the calibration chamber under vacuum conditions; wherein, the background vacuum degree of the first chamber, the second chamber, and the calibration chamber under vacuum conditions is less than or equal to 5 × 10⁻⁶. - 8 Pa;

[0030] Step S3: Supply a stable flow rate of working gas to the plasma source through the gas supply module, and start the plasma source to begin discharging;

[0031] Step S4: Activate the ion acceleration extraction device, the first ion beam collimation device, the ion energy screening device, and the second ion beam collimation device, and adjust the experimental parameters so that the ion beam meets the requirements of initial velocity v0 and emittance ε; the experimental parameters include the gas supply flow rate of the gas supply module, the discharge voltage of the plasma source, and the voltage of the ion beam deceleration device;

[0032] Step S5: Activate the ion beam deceleration device to modulate the velocity of the ion beam output from the second chamber to vm / s;

[0033] Step S6: Move the ion beam measuring device out of the beam region and move the ion neutralization device to the ion beam measuring position so that the measured ion beam current is consistent with the ion beam current entering the ion neutralization device. Using the current value on the ion neutralization device as a reference, adjust the experimental parameters until the ammeter reading on the ion neutralization device is stable.

[0034] Step S7: Start the DC high-voltage power supply of the charged particle stripping device, so that the charged particles in the neutralized ion beam are deflected and stripped off, forming a high-speed directional flow that enters the calibration chamber.

[0035] Step S8: Calculate the standard pressure P of the high-speed directional flow according to the following formula:

[0036]

[0037] Where α is the transparency of the ion neutralization device, I n is the current value on the ion neutralization device; m is the atomic mass; A is the measurement area of ​​the ion beam measurement device;

[0038] Step S9: Calibrate the space pressure sensor to be calibrated based on the calculated standard pressure of the high-speed directional flow and the reading of the space pressure sensor to be calibrated.

[0039] According to one technical solution of the present invention, step S9 specifically includes:

[0040] By adjusting the experimental parameters, the current value on the ion neutralization device was gradually increased to obtain a high-speed directional flow with a velocity of vm / s and different standard pressures. Several pressure calibration points were uniformly selected within each order of magnitude of the high-speed directional flow generation pressure range to conduct experiments. The reading of the pressure sensor to be calibrated at each of the pressure calibration points was recorded as P4, and the calibration coefficient K was calculated according to the following formula:

[0041]

[0042] Wherein, P2 is the pressure value of the calibration chamber under vacuum, P3 is the reading of the pressure sensor of the space to be calibrated corresponding to the pressure value of the calibration chamber under vacuum; P is the standard pressure of the high-speed directional flow; P4 is the reading of the pressure sensor of the space to be calibrated at the calibration point;

[0043] The final calibration coefficient is obtained by averaging the calibration coefficients corresponding to all the pressure calibration points.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] This invention proposes a ground calibration device and method for space pressure sensors. The calibration device is based on the principles of plasma discharge and surface grazing Auger neutralization. It achieves a velocity range of (3–43) km / s and a pressure range of (5 × 10⁻⁶) km / s by ionizing the working gas, extracting and accelerating, aligning, screening, aligning again, decelerating, measuring, neutralizing, and deflecting. -7 ~1) A standard high-speed directional flow of Pa is used as the calibration standard for space pressure sensors. Compared with traditional directional flow pressure ground calibration devices, this invention can obtain a standard directional flow with a wider velocity range, more accurately simulating the high-speed directional flow environment faced by spacecraft during on-orbit operation on the ground. This can effectively improve the reliability and accuracy of space pressure sensor measurements and has the advantages of flexible operation and high calibration efficiency. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0047] Figure 1 This schematic diagram illustrates the structure of a ground calibration device for a space pressure sensor provided in an embodiment of the present invention.

[0048] Figure 2 This is a schematic diagram illustrating the structure of the gas supply module provided in an embodiment of the present invention.

[0049] Figure 3 This schematic diagram illustrates the structure of a high-speed directional flow generation module provided in an embodiment of the present invention.

[0050] Figure 4 The schematic diagram illustrates the structure of the ultra-high vacuum module provided in an embodiment of the present invention.

[0051] The correspondence between component names and reference numerals in the accompanying drawings is as follows:

[0052] 1. Gas supply module; 2. High-speed directional flow generator module; 3. Ultra-high vacuum module;

[0053] 1-1 Gas source; 1-2 Inlet valve; 1-3 Mass flow meter;

[0054] 2-1 Plasma source; 2-2 Ion acceleration and extraction device; 2-3 First ion beam collimation device; 2-4 First flange; 2-5 Ion energy screening device; 2-6 Second flange; 2-7 Second ion beam collimation device; 2-8 Ion beam deceleration device; 2-9 Ion beam current measurement device; 2-10 Ion neutralization device; 2-11 Bellows; 2-12 Third flange; 2-13 Charged particle stripping device; 2-14 Fourth flange; 2-15 First chamber; 2-16 Second chamber; 2-17 First ultra-high vacuum pump group;

[0055] 3-1 Calibration chamber; 3-2 Position control device; 3-3 Fifth flange; 3-4 Second ultra-high vacuum pump set. Detailed Implementation

[0056] The description of the embodiments in this specification should be taken in conjunction with the accompanying drawings, which should form part of the complete specification. In the drawings, the shape or thickness of the embodiments may be exaggerated and may be indicated in a simplified or convenient manner. Furthermore, parts of the various structures in the drawings will be described separately; it is worth noting that elements not shown in the figures or not described in words are in a form known to those skilled in the art.

[0057] The descriptions of the embodiments herein, including any references to directions and orientations, are for ease of description only and should not be construed as limiting the scope of the invention. The following description of preferred embodiments involves combinations of features, which may exist independently or in combination; the invention is not particularly limited to the preferred embodiments. The scope of the invention is defined by the claims.

[0058] like Figure 1As shown, the present invention provides a ground calibration device for a space pressure sensor, comprising a gas supply module 1, a high-speed directional flow generation module 2, and an ultra-high vacuum module 3. The gas supply module 1 provides a stable flow rate of working gas; the high-speed directional flow generation module 2 is connected to the outlet of the gas supply module 1 and generates a high-speed directional flow with a standard pressure, serving as the standard for space sensor calibration; the ultra-high vacuum module 3 includes a calibration chamber 3-1, a first ultra-high vacuum pump group 3-4, and an attitude control device 3-2, providing the necessary background vacuum environment for the calibration of the space pressure sensor to be calibrated.

[0059] like Figure 2 As shown, the gas supply module 1 includes a gas source 1-1, an inlet valve 1-2, and a mass flow meter 1-3 connected in sequence. The output end of the mass flow meter 1-3 is connected to the input end of the high-speed directional flow generator module 2. The various components of the gas supply module 1 are connected in sequence, and the output gas flow rate is controlled by the mass flow meter 1-3.

[0060] like Figure 3 As shown, the high-speed directional flow generation module 2 includes a first chamber 2-15, a second chamber 2-16, an ion energy screening device 2-5, a charged particle stripping device 2-13, and a second ultra-high vacuum pump group 2-17. The first chamber 2-15 contains a plasma source 2-1, an ion acceleration and extraction device 2-2, and a first ion beam collimation device 2-3 arranged sequentially and coaxially. The first ion beam collimation device 2-3 is coaxially arranged with the outlet of the first chamber 2-15. The second chamber 2-16 contains a second ion beam collimation device 2-7, an ion beam deceleration device 2-8, an ion beam current measurement device 2-9, and an ion neutralization device 2-10 arranged sequentially. The second ion beam collimation device 2-7, the ion beam deceleration device 2-8, and the ion neutralization device 2-10 are coaxially arranged with the inlet and outlet of the second chamber 2-16. The inlet and outlet of the ion energy screening device 2-5 are connected to the outlet of the first chamber 2-15 and the inlet of the second chamber 2-16 via the first flange 2-4 and the second flange 2-6, respectively. The charged particle stripping device 2-13 is located at the outlet of the second chamber 2-16 and is connected to the second chamber 2-16 via the third flange 2-12. The charged particle stripping device 2-13 is connected to the calibration chamber 3-1 via the fourth flange 2-14. The second ultra-high vacuum pump group 2-17 communicates with the interior of the first chamber 2-15 and the second chamber 2-16 to maintain a vacuum state inside the first chamber 2-15 and the second chamber 2-16.

[0061] like Figure 4As shown, the ultra-high vacuum module 3 includes a calibration chamber 3-1 and a first ultra-high vacuum pump group 3-4. The air inlet of the calibration chamber 3-1 is connected to the output end of the high-speed directional flow generator module 2. The pressure sensor of the space to be calibrated is placed inside the calibration chamber 3-1 and is coaxially arranged with the air inlet of the calibration chamber 3-1 and the first ultra-high vacuum pump group 3-4 to ensure that the flow field inside the calibration chamber 3-1 is axially distributed, thereby reducing the influence on the high-speed directional flow field. The attitude control device 3-2 is placed inside the calibration chamber 3-1 and is used to fix the pressure sensor of the space to be calibrated and adjust its position and azimuth angle.

[0062] The working principle of this invention is as follows:

[0063] First, a base vacuum is established in the first chamber 2-15, the second chamber 2-16, and the calibration chamber 3-1. Then, gas is supplied to the plasma source 2-1 at a constant flow rate through the gas supply module 1. The working gas is ionized into plasma in the plasma source 2-1, and the ions in the plasma are extracted and accelerated to 2.2 × 10⁻⁶ by the ion beam acceleration and extraction device 2-2. 5 m / s~3.8×10 5 The ion beam is initially set at a speed of m / s, and then collimated by the first ion beam collimator 2-3 to reduce its emissivity. After entering the ion energy screening device 2-5, ions of specific energies are extracted from the ion beam and passed through the second ion beam collimator 2-7 to obtain a monoenergetic and collimated ion beam. The velocity of the monoenergetic ion beam can be modulated to 3 × 10 m / s by adjusting the voltage applied to the ion beam deceleration device 2-8. 3 m / s~4.3×10 4 m / s, in conjunction with ion beam current measurement device 2-9, to measure the ion beam velocity v and flux. In addition, characteristic parameters such as emittance ε are measured in situ at different times. After the characteristic parameters of the ion beam are measured by the ion beam current measuring device 2-9, the ion neutralization device 2-10 is moved axially to the measurement position so that the ion beam being measured is consistent with the ion beam entering the ion neutralization device 2-10. Experimental parameters such as gas supply flow rate and discharge voltage are adjusted to ensure that the current I on the ion neutralization device 2-10 is... n =3.5×10 -8 A~0.9A. Most ions in the ion beam capture electrons in the ion neutralization device 2-10, becoming neutral atoms and forming a composite particle beam without momentum loss. The composite particle beam then enters the charged particle stripping device 2-13, where charged particles are stripped away, forming a standard high-speed directional flow with known collimation, single energy, velocity, and flux. A high-purity monatomic gas is used as the working gas, and its ion mass m can be considered... i Equal to the atomic mass m, the pressure P of a standard high-speed directional flow can be calculated using the following formula:

[0064]

[0065] By adjusting parameters such as the gas flow rate of the gas supply module 1, the discharge voltage of the plasma source 2-1, and the voltage of the ion beam deceleration device 2-8, high-speed directional flow with different pressures at a certain velocity can be obtained. The space pressure sensor to be calibrated is fixed on the attitude control device 3-2. Adjusting the attitude control device 3-2 allows the space pressure sensor to be positioned at the outlet of the high-speed directional flow generating module 2 and kept coaxial with it. In this way, using the high-speed directional flow pressure output by the high-speed directional flow generating module 2 as a standard, the space pressure sensor can be calibrated on the ground.

[0066] In an embodiment of the present invention, the ion beam measuring device 2-9 is used for in-situ time-division measurement of the ion beam. The ion beam measuring device 2-9 is positioned on the axis of the second chamber 2-16 as the ion beam measurement position, which is coaxially arranged with the outlet of the second chamber 2-16. A first transmission mechanism is provided on the ion beam measuring device 2-9 to drive it to or from the ion beam measurement position. The first transmission mechanism can be a lifting device perpendicular to the axial direction of the second chamber 2-16, and its movement to or from the ion beam measurement position is achieved by lifting the ion beam measuring device 2-9. A second transmission mechanism is provided between the ion neutralization device 2-10 and the outlet of the second chamber 2-16. The second transmission mechanism is used to drive the ion neutralization device 2-10 to translate along the axial direction of the second chamber 2-16 to or from the ion beam measurement position. The second transmission mechanism can be a driving device for driving the translation of the ion neutralization device 2-10 and a bellows 2-11 set between the ion neutralization device 2-10 and the outlet of the second chamber 2-16. The ion neutralization device 2-10 is connected to the second chamber 2-16 through the bellows 2-11 to achieve axial parallel movement of the ion neutralization device 2-10, thereby ensuring that the ion current measured by the ion beam measuring device 2-9 is consistent with the ion current entering the ion neutralization device 2-10.

[0067] In embodiments of the present invention, such as Figure 4 As shown, with the horizontal plane where the axis of the calibration chamber 3-1 is located as a reference, the posture control device 3-2 has at least four degrees of freedom: horizontal axial direction, horizontal radial direction, vertical diameter direction, and horizontal circumferential direction, so that the space pressure sensor installed on the posture control device 3-2 can move and rotate within the calibration chamber 3-1.

[0068] In an embodiment of the present invention, plasma source 2-1 is an ECR plasma source or a laser plasma source.

[0069] In an embodiment of the present invention, preferably, the first ultra-high vacuum pump group 3-4 and the second ultra-high vacuum pump group 2-17 are composed of a dry pump, a molecular pump, an ion pump and a cryogenic pump, and their pumping speed is ≥1×10⁻⁶. 4 L / s, so as to establish <5×10 L / s in the first chamber 2-15, the second chamber 2-16 and the calibration chamber 3-1. -8 The background vacuum environment of Pa.

[0070] In an embodiment of the present invention, preferably, the measuring area of ​​the ion beam measuring device 2-9 is the same as the effective neutralization area of ​​the ion neutralization device 2-10, both being A. The ion neutralization device 2-10 can be a grid plate, and the transparency of the ion neutralization device 2-10 is the ratio of its effective neutralization area to the grid plate area. The transparency of the ion neutralization device 2-10 is α (α = 0.4). During use, it is grounded, and a high-precision ammeter is used to measure the current I on it. n .

[0071] In an embodiment of the present invention, preferably, a DC high voltage U2 (U2 = 2000V) is applied to the charged particle stripping device 2-13 to achieve the effect of stripping charged particles in the beam using an electric field.

[0072] In an embodiment of the present invention, preferably, the ground calibration device for the space pressure sensor uses the following formula to calculate the measurement uncertainty of the ground calibration device:

[0073]

[0074] In the formula, u[I n ] is the measurement uncertainty of the current on the ion neutralization device 2-10 (u[I) n u[v] = 0.01%; u[v] is the uncertainty introduced by the ion beam velocity measurement (u[v] = 2.1%); u[L] is the length measurement uncertainty introduced when obtaining the transparency α and effective neutralization area of ​​the ion neutralization device 2-10 (u[L] = 0.01%); u2 is the uncertainty introduced by the stability of the high-speed directional flow generation module 2 (u2 = 0.08%); u3 is the uncertainty introduced by the ambient temperature (u3 = 0.01%); u4 is the uncertainty introduced by the background pressure measurement (u4 = 0.4%). Then u can be calculated. c =2.1%.

[0075] The expanded uncertainty of the ground calibration device for the space pressure sensor can be calculated by the following formula:

[0076] U = k·u c

[0077] In the formula, U represents the expanded uncertainty of the ground calibration device for the space pressure sensor, and k is the coverage factor, which is taken as k = 2. Therefore, the expanded uncertainty of the ground calibration device for the space pressure sensor is U = 4.2%.

[0078] This invention provides a method based on a ground calibration device for a space pressure sensor, comprising the following steps:

[0079] Step S1: Fix the pressure sensor to be calibrated in the calibration chamber 3-1, and adjust the posture control device 3-2 to make the pressure sensor to be calibrated coaxial with the air inlet of the calibration chamber 3-1.

[0080] Step S2: Start the first ultra-high vacuum pump group 3-4 and the second ultra-high vacuum pump group 2-17 to evacuate the first chamber 2-15, the second chamber 2-16, and the calibration chamber 3-1. Record the pressure value P2 of the calibration chamber 3-1 under vacuum conditions. The background vacuum level of the first chamber 2-15, the second chamber 2-16, and the calibration chamber 3-1 under vacuum conditions is less than or equal to 5 × 10⁻⁶. -8 Pa;

[0081] Start the first ultra-high vacuum pump group 2-17 and the second ultra-high vacuum pump group 3-4 to pump the pressure in the first chamber 2-15, the second chamber 2-16 and the calibration chamber 3-1 to ≤5×10 -8 The background vacuum level in Pa is recorded as P0 (P0 = 2.2 × 10⁻⁶). - 8 Pa), P1 (P1 = 2.5 × 10 -8 Pa) and P2 (P2=1.6×10 -8 Pa), and record the reading of the pressure sensor to be calibrated as P3 (P3 = 1.8 × 10 Pa). -8 Pa).

[0082] Step S3: Supply a stable flow of working gas to plasma source 2-1 through gas supply module 1, and start plasma source 2-1 to start discharging;

[0083] A stable flow rate of He gas (m³) is supplied to plasma source 2-1 via gas supply module 1. He =6.65×10 -27 kg), and start plasma source 2-1 to begin discharging.

[0084] Step S4: Activate the ion acceleration and extraction device 2-2, the first ion beam collimation device 2-3, the ion energy screening device 2-5, and the second ion beam collimation device 2-7, and adjust the experimental parameters to ensure that the ion beam velocity is the initial velocity v0 and the emittance is ε. The experimental parameters include the gas supply flow rate of the gas supply module 1, the discharge voltage of the plasma source 2-1, and the voltage of the ion beam deceleration device 2-8; wherein the initial velocity v0 = 2.2 × 10⁻⁶. 5 m / s~3.8×10 5 m / s, emittance ε < 0.2πmm·mrad;

[0085] Step S5: Activate ion beam deceleration device 2-8 to modulate the velocity of the ion beam output from the second chamber 2-16 to v m / s; v = 7.8 × 10 3 m / s;

[0086] Step S6: Move the ion beam measuring device 2-9 out of the beam region and move the ion neutralization device 2-10 to the ion beam measuring position to ensure that the measured ion beam current is consistent with the ion beam current entering the ion neutralization device 2-10. Using the current value on the ion neutralization device 2-10 as a reference, adjust the experimental parameters until the ammeter reading on the ion neutralization device 2-10 stabilizes. For example, adjust the experimental parameters to make I... n =1.93×10 -7 A; Ammeter reading I on ion neutralization device 2-10 n The range can be 7×10 -7 A~0.1A;

[0087] Step S7: Start the DC high voltage power supply of the charged particle stripping device 2-13 to deflect and strip away the charged particles in the neutralized ion beam, forming a high-speed directional flow that enters the calibration chamber 3-1.

[0088] Step S8: Calculate the standard pressure P of the high-speed directional flow according to the following formula:

[0089]

[0090] Where α is the transparency of ion neutralization device 2-10, and I n denoted as , where is the current value on ion neutralization device 2-10; m is the atomic mass; and A is the measurement area of ​​ion beam measuring device 2-9.

[0091] Substituting the above parameters into the formula, we can calculate P = 5 × 10 -7 Pa.

[0092] Step S9: Calibrate the space pressure sensor to be calibrated based on the calculated standard pressure of the high-speed directional flow and the reading of the space pressure sensor to be calibrated.

[0093] Step S9 specifically includes:

[0094] By adjusting the experimental parameters and gradually increasing the current value on ion neutralization device 2-10, a velocity of v = 7.8 × 10⁻⁶ was obtained. 3 High-speed directional flow with speeds of m / s and different standard pressures, within the pressure range generated by the high-speed directional flow (5×10 m / s). -7 Three pressure calibration points were evenly selected within each pressure range of ~1 Pa to conduct the test. The reading of the pressure sensor in the space to be calibrated at each pressure calibration point was recorded as P4, and the calibration coefficient K was calculated according to the following formula:

[0095]

[0096] Wherein, P2 is the pressure value of calibration chamber 3-1 under vacuum, P3 is the reading of the pressure sensor of the space to be calibrated corresponding to the pressure value of calibration chamber 3-1 under vacuum, P is the standard pressure of the high-speed directional flow, and P4 is the reading of the pressure sensor of the space to be calibrated at the calibration point.

[0097] The average value of the calibration coefficients corresponding to all pressure calibration points is taken to obtain the final calibration coefficient of 0.94.

[0098] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0099] Finally, it should be noted that the above description represents a preferred embodiment of the present invention. It should be pointed out that although preferred embodiments have been described, those skilled in the art, once they understand the basic inventive concept of the present invention, can make various improvements and modifications without departing from the principles described herein. These improvements and modifications should also be considered within the scope of protection of the present invention. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

Claims

1. A ground calibration device for a space pressure sensor, characterized in that, include: Gas supply module (1) is used to provide a stable flow rate of working gas; The high-speed directional flow generating module (2) is connected to the outlet end of the gas supply module (1) and is used to output a high-speed directional flow. The ultra-high vacuum module (3) includes a calibration chamber (3-1) and a first ultra-high vacuum pump group (3-4). The air inlet of the calibration chamber (3-1) is connected to the output end of the high-speed directional flow generation module (2). The pressure sensor of the space to be calibrated is set in the calibration chamber (3-1) and is coaxially arranged with the air inlet of the calibration chamber (3-1) and the first ultra-high vacuum pump group (3-4). The high-speed directional flow generation module (2) includes a first chamber (2-15), a second chamber (2-16), an ion energy screening device (2-5), a charged particle stripping device (2-13), and a second ultra-high vacuum pump group (2-17); The first chamber (2-15) is provided with a plasma source (2-1), an ion acceleration extraction device (2-2) and a first ion beam collimation device (2-3) arranged in sequence and coaxially inside. The first ion beam collimation device (2-3) is coaxially arranged with the gas outlet of the first chamber (2-15). The second chamber (2-16) is equipped with a second ion beam collimation device (2-7), an ion beam deceleration device (2-8), an ion beam current measurement device (2-9), and an ion neutralization device (2-10) arranged in sequence. The second ion beam collimation device (2-7), the ion beam deceleration device (2-8), and the ion neutralization device (2-10) are coaxially arranged with the air inlet and air outlet of the second chamber (2-16). The air inlet and air outlet of the ion energy screening device (2-5) are respectively connected to the air outlet of the first chamber (2-15) and the air inlet of the second chamber (2-16). The charged particle stripping device (2-13) is installed at the air outlet of the second chamber (2-16); The second ultra-high vacuum pump unit (2-17) is in communication with the interior of the first chamber (2-15) and the second chamber (2-16) to maintain the interior of the first chamber (2-15) and the second chamber (2-16) under vacuum.

2. The calibration device for a ground-based space pressure sensor according to claim 1, characterized in that, The gas supply module (1) includes a gas source (1-1), an air inlet valve (1-2), and a mass flow meter (1-3) connected in sequence. The output end of the mass flow meter (1-3) is connected to the input end of the high-speed directional flow generation module (2).

3. The ground calibration device for a space pressure sensor according to claim 1, characterized in that, The position of the ion beam measuring device (2-9) on the axis of the second chamber (2-16) is the ion beam measuring position, and the ion beam measuring position is coaxially arranged with the gas outlet of the second chamber (2-16). The ion beam measuring device (2-9) is provided with a first transmission mechanism for driving the ion beam measuring device (2-9) to reach or leave the ion beam measuring position; a second transmission mechanism is provided between the ion neutralization device (2-10) and the outlet of the second chamber (2-16), the second transmission mechanism being used to drive the ion neutralization device (2-10) to translate along the axial direction of the second chamber (2-16) to reach or leave the ion beam measuring position.

4. The ground calibration device for a space pressure sensor according to claim 1, characterized in that, The ultra-high vacuum module (3) also includes: The posture control device (3-2) is installed in the calibration chamber (3-1) to fix the pressure sensor to be calibrated and to adjust its position and azimuth.

5. The ground calibration device for a space pressure sensor according to claim 4, characterized in that, The posture control device (3-2) has at least the following degrees of freedom: horizontal axis, horizontal radial direction, vertical diameter direction, and horizontal circumferential direction.

6. The ground calibration device for a space pressure sensor according to claim 1, characterized in that, The plasma source (2-1) is an ECR plasma source or a laser plasma source.

7. The ground calibration device for a space pressure sensor according to claim 1, characterized in that, The measuring area of ​​the ion beam measuring device (2-9) is the same as the effective neutralization area of ​​the ion neutralization device (2-10).

8. The ground calibration device for a space pressure sensor according to claim 1, characterized in that, The expanded uncertainty of the ground calibration device is 4.2%.

9. A method for a ground calibration apparatus for a space pressure sensor according to any one of claims 1 to 8, characterized in that, Includes the following steps: Step S1: Fix the pressure sensor to be calibrated in the calibration chamber (3-1) so that the pressure sensor to be calibrated is coaxial with the air inlet of the calibration chamber (3-1); Step S2: Start the first ultra-high vacuum pump group (3-4) and the second ultra-high vacuum pump group (2-17) to evacuate the first chamber (2-15), the second chamber (2-16), and the calibration chamber (3-1). Record the pressure value P2 of the calibration chamber (3-1) under vacuum conditions; wherein, the background vacuum degree of the first chamber (2-15), the second chamber (2-16), and the calibration chamber (3-1) under vacuum conditions is less than or equal to 5 × 10⁻⁶. -8 Pa; Step S3: Provide a stable flow rate of working gas to the plasma source (2-1) through the gas supply module (1), and start the plasma source (2-1) to discharge; Step S4: Start the ion acceleration extraction device (2-2), the first ion beam collimation device (2-3), the ion energy screening device (2-5), and the second ion beam collimation device (2-7), and adjust the experimental parameters so that the ion beam meets the requirements of initial velocity v0 and emittance ε; the experimental parameters include the gas supply flow rate of the gas supply module (1), the discharge voltage of the plasma source (2-1), and the voltage of the ion beam deceleration device (2-8); Step S5: Activate the ion beam deceleration device (2-8) to modulate the speed of the ion beam output from the second chamber (2-16) to vm / s; Step S6: Move the ion beam measuring device (2-9) out of the beam region and move the ion neutralization device (2-10) to the ion beam measuring position so that the measured ion beam current is consistent with the ion beam current entering the ion neutralization device (2-10). Using the current value on the ion neutralization device (2-10) as a reference, adjust the experimental parameters until the ammeter reading on the ion neutralization device (2-10) is stable. Step S7: Start the DC high voltage power supply of the charged particle stripping device (2-13) to deflect and strip the charged particles in the neutralized ion beam, forming a high-speed directional flow that enters the calibration chamber (3-1). Step S8: Calculate the standard pressure P of the high-speed directional flow according to the following formula: Wherein, α is the transparency of the ion neutralization device (2-10), and I n The current value on the ion neutralization device (2-10) is denoted as m; the atomic mass is denoted as A; and the measurement area of ​​the ion beam measuring device (2-9) is denoted as A. Step S9: Calibrate the space pressure sensor to be calibrated based on the calculated standard pressure of the high-speed directional flow and the reading of the space pressure sensor to be calibrated.

10. The method according to claim 9, characterized in that, Step S9 specifically includes: By adjusting the experimental parameters, the current value on the ion neutralization device (2-10) was gradually increased to obtain a high-speed directional flow with a velocity of vm / s and different standard pressures. Several pressure calibration points were uniformly selected within each order of magnitude of the high-speed directional flow generation pressure range to conduct experiments. The reading of the pressure sensor to be calibrated at each pressure calibration point was recorded as P4, and the calibration coefficient K was calculated according to the following formula: Wherein, P2 is the pressure value of the calibration chamber (3-1) under vacuum, P3 is the reading of the pressure sensor of the space to be calibrated corresponding to the pressure value of the calibration chamber (3-1) under vacuum; P is the standard pressure of the high-speed directional flow; P4 is the reading of the pressure sensor of the space to be calibrated at the calibration point; The final calibration coefficient is obtained by averaging the calibration coefficients corresponding to all the pressure calibration points.

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