Method for measuring transient temperature field of alkali metal cell multi-channel

Abstract

A kind of alkali gas chamber multichannel transient temperature field measurement method is favorable to guarantee the reliability and long-term stability of alkali gas chamber, it is characterized in that, including the following steps: step 1, according to temperature field reconstruction theory, the spatial layout of multiple temperature measuring points is carried out on the outer wall and inside of alkali gas chamber, and the temperature field of the alkali gas chamber to be measured is formed;Step 2, for the multiple temperature measuring points, platinum resistance probe is laid out, and a platinum resistance temperature sensor is arranged at each temperature measuring point;Step 3, the temperature field of alkali gas chamber is measured in real time using an electric control system, and the temperature T, transmission time t and transmission distance L of each temperature measuring point are obtained;Step 4, the temperature gradient of the gas chamber and the discretization temperature gradient module index are calculated, to evaluate the uniformity and temperature gradient of the temperature field of alkali gas chamber.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of atomic thermotics, and particularly to a method for measuring a multi-channel transient temperature field of an alkali metal cell, which can realize real-time detection and analysis of the temperature field of the alkali metal cell through a multi-channel platinum resistance temperature measuring probe and a temperature field reconstruction theory, and is conducive to evaluating the uniformity and gradient of the temperature field in the alkali metal cell. BACKGROUND

[0002] Traditional temperature measurement is mostly single-point measurement or multi-point time-sharing measurement. However, in the field of quantum sensing, the uniformity and gradient of the temperature field are strictly required to be measured and analyzed, and the traditional temperature measurement mode cannot meet the demand, which requires the use of a temperature sensor array to simultaneously collect the temperature of multiple points in the space. In thermal physics, the diffusion of heat is usually measured by the temperature trend of the coordinate points in the space, so the greater the density of the temperature sensor distribution in the space, the more accurate the detection of the heat flow direction. However, the commonly used sensors currently have the disadvantages of being able to measure only the temperature fluctuation of a single measuring point and being out of synchronization, and cannot simultaneously measure and calculate synchronously, which cannot meet the research needs of the field of quantum sensing.

[0003] A temperature control method for an alkali metal cell based on light-thermal deflection (CN202211065427.0) in the prior art gives a method for measuring the temperature of an alkali metal cell, but it is based on the principle of light-thermal deflection to measure the temperature. The technology realizes the measurement of the temperature of the alkali metal cell by the relationship between the light-thermal deflection angle and the refractive index of the alkali metal cell, and by using different alkali metal atomic number densities to bring different alkali metal cell refractive indices, instead of accurately distributing the platinum resistance around and inside the alkali metal cell. Therefore, the temperature measurement accuracy of this technology is not high, and it cannot measure the temperature gradient change rate and temperature field transmission rate between multiple points in the cell and other indicators. In addition, the focus of this technology is on the physical mechanism analysis of the light-thermal deflection method, which analyzes the information of the overall temperature field inside the cell obtained by the light-thermal deflection method, instead of the temperature information of the surface of the cell measured by the infrared temperature measurement method and other technologies. At the same time, this technology uses a far-detuned detection beam, which does not destroy the polarization of the atoms, ensuring real-time and accuracy.

[0004] In order to realize the multi-channel spatial temperature field measurement, a distributed sensor array and parallel temperature data acquisition method are usually adopted, which greatly improves the synchronization of temperature data acquisition of the sensor array compared with the traditional acquisition method one by one, and has important significance for the detection of temperature points in space and the research of temperature field and temperature gradient in thermophysics, and at the same time has the advantages of small volume, low power consumption, long-distance data transmission and the like, and can be applied to multi-point temperature measurement of large space. However, the relative precision of the measurement method is poor, and temperature data correction is required for occasions with high temperature precision requirements. On the other hand, the measurement method has more points and complex wiring, and is only suitable for large space temperature field measurement, and cannot accurately arrange points in small alkali metal gas chamber space, and at the same time the method lacks design of various space deformation structures. SUMMARY

[0005] The alkali metal gas chamber multi-channel transient temperature field measurement method provided by the present application is used for solving the problems in the prior art, and the spatial layout of the plurality of temperature measuring points on the outer wall and inside of the alkali metal gas chamber is performed through the temperature field reconstruction theory, the platinum resistance probe is designed through the temperature field reconstruction theory, the temperature field of the alkali metal gas chamber is measured in real time by using the electric control system, and indexes such as the temperature gradient change rate and the temperature field transmission rate of the gas chamber are calculated, so as to be beneficial to guarantee the reliability and long-term stability of the alkali metal gas chamber.

[0006] The technical solution of the present application is as follows:

[0007] An alkali metal gas chamber multi-channel transient temperature field measurement method, characterized in that it comprises the following steps:

[0008] Step 1: According to the temperature field reconstruction theory, the spatial layout of a plurality of temperature measuring points on the outer wall and inside of the alkali metal gas chamber is performed, and the temperature field of the to-be-measured alkali metal gas chamber is formed;

[0009] Step 2: The platinum resistance probe is arranged for the plurality of temperature measuring points, and one platinum resistance temperature sensor is arranged at each temperature measuring point;

[0010] Step 3: The temperature field of the alkali metal gas chamber is measured in real time by using the electric control system, and the temperature T, the transmission time t and the transmission distance L of each temperature measuring point are obtained;

[0011] Step 4: The temperature gradient and the discretized temperature gradient module index of the gas chamber are calculated, so as to be used for evaluating the uniformity and temperature gradient of the temperature field of the alkali metal gas chamber.

[0012] Step 1 includes designing the spatial layout of the air chamber using the probe grid layout module, discretizing the area to be measured according to the temperature field algebraic reconstruction algorithm, establishing an xy rectangular coordinate system and an st rectangular coordinate system obtained by rotating the xy rectangular coordinate system to the left by an angle Φ, dividing the x-direction into M grids on average and the y-direction into N grids on average, forming M*N grids.

[0013] Step 2 includes a platinum resistance temperature sensor 1 sealed in the center of the alkali metal gas chamber, a platinum resistance temperature sensor 2 arranged on the left outer wall of the alkali metal gas chamber, and a platinum resistance temperature sensor 3 arranged on the right outer wall of the alkali metal gas chamber. The alkali metal gas chamber is a double-tailed glass gas chamber. Tail tube 1 is connected to the top surface of the gas chamber, serving as a passage for placing the platinum resistance temperature sensor 1 into the gas chamber. Tail tube 2 is connected to the bottom surface of the gas chamber, serving as a passage for the pins of the platinum resistance temperature sensor 1 to exit the gas chamber. There are two through holes between tail tube 2 and the bottom wall, with a diameter of 1 mm and a spacing of 2 mm, for placing the two pins of the platinum resistance temperature sensor 1.

[0014] The electronic control system in step 3 includes a multi-channel platinum resistance thermometer, an analog switch and signal conditioning circuit, an AD data acquisition system, an FPGA, an STM32 microcontroller main controller, and a host computer connected in sequence. The STM32 microcontroller main controller is connected to the temperature compensation circuit in sequence through the FPGA, DA data output, and signal conditioning circuit.

[0015] Step 3 includes obtaining T1, T2, T3, and t. 12 , t 13 L 12 , and L 13 T1 is the temperature at measuring point 1 at the center of the alkali metal chamber, T2 is the temperature at measuring point 2 on the left outer wall of the alkali metal chamber, T3 is the temperature at measuring point 3 on the right outer wall of the alkali metal chamber, and t 12 It is the temperature transfer time between temperature measuring point 1 and temperature measuring point 2, t 13 L is the temperature transfer time between temperature measuring point 1 and temperature measuring point 3. 12 L is the distance between temperature measuring point 1 and temperature measuring point 2. 13 It is the distance between temperature measuring point 1 and temperature measuring point 3.

[0016] Step 4 includes the following expression:

[0017]

[0018] Among them G 12 It is the temperature gradient between temperature measuring point 1 and temperature measuring point 2, G 13 It is the temperature gradient between temperature measuring point 1 and temperature measuring point 3, v 12 It is the temperature field transfer rate between temperature measurement point 1 and temperature measurement point 2, v 13is the temperature field transmission rate between temperature measuring point 1 and temperature measuring point 3, u 12 is the temperature gradient change rate between temperature measuring point 1 and temperature measuring point 2, u 13 is the temperature gradient change rate between temperature measuring point 1 and temperature measuring point 3.

[0019] The temperature data in the temperature data acquisition algorithm process executed by the electric control system in step 3 is collected in an external interruption mode, the temperature data of each platinum resistance temperature sensor is collected by using an interruption service program, the data transmitted by each platinum resistance temperature sensor is polled to collect the data, the interruption service program of the FPGA is triggered when the temperature exceeds 30 degrees Celsius, T1, T2 and T3 are obtained by reading the register values, and G 12 , G 13 and the discretized temperature gradient module A ij are calculated.

[0020] The temperature data acquisition algorithm process includes the following steps:

[0021] Step A1, the data of the first to third platinum resistance temperature sensors is collected by polling the data transmitted by each platinum resistance temperature sensor;

[0022] Step A2, it is judged whether the interruption service is triggered, if not, it returns to step A1, if yes, it enters step A3;

[0023] Step A3, the FPGA interruption service function is entered;

[0024] Step A4, the three-channel temperature values T1, T2 and T3 are read;

[0025] Step A5, the temperature gradient and the discretized temperature gradient module are calculated and displayed in real time.

[0026] Step 4 includes the following expressions:

[0027]

[0028] A=LF,

[0029]

[0030] Where A ij is the discretized temperature gradient module, i and j are the numbers of the grid, f j is the measured temperature value of the jth grid position, L ij is the path length between the ith grid and the jth grid, [PXS(T)] j represents f j , A is the temperature gradient module matrix, L is the path length matrix, F is the temperature matrix, is f jThe (k+1)th iteration, It is f j The k-th iteration, where k is the iteration number, λ is the iteration step size, n is the grid number, and L in It is the path length between the i-th grid and the n-th grid.

[0031] The technical effects of this invention are as follows: This invention provides a multi-channel transient temperature field measurement method for alkali metal gas chambers. It uses temperature field reconstruction theory to spatially arrange multiple temperature measurement points on the outer wall and inside of the alkali metal gas chamber, uses temperature field reconstruction theory to design the placement of platinum resistance probes, and uses an electronic control system to measure the temperature field of the alkali metal gas chamber in real time. It can calculate indicators such as the temperature gradient and discretized temperature gradient modulus of the gas chamber, thereby evaluating the uniformity and temperature gradient of the temperature field of the alkali metal gas chamber.

[0032] Compared with the prior art, the present invention has the following characteristics:

[0033] 1. This invention proposes a new method for multi-channel temperature measurement of alkali metal gas chambers based on temperature field reconstruction theory.

[0034] 2. This invention can measure the temperature field of spatially deformable structures, including linear and cross-shaped configurations.

[0035] 3. This invention enables the measurement of the temperature gradient in the alkali metal gas chamber, thereby ensuring the uniformity and long-term stability of the temperature field in the alkali metal gas chamber. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the probe grid division principle of a multi-channel transient temperature field measurement method for alkali metal gas chambers according to the present invention. Figure 1 It includes an xy rectangular coordinate system, dividing the x-direction into M grids and the y-direction into N grids, for a total of M*N grids. Figure 1 The actual example uses a 5*6 grid (M=5, N=6). f1b1 represents multiplying the temperature value f1 of that grid by the spatial distance b1 from the center of the gas chamber, and so on. MN b MN This indicates the temperature value f of the grid number. MN Spatial distance b from the center of the air chamber MN Multiplication. The st coordinate axis is obtained by rotating the xy coordinate axis to the left by an angle Φ, and its function is to correct the position of the sensor probe. p i It is a line parallel to the s-axis and is used to correct the s-axis deflection angle.

[0037] Figure 2 This is a schematic diagram of the electrical control system of the multi-channel transient temperature field measurement method for alkali metal gas chambers according to the present invention. Figure 2The measurement device includes a multi-channel platinum resistance connected in sequence, an analog switch, a signal conditioning circuit, AD data acquisition (AD is analog-to-digital conversion), an FPGA (programmable logic array), an STM32 single-chip microcomputer host (STM32 represents the specification), and an upper computer.

[0038] Figure 3 The figure is a schematic diagram of a measurement device involved in a multi-channel transient temperature field measurement method of an alkali metal gas chamber. Figure 3 The glass chamber is in the form of a double tail pipe, tail pipe 1 is connected to the top surface of the chamber as a passage for placing the platinum resistance temperature sensor into the chamber, tail pipe 2 is connected to the bottom surface of the chamber as a passage for leading out the pins of the platinum resistance temperature sensor Pt1 from the chamber, there are two through holes with a diameter of 1 mm and a spacing of 2 mm between tail pipe 2 and the bottom wall for placing the two pins of the platinum resistance temperature sensor Pt1, the platinum resistance temperature sensor Pt1 is sealed at the center position of the glass chamber, and the platinum resistance temperature sensors Pt2 and Pt3 are arranged on the outer wall of the glass chamber.

[0039] Figure 4 The figure is a temperature gradient algorithm flowchart of the multi-channel transient temperature field measurement method of the alkali metal gas chamber. Figure 4 The method includes the following steps: step 1, collecting first to third platinum resistance data by polling data transmitted by each platinum resistance; step 2, judging whether an interrupt service is triggered, if not, returning to step 1, and if yes, entering step 3; step 3, entering an FPGA interrupt service function; step 4, reading three-channel platinum resistance temperature values; and step 5, calculating and displaying a temperature gradient and a discretized temperature gradient module in real time. DETAILED DESCRIPTION

[0040] The application will be described below in conjunction with the accompanying drawings Figures 1-4 and examples.

[0041] Figure 1 The figure is a probe grid division principle schematic diagram of the multi-channel transient temperature field measurement method of the alkali metal gas chamber. Figure 2 The figure is an electric control system principle schematic diagram of the multi-channel transient temperature field measurement method of the alkali metal gas chamber. Figure 3 The figure is a schematic diagram of a measurement device involved in a multi-channel transient temperature field measurement method of an alkali metal gas chamber. Figure 4 The figure is a temperature gradient algorithm flowchart of the multi-channel transient temperature field measurement method of the alkali metal gas chamber. Figures 1 to 4As shown, a kind of alkali gas chamber multi-channel transient temperature field measurement method includes the following steps: step 1, according to temperature field reconstruction theory, the spatial layout of multiple temperature measuring points is carried out on the outer wall and inside of alkali gas chamber, and the temperature field of the alkali gas chamber to be measured is formed;Step 2, for the multiple temperature measuring points, platinum resistance probe is arranged, and a platinum resistance temperature sensor is arranged at each temperature measuring point;Step 3, the temperature field of alkali gas chamber is measured in real time by using electric control system, and the temperature T, transmission time t and transmission distance L of each temperature measuring point are obtained;Step 4, the temperature gradient of gas chamber and the discrete temperature gradient module index are calculated, to evaluate the uniformity and temperature gradient of the temperature field of alkali gas chamber.

[0042] Step 1 includes using probe grid point module to carry out gas chamber spatial point design, according to temperature field algebraic reconstruction algorithm, the measured region is discretized and the st rectangular coordinate system obtained by rotating the xy rectangular coordinate system to the left by angle Φ is established, M grids are averagely divided along x direction, N grids are averagely divided along y direction, and M*N grids are formed. Step 2 includes platinum resistance temperature sensor 1 sealed in the center of alkali gas chamber, platinum resistance temperature sensor 2 arranged on the left outer wall of alkali gas chamber, and platinum resistance temperature sensor 3 arranged on the right outer wall of alkali gas chamber, the alkali gas chamber is a double-tube glass gas chamber, tail pipe 1 is connected to the top surface of the gas chamber as a passage for placing platinum resistance temperature sensor 1 into the gas chamber, tail pipe 2 is connected to the bottom surface of the gas chamber as a passage for leading out the pins of platinum resistance temperature sensor 1, there are two through holes with a diameter of 1mm and a spacing of 2mm between tail pipe 2 and bottom wall for placing two pins of platinum resistance temperature sensor 1.

[0043] The electric control system in step 3 includes multi-channel platinum resistance, analog switch and signal conditioning circuit, AD data acquisition, FPGA, STM32 single-chip microcomputer main control and upper computer connected in sequence, and the STM32 single-chip microcomputer main control is connected with temperature compensation circuit through FPGA, DA data output and signal conditioning circuit in sequence. Step 3 includes obtaining T1, T2, T3, t 12 , t 13 , L 12 , and L 13 , T1 is the temperature at temperature measuring point 1 in the center of alkali gas chamber, T2 is the temperature at temperature measuring point 2 on the left outer wall of alkali gas chamber, T3 is the temperature at temperature measuring point 3 on the right outer wall of alkali gas chamber, t 12 is the temperature transmission time of temperature measuring point 1 and temperature measuring point 2, t 13 is the temperature transmission time of temperature measuring point 1 and temperature measuring point 3, L 12 is the distance between temperature measuring point 1 and temperature measuring point 2, L 13 is the distance between temperature measuring point 1 and temperature measuring point 3.

[0044] The following expression is included in Step 4:

[0045]

[0046] Where G 12 is the temperature gradient between temperature measuring point 1 and temperature measuring point 2, G 13 is the temperature gradient between temperature measuring point 1 and temperature measuring point 3, v 12 is the temperature field transmission rate between temperature measuring point 1 and temperature measuring point 2, v 13 is the temperature field transmission rate between temperature measuring point 1 and temperature measuring point 3, u 12 is the temperature gradient change rate between temperature measuring point 1 and temperature measuring point 2, u 13 is the temperature gradient change rate between temperature measuring point 1 and temperature measuring point 3. In Step 3, the temperature data acquisition algorithm flow executed by the electronic control system includes collecting temperature data in an external interrupt manner, collecting temperature data of each platinum resistance temperature sensor using an interrupt service program, collecting data from each platinum resistance temperature sensor through polling, triggering the FPGA interrupt service program when the temperature exceeds 30 degrees Celsius, obtaining T1, T2, and T3 by reading the register value, and calculating G 12 , G 13 , and the discretized temperature gradient module A ij .

[0047] The temperature data acquisition algorithm flow includes the following steps: Step A1, collecting first to third platinum resistance temperature sensor data by polling data from each platinum resistance temperature sensor; Step A2, determining whether to trigger an interrupt service, if not, returning to Step A1, if yes, entering Step A3; Step A3, entering the FPGA interrupt service function; Step A4, reading three-channel temperature values T1, T2, and T3; Step A5, calculating and displaying the temperature gradient and the discretized temperature gradient module in real time.

[0048] The following expression is included in Step 4:

[0049]

[0050] A = LF,

[0051]

[0052] Where A ij is the discretized temperature gradient module, i and j are the numbers of the grid, f j is the temperature value measured at the jth grid position, L ij is the path length between the ith grid and the jth grid, and [PXS(T)] j represents f jA is the temperature gradient magnitude matrix, L is the path length matrix, and F is the temperature matrix. It is f j The (k+1)th iteration, It is f j The k-th iteration, where k is the iteration number, λ is the iteration step size, n is the grid number, and L in It is the path length between the i-th grid and the n-th grid.

[0053] This invention relates to a multi-channel transient temperature field measurement method for alkali metal chambers. The method utilizes temperature field reconstruction theory to spatially arrange multiple temperature measurement points on the outer wall and inside the alkali metal chamber. The platinum resistance probe placement is designed using the same theory. An electronic control system is used to measure the temperature field of the alkali metal chamber in real time, thereby calculating indicators such as the chamber temperature gradient and discretized temperature gradient modulus to evaluate the uniformity and temperature gradient of the alkali metal chamber temperature field. This multi-channel transient temperature field measurement method enables precise placement of temperature sensors within the alkali metal chamber and allows for the design of placement points in various spatial deformation structures. Through this multi-channel transient temperature measurement scheme, accurate measurement and refined analysis of the alkali metal chamber temperature field can be achieved.

[0054] This invention proposes a multi-channel transient temperature field measurement method for alkali metal gas chambers, including a probe grid layout module, a multi-channel platinum resistance temperature measurement circuit module, and a data acquisition and processing module.

[0055] The probe grid layout module is used to design the spatial layout of the air chamber using temperature field reconstruction theory. It discretizes the area to be measured and establishes a rectangular coordinate system based on the algebraic reconstruction algorithm of the temperature field. Figure 1 As shown, the x-direction is divided into M grids on average, and the y-direction is divided into N grids on average, for a total of MN grids. f1b1 represents the product of the temperature value f1 of grid number 1 and its spatial distance b1 from the center of the gas chamber, and so on. The st coordinate axis is obtained by rotating the xy coordinate axis to the left by Φ, and its function is to correct the position of the sensor probe. p i It is a line parallel to the s-axis, used to correct the s-axis deflection angle. Based on the above research on temperature field reconstruction theory, various point layout configurations for temperature field measurement sensor probes within the grid can be designed.

[0056] The specific method involves dividing the plane or space into grids. The principle is to acquire projection data of the temperature field to be measured in multiple directions, and then use a corresponding algorithm to measure and reconstruct the temperature field. This study uses the ART (Algebraic Reconstruction Algorithm) for temperature field reconstruction. The specific process is as follows: First, the region to be measured is discretized into MN grids. After discretization, the temperature gradient magnitude can be expressed as...

[0057]

[0058] where i and j are the grid numbers; f j is the measured temperature value of the jth grid position; L ij is the path length between the ith grid and the jth grid. Denoted as a matrix, it is denoted as the temperature gradient matrix, which is in the form of

[0059] A = LF (2)

[0060] Then the ART algorithm is used to solve the above equation group. The basic idea is to first give an initial solution, and the initial solution is generally 0 under the condition of no prior information; then the residual error between the current calculated temperature value and the measured temperature value is calculated, and the correction is made along the temperature propagation path; then the iteration is continuously carried out until the temperature residual error value meets the reconstruction accuracy requirement. The iteration formula for correcting the jth grid using the ith grid is

[0061]

[0062] where k is the iteration number; λ is the iteration step length.

[0063] The iteration type algorithm has a relatively wide application in the temperature field reconstruction technology because it does not need the temperature values in the full view angle range.

[0064] Reference Figure 2 The multi-channel platinum resistance temperature measurement circuit module functions to measure the multi-channel temperature values by using the electric control system and to simultaneously and synchronously measure the temperature through a unified clock signal, thereby forming the spatial temperature field distribution. The composition includes a power module, an STM32 single-chip microcomputer main control module, an FPGA programmable logic gate array module, a digital-to-analog conversion module, a DDS signal generation module, and a temperature measurement module.

[0065] The data acquisition and processing module functions to acquire and process the voltage signals, to convert the voltage signals into temperature signals, and to quantify the transient temperature field changes of the gas chamber environment. At the same time, the interpolation algorithm is used to display the temperature field change curve in real time and to transmit it to the upper computer for processing and calculation, so as to obtain the transient temperature field change condition.

[0066] The gas chamber is the measurement object of the temperature field measurement sensor. The shape is a spherical gas chamber with a diameter of 30 mm, a tail pipe length of 25 mm, and a contraction diameter of 10 mm.

[0067] As Figure 2As shown, the whole electric control system includes multi-channel platinum resistance, analog switch and signal conditioning circuit, AD analog-digital conversion data acquisition, FPGA (programmable logic gate), STM32 single-chip microcomputer main control, host computer, DA digital-analog conversion data output, temperature compensation circuit, etc. modules. Combined with the functional requirements of the temperature measurement system, taking FPGA and single-chip microcomputer as the core, combining software and hardware design, and combining RTC (real-time clock) and RTOS (real-time operating system) to realize clock synchronization, so that the multi-channel platinum resistance can measure temperature synchronously. RTC provides accurate time information, and RTOS can realize the scheduling and management of real-time tasks. The multi-channel platinum resistance is realized by using constant current source method combined with sampling resistance and analog switch. The temperature compensation circuit adjusts the circuit parameters according to the detected environmental temperature, so that the multi-channel platinum resistance is more stable and reliable in a wide temperature range. The signal conditioning circuit includes operational amplifier and other circuit elements. The host computer is used to display the temperature field change curve and temperature gradient parameters in real time.

[0068] As shown in Figure 3 In order to realize the accurate measurement of the temperature field of the alkali metal gas chamber, a glass chamber temperature sensor probe is used. The probe contains three platinum resistance temperature sensors, which are similar in shape and size to the shape of the alkali metal gas chamber, such as spherical probe and square probe. The platinum resistance temperature sensor 1 is sealed at the center position of the glass chamber, and the platinum resistance temperature sensors 2 and 3 are arranged on the outer wall of the glass chamber respectively and oppositely. The probe glass chamber is designed in the form of double tail pipes. The tail pipe 1 is connected to the top surface of the chamber as a passage for placing the platinum resistance temperature sensor into the chamber. The tail pipe 2 is connected to the bottom surface of the chamber as a passage for leading out the pins of the platinum resistance temperature sensor from the chamber. There are two through holes with a diameter of 1 mm and a spacing of 2 mm between the tail pipe 2 and the bottom wall for placing the two pins of the platinum resistance temperature sensor. The two through holes are designed to prevent short circuit caused by the contact of the pins of the platinum resistance temperature sensor. The platinum resistance temperature sensor for measuring the temperature of the outer wall of the chamber can be pasted on the glass wall of the chamber with insulating heat-conducting glue.

[0069] The temperature at the temperature measurement point 1 is represented by T1, the temperature at the temperature measurement point 2 is represented by T2, the temperature at the temperature measurement point 3 is represented by T3, the temperature transmission time between the temperature measurement point 1 and the temperature measurement point 2 is represented by t 12 The distance is represented by L 12 The temperature transmission time between the temperature measurement point 1 and the temperature measurement point 3 is represented by t 13 The distance is represented by L 13 Therefore, the temperature gradient G 12 of the measurement point 1 and the measurement point 2 can be represented as:

[0070]

[0071] Similarly, the temperature gradient G13 It can be represented as:

[0072]

[0073] Temperature field transfer rate v at measuring point 1 and measuring point 2 12 It can be represented as:

[0074]

[0075] Similarly, the temperature field transmission rate v at measuring points 1 and 3 can be obtained. 13 It can be represented as:

[0076]

[0077] The rate of change of temperature gradient u at measuring point 1 and measuring point 2 12 It can be represented as:

[0078]

[0079] Similarly, the temperature field transmission rate u at measuring points 1 and 3 can be obtained. 13 It can be represented as:

[0080]

[0081] Software algorithm design: such as Figure 4 As shown, the temperature data acquisition algorithm primarily uses external interrupts to acquire temperature data. The interrupt service routine collects the temperature data from the platinum resistance thermometers (PTS). By polling the data from each PTS, the data from the first to the third PTS is acquired. When the temperature exceeds 30 degrees Celsius, the FPGA interrupt service routine is triggered, reading the corresponding register values ​​to obtain the temperature data T1, T2, and T3 for the first to third PTS. Combining this with the aforementioned temperature field reconstruction theory, the temperature gradient G is calculated for each PTS. 12 and G 13 And the discretized temperature gradient modulus A ij The specific process is as follows: Figure 4 As shown.

[0082] This invention relates to a multi-channel transient temperature field measurement method for alkali metal gas chambers. It achieves real-time detection and analysis of the temperature field within the alkali metal gas chamber using a multi-channel platinum resistance temperature probe and temperature field reconstruction theory, evaluating the uniformity and gradient of the temperature field inside the alkali metal gas chamber. This method belongs to the field of atomic thermal electronic control systems.

[0083] A method for measuring the transient temperature field of an alkali metal gas chamber using a multi-channel method, the measuring device comprising a probe grid layout module, a multi-channel platinum resistance temperature measurement circuit module, and a data acquisition and processing module.

[0084] The alkali metal gas chamber adopts a double-tail pipe structure, so that the platinum resistance probe can be placed in the center of the gas chamber.

[0085] In the platinum resistance temperature measurement circuit, the platinum resistance temperature measurement probe is designed based on the temperature field reconstruction theory, the software system adopts FreeRTOS (a kind of real-time operating system RTOS), which is convenient for simultaneous temperature measurement of multiple platinum resistances, and the hardware system adopts the design mode of FPGA (programmable logic gate array) combined with STM32 single-chip microcomputer main control.

[0086] A kind of alkali metal gas chamber multi-channel transient temperature field measurement method.The specific method is, according to the temperature field reconstruction grid point theory, platinum resistance 1 is fixed at the center of the gas chamber and adopts double tail pipe structure to lead wire to the electric control system and data acquisition and processing system, while the remaining 2 platinum resistances are fixed at the center of the two opposite surface outer walls of the gas chamber with insulating heat-conducting glue, so that the three platinum resistances form a planar linear temperature measurement array.Temperature field index calculation method is: the temperature difference between the temperature measurement points is divided by the space distance between the temperature measurement points to obtain the temperature gradient between the two points, the temperature difference between the temperature measurement points is divided by the temperature transmission time between the temperature measurement points to obtain the temperature field transmission rate between the two points, the temperature difference between the temperature measurement points is divided by the space distance between the temperature measurement points and divided by the temperature transmission time between the temperature measurement points to obtain the temperature gradient change rate between the two points, the temperature value of each grid in the discretization grid is multiplied by the distance between the grid and other grids and summed to obtain the temperature gradient module, and its matrix form is recorded as temperature gradient module matrix.

[0087] The contents not described in detail in the specification of the present application belong to the prior art known to those skilled in the art. It is pointed out that the above description is helpful for those skilled in the art to understand the present application, but does not limit the protection scope of the present application. Any equivalent replacement, modification, improvement and / or deletion of the above description without departing from the essential content of the present application falls within the protection scope of the present application.

Claims

1. A method of measuring a multi-channel transient temperature field in an alkali metal cell, characterized by, It comprises the following steps: Step 1, according to the temperature field reconstruction theory, the spatial layout of multiple temperature measuring points is carried out on the outer wall and the inside of the alkali metal gas chamber, and the temperature field of the alkali metal gas chamber to be measured is formed; Step 2, the platinum resistance probe is distributed at the multiple temperature measuring points, and a platinum resistance temperature sensor is arranged at each temperature measuring point; Step 3, the temperature T, the transmission time t and the transmission distance L of each temperature measuring point are obtained by using the electric control system to measure the temperature field of the alkali metal gas chamber in real time; Step 4, the temperature gradient of the gas chamber and the discretization temperature gradient module index are calculated to evaluate the uniformity and temperature gradient of the temperature field of the alkali metal gas chamber; In step 1, the gas chamber space distribution design is carried out by using the probe grid distribution module, the measured area is discretized according to the temperature field algebraic reconstruction algorithm, an xy rectangular coordinate system is established, the st rectangular coordinate system is obtained by rotating the xy rectangular coordinate system to the left by an angle Φ, M grids are evenly divided along the x direction, N grids are evenly divided along the y direction, and M*N grids are formed; In step 4, the following expressions are included: A = LF, where A ij is the discretized temperature gradient matrix, i and j are the grid numbers, f j is the temperature value measured at the jth grid location, L ij is the path length between the ith grid and the jth grid, [PXS(T)] j represents f j , A is the temperature gradient matrix, L is the path length matrix, F is the temperature matrix, is the k+1th iteration of f j , A is the temperature gradient matrix, L is the path length matrix, F is the temperature matrix, is the kth iteration of f j , k is the iteration number, λ is the iteration step, n is the grid number, L in is the path length between the ith grid and the nth grid.

2. The method of claim 1, wherein, In step 2, the platinum resistance temperature sensor 1 is sealed in the center of the alkali metal gas chamber, the platinum resistance temperature sensor 2 is arranged on the left outer wall of the alkali metal gas chamber, and the platinum resistance temperature sensor 3 is arranged on the right outer wall of the alkali metal gas chamber, the alkali metal gas chamber is a double-tube glass gas chamber, the tail pipe 1 is connected to the top surface of the gas chamber as a passage for placing the platinum resistance temperature sensor 1 into the gas chamber, the tail pipe 2 is connected to the bottom surface of the gas chamber as a passage for leading out the pins of the platinum resistance temperature sensor 1 from the gas chamber, there are two through holes with a diameter of 1mm and a spacing of 2mm between the tail pipe 2 and the bottom wall for placing the two pins of the platinum resistance temperature sensor 1.

3. The method of claim 1, wherein, The electric control system in step 3 comprises a multi-channel platinum resistance, an analog switch and a signal conditioning circuit, an AD data acquisition, an FPGA, an STM32 single-chip microcomputer main control and an upper computer connected in sequence, and the STM32 single-chip microcomputer main control is connected with a temperature compensation circuit through the FPGA, a DA data output and a signal conditioning circuit in sequence.

4. The method of claim 1, wherein, T1, T2, T3, t 12 , t 13 , L 12 , and L 13 , T1 is the temperature at the center temperature measuring point 1 of the alkali metal cell, T2 is the temperature at the left outer wall temperature measuring point 2 of the alkali metal cell, T3 is the temperature at the right outer wall temperature measuring point 3 of the alkali metal cell, t 12 is the temperature transmission time between the temperature measuring point 1 and the temperature measuring point 2, t 13 is the temperature transmission time between the temperature measuring point 1 and the temperature measuring point 3, L 12 is the distance between the temperature measuring point 1 and the temperature measuring point 2, and L 13 is the distance between the temperature measuring point 1 and the temperature measuring point 3.

5. The method of claim 4, wherein, In step 4, the following expressions are included: where G 12 is the temperature gradient between temperature measurement point 1 and temperature measurement point 2, G 13 is the temperature gradient between temperature measurement point 1 and temperature measurement point 3, v 12 is the temperature field transmission rate between temperature measurement point 1 and temperature measurement point 2, v 13 is the temperature field transmission rate between temperature measurement point 1 and temperature measurement point 3, u 12 is the temperature gradient change rate between temperature measurement point 1 and temperature measurement point 2, u 13 is the temperature gradient change rate between temperature measurement point 1 and temperature measurement point 3.

6. The method of claim 5, wherein, The temperature data in the temperature data collection algorithm flow executed by the electric control system in step 3 is collected in an external interruption mode, the temperature data of each platinum resistance temperature sensor is collected by using an interruption service program, the data transmitted by each platinum resistance temperature sensor is collected by polling, the interruption service program of the FPGA is triggered when the temperature exceeds 30 degrees Celsius, T1, T2 and T3 are obtained by reading the register values, and G 12 , G 13 , and the discretized temperature gradient module A ij are calculated.

7. The method of claim 6, wherein, The temperature data acquisition algorithm process comprises the following steps: Step A1, the data transmitted by each platinum resistance temperature sensor is polled to acquire the first to third platinum resistance temperature sensor data; Step A2, it is judged whether the interrupt service is triggered, if not, it returns to step A1, if yes, it enters step A3; Step A3, enter the FPGA interrupt service function; Step A4, read the three-channel temperature values T1, T2 and T3; Step A5, calculate and display the temperature gradient and the discretization temperature gradient module in real time.

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