A method for designing a window of a magnetic shielding room based on a shielding pipeline and an active magnetic compensation coil

Abstract

The application discloses a kind of based on shielding pipeline and active magnetic compensation coil's magnetic shielding room window design method, including shielding pipeline and active magnetic compensation coil, the shielding pipeline is located at the opening of each shielding layer of magnetic shielding room, is connected with each shielding layer opening using the mode of welding, the length of each layer shielding pipeline and the opening size of each layer shielding layer satisfy specific relationship;The active magnetic compensation coil is located outside the outermost shielding pipeline, and its specific position and size are determined using the method of traversal solution.This application not only has the same shielding effect with closed magnetic shielding room, but also solves the current problems, such as difficult communication between personnel in the room and the outside world, low comfort, caused by the closed structure of magnetic shielding room.

Description

Technical Field

[0001] This invention relates to the fields of passive magnetic shielding and active magnetic compensation technology for magnetically shielded rooms, and in particular to a window design method for magnetically shielded rooms based on shielded pipes and active magnetic compensation coils. Background Technology

[0002] Magnetic fields are widely present in scientific experiments, involving multiple fields such as geophysics, military, materials science, and biomedicine. Magnetoencephalography (MEG) is one important application. MEG values ​​are tens of fT, therefore, measurements require an extremely low magnetic field environment. However, in a typical geomagnetic environment, the magnetic field strength is 50,000 nT, six orders of magnitude higher than that of MEG. Furthermore, many interfering magnetic fields exist in the environment, and these interfering magnetic fields are also several orders of magnitude stronger than those of MEG. Therefore, MEG measurements must be conducted in a typical magnetically shielded room.

[0003] Most currently designed magnetically shielded rooms are closed structures, meaning they only have an opaque door for personnel to enter and exit, and some small openings for sensor access. However, a fully enclosed magnetically shielded room hinders communication between the person inside and the outside world, and the enclosed environment reduces patient comfort. Therefore, designing a magnetically shielded room with a transparent window is of great significance. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a window design method for a magnetically shielded room based on shielded pipes and active magnetic compensation coils, thereby solving the problems of difficulty in communication between people inside the room and the outside world, and low comfort levels caused by the enclosed structure of magnetically shielded rooms.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for designing a window for a magnetically shielded room based on shielded pipes and an active magnetic compensation coil is disclosed. The method involves setting up an inner shielded pipe and an outer shielded pipe, which are connected to the inner and outer shielding layers of the magnetically shielded room, respectively. The inner and outer shielded pipes are welded to the openings of the inner and outer shielding layers of the magnetically shielded room. The lengths of the inner and outer shielded pipes are optimally determined to minimize the residual magnetic field at the center point of the magnetically shielded room. An active magnetic compensation coil is installed outside the outer shielded pipe to generate a compensating magnetic field, offsetting magnetic leakage caused by the window opening and ensuring the residual magnetic field distribution in the working area of ​​the magnetically shielded room reaches the level before the window was opened. The specific location and size of the active magnetic compensation coil are determined using a traversal method, aiming to ensure that the residual magnetic field distribution in the central area of ​​the magnetically shielded room follows the same trend as that in the central area of ​​a closed magnetically shielded room, thus determining the size of the active magnetic compensation coil and its specific location within the outer shielded pipe.

[0007] Furthermore, the inner and outer shielding pipes are fixed to the outside of each opening of the magnetic shielding room. The shape and size of each opening match the cross-sectional shape and size of the connected inner and outer shielding pipes. The materials of the inner and outer shielding pipes are the same as the shielding layer material of the magnetic shielding room.

[0008] Furthermore, the length of the shielding pipes connected to each layer of openings is different, and the length of the shielding pipes in each layer is determined by optimal solution, with the goal of minimizing the residual magnetic field at the center point of the magnetic shielding room, to determine the optimal length of the shielding pipes in each layer.

[0009] Furthermore, the length of the shielding pipe obtained by the optimal solution is: the length of the inner shielding pipe is half the size of the opening of the inner shielding layer of the magnetic shielding room, and the length of the outer shielding pipe is equal to the size of the opening of the outer shielding layer of the magnetic shielding room.

[0010] Furthermore, the active magnetic compensation coil is a uniform multi-turn coil with the same shape as the outer shielding pipe, but larger in size.

[0011] Furthermore, the specific location and size of the active magnetic compensation coil are determined using a traversal method, as follows:

[0012] Taking the four vertices and the center point of the working area as reference points, denoted as points p1, p2, p3, p4, and o, the magnitude of the residual magnetic field of the enclosed magnetically shielded room at these five points is denoted as B. P1 B P2 B P3 B P4 The residual magnetic field strength at these five points in the window-shielded magnetic room is B. p1 ′,B p2′,B p3 ′,B p4 ′,B o The design error function E is as follows:

[0013]

[0014] Furthermore, we find the minimum value of the above error function, denoted as the objective function F, as follows:

[0015] F = min(E);

[0016] Furthermore, the optimal solution steps for determining the specific location and size of the active magnetic compensation coil are as follows:

[0017] Stpe1: Design the active magnetic compensation coil to be close to the outer wall of the outer shielding pipe. Let the side length of the active magnetic compensation coil be a, and the length of the outer shielding pipe be b.

[0018] Stpe2: First, place the active magnetic compensation coil at one end of the outer shielded pipe, take a step size Δb, and move the active magnetic compensation coil to the other end of the outer shielded pipe in sequence according to the step size Δb. Calculate the error function E after each movement of the active magnetic compensation coil position.

[0019] Stpe3: Obtain the objective function F through the error function E, and record the specific position of the active magnetic compensation coil that satisfies the objective function. This position is the optimal position of the active magnetic compensation coil.

[0020] Stpe4: At the optimal position, take an increment Δa and successively set the side length of the active magnetic compensation coil to a+n*Δa, where n=0,1,2,3... and n*Δa≤3a, and calculate the error function E after each change of the side length of the active magnetic compensation coil;

[0021] Step 5: Obtain the objective function F through E, and denote the side length of the active magnetic compensation coil that satisfies the objective function F. This size is the optimal side length of the active magnetic compensation coil.

[0022] By following the above five steps, the specific location and size of the active magnetic compensation coil can be determined.

[0023] The present invention discloses the following technical effects:

[0024] The present invention relates to a window design for a magnetically shielded room based on shielded pipes and active magnetic compensation coils. This design is simple and not only provides excellent shielding but also solves the problems of limited communication and low comfort levels caused by the enclosed structure of current magnetically shielded rooms. The window design based on shielded pipes and active magnetic compensation coils ensures that the residual magnetic field distribution in the working area of ​​the magnetically shielded room is the same as that of a closed magnetically shielded room, and the overall residual magnetic field magnitude is even smaller than that of a closed magnetically shielded room. Attached Figure Description

[0025] 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 introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 An overall structural diagram of a window design method for a magnetically shielded room based on a shielded pipe and an active magnetic compensation coil, provided in an embodiment of the present invention;

[0027] Figure 2 This is a partial sectional view of the designed window provided in an embodiment of the present invention;

[0028] Figure 3 The residual magnetic field distribution diagram of the central region cross section of a closed magnetically shielded room provided by COMSOL software simulation in an embodiment of the present invention;

[0029] Figure 4 The residual magnetic field distribution diagram of the central region cross section of the magnetically shielded room when only the window is open but no shielding pipe and compensation coil are added, provided by the COMSOL software simulation for the embodiments of the present invention;

[0030] Figure 5 The residual magnetic field distribution diagram of the cross-section of the central region of a magnetically shielded room when the window of a shielded pipe is opened but no compensation coil is added, as simulated by COMSOL software in an embodiment of the present invention;

[0031] Figure 6 COMSOL software simulation provided for embodiments of the present invention Figure 1 The residual magnetic field distribution diagram of the central region section of the structure.

[0032] Wherein, 1 represents the inner shielding layer of the magnetic shielding room; 2 represents the outer shielding layer of the magnetic shielding room; 3 represents the inner shielding pipe; 4 represents the outer shielding pipe; and 5 represents the active magnetic compensation coil. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 and Figure 2 As shown, this invention provides a window design method for a magnetically shielded room based on shielded pipes and active magnetic compensation coils, comprising:

[0036] An inner shielding pipe 3 and an outer shielding pipe 4 are provided. The inner shielding pipe 3 and the outer shielding pipe 4 are respectively connected to the inner shielding layer 1 and the outer shielding layer 2 of the magnetic shielding room located in the magnetic shielding room. They are generally connected by welding.

[0037] Furthermore, the lengths of the inner shielding pipe 3 and the outer shielding pipe 4 are optimally calculated to minimize the residual magnetic field at the center point of the magnetic shielding room. As a result, in this embodiment, the length of the inner shielding pipe 3 is half the size of the opening of the inner shielding layer 1 of the magnetic shielding room, and the length of the outer shielding pipe 4 is equal to the size of the opening of the outer shielding layer 2 of the magnetic shielding room.

[0038] An active magnetic compensation coil 5 is installed outside the outer shielding pipe 4. By generating a compensation magnetic field, the magnetic leakage caused by opening the window in the magnetic shielding room is offset, so that the remaining magnetic field distribution in the working area of ​​the magnetic shielding room reaches the level before the window is opened.

[0039] Furthermore, the specific location and size of the active magnetic compensation coil 5 are determined by a traversal method, with the goal of making the residual magnetic field distribution in its working area the same as that of the enclosed magnetic shielding room.

[0040] Furthermore, taking the four vertices and the center point of the working area as reference points, denoted as points p1, p2, p3, p4, and o, the magnitude of the residual magnetic field of the enclosed magnetic shielding room at these five points is denoted as B. P1 B P2 B P3 B P4 Let B0 represent the magnitude of the residual magnetic field at these five points in the windowed magnetic shielding room designed in this invention. p1 ′,B p2 ′,B p3 ′,B p4 ′,B o The design error function E is as follows:

[0041]

[0042] Furthermore, we find the minimum value of the above error function, denoted as the objective function F, as follows:

[0043] F = min(E);

[0044] Furthermore, the optimal solution steps for determining the specific location and size of the active magnetic compensation coil 5 are as follows:

[0045] Stpe1: Design the active magnetic compensation coil 5 to be close to the outer wall of the outer shielding pipe 4. Let the side length of the active magnetic compensation coil 5 be a, and the length of the outer shielding pipe 4 be b.

[0046] Stpe2: First, place the active magnetic compensation coil 5 at one end of the outer shielding pipe 4, take a step size Δb, and move the active magnetic compensation coil 5 to the other end of the outer shielding pipe 4 in sequence according to the step size Δb. Calculate the error function E after each movement of the active magnetic compensation coil 5.

[0047] Stpe3: Obtain the objective function F through the error function E, and record the specific position of the active magnetic compensation coil 5 that satisfies the objective function. This position is the optimal position of the active magnetic compensation coil 5.

[0048] Stpe4: At the optimal position, take the increment Δa and set the side length of the active magnetic compensation coil 5 to a+n*Δa in turn, where n=0,1,2,3... and n*Δa≤3a. Calculate the error function E after each change of the side length of the active magnetic compensation coil 5.

[0049] Step 5: Obtain the objective function F through the error function E, and denote the side length of the active magnetic compensation coil 5 that satisfies the objective function. This side length is the optimal size of the active magnetic compensation coil 5.

[0050] By following the above five steps, the specific location and size of the active magnetic compensation coil 5 can be determined.

[0051] like Figure 4 and Figure 5 As shown, when the magnetically shielded room has windows and inner shielding pipe 3 and outer shielding pipe 4 are added, the distribution of the residual magnetic field in the central area has the same trend as when the inner shielding pipe 3 and outer shielding pipe 4 are not added, but the overall shielding effect is increased by S times. The expression for S is as follows:

[0052]

[0053] Among them, T1 is Figure 4 The center value of the distribution range of the residual magnetic field magnitude, T2 is Figure 5The center value of the distribution range of the remaining magnetic field size is used to improve the shielding effect by about 19 times in this embodiment.

[0054] like Figure 3 and Figure 6 As shown, the window design method of the present invention, which combines the inner shielding pipe 3, the outer shielding pipe 4, and the active magnetic compensation coil 5, can make the residual magnetic field distribution in the central area after the window is opened the same as the residual magnetic field distribution in the closed magnetic shielding room, or even smaller overall residual magnetic field.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for designing window openings in a magnetically shielded room based on shielded pipes and active magnetic compensation coils, characterized in that: An inner and outer shielding pipe are installed, connected to the inner and outer shielding layers of the magnetic shielding room, respectively. The inner and outer shielding pipes are welded to the openings of the inner and outer shielding layers of the magnetic shielding room. The lengths of the inner and outer shielding pipes are optimally calculated to minimize the residual magnetic field at the center point of the magnetic shielding room. An active magnetic compensation coil is installed outside the outer shielding pipe to generate a compensation magnetic field, offsetting magnetic leakage caused by opening windows in the magnetic shielding room, thus ensuring the residual magnetic field distribution in the working area of ​​the magnetic shielding room reaches the level before opening windows. The specific location and size of the active magnetic compensation coil are determined using a traversal method, aiming to ensure the distribution of the residual magnetic field in the center area of ​​the magnetic shielding room matches the distribution trend of the residual magnetic field in the center area of ​​a closed magnetic shielding room. The length of the inner shielding pipe is half the size of the opening of the inner shielding layer of the magnetic shielding room, and the length of the outer shielding pipe is equal to the size of the opening of the outer shielding layer of the magnetic shielding room. The active magnetic compensation coil is a uniform multi-turn coil, with the same shape as the outer shielding pipe, but larger in size. The specific location and size of the active magnetic compensation coil are obtained by a traversal method, as follows: Take the four vertices and the center point of the working area as reference points, and denote them as points. Then, record the magnitude of the residual magnetic field at these five points in the enclosed magnetically shielded room as: The residual magnetic field strength of the magnetically shielded room with open windows at the above five points is: Design error function ,as follows: ； Find the minimum value of the above error function E, denoted as the objective function to be solved. ,as follows: ； The optimal steps for determining the specific location and size of the active magnetic compensation coil are as follows: Step 1: Place the active magnetic compensation coil tightly against the outer wall of the outer shielding pipe, and record the side length of the active magnetic compensation coil as... The length of the outer shielding pipe is ; Step 2: First, place the active magnetic compensation coil at one end of the outer shielded pipe and determine the step size. , in sequence according to step size Move the active magnetic compensation coil to the other end of the outer shielded pipe and calculate the error function after each movement of the active magnetic compensation coil. ; Step 3: Using the error function Find the objective function Let the objective function be satisfied. The specific location of the lower active magnetic compensation coil is the optimal location of the active magnetic compensation coil; Step 4: At the optimal position, take the increment. The side lengths of the active magnetic compensation coils are sequentially set to... ,in and Calculate the error function after each change in the side length of the active magnetic compensation coil. ; Step 5: Using the error function Find the objective function Let the objective function be satisfied. The side length of the lower active magnetic compensation coil is the optimal side length of the active magnetic compensation coil. By following the above five steps, the specific location and size of the active magnetic compensation coil can be determined.

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