A deformable surface for regulating the wavefront shape of a w-band microwave beam

Abstract

The application discloses a deformable surface for regulating W-waveband microwave beam wavefront shape, relates to the microwave diagnosis technical field of magnetic confinement nuclear fusion plasma, and comprises a mirror surface assembly which comprises a plurality of strip-shaped reflecting units arranged in sequence and is connected in series through a hinge structure between two adjacent strip-shaped reflecting units, the hinge structure allowing relative angular displacement between the adjacent reflecting units; a driving array which comprises a plurality of stepping push rod motors, a push rod of the stepping push rod motor being drivenly connected with a back side support of the mirror surface assembly through a push rod connecting piece; and a reflecting layer used for covering a reflecting side surface of the mirror surface assembly. The deformable surface for regulating W-waveband microwave beam wavefront shape can realize continuous and accurate regulation of mirror surface curvature through cooperative control of the plurality of stepping push rod motors and adapt to dynamic changes of the plasma shape.

Description

Technical Field

[0001] This invention relates to the field of microwave diagnostic technology for magnetically confined nuclear fusion plasma, specifically a deformable surface for controlling the wavefront shape of a W-band microwave beam. Background Technology

[0002] In magnetic confinement fusion plasma diagnostics, microwave imaging reflectometers (MIRs) are an important tool for measuring two-dimensional density fluctuations. Their basic principle involves emitting microwaves of a specific frequency into the plasma, which are reflected at the plasma cutoff layer (isodensity surface). By receiving and analyzing the interference pattern of the reflected waves through a large-aperture optical system, the two-dimensional density fluctuation information of the cutoff layer can be reconstructed.

[0003] To obtain high-quality imaging signals, the microwave beam incident on the cutoff layer must have a wavefront curvature that matches the shape of the cutoff layer and a sufficiently large spot size. However, the plasma shape (including the cutoff layer curvature) in a tokamak device dynamically changes with discharge parameters. Currently, MIR optical paths typically use high-density polyethylene lenses or metal mirrors with fixed curvatures to shape the wavefront, lacking real-time adjustment capabilities, which leads to a decrease in diagnostic performance when the plasma shape changes.

[0004] For wavefront manipulation of W-band microwaves (75-110 GHz), existing technologies face the following challenges: 1. Limited by the space around the magnetic confinement device, it is impossible to directly add a stepping slide to the existing microwave lens optical path for wavefront adjustment, requiring a more flexible and integrated method. 2. Since the operating frequency of microwave imaging reflectometers is in the W-band (75-110 GHz), the wavelength of photoelectric deformable mirrors commonly used in adaptive optics is too long, resulting in insufficient adjustment capability; furthermore, the aperture of photoelectric deformable mirrors is too small to meet the requirements of microwave beams with spot radii of tens of centimeters. For electromagnetic metasurfaces based on printed circuit boards, the wavelength is too short, the size of the metastructure approaches the precision limit of printed circuits, and a large number of structural units are required, leading to high manufacturing costs. Summary of the Invention

[0005] The purpose of this invention is to provide a deformable surface for controlling the wavefront shape of W-band microwave beams, thereby overcoming the shortcomings of the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a deformable surface for controlling the wavefront shape of a W-band microwave beam, comprising: a mirror assembly, which includes a plurality of sequentially arranged strip-shaped reflective units, and adjacent strip-shaped reflective units are connected in series by a hinge structure, wherein the hinge structure allows relative angular displacement between adjacent reflective units; a drive array, which includes a plurality of stepper push rod motors, wherein the push rods of the stepper push rod motors are drivenly connected to the back support of the mirror assembly through push rod connectors; a reflective layer, which is used to cover the reflective side surface of the mirror assembly; and a control system, which includes a microcontroller circuit board, a stepper motor drive module, and a relay module, wherein the microcontroller circuit board is used to receive target wavefront shape commands and control the movement of the stepper push rod motors.

[0007] Preferably, each strip-shaped reflective unit and each hinge structure of the mirror assembly are integrally formed using fused deposition modeling 3D printing technology, and the hinge shaft gap is set to half the height of the printed layer.

[0008] Preferably, the reflective layer is a metal foil adhered to the reflective side of the mirror assembly.

[0009] Preferably, the push rod connector is connected to the back side bracket by a back fixing screw, and the push rod connector and the smooth section of the back fixing screw form a connection structure that can rotate relative to each other.

[0010] Preferably, the stepper motor drive module in the control system is mounted on the drive module mounting plate, the microcontroller circuit board is mounted on the microcontroller mounting plate, and each mounting plate is fixed to the bottom fixing plate.

[0011] Preferably, the control system is configured to receive the radius of curvature parameter and automatically calculate the target displacement of each stepper motor based on the parameter.

[0012] Preferably, it has a control method, which includes the following steps: setting the target wavefront shape parameters through the host computer operation interface; the microcontroller circuit board receiving the parameters and calculating the target displacement of each stepper motor; the stepper motor drive module driving the stepper motor to move to the target position; and the mirror assembly deforming to the target shape to regulate the wavefront of the W-band microwave beam.

[0013] A deformable reflector system includes: a deformable surface as described above; a mechanical frame including a bottom fixing plate, side fixing plates, and a motor array mounting plate for supporting and fixing the components; and stepper motors are alternately mounted on the motor array mounting plate.

[0014] Preferably, it also includes a high-density polyethylene lens, and the deformable surface and the high-density polyethylene lens are combined to form a complete beam control optical path.

[0015] In the above technical solution, the present invention provides a deformable surface for controlling the wavefront shape of a W-band microwave beam. Through the coordinated control of multiple stepper motors, it can achieve continuous and precise adjustment of the mirror curvature, adapting to dynamic changes in plasma shape. Furthermore, it employs an integrated hinge structure and modular design, resulting in a small overall size, suitable for installation and use around fusion devices with limited space. Moreover, the core deformable surface is manufactured using fused deposition modeling (FDM) 3D printing, significantly reducing costs compared to metasurfaces fabricated through precision optical processing or micro / nano-fabrication.

[0016] On the other hand, the adoption of stepper motor drive and closed-loop control enables sub-millimeter-level displacement accuracy, meeting the requirements of W-band microwave modulation. The rotatable connection design between the push rod connector and the rear fixing screw avoids lateral bending moments on the motor due to mirror deformation, extending the equipment's lifespan. Furthermore, through a graphical host computer interface, operators can intuitively set the target wavefront parameters, and the system automatically completes complex calculations and control processes. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0018] Figure 1 This is a schematic diagram of the overall structure provided for an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the reflection module provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the connection between the stepper motor and the deformed surface provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a partial structure of the deformed surface provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the control program operation panel interface provided in an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Mirror assembly; 101. Back side bracket; 102. Hinge structure; 2. Push rod connector; 3. Stepper push rod motor; 4. Stepper motor drive module; 5. Microcontroller circuit board; 6. 12V to 3.3V step-down module; 7. Relay module; 8. 12V switching power supply; 9. High-density polyethylene lens; 10. Bottom fixing plate; 11. Side fixing plate; 12. Motor array mounting plate; 13. Drive module mounting plate; 14. Microcontroller mounting plate; 15. Rear fixing screws. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] Please see Figure 1-5 This invention provides a deformable surface for controlling the wavefront shape of a W-band microwave beam, comprising a mirror assembly 1 (deformable surface), a driving array, a reflective layer, and a control system. The mirror assembly 1 (deformable surface) includes multiple strip-shaped reflective units arranged sequentially, and adjacent strip-shaped reflective units are connected in series via a hinge structure 102, which allows relative angular displacement between adjacent reflective units. The driving array includes multiple stepper motors 3, and the push rods of the stepper motors 3 are drivenly connected to the back support 101 of the mirror assembly 1 via push rod connectors 2. The reflective layer is used to cover the reflective side surface of the mirror assembly 1. The control system includes a microcontroller circuit board 5, a stepper motor drive module 4, and a relay module 7. The microcontroller circuit board 5 is used to receive the target wavefront shape command and control the movement of the stepper motors 3.

[0022] Among them, each strip-shaped reflective unit and each hinge structure 102 of the mirror component 1 are integrally formed by fused deposition modeling 3D printing technology, and the rotation shaft gap of the hinge structure 102 is set to half the height of the printed layer.

[0023] The reflective layer is a metal foil attached to the reflective side of the mirror assembly 1.

[0024] The push rod connector 2 is connected to the back side bracket 101 via the back fixing screw 15, and the push rod connector 2 and the smooth section of the back fixing screw 15 form a connection structure that can rotate relative to each other.

[0025] In the control system, the stepper motor drive module 4 is mounted on the drive module mounting plate 13, the microcontroller circuit board 5 is mounted on the microcontroller mounting plate 14, and each mounting plate is fixed to the bottom fixing plate 10.

[0026] The control system is configured to receive the radius of curvature parameter and automatically calculate the target displacement of each stepper motor 3 based on the parameter.

[0027] The control method includes the following steps: setting the target wavefront shape parameters through the host computer operation interface; receiving the parameters and calculating the target displacement of each stepper motor 3; driving the stepper motor 3 to move to the target position through the stepper motor drive module 4; and deforming the mirror assembly 1 to the target shape to regulate the wavefront of the W-band microwave beam.

[0028] Based on the above: like Figure 4As shown, it displays some structural units of the deformable surface. The mirror assembly (deformable surface) consists of a series of elongated units, with two elongated units connected as a whole by a built-in hinge structure 102. Since the gap between the hinge axes is set to half the height of the FDM-3D printing layer, after 3D printing, the inner and outer surfaces of the hinges will contact each other but not adhere. At this point, the two elongated units can generate a small-angle rotational displacement around the hinge axis. In other dimensions, the relative movement between the two is fully restricted by the hinge, ensuring the shape of the deformable surface is controllable. At this point, a push rod motor 3 is installed every 3-4 structural units on the back side of the deformable surface to position the shape of the deformable surface, thus meeting the reflection requirements of the spatial beam. To ensure efficient reflection of the deformable surface, a layer of copper foil tape needs to be applied to the printed deformable surface. like Figure 3 As shown, the push rod connector 2 is manufactured using fused deposition modeling (FDM) 3D printing to ensure consistent processing precision. The push rod connector 2 is threaded to the end of the push rod, and the surface shape is positioned by the movement of the push rod motor 3. The back fixing screw 15 is threaded to the back support 101 of the deformed surface 1 to prevent the back fixing screw 15 from falling off during operation. The relative movement between the deformed surface back support 101 and the push rod connector 2 around the back fixing screw 15 avoids excessive lateral bending moment on the push rod motor 3 when the angle between the deformed surface and the initial position is too large, thus preventing accelerated motor wear.

[0029] A deformable reflector system includes: a deformable surface; a mechanical frame including a bottom fixing plate 10, a side fixing plate 11, and a motor array mounting plate 12 for supporting and fixing the components; and stepper motors 3 alternately mounted on the motor array mounting plate 12.

[0030] It also includes a high-density polyethylene lens 9, and the deformable surface and the high-density polyethylene lens 9 are combined to form a complete beam control optical path.

[0031] Furthermore, after the control program is programmed into the microcontroller, a computer acts as the host computer for control. The host computer sends the displacement distance of each motor to the microcontroller, and the microcontroller sequentially sends pulse signals through its pins to the pulse inputs of each stepper motor drive module according to the instructions. To improve the utilization of the microcontroller pins, the direction input of each stepper motor drive module is controlled by a single pin. However, the push-pull current of a single pin cannot simultaneously drive the inputs of all drive modules. Therefore, a relay is needed to directly connect the positive or negative terminal of the power supply to the direction input of the drive module. Once all the push-pull motors have moved to the set position, the microcontroller returns a signal to the host computer indicating that the operation is complete and enters a state of waiting for the next instruction.

[0032] As an embodiment of the present invention, such as Figure 1 As shown, two deformable mirror systems paired with a high-density polyethylene lens are used to simultaneously adjust the wavefront shape and spot size of a microwave beam. First, the lens parameters and adjustment range of the deformable surfaces in the optical path need to be determined based on the experimental requirements. The optical path design process is as follows: First, the two deformable surfaces are set as planar reflectors. The microwave lens between the two systems, combined with the external optical path, adjusts the wavefront in the vertical direction of the beam to approach the target requirement, while simultaneously constraining the spot in the horizontal direction to prevent divergence. Then, the curvature of the two deformable surfaces is changed. For each wavefront shape, the maximum achievable spot radius is selected, and the curvature of the two deformable surfaces at this point serves as the corresponding wavefront shape. Finally, within the adjustment range, the correspondence between the wavefront shape and the curvature of the two deformable surfaces is established. This allows the wavefront shape to be adjusted during the experiment by changing the curvature of the two deformable surfaces. This ensures that the spot size meets the observation requirements while changing the wavefront curvature at the target location.

[0033] Then assemble the circuit control section of the deformable mirror system. Figure 2 In the design, 11 pairs of stepper motors 3 are arranged in two rows, left and right, to ensure uniform force distribution on both sides of the deformable surface. Simultaneously, the stepper motors 3 are staggered on the motor array mounting plate 12, reducing the vertical spacing and allowing for more precise control of the surface shape. Eleven stepper motor drive modules 4 are mounted on mounting posts on the drive module mounting plate 13. Potentiometers on the drive modules adjust the output current, enabling simultaneous driving of two stepper motors. The microcontroller circuit board 5, the 12V to 3.3V step-down module 6, and the relay module 7 are mounted at corresponding positions on the microcontroller mounting plate 14. The signal control lines and power supply lines of each part are connected, and the microcontroller is connected to the host computer to establish communication. Each motor channel is tested through the "control program operation panel." After confirming that all motors are operating normally, the extension length of the stepper motors is moved to the same position, and the stepper connector 2 is fixed to each stepper motor 3.

[0034] Then, the switching power supply 8, motor array mounting plate 12, drive module mounting plate 13, and microcontroller mounting plate 14 are respectively installed onto the bottom fixing plate 10, as follows: Figure 2 As shown. The gaps between the mounting plates ensure good heat dissipation, preventing damage caused by overheating of the stepper actuator motor 3 and the stepper motor drive module 4. The motor array mounting plate is adjusted to a vertical position and fixed with the help of the side fixing plate 11.

[0035] Finally, the bracket fixing hole 101 behind the deformable surface 1 is connected to the push rod connector 2 via the deformable surface fixing screw 15, as follows: Figure 3As shown. To increase the operating space for fixing the deformable surface, all push rod motors can be moved to their maximum stroke position via the "Control Program Operation Panel". The deformable surface fixing screw 15 is fixed to the bracket fixing hole 101 by threads, and the deformable surface fixing screw 15 and the smooth inner wall of the rod connector 2 can rotate relative to each other. After installing the entire system according to the above steps, the microcontroller can be controlled via the "Control Program Operation Panel" to operate the movement of the push rod motors and realize the adjustment of the optical path by the deformable surface.

[0036] The host computer's "control program operation panel" is as follows: Figure 5 As shown. First, establish communication via serial port: Select the serial port corresponding to the microcontroller in the "Serial Port Name" field at the top left, and click the "Connect" serial port switch. When the "Serial Port Connection Status" is green, it indicates that the "Control Program Operation Panel" of the host computer has successfully established communication with the microcontroller. Then, set an appropriate motor movement speed: Too fast a movement speed will cause a decrease in the torque thrust of the stepper motor, resulting in missed steps in the pulse response and reducing the accuracy of positioning. The "Speed" of the motor movement speed is usually set to around "3 r / s". For "Microstepping", enter the correct microstepping value according to the settings of the drive module, and then click "OK" to send the speed setting command to the microcontroller. The middle section allows for the movement of individual motors: Before installing the deformable surface, fine-tune and calibrate the position of each motor. Enter an appropriate value in the "Displacement" field of the corresponding channel motor, and then click "Forward / Backward" to control the movement of the channel motor to confirm that each motor and drive module is functioning normally. After installing the deformable surface, use "Unified Forward / Backward" to move the deformable surface to the correct position as a whole, which can compensate for the machining errors of the overall frame. After movement, the positions of each motor will be displayed in the "Current Position". The "Pulse Step Length" is set according to the stepper motor's step angle; that is, after each pulse signal is received, the rotor inside the motor will rotate 15 degrees, and the corresponding motor push rod will extend 0.0256mm. A "Mechanical Zeroing" function is also set in the middle section, quickly moving all motor push rods to the shortest extension length and updating the "Current Position" to 0. The right side shows the overall control of the push rod motor array during the experiment: when "Use Curvature Radius" is off, the position of each group of motors can be set individually, thus setting the deformed surface to non-circular shapes such as parabolas and ellipses through interpolation; when "Use Curvature Radius" is on, by inputting the center position and surface curvature parameters, the program quickly calculates the set position of each push rod based on the motor's "Y-axis position" in the vertical direction. Finally, clicking the "OK" button sends a command to the microcontroller to quickly change the shape of the deformed surface. After each displacement, the position data of each motor is synchronously displayed on the "Current Position" of the operation panel to prevent the push rod from exceeding its travel range during operation.

[0037] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A deformable surface for controlling the wavefront shape of a W-band microwave beam, characterized in that, include: The mirror assembly (1) includes a plurality of strip-shaped reflective units arranged in sequence, and adjacent strip-shaped reflective units are connected in series by a hinge structure (102), which allows relative angular displacement between adjacent reflective units. The drive array includes multiple stepper motors (3), the push rods of which are driven to the back support (101) of the mirror assembly (1) via push rod connectors (2); A reflective layer for covering the reflective side surface of the mirror assembly (1); The control system includes a microcontroller circuit board (5), a stepper motor drive module (4), and a relay module (7). The microcontroller circuit board (5) is used to receive the target wavefront shape command and control the action of the stepper push rod motor (3).

2. The deformable surface for controlling the wavefront shape of a W-band microwave beam according to claim 1, characterized in that, Each strip-shaped reflective unit and each hinge structure (102) of the mirror assembly (1) are integrally formed using 3D printing technology, and the hinge shaft gap of the hinge structure (102) is set to half the height of the printed layer.

3. A deformable surface for controlling the wavefront shape of a W-band microwave beam according to claim 1, characterized in that, The reflective layer is a metal foil attached to the reflective side of the mirror assembly (1).

4. A deformable surface for controlling the wavefront shape of a W-band microwave beam according to claim 1, characterized in that, The push rod connector (2) is connected to the back side bracket (101) by the back fixing screw (15), and the push rod connector (2) and the smooth section of the back fixing screw (15) form a connection structure that can rotate relative to each other.

5. A deformable surface for controlling the wavefront shape of a W-band microwave beam according to claim 1, characterized in that, The stepper motor drive module (4) in the control system is mounted on the drive module mounting plate (13), and the microcontroller circuit board (5) is mounted on the microcontroller mounting plate (14). Each mounting plate is fixed to the bottom fixing plate (10).

6. A deformable surface for controlling the wavefront shape of a W-band microwave beam according to claim 1, characterized in that, The control system is configured to receive the radius of curvature parameter and automatically calculate the target displacement of each stepper motor (3) based on the parameter.

7. A deformable surface for controlling the wavefront shape of a W-band microwave beam according to claim 1, comprising a control method, characterized in that, The control method includes the following steps: Set the target wavefront shape parameters through the host computer operation interface; The microcontroller circuit board (5) receives parameters and calculates the target displacement of each stepper motor (3); The stepper motor drive module (4) drives the stepper push rod motor (3) to move to the target position; The mirror assembly (1) is deformed to the target shape to modulate the wavefront of the W-band microwave beam.

8. A deformable reflector system, characterized in that, include: The deformable surface as described in any one of claims 1-7; The mechanical frame includes a bottom fixing plate (10), a side fixing plate (11), and a motor array mounting plate (12) for supporting and fixing the components; The stepper motors (3) are staggered on the motor array mounting plate (12).

9. A deformable surface for controlling the wavefront shape of a W-band microwave beam according to claim 8, characterized in that, It also includes a high-density polyethylene lens (9), and the deformable surface and the high-density polyethylene lens (9) are combined to form a complete beam control optical path.

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