A real-time monitoring system for millimeter-wave coherent scattering turbulence quasi-continuous wave spectrum

Abstract

The present invention provides a real-time monitoring system for the quasi-continuous wavenumber spectrum of millimeter-wave coherent scattering turbulence, belonging to the technical field of magnetic confinement fusion plasma diagnosis. The system comprises a target plasma region, a combination of a first concave mirror and a second concave mirror, a vacuum window, a first convex lens, a second convex lens, a lens holder and a movement system, a mini-lens, and a millimeter-wave receiver array. By optimizing the combination and arrangement of optical mirrors, the present invention expands the receiving solid angle corresponding to the wavenumber range of the scattered signal. Furthermore, in a superconducting tokamak, a fixed-power microwave source is used to mark the power response of each millimeter-wave receiver to it, clarifying the power response coefficient between them, thereby achieving real-time monitoring of the turbulent wavenumber spectrum. Furthermore, a method is proposed to increase the number or installation density of millimeter-wave receivers along a direction perpendicular to the optical axis of the signal receiving optical path, thereby extending the turbulent wavenumber monitoring range or facilitating a denser turbulent wavenumber spectrum, thereby achieving quasi-continuous turbulent wavenumber spectrum monitoring.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic confinement fusion plasma diagnosis, and in particular relates to a millimeter wave coherent scattering turbulence quasi-continuous wave number spectrum real-time monitoring system. Background Art

[0002] Tokamak fusion power plants require long-pulse operation to reduce power generation costs. Therefore, all tokamak fusion devices currently under construction and planning utilize an all-superconducting design. Turbulence-induced transport observed in all-superconducting tokamak fusion devices often far exceeds neoclassical levels, resulting in significant energy losses. Research into the mechanisms of turbulent transport is urgently needed. Measuring, understanding, and controlling anomalous transport is crucial to improving auxiliary heating efficiency and reaching the fusion ignition threshold. This not only offers significant commercial value for controlling controlled fusion reactors but also broadens our understanding of high-temperature physics and holds significant academic research value. Turbulence, the primary mechanism of anomalous transport in plasmas, exhibits multiple wavenumber modes, including the low-wavenumber ion temperature gradient mode, microtear mode, and kinetic balloon mode; the medium-wavenumber trapped electron mode and small-scale electron temperature gradient mode; and the high-wavenumber electron temperature gradient mode. In numerical simulations of plasma physics, the wavenumber spectrum of turbulence is continuous, not discrete. However, these simulation results urgently require experimental verification. Simultaneous measurements of turbulence at different wavenumbers provide an intuitive understanding of the dominant transport type, contribution ratio, and interactions. Furthermore, the evolution of the continuous wavenumber spectrum under different plasma control conditions provides crucial physical measurement evidence for understanding turbulent physics and feedback regulation to suppress anomalous transport, possessing both high academic research value and broad practical application.

[0003] In a fully superconducting tokamak, Doppler backscattering diagnostics were previously used to obtain a fragment of the turbulent wavenumber spectrum of a single plasma discharge. The full wavenumber spectrum was then completed through repeated plasma discharge experiments. This places extremely high demands on the repeatability of plasma experiments and encounters multiple practical difficulties. This is a costly experimental approach. Therefore, there is an urgent need to develop a coherent scattering quasi-continuous spectrum diagnostic system, building on previous experiments and numerical simulations, to effectively reduce experimental costs and significantly improve data confidence.

[0004] The coherent scattering diagnostic system using the millimeter wave band needs to directly measure the wave number continuous spectrum of turbulence, which requires the following: (1) the realization of a quasi-continuous wave number spectrum in a single plasma discharge; (2) the need to achieve large-scale turbulence wave number spectrum monitoring; (3) the evolution of the wave number continuous spectrum over time (i.e., real-time) to verify the feasibility and operational efficiency of the turbulence control method. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a millimeter-wave coherent scattering turbulence quasi-continuous wave number spectrum real-time monitoring system.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A millimeter-wave coherent scattering turbulence quasi-continuous wavenumber spectrum real-time monitoring system comprises a target plasma region, a combination of a first concave mirror and a second concave mirror, a vacuum window, a first convex lens, a second convex lens, a lens holder and a moving system, a mini-lens and a millimeter-wave receiver combination array arranged in sequence; the combination of the first concave mirror and the second concave mirror is located on the plasma side of the superconducting tokamak window tube neck, optically converges the scattered signal output from the full superconducting tokamak device, and achieves the coincidence of the focal plane of the scattered signal and the detector plane, thereby optically amplifying the scattered signal and expanding the receiving solid angle corresponding to the wavenumber range of the scattered signal (i.e., the larger the solid angle, the larger the wavenumber range); the vacuum window is located at the outermost side of the superconducting tokamak window tube neck, and isolates the superconducting tokamak device from the atmosphere and ensures high transmittance of millimeter waves; the convex angle of the first convex lens Facing the vacuum window, the plane side of the first convex lens is parallel to the plane of the vacuum window, and the centers of both planes pass through the scattered signal optical axis to ensure that the scattered signal with a larger receiving solid angle passes through the first convex lens; after passing through the first convex lens, the scattered signal converges at the focus and begins to diverge as the distance increases; the second convex lens is installed on a lens bracket and a moving system that can move along the scattered signal optical axis; the second convex lens converts the divergent light after passing through the focus of the first convex lens into parallel light, which is convenient for being received by the subsequent mini lens and millimeter wave receiver combination array; the mini lens and millimeter wave receiver combination array includes a mini lens array and a millimeter wave receiver array; a single convex lens in the mini lens array converges the parallel light passing through the second convex lens within its diameter height; finally, the parallel light is received by the millimeter wave receiver array converged at the focus.

[0008] Preferably, each receiver from top to bottom in the millimeter wave receiver array sequentially receives corresponding turbulence wave numbers from high to low.

[0009] Preferably, the vacuum window is sealed with high-density polyethylene material.

[0010] Preferably, the distance between the second convex lens and the first convex lens is greater than the focal length of the first convex lens.

[0011] Preferably, the multiple convex lenses in the mini lens array have the same size, and their diameters are one tenth of the second convex lens.

[0012] Preferably, the first convex lens, the second convex lens and the mini lens array are made of high-density polyethylene.

[0013] Preferably, the beam waist of the scattering signal receiving optical path of the coherent scattering diagnostic system is located at the center of the target plasma region.

[0014] Preferably, the apertures of the first convex lens and the second convex lens are not less than the aperture of the vacuum window; the apertures of the first concave mirror and the second concave mirror are not less than the aperture of the vacuum window.

[0015] Preferably, the reflection angles of the first concave mirror and the second concave mirror do not exceed 90 degrees, and the reflection angle of the first concave mirror is not less than 45 degrees.

[0016] Preferably, the channels of the mini lens array and the millimeter wave receiver array correspond one to one to form a mini lens and millimeter wave receiver combination array, the mini lens and the millimeter wave receiver are bound together and fixed, and can be flexibly raised and lowered vertically; the millimeter wave receiver includes multiple channels for detecting scattered signals of different frequencies or directions.

[0017] Beneficial effects:

[0018] 1. The combination of the first concave mirror and the second concave mirror in the present invention realizes the large-aperture collection of scattered signals of different wavenumbers in the scattering volume, and realizes wide wavenumber measurement through a narrow observation window after convergence, while effectively simplifying the design of the optical system and reducing the difficulty of processing, installation and calibration. The combination of the first convex lens and the second convex lens optically converges the scattered signals output from the full superconducting tokamak, realizes the coincidence of the focal plane of the scattered signal and the detector plane, optically amplifies the scattered signal and expands the receiving solid angle of the scattered signal. Such a design can map scattered signals from different directions in the same area to detectors at different heights, thereby achieving a one-to-one mapping relationship between the scattering angle and the detector height. Since there is a mapping relationship between the direction of the scattered signal and the turbulent wavenumber to be detected, a one-to-one mapping between the detector height and the turbulent wavenumber is obtained.

[0019] 2. The measurement limit of the full turbulent wavenumber spectrum depends on the spatial dimensions and mounting position of the first and second concave mirrors. Mounting this combination near the plasma side of the superconducting tokamak's neck increases the measurement limit of the full turbulent wavenumber spectrum. Spectral information within the detectable wavenumber range is fully mapped onto the detector plane. This allows direct acquisition of the full wavenumber spectrum by adjusting the number of detectors and mounting density, eliminating the need for repeated experiments or idealistic assumptions.

[0020] 3. Millimeter-wave receivers and mini-lenses form a mini-lens and millimeter-wave receiver array, which is attached to a lens holder and motion system, enabling synchronous and flexible vertical movement. These arrays are arranged from top to bottom. If the top and bottom arrays, and the arrays within their range, are closely spaced, the wavenumbers monitored in adjacent channels can be denser, achieving a near-continuous wavenumber spectrum, but the overall range of monitored wavenumbers will be reduced. If the top and bottom arrays are sparsely spaced, the wavenumbers monitored in adjacent channels will be sparser, but the overall range of monitored wavenumbers will be expanded. The flexible arrangement, design, and installation of the millimeter-wave receiver and mini-lens array allows for flexible adjustment of the overall range of the monitored wavenumber spectrum or the density of the wavenumbers according to experimental needs, enabling monitoring of turbulence signals across a wide range of wavenumber spectra or a near-continuous wavenumber spectrum.

[0021] 4. Five detection channels cannot simultaneously guarantee a wide range of wavenumbers in the monitored wavenumber spectrum and quasi-continuous wavenumbers monitored by each channel. However, a vertical arrangement of 10 or more one-to-one mini-lens and millimeter-wave receiver combination arrays can ensure both the wavenumber range of the wavenumber spectrum and the density of wavenumbers between detection channels, thus achieving quasi-continuous wavenumber spectrum monitoring of turbulence.

[0022] 5. The present invention utilizes a fixed-power microwave source in a superconducting tokamak to mark the power response of each millimeter receiver to it, clarifies the power response coefficient between them, and realizes real-time monitoring of the turbulence wavenumber spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of a millimeter-wave coherent scattering turbulence quasi-continuous wave number spectrum real-time monitoring system of the present invention.

[0024] Among them, the figure markings are: target plasma area 1, first concave mirror 2, second concave mirror 3, vacuum window 4, first convex lens 5, second convex lens 6, lens holder and moving system 7, mini lens and millimeter wave receiver combination array 8. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] like Figure 1 As shown, a millimeter-wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system of this embodiment includes a target plasma region 1, a first concave mirror 2, a second concave mirror 3, a vacuum window 4, a first convex lens 5, a second convex lens 6, a lens holder and movement system 7, and a mini-lens and millimeter-wave receiver array 8, which are arranged in sequence. The combination of the first concave mirror 2 and the second concave mirror 3 is located near the plasma side of the superconducting tokamak window tube neck. They optically converge the scattered signals output from the fully superconducting tokamak device to obtain a coherent scattering signal receiving beam, aligning the focal plane of the scattered signals with the detector plane, thereby optically amplifying the scattered signals and expanding the receiving solid angle of the scattered signals. The vacuum window 4 is sealed with high-density polyethylene material. It is located at the outermost edge of the superconducting tokamak window tube neck and isolates the superconducting tokamak device from the atmosphere and ensures high millimeter-wave transmittance. The center of the first convex lens 5 is close to the vacuum window 4. The convex surface of the first convex lens 5 faces the vacuum window 4, and the flat side of the first convex lens 5 is parallel to the plane of the vacuum window 4. The centers of both planes pass through the scattered signal optical axis, ensuring that scattered signals across a wide solid angle can pass through the first convex lens 5. After passing through the first convex lens 5, the scattered signals converge at the focal point and begin to diverge as the distance increases. The distance between the second convex lens 6 and the first convex lens 5 must be greater than the focal length of the first convex lens 5. The second convex lens 6 is mounted on a lens holder and movement system 7 that can move along the scattered signal optical axis. The second convex lens 6 converts the divergent light after passing through the focal point of the first convex lens 5 into parallel light, making it easier to receive by the subsequent mini-lens and millimeter-wave receiver array 8. The mini-lens and millimeter-wave receiver array 8 comprises a mini-lens array and a millimeter-wave receiver array. The five convex lenses in the mini-lens array are identical in size, with their diameters approximately one-tenth that of the second convex lens 6. A single convex lens in the mini-lens array can converge parallel light within its diameter after passing through the second convex lens 6. Finally, the parallel light is received by the millimeter wave receiver array focused at the focal point.

[0027] Each receiver from top to bottom in the millimeter wave receiver array receives the corresponding turbulence wave number from high to low in turn.

[0028] Preferably, the first convex lens 5 , the second convex lens 6 and the mini lens array are made of high-density polyethylene (HDPE).

[0029] Preferably, the beam waist of the scattering signal receiving optical path of the coherent scattering diagnostic system is located at the center of the target plasma region 1 .

[0030] Preferably, the apertures of the first convex lens 5 and the second convex lens 6 should not be smaller than the aperture of the vacuum window 4 .

[0031] Preferably, the apertures of the first concave mirror 2 and the second concave mirror 3 should not be smaller than the aperture of the vacuum window 4 .

[0032] Preferably, the reflection angles of the first concave mirror 2 and the second concave mirror 3 do not exceed 90 degrees, and the reflection angle of the first concave mirror 2 is not less than 45 degrees.

[0033] Preferably, the channels of the mini lens array and the millimeter wave receiver array correspond one to one to form a mini lens and millimeter wave receiver combination array 8 , which are bound together and mounted on the lens holder and moving system 7 .

[0034] Preferably, the mini lens and the millimeter wave receiver are bound together and fixed, and can be flexibly lifted and lowered vertically.

[0035] Preferably, the millimeter wave receiver includes multiple channels for detecting scattered signals of different frequencies or directions.

[0036] Preferably, the millimeter wave receiver detects millimeter waves of different frequencies by secondary mixing.

Claims

1. A millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system, characterized in that: The invention comprises a target plasma region, a combination of a first concave mirror and a second concave mirror, a vacuum window, a first convex lens, a second convex lens, a lens bracket and a moving system, a mini lens and a millimeter wave receiver combination array which are arranged in sequence; the combination of the first concave mirror and the second concave mirror is located on the side of the superconducting tokamak window tube neck close to the plasma, optically converges the scattered signal output from the superconducting tokamak device, and realizes that the focal plane of the scattered signal coincides with the detector plane, thereby optically amplifying the scattered signal and expanding the receiving solid angle of the corresponding wave number range of the scattered signal; the vacuum window is located on the outermost side of the superconducting tokamak window tube neck, and isolates the superconducting tokamak device from the atmosphere and ensures high transmittance of millimeter waves; the convex surface of the first convex lens faces the vacuum window, and the flat side of the first convex lens faces the vacuum window. The planes of the empty windows are parallel to each other, and the centers of both planes pass through the scattered signal optical axis, ensuring that scattered signals with a larger reception solid angle pass through the first convex lens. After passing through the first convex lens, the scattered signals converge at the focal point and begin to diverge as the distance increases. The second convex lens is mounted on a lens holder and a moving system that moves along the scattered signal optical axis. The second convex lens converts the divergent light after passing through the focal point of the first convex lens into parallel light, making it easier to be received by a subsequent mini-lens and millimeter-wave receiver combination array. The mini-lens and millimeter-wave receiver combination array includes a mini-lens array and a millimeter-wave receiver array. A single convex lens in the mini-lens array converges parallel light within its diameter height after passing through the second convex lens. Finally, the parallel light is received by the millimeter-wave receiver array converged at the focal point.

2. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1 is characterized in that: Each receiver from top to bottom in the millimeter wave receiver array receives the corresponding turbulence wave number from high to low in turn.

3. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1, characterized in that: The vacuum window is sealed with high-density polyethylene material.

4. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1, characterized in that: The distance between the second convex lens and the first convex lens is greater than the focal length of the first convex lens.

5. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1, characterized in that: The multiple convex lenses in the mini lens array have the same size, and their diameters are one tenth of the second convex lens.

6. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1, characterized in that: The first convex lens, the second convex lens and the mini lens array are made of high-density polyethylene.

7. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1, characterized in that: The beam waist of the scattering signal receiving optical path of the coherent scattering diagnostic system is located at the center of the target plasma area.

8. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1, characterized in that: The apertures of the first convex lens and the second convex lens are not less than the aperture of the vacuum window; the apertures of the first concave mirror and the second concave mirror are not less than the aperture of the vacuum window.

9. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1, characterized in that: The reflection angles of the first concave mirror and the second concave mirror do not exceed 90 degrees, and the reflection angle of the first concave mirror is not less than 45 degrees.

10. The millimeter wave coherent scattering turbulence quasi-continuous wave spectrum real-time monitoring system according to claim 1, characterized in that: The channels of the mini-lens array and the millimeter-wave receiver array correspond one to one to form a mini-lens and millimeter-wave receiver combination array. The mini-lens and millimeter-wave receiver are bound together and fixed, and can be flexibly raised and lowered vertically. The millimeter-wave receiver includes multiple channels for detecting scattered signals of different frequencies or directions.

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