Interference fringe calibration system and method for Doppler coherent imaging spectrum diagnosis

Abstract

The invention discloses an interference fringe calibration system and method for Doppler coherent imaging spectrum diagnosis. The system comprises a forward and reverse dual-optical-path Doppler coherent imaging system and an external moving light source. And the forward and reverse dual-optical-path Doppler coherent imaging system performs interference fringe imaging on light of which the wavelength is a target multi-state spectral line in the same light-emitting region in the magnetic confinement plasma device from two opposite directions. The external light source is moved to realize switching between an internal particle light-emitting measurement mode and an external laser measurement mode of the device. The actual central wavelength of the target multi-state spectral line can be calculated by combining the interference fringe image of the target multi-state spectral line of the light-emitting area in the device and the interference fringe image of the external laser, and the phase distribution of the interference fringes when the light-emitting particles in the device do non-directional motion is obtained to realize calibration. According to the invention, the problem of inaccurate particle velocity measurement caused by inconsistency between the central wavelength calculated by the database and the actual central wavelength during interference fringe calibration can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of interference fringe calibration for spectral diagnosis, and in particular to an interference fringe calibration system and method for Doppler coherent imaging spectral diagnosis of a magnetic confinement plasma device. Background Art

[0002] Nuclear fusion energy has the outstanding advantages of abundant reserves, environmental friendliness, and inherent safety, and is expected to solve future human energy needs and environmental problems. Magnetic confinement plasma devices use magnetic fields to confine plasma, which is one of the important ways to achieve controlled nuclear fusion. Magnetic confinement plasma devices include tokamaks, stellarators, reverse field pinches, linear devices, etc. The main difference between them is the different ways or configurations of the magnetic fields used to confine plasma. A large number of studies at home and abroad have shown that the velocity distribution of plasma has an important influence on the confinement performance of magnetic confinement plasma devices and the heat load on the device wall.

[0003] Doppler coherence imaging is a spectral diagnostic technology used to measure the two-dimensional distribution of particle (including neutral particles and charged particles) flow velocity. It has been applied to plasma research in some tokamaks, stellarators and linear devices. It also has application prospects in the measurement of flow velocity in flames, auroras, plasma thrusters, and the Earth's atmosphere. The basic principle of Doppler coherence imaging spectral diagnosis is to use a bandpass filter to filter the visible light emitted by the particles themselves to obtain the light of the target spectrum line, and then use a static modulated polarization interferometer to encode the spectrum information of the target spectrum line on the two-dimensional interference fringe image. When the luminous particle has a directional motion relative to the detector, the Doppler frequency shift phenomenon occurs, that is, the frequency / wavelength of the detected light changes. The directional motion speed v of the luminous particle relative to the detector D The relationship between the wavelength with and without directional motion (λ and λ0, respectively) is shown in formula (1). Where u is the propagation speed of light, and λ0 is also called the central wavelength. When the luminous particle has directional motion relative to the detector and the detected wavelength changes, the interference fringes of Doppler coherent imaging spectroscopy diagnosis will move (that is, the phase of the interference fringes changes), and the dependence between the phase difference and the wavelength difference is shown in formula (2). Where φ m and φ C are the phases of interference fringes with and without directional motion, is the group delay parameter of the Doppler coherent imaging spectrum diagnostic system. The dependence between phase difference and velocity can be deduced from formula (1) and formula (2), as shown in formula (3). By comparing the phase of the interference fringe image with and without directional motion, the flow velocity v of the luminous particle can be calculated from the phase difference of the interference fringe. DTherefore, it is very critical to obtain the phase distribution of interference fringes (hereinafter referred to as interference fringes calibration) when the luminescent particles move in an undirected manner (ie, under the condition of central wavelength λ0).

[0004] v D =u(λ0-λ) / λ (1)

[0005]

[0006] There are many kinds of particles (hydrogen, deuterium, helium, carbon, nitrogen, oxygen, etc.) emitting light in magnetic confinement plasma devices. Due to the fine atomic energy level structure, the atomic spectral lines emitted by a certain particle due to energy level transitions are often not single, but present multiple states. The wavelengths of these multiplet spectral lines are very close (can be as low as 0.1 nanometers or even 0.01 nanometers). In order to cover the particle velocity measurement range in magnetic confinement plasma devices (on the order of 0 to hundreds of kilometers per second), the bandwidth of the bandpass filter for Doppler coherent imaging spectroscopy diagnosis is usually at the nanometer level, so it is difficult to filter out one of the multiplet spectral lines alone. Existing Doppler coherent imaging interference fringe calibrations all use the average wavelength λ with the relative light intensity of each spectral line in the multiplet spectral line as the weight. cal =∑ i I relative,i λ i As the central wavelength of the multiplet spectrum. i is the wavelength of the i-th spectral line, I relative,i Its relative light intensity.

[0007] However, the relative intensity of the target multiplet spectral lines selected by Doppler coherent imaging spectroscopy diagnosis is currently calculated using the Atomic Spectra Database (ASD) of the National Institute of Standards and Technology (NIST). This database only considers the energy level transition probability and the statistical weight of excited state atoms of the atomic spectral lines of the same luminescent particles when calculating the relative intensity, but the actual relative intensity depends on the actual light source. For magnetic confinement plasma devices, due to the presence of multiple particles and a large number of spectral lines, the relative intensity of the multiplet spectral lines will be affected by adjacent spectral lines and background light. These lights that cannot be filtered within the filtering range of the filter will change the relative intensity of the multiplet spectral lines. Therefore, the central wavelength will also change accordingly.

[0008] The existing interference fringe calibration of Doppler coherent imaging spectroscopy diagnosis of magnetic confinement plasma devices uses a wavelength-tunable laser to directly obtain the interference fringe phase under the central wavelength condition calculated by the ASD database, or uses a spectral lamp with characteristic spectral lines to obtain the interference fringe phase under the wavelength condition close to the calculated central wavelength, and then extrapolates the interference fringe phase to the interference fringe phase under the central wavelength condition calculated by the ASD database based on the static modulation polarization interferometer model. Note that the above two calibration methods ultimately use the interference fringe phase distribution under the central wavelength condition calculated by the ASD database as the calibration image. As mentioned above, in magnetic confinement plasma devices, the influence of adjacent spectral lines and background light can cause the actual central wavelength to be inconsistent with the central wavelength calculated by the ASD database. Therefore, the existing interference fringe calibration method itself has the problem of inaccurate particle velocity measurement due to the inconsistency between the central wavelength calculated by the database and the actual central wavelength. Summary of the invention

[0009] The purpose of the present invention is to solve the shortcomings of the existing Doppler coherence imaging spectrum diagnosis interference fringe calibration on a magnetic confinement plasma device, and to provide an interference fringe calibration system and method for Doppler coherence imaging spectrum diagnosis, which can avoid the problem of inaccurate particle velocity measurement due to the inconsistency between the central wavelength calculated by the database and the actual central wavelength during the interference fringe calibration. The system and method have ingenious design, high reliability and strong practicality, and meet the use requirements of Doppler coherence imaging spectrum diagnosis measurement of a magnetic confinement plasma device.

[0010] The present invention is achieved through the following technical solutions:

[0011] In a first aspect, the present invention provides an interference fringe calibration system for Doppler coherent imaging spectral diagnosis, comprising a plurality of groups of forward and reverse dual-path Doppler coherent imaging systems and an external mobile light source; each group of forward and reverse dual-path Doppler coherent imaging systems comprises two Doppler coherent imaging systems, which are used to perform interference fringe imaging of light with a wavelength of a target multiplet spectrum line in the same luminous area inside a magnetic confinement plasma device from two opposite directions respectively; the external mobile light source can be moved into each Doppler coherent imaging system to perform interference fringe imaging of the external mobile light source.

[0012] As a preferred embodiment of the present invention, each Doppler coherent imaging system includes a first-stage convex lens, a transmission optical fiber array, a second-stage convex lens, a third-stage convex lens, a fourth-stage convex lens, a bandpass filter, a static modulation polarization interferometer, a fifth-stage convex lens and a detection camera arranged in sequence, and the external mobile light source can be moved between the second-stage convex lens and the third-stage convex lens.

[0013] As a preferred solution of the present invention, the first-stage convex lenses of two Doppler coherent imaging systems in the same group are symmetrically arranged on both sides of the luminous object surface in the magnetic confinement plasma device.

[0014] As a preferred solution of the present invention, the bandpass filter, static modulation polarization interferometer, fifth-order convex lens and detection camera are all arranged in a constant temperature and shock-absorbing box, and the constant temperature and shock-absorbing box is preferably a constant temperature and shock-absorbing electromagnetic shielding room.

[0015] As a preferred embodiment of the present invention, the image plane of the first-stage convex lens coincides with the object plane at the head end of the transmission optical fiber array, and the image plane at the tail end of the transmission optical fiber array is located in the focal plane of the second-stage convex lens. After forming parallel light, it is imaged through the third-stage convex lens. The formed image plane is located in the focal plane of the fourth-stage convex lens. After forming parallel light, it passes through a bandpass filter, a static modulation polarization interferometer and a fifth-stage convex lens to form an interference fringe image, which is then photographed by a detection camera.

[0016] As a preferred embodiment of the present invention, the external movable light source includes a wavelength tunable laser and an integrating sphere. The integrating sphere can be moved between the second-stage convex lens and the third-stage convex lens. The laser output by the wavelength tunable laser enters the integrating sphere to form an extended light source and enters the third-stage convex lens.

[0017] As a preferred embodiment of the present invention, the external mobile light source also includes a splitter fiber bundle and a wavelength meter. The splitter fiber bundle is connected to the wavelength tunable laser to split the laser output by the wavelength tunable laser into two beams, one of which enters an integrating sphere to form an extended light source, and the other enters the wavelength meter to measure the laser wavelength.

[0018] As a preferred solution of the present invention, the integrating sphere is mounted on a displacement platform, and the displacement platform can drive the integrating sphere to move between the second-stage convex lens and the third-stage convex lens in each Doppler coherent imaging system.

[0019] In a second aspect, the present invention provides an interference fringe calibration method for Doppler coherent imaging spectral diagnosis, using the interference fringe calibration system for Doppler coherent imaging spectral diagnosis described in the first aspect, comprising:

[0020] Move the external mobile light source to the first Doppler coherent imaging system of the same group, set the wavelength of the external mobile light source to the calculated central wavelength of the target multiplet spectrum line given by the ASD atomic spectrum database, obtain the interference fringe image CA, demodulate it, and obtain the initial calibration phase φ CA , the initial calibration phase at the center of the image is denoted as φ CA,0 ;

[0021] Move the external mobile light source to the second Doppler coherent imaging system in the same group, set the wavelength of the external mobile light source to the calculated central wavelength of the target multiplet spectrum line given by the ASD atomic spectrum database, obtain the interference fringe image CB, demodulate it, and obtain the initial calibration phase φ CB , the initial calibration phase at the center of the image is denoted as φ CB,0 ;

[0022] Remove the external mobile light source, and use the two Doppler coherent imaging systems of the same group to perform interference fringe imaging of the light with the wavelength of the target multiplet spectrum line in the same luminous area inside the magnetic confinement plasma device from two opposite directions. The first and second Doppler coherent imaging systems of the same group obtain the interference fringe images MA and MB, respectively, and demodulate them respectively to obtain the measured phase φ MA and φ MB , the measured phase at the center of the image is denoted as φ MA,0 and φ MB,0 ;

[0023] According to the dependence between phase difference and velocity in the Doppler coherence imaging spectrum diagnosis principle, the measured phase φ at the center of the image is MA,0 Relative to the initial calibration phase φ CA,0 The change of , obtains the initial flow rate v of the luminous particles DA,0 , from the measured phase φ at the center of the image MB,0 Relative to the initial calibration phase φ CB,0 The change of , obtains the initial flow rate v of the luminous particles DB,0 ;

[0024] For the initial flow rate v DA,0 and v DB,0 After correction, the corrected speeds are v ′ DA,0 =v DA,0 -(v DA,0 +v DB,0 ) / 2 and v ′ DB,0 =v DB,0 -(v DA,0 +v DB,0 ) / 2; According to the dependence between phase difference and velocity in the Doppler coherence imaging spectrum diagnosis principle, the corrected velocity v ′ DA,0 and the measured phase φ MA,0 , inversely deduce the corrected calibration phase φ ′ CA,0 According to the dependence between phase difference and wavelength difference in the Doppler coherent imaging spectrum diagnosis principle, the initial calibration phase φ CA,0 , the corrected calibration phase φ′ CA,0 and the calculated central wavelength of the target multiplet spectral line given by the ASD atomic spectrum database, the actual central wavelength of the target multiplet spectral line is obtained; or, according to the dependence between the phase difference and the speed in the Doppler coherent imaging spectrum diagnosis principle, the corrected speed v ′ DB,0 and the measured phase φ MB,0 , inversely deduce the corrected calibration phase φ ′ CB,0 According to the dependence between phase difference and wavelength difference in the Doppler coherent imaging spectrum diagnosis principle, the initial calibration phase φ CB,0 , the corrected calibration phase φ ′ CB,0 and the calculated central wavelength of the target multiplet spectral line given by the ASD atomic spectrum database to obtain the actual central wavelength of the target multiplet spectral line;

[0025] Move the external moving light source to the first Doppler coherent imaging system of the same group, set the wavelength of the external moving light source to the actual central wavelength of the target multiplet spectrum line, obtain the interference fringe image CA, demodulate it, and obtain the actual calibration phase φ CA ′, that is, the phase distribution of interference fringes when the luminous particles in the magnetic confinement plasma device move without direction, to complete the calibration of the interference fringes; or, move the external mobile light source to the second Doppler coherent imaging system of the same group, set the wavelength of the external mobile light source to the actual central wavelength of the target multiplet spectrum line, obtain the interference fringe image CB, demodulate it, and obtain the actual calibration phase φ CB ′, that is, the phase distribution of the interference fringes when the luminous particles inside the magnetic confinement plasma device move without direction, completes the calibration of the interference fringes.

[0026] As a preferred solution of the present invention, according to the dependence between phase difference and velocity in the Doppler coherent imaging spectrum diagnosis principle, the measured phase φ MA Relative to the actual calibration phase φ CA ′, the two-dimensional distribution v of the luminous particle velocity measured by the first Doppler coherent imaging system of the same group can be obtained ′ DA ; or, by measuring the phase φ MB Relative to the actual calibration phase φ CB ′, the two-dimensional distribution v of the luminous particle flow velocity measured by the second Doppler coherent imaging system of the same group can be obtained ′ DB .

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] The invention adopts a forward and reverse dual-path Doppler coherent imaging method to perform interference fringe imaging on light with a wavelength of a target multiplet spectrum line in the same luminescent area inside a magnetic confinement plasma device from two opposite directions; adopts a method of moving an external laser light source to realize the switching between a particle luminescence measurement mode inside the magnetic confinement plasma device and an external laser measurement mode; then, combining the interference fringe image of the target multiplet spectrum line in the luminescent area inside the magnetic confinement plasma device and the interference fringe image of the external laser, the actual central wavelength of the target multiplet spectrum line is calculated, and finally the phase distribution of the interference fringes when the luminescent particles inside the magnetic confinement plasma device move without orientation is obtained, and the calibration of the interference fringes is realized; the problem of inaccurate particle velocity measurement caused by the inconsistency between the calculated central wavelength of the database and the actual central wavelength during the calibration of the interference fringes can be avoided, the design is ingenious, the reliability is high, the practicability is strong, and the use requirements of Doppler coherent imaging spectrum diagnosis measurement of the magnetic confinement plasma device are met. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0030] Figure 1 This is a design diagram of the interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis in the present invention;

[0031] Figure 2 It is a schematic diagram of the state of the calibration system of the present invention when it is in the particle luminescence measurement mode inside the device;

[0032] Figure 3 It is a schematic diagram of the state of the calibration system of the present invention when it is in the device external laser measurement mode I;

[0033] Figure 4 It is a schematic diagram of the state of the calibration system of the present invention when it is in the device external laser measurement mode II.

[0034] Marks and corresponding parts names in the attached drawings:

[0035] 1-light emitting object surface in magnetic confinement plasma device, 2-first stage convex lens, 3-image plane 1A, 4-image plane 1B, 5-transmission optical fiber array, 6-image plane 2A, 7-image plane 2B, 8-second stage convex lens, 9-third stage convex lens, 10-image plane 3A, 11-image plane 3B, 12-fourth stage convex lens, 13-bandpass filter, 14-static modulation polarization interferometer, 15-fifth stage convex lens, 16-interference fringe image A, 17-interference fringe image B, 18-detection camera, 19-constant temperature and vibration reduction electromagnetic shielding room, 20-wavelength tunable laser, 21-spectroscopy optical fiber bundle, 22-wavelength meter, 23-integrating sphere, 24-displacement platform;

[0036] 25 - interference fringe image MA in the device internal particle luminescence measurement mode, 26 - interference fringe image MB in the device internal particle luminescence measurement mode, 27 - interference fringe image CA in the device external laser measurement mode I, 28 - interference fringe image CB in the device external laser measurement mode II. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0039] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0040] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0041] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0042] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that

[0043] For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0044] The interference fringe calibration of the existing magnetic confinement plasma device Doppler coherent imaging spectrum diagnosis uses the average wavelength λ with the relative intensity of each spectral line in the multiple spectral line as the weight cal =∑ i I relative,i λ i As the central wavelength of the multiplet spectrum. i is the wavelength of the i-th spectral line, I relative,i Its relative light intensity.

[0045] At present, the relative intensity of the target multiplet spectral lines selected for Doppler coherent imaging spectroscopy diagnosis is calculated using the Atomic Spectra Database (ASD) of the National Institute of Standards and Technology (NIST). This database only considers the energy level transition probability and the statistical weight of excited state atoms of the atomic spectral lines of the same luminescent particles when calculating the relative intensity, but the actual relative intensity also depends on the actual light source. For magnetic confinement plasma devices, due to the presence of multiple particles and a large number of spectral lines, the relative intensity of the multiplet spectral lines will be affected by adjacent spectral lines and background light. These lights that cannot be filtered within the filtering range of the filter will change the relative intensity of the multiplet spectral lines. Therefore, the central wavelength will also change accordingly.

[0046] The carbon ion (C 2+ ) as an example, in the range of 464-466 nanometers, the vacuum wavelength λ of the CIII triplet spectrum i The relative intensities of the CIII triplet state lines are 464.8720 nm, 465.1548 nm, and 465.2775 nm, respectively. relative,iare 0.5556, 0.3336, and 0.1108 respectively. According to the above, the central wavelength calculated by taking the relative intensity of each spectral line in the multiplet spectral line as the weight is λ cal The following two situations will cause the central wavelength λ calculated by the database to be cal There is a deviation from the actual central wavelength λ0:

[0047] (1) Due to the existence of spectral line broadening, if the adjacent spectral lines of the CIII triplet line (such as the oxygen ion OII lines with wavelengths of 465.0437 nm and 465.2141 nm) cause a 5% increase in the intensity of the 465.1548 nm line of CIII, then the relative intensity of the CIII triplet line I relative,i will become 0.5291, 0.3653, 0.1055, so that the actual center wavelength becomes 465.0181 nanometers. The actual center wavelength differs from the center wavelength calculated by the database by 0.0068 nanometers. According to the Doppler frequency shift, that is, formula (1) in the background technology, the center wavelength of the database is used for interference fringe calibration, which will introduce an equivalent velocity deviation error u(λ0-λ cal ) / λ cal ≈4.4km / s. For a Doppler coherent imaging spectroscopy diagnostic system with a group delay parameter of 1500, a phase change of π(-π) can measure a directional velocity of 100km / s(-100km / s), and the phase deviation introduced by the central wavelength deviation is ~8°;

[0048] (2) If there is a background light of 3% intensity, the relative intensity of the CIII triplet line I relative,i will become 0.5372, 0.3336, 0.1292, and the actual center wavelength will become 465.0187 nanometers. The actual center wavelength differs from the center wavelength calculated by the database by 0.0074 nanometers. According to the Doppler frequency shift, that is, formula (1) in the background technology, the center wavelength calculated by the database is used for interference fringe calibration, which will introduce an equivalent velocity deviation error u(λ0-λ cal ) / λ cal ≈4.8km / s. For a phase change of π(-π), a Doppler coherent imaging spectroscopy diagnostic system (whose group delay parameter is 1500) with a directional velocity of 100km / s(-100km / s) can be measured, and the phase deviation introduced by the central wavelength deviation is ~9°.

[0049] In order to solve the shortcomings of the existing Doppler coherent imaging spectrum diagnosis interference fringe calibration on the magnetic confinement plasma device, that is, the problem of inaccurate particle velocity measurement due to the inconsistency between the central wavelength calculated by the database and the actual central wavelength, the inventors proposed an interference fringe calibration system and method for Doppler coherent imaging spectrum diagnosis after in-depth research. By adopting a forward and reverse dual-path Doppler coherent imaging system and an external mobile light source, combined with the interference fringe image of the target multiplet spectrum line in the luminous area inside the magnetic confinement plasma device and the interference fringe image of the external laser, the actual central wavelength of the target multiplet spectrum line can be calculated, the phase distribution of the interference fringes when the luminous particles inside the magnetic confinement plasma device move without direction, and the calibration of the interference fringes can be achieved.

[0050] Example 1

[0051] Please refer to Figure 1 An interference fringe calibration system for Doppler coherence imaging spectral diagnosis provided in an embodiment of the present application includes a plurality of groups of forward and reverse dual-path Doppler coherence imaging systems and an external mobile light source; each group of forward and reverse dual-path Doppler coherence imaging systems includes two Doppler coherence imaging systems, which are used to perform interference fringe imaging of light with a wavelength of a target multiplet spectrum line in the same luminous area inside a magnetic confinement plasma device from two opposite directions; the external mobile light source can be moved to each Doppler coherence imaging system to perform interference fringe imaging of the external mobile light source.

[0052] It should be noted that, in this embodiment, only one group of forward and reverse dual-path Doppler coherent imaging systems, in which two Doppler coherent imaging systems are used as an example for explanation. Of course, multiple groups of forward and reverse dual-path Doppler coherent imaging systems can also be used, such as two groups, three groups, four groups, etc. However, as the number of Doppler coherent imaging systems increases, the overall cost will also increase. Therefore, using two Doppler coherent imaging systems is the best economical solution to achieve the interference fringe calibration.

[0053] The interference fringe calibration system in this embodiment adopts the forward and reverse dual-path Doppler coherent imaging method to perform interference fringe imaging on the light with the wavelength of the target multiplet spectrum line in the same luminescent area inside the magnetic confinement plasma device from two opposite directions; by moving the external mobile light source, the switching between the particle luminescence measurement mode inside the magnetic confinement plasma device and the external mobile light source measurement mode can be realized; and by combining the interference fringe image of the target multiplet spectrum line in the luminescent area inside the magnetic confinement plasma device and the interference fringe image of the external mobile light source, the actual central wavelength of the target multiplet spectrum line can be calculated, and finally the phase distribution of the interference fringes when the luminescent particles inside the magnetic confinement plasma device move without direction is obtained, so as to realize the calibration of the interference fringes; the interference fringe calibration system can avoid the problem of inaccurate particle velocity measurement caused by the inconsistency between the central wavelength calculated by the database and the actual central wavelength during the interference fringe calibration, and has a clever design, high reliability and strong practicality, and meets the use requirements of Doppler coherent imaging spectrum diagnostic measurement of magnetic confinement plasma devices.

[0054] According to some embodiments of the present application, each Doppler coherent imaging system includes a first-stage convex lens 2, a transmission optical fiber array 5, a second-stage convex lens 8, a third-stage convex lens 9, a fourth-stage convex lens 12, a bandpass filter 13, a static modulation polarization interferometer 14, a fifth-stage convex lens 15 and a detection camera 18, which are arranged in sequence, and the external mobile light source can be moved between the second-stage convex lens 8 and the third-stage convex lens 9. Since each Doppler coherent imaging system is a set of independent imaging light paths, two Doppler coherent imaging systems can be used to perform interference fringe imaging of light with a wavelength of a target multiplet spectrum line in the same luminous area inside the magnetic confinement plasma device from two opposite directions; at the same time, since the external mobile light source can be moved between the second-stage convex lens 8 and the third-stage convex lens 9, it can block the light emitted by particles inside the magnetic confinement plasma device and output the light to the third-stage convex lens 9, thereby switching the measurement light source from the luminous object surface 1 in the magnetic confinement plasma device to the external mobile light source, thereby realizing interference fringe imaging of the external mobile light source.

[0055] According to some embodiments of the present application, the first-stage convex lenses 2 of the two Doppler coherent imaging systems in the same group are symmetrically arranged on both sides of the luminous object surface 1 in the magnetic confinement plasma device. By adopting the above design, interference fringe imaging is performed on the light with a wavelength of the target multiplet spectrum line in the same luminous area inside the magnetic confinement plasma device from two opposite directions, and the flow velocities of the luminous particles at the center of the image obtained by the two optical paths based on the Doppler effect are equal and opposite, which is convenient for the subsequent correction of the initial flow velocity.

[0056] According to some embodiments of the present application, the bandpass filter 13, the statically modulated polarization interferometer 14, the fifth-order convex lens 15, and the detection camera 18 are all arranged in a constant temperature shock-absorbing box, and the constant temperature shock-absorbing box is preferably a constant temperature shock-absorbing electromagnetic shielding room 19. By installing the bandpass filter 13, the statically modulated polarization interferometer 14, the fifth-order convex lens 15, and the detection camera 18 in a constant temperature shock-absorbing electromagnetic shielding room 19, the influence of vibration displacement and temperature change on the statically modulated polarization interferometer 14 and the interference fringe image can be avoided, and the electromagnetic field can be prevented from interfering with the detection camera 18.

[0057] It should be noted that the bandpass filter 13, static modulation polarization interferometer 14, fifth-order convex lens 15 and detection camera 18 in the two Doppler coherent imaging systems can be arranged together in a constant temperature and shock-absorbing electromagnetic shielding room 19, and of course they can also be separately arranged in two constant temperature and shock-absorbing electromagnetic shielding rooms.

[0058] According to some embodiments of the present application, the image plane of the first-stage convex lens 2 coincides with the object plane at the head end of the transmission optical fiber array 5, and the image plane at the tail end of the transmission optical fiber array 5 is located at the focal plane of the second-stage convex lens 8. After forming parallel light, it is imaged through the third-stage convex lens 9. The formed image plane is located at the focal plane of the fourth-stage convex lens 12. After forming parallel light, it passes through the bandpass filter 13, the static modulation polarization interferometer 14 and the fifth-stage convex lens 15 to form an interference fringe image, which is photographed by the detection camera 18. By using the transmission optical fiber array 5 to transmit the image plane of the first-stage convex lens 2 in space, the advantage is that the entire optical path does not have to be in a straight line, which is more flexible in space. In addition, optical fiber transmission allows the optical path and optical devices (mainly the detection camera 18) behind to be arranged at a long distance to avoid them being interfered by the electromagnetic field of the magnetic confinement plasma device.

[0059] According to some embodiments of the present application, the external movable light source includes a wavelength tunable laser 20 and an integrating sphere 23. The integrating sphere 23 can be moved between the second-stage convex lens 8 and the third-stage convex lens 9. The laser output by the wavelength tunable laser 20 enters the integrating sphere 23 to form an extended light source and enters the third-stage convex lens 9.

[0060] According to some embodiments of the present application, the external mobile light source also includes a splitter fiber bundle 21 and a wavelength meter 22. The splitter fiber bundle 21 is connected to the wavelength tunable laser 20 to split the laser output by the wavelength tunable laser 20 into two beams, one of which enters the integrating sphere 23 to form an extended light source, and the other enters the wavelength meter 22 to measure the laser wavelength. The laser wavelength can be adjusted according to the wavelength result measured by the wavelength meter 22.

[0061] According to some embodiments of the present application, the integrating sphere 23 is mounted on a displacement platform 24, and the displacement platform 24 can drive the integrating sphere 23 to move between the second-stage convex lens 8 and the third-stage convex lens 9 in two Doppler coherent imaging systems. By mounting the integrating sphere 23 on the displacement platform 24, a position adjustment function is provided, and when the integrating sphere 23 moves between the second-stage convex lens 8 and the third-stage convex lens 9 in any one of the Doppler coherent imaging systems, the measuring light source can be switched from the luminous object plane 1 in the magnetic confinement plasma device to an external laser.

[0062] Specifically, the interference fringe calibration system adopts a forward and reverse dual-path Doppler coherent imaging method. When the magnetic confinement plasma device is discharged, two first-stage convex lenses 2 are symmetrically arranged about the luminous object surface 1 in the magnetic confinement plasma device to image the same luminous object surface from two opposite directions, forming image planes 1A3 and 1B4, which are then transmitted through two transmission optical fiber arrays 5 respectively. Image planes 2A6 and 2B7 at the tail ends of the transmission optical fiber arrays 5 are respectively located at the focal planes of two second-stage convex lenses 8. After forming parallel light, two third-stage convex lenses 9 are used to image, and the formed image planes 3A10 and 3B11 are respectively located at the focal planes of two fourth-stage convex lenses 12. After each forming parallel light, they pass through a bandpass filter 13, a static modulation polarization interferometer 14 and a fifth-stage convex lens 15 respectively to form interference fringe images A16 and B17 of target multiple state spectrum lines, which are then photographed by two detection cameras 18. The bandpass filter 13, the static modulation polarization interferometer 14, the fifth-stage convex lens 15, and the detection camera 18 are installed in a constant temperature shock-absorbing electromagnetic shielding room 19 to avoid the influence of vibration displacement and temperature change on the static modulation polarization interferometer 14, and to prevent the electromagnetic field from interfering with the detection camera 18. When the position of the integrating sphere 23 installed on the displacement platform 24 is moved to the middle of the second-stage convex lens 8 and the third-stage convex lens 9, the measurement light source can be switched from the luminous object surface 1 in the magnetic confinement plasma device to the extended light source of the wavelength tunable laser 20. The light output by the wavelength tunable laser 20 is divided into two beams by using a splitter fiber bundle 21. One beam enters the wavelength meter 22 to measure the laser wavelength. According to the measurement result of the wavelength meter 22, the wavelength of the wavelength tunable laser 20 can be adjusted. The other beam enters the integrating sphere 23 to form an extended light source, and then passes through the third-stage convex lens 9, the fourth-stage convex lens 12, the bandpass filter 13, the static modulation polarization interferometer 14 and the fifth-stage convex lens 15 in sequence to form interference fringe images A16 and B17 of the external laser, which are then photographed by two detection cameras 18.

[0063] Example 2

[0064] Please refer to Figures 2 to 4The interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis in this application has three working modes, namely, the particle luminescence measurement mode inside the magnetic confinement plasma device (see Figure 2 ), external laser measurement mode I of magnetic confinement plasma device (see Figure 3 ) and external laser measurement mode II of magnetic confinement plasma device (see Figure 4 ). By combining the three working modes, the phase distribution of interference fringes when the luminous particles in the magnetic confinement plasma device move without direction (that is, under the actual central wavelength of the target multiplet spectrum line) can be obtained, and the interference fringes calibration can be achieved.

[0065] An interference fringe calibration method for Doppler coherent imaging spectroscopy diagnosis provided in the embodiments of the present application adopts the interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis described in Embodiment 1, comprising:

[0066] Using the external laser measurement mode I of the magnetic confinement plasma device, the integrating sphere 23 is moved to the position of the integrating sphere 23 under the external laser measurement mode I of the magnetic confinement plasma device (such as Figure 3 The wavelength of the wavelength tunable laser 20 is set to the calculated central wavelength of the target multiplet spectrum line given by the ASD atomic spectrum database, and the interference fringe image CA 27 in the external laser measurement mode I of the magnetic confinement plasma device is taken and demodulated to obtain the initial calibration phase φ CA , the initial calibration phase at the center of the image is denoted as φ CA,0 .

[0067] Using the external laser measurement mode II of the magnetic confinement plasma device, the integrating sphere 23 is moved to the position of the integrating sphere 23 under the external laser measurement mode II of the magnetic confinement plasma device (such as Figure 4 The wavelength of the wavelength tunable laser 20 is set to the calculated central wavelength of the target multiplet spectrum line given by the ASD atomic spectrum database, and the interference fringe image CB 28 in the external laser measurement mode II of the magnetic confinement plasma device is taken and demodulated to obtain the initial calibration phase φ CB , the initial calibration phase at the center of the image is denoted as φ CB,0 .

[0068] Using the magnetic confinement plasma device internal particle luminescence measurement mode, the integrating sphere 23 is moved to the position of the integrating sphere 23 in the magnetic confinement plasma device internal particle luminescence measurement mode (such as Figure 2 ), capture interference fringe images MA 25 and MB 26 in the luminescence measurement mode of particles inside the magnetic confinement plasma device, demodulate them respectively, and obtain the measurement phase φMA and φ MB , the measured phase at the center of the image is denoted as φ MA,0 and φ MB,0 .

[0069] According to the dependence between phase difference and velocity in the Doppler coherence imaging spectrum diagnosis principle (i.e., formula (3) in the background technology), the measured phase φ at the center of the image is MA,0 Relative to the initial calibration phase φ CA,0 The change of , obtains the initial flow rate v of the luminous particles DA,0 , from the measured phase φ at the center of the image MB,0 Relative to the initial calibration phase φ CB,0 The change of , obtains the initial flow rate v of the luminous particles D8,0 .

[0070] According to the design of the forward and reverse dual-path Doppler coherent imaging of the fringe calibration system, the interference fringe imaging of the light with the wavelength of the target multiplet spectrum line in the same luminous area inside the magnetic confinement plasma device is performed from two opposite directions. The flow velocities of the luminous particles at the center of the image obtained by the two light paths based on the Doppler effect are equal and opposite (that is, the sum is 0), so the initial flow velocity v DA,0 and v DB,0 The corrected speeds are v ′ DA,0 =v DA,0 -(v DA,0 +v DB,0 ) / 2 and v ′ DB,0 =v DB,0 -(v DA,0 +v DB,0 ) / 2. According to the dependence between phase difference and velocity in the Doppler coherence imaging spectrum diagnosis principle (i.e., formula (3) in the background technology), the corrected velocity v ′ DA,0 and the measured phase φ MA,0 , inversely deduce the corrected calibration phase φ ′ CA,0 According to the dependence between phase difference and wavelength difference in the Doppler coherent imaging spectrum diagnosis principle (i.e., formula (2) in the background technology), the initial calibration phase φ CA,0 , the corrected calibration phase φ ′ CA,0 The actual central wavelength of the target multiplet spectral line is obtained by combining the calculated central wavelength of the target multiplet spectral line given by the ASD atomic spectrum database. Of course, the dependence between the phase difference and the speed in the Doppler coherent imaging spectrum diagnosis principle (i.e., formula (3) in the background technology) can be used to obtain the corrected speed v ′DB,0 and the measured phase φ MB,0 , inversely deduce the corrected calibration phase φ ′ CB,0 According to the dependence between phase difference and wavelength difference in the Doppler coherent imaging spectrum diagnosis principle (i.e., formula (2) in the background technology), the initial calibration phase φ CB,0 , the corrected calibration phase φ ′ CB,0 The actual central wavelength of the target multiplet spectral line is obtained by using the calculated central wavelength of the target multiplet spectral line given by the ASD atomic spectrum database.

[0071] Then, the external laser measurement mode I of the magnetic confinement plasma device is adopted, and the integrating sphere 23 is moved to the position of the integrating sphere 23 under the external laser measurement mode I of the magnetic confinement plasma device (such as Figure 3 ), set the wavelength of the wavelength tunable laser 20 to the actual central wavelength of the target multiplet spectrum, capture the interference fringe image CA27 in the external laser measurement mode I of the magnetic confinement plasma device, demodulate it, and obtain the actual calibration phase φ CA ', that is, the phase distribution of the interference fringes when the luminous particles in the magnetic confinement plasma device move without direction, to complete the calibration of the interference fringes. Of course, the external laser measurement mode II of the magnetic confinement plasma device can also be used to move the integrating sphere 23 to the position of the integrating sphere 23 in the external laser measurement mode II of the magnetic confinement plasma device (such as Figure 4 The wavelength of the wavelength tunable laser 20 is set to the actual central wavelength of the target multiplet spectrum line, and the interference fringe image CB 28 is obtained, which is demodulated to obtain the actual calibration phase φ CB ′, that is, the phase distribution of the interference fringes when the luminous particles inside the magnetic confinement plasma device move without direction, completes the calibration of the interference fringes.

[0072] Subsequently, according to the dependence between phase difference and velocity in the Doppler coherent imaging spectrum diagnosis principle (i.e., formula (3) in the background technology), the measured phase φ MA Relative to the actual calibration phase φ CA ′, the two-dimensional distribution v of the luminous particle velocity measured by the first Doppler coherent imaging system of the same group can be obtained ′ DA Of course, it is also possible to measure the phase φ MB Relative to the actual calibration phase φ CB ′, the two-dimensional distribution v of the luminous particle flow velocity measured by the second Doppler coherent imaging system of the same group can be obtained ′ DB .

[0073] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis, characterized in that: It comprises a plurality of groups of forward and reverse dual-path Doppler coherent imaging systems and an external mobile light source; each group of forward and reverse dual-path Doppler coherent imaging systems comprises two Doppler coherent imaging systems, which are used to respectively perform interference fringe imaging on light with a wavelength of a target multiplet spectrum line in the same luminous area inside a magnetic confinement plasma device from two opposite directions; the external mobile light source can be moved into each Doppler coherent imaging system to perform interference fringe imaging of the external mobile light source.

2. The interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis according to claim 1, characterized in that: Each Doppler coherent imaging system includes a first-stage convex lens, a transmission optical fiber array, a second-stage convex lens, a third-stage convex lens, a fourth-stage convex lens, a bandpass filter, a static modulation polarization interferometer, a fifth-stage convex lens and a detection camera arranged in sequence, and the external mobile light source can be moved between the second-stage convex lens and the third-stage convex lens.

3. The interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis according to claim 2, characterized in that: The first-stage convex lenses of two Doppler coherent imaging systems in the same group are symmetrically arranged on both sides of the luminous object surface in the magnetic confinement plasma device.

4. The interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis according to claim 2, characterized in that: The bandpass filter, static modulation polarization interferometer, fifth-order convex lens and detection camera are all arranged in a constant temperature and shock-absorbing box, and the constant temperature and shock-absorbing box is preferably a constant temperature and shock-absorbing electromagnetic shielding room.

5. The interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis according to claim 2, characterized in that: The image plane of the first-stage convex lens coincides with the object plane at the head end of the transmission optical fiber array, and the image plane at the tail end of the transmission optical fiber array is located in the focal plane of the second-stage convex lens. After forming parallel light, it is imaged through the third-stage convex lens. The formed image plane is located in the focal plane of the fourth-stage convex lens. After forming parallel light, it passes through a bandpass filter, a static modulation polarization interferometer and a fifth-stage convex lens to form an interference fringe image, which is then photographed by a detection camera.

6. The interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis according to any one of claims 2 to 5, characterized in that: The external movable light source includes a wavelength tunable laser and an integrating sphere. The integrating sphere can be moved between the second convex lens and the third convex lens. The laser output by the wavelength tunable laser enters the integrating sphere to form an extended light source and enters the third convex lens.

7. The interference fringe calibration system for Doppler coherent imaging spectrum diagnosis according to claim 6, characterized in that: The external mobile light source also includes a splitter fiber bundle and a wavelength meter. The splitter fiber bundle is connected to the wavelength tunable laser to split the laser output by the wavelength tunable laser into two beams, one of which enters the integrating sphere to form an extended light source, and the other enters the wavelength meter to measure the laser wavelength.

8. The interference fringe calibration system for Doppler coherent imaging spectrum diagnosis according to claim 6, characterized in that: The integrating sphere is mounted on a displacement platform, and the displacement platform can drive the integrating sphere to move between the second-stage convex lens and the third-stage convex lens in each Doppler coherent imaging system.

9. An interference fringe calibration method for Doppler coherent imaging spectroscopy diagnosis, using the interference fringe calibration system for Doppler coherent imaging spectroscopy diagnosis according to any one of claims 1 to 8, characterized in that: include: Move the external mobile light source to the first Doppler coherent imaging system of the same group, set the wavelength of the external mobile light source to the calculated central wavelength of the target multiplet spectrum line given by the ASD atomic spectrum database, obtain the interference fringe image CA, demodulate it, and obtain the initial calibration phase φ CA , the initial calibration phase at the center of the image is denoted as φ CA,0 ; Move the external mobile light source to the second Doppler coherent imaging system in the same group, set the wavelength of the external mobile light source to the calculated central wavelength of the target multiplet spectrum line given by the ASD atomic spectrum database, obtain the interference fringe image CB, demodulate it, and obtain the initial calibration phase φ CB , the initial calibration phase at the center of the image is denoted as φ CB,0 ; Remove the external mobile light source, and use the two Doppler coherent imaging systems of the same group to perform interference fringe imaging of the light with the wavelength of the target multiplet spectrum line in the same luminous area inside the magnetic confinement plasma device from two opposite directions. The first and second Doppler coherent imaging systems of the same group obtain the interference fringe images MA and MB, respectively, and demodulate them respectively to obtain the measured phase φ MA and φ MB , the measured phase at the center of the image is denoted as φ MA,0 and φ MB,0 ; According to the dependence between phase difference and velocity in the Doppler coherence imaging spectrum diagnosis principle, the measured phase φ at the center of the image is MA,0 Relative to the initial calibration phase φ CA,0 The change of , obtains the initial flow rate v of the luminous particles DA,0 , from the measured phase φ at the center of the image MB,0 Relative to the initial calibration phase φ CB,0 The change of luminous particles is used to obtain the initial flow rate v DB,0 ; For the initial flow rate v DA,0 and v DB,0 After correction, the corrected speeds are v ′ DA,0 =v DA,0 -(v DA,0 +v DB,0 ) / 2 and v ′ DB,0 =v DB,0 -(v DA,0 +v DB,0 ) / 2; According to the dependence between phase difference and velocity in the Doppler coherence imaging spectrum diagnosis principle, the corrected velocity v ′ DA,0 and the measured phase φ MA,0 , inversely deduce the corrected calibration phase φ ′ CA,0 According to the dependence between phase difference and wavelength difference in the Doppler coherent imaging spectrum diagnosis principle, the initial calibration phase φ CA,0 , the corrected calibration phase φ ′ CA,0 and the calculated central wavelength of the target multiplet spectral line given by the ASD atomic spectrum database, the actual central wavelength of the target multiplet spectral line is obtained; or, according to the dependence between the phase difference and the speed in the Doppler coherent imaging spectrum diagnosis principle, the corrected speed v ′ DB,0 and the measured phase φ MB,0 , inversely deduce the corrected calibration phase φ ′ CB,0 According to the dependence between phase difference and wavelength difference in the Doppler coherent imaging spectrum diagnosis principle, the initial calibration phase φ CB,0 , the corrected calibration phase φ ′ CB,0 and the calculated central wavelength of the target multiplet spectral line given by the ASD atomic spectrum database to obtain the actual central wavelength of the target multiplet spectral line; Move the external moving light source to the first Doppler coherent imaging system of the same group, set the wavelength of the external moving light source to the actual central wavelength of the target multiplet spectrum line, obtain the interference fringe image CA, demodulate it, and obtain the actual calibration phase φ CA ′, that is, the phase distribution of interference fringes when the luminous particles in the magnetic confinement plasma device move without direction, to complete the calibration of the interference fringes; or, move the external mobile light source to the second Doppler coherent imaging system of the same group, set the wavelength of the external mobile light source to the actual central wavelength of the target multiplet spectrum line, obtain the interference fringe image CB, demodulate it, and obtain the actual calibration phase φ CB ′, that is, the phase distribution of the interference fringes when the luminous particles inside the magnetic confinement plasma device move without direction, completes the calibration of the interference fringes.

10. The interference fringe calibration method for Doppler coherent imaging spectrum diagnosis according to claim 9, characterized in that: According to the dependence between phase difference and velocity in the Doppler coherence imaging spectrum diagnosis principle, the measured phase φ MA Relative to the actual calibration phase φ CA ′, the two-dimensional distribution v of the luminous particle velocity measured by the first Doppler coherent imaging system of the same group can be obtained ′ DA ; or, by measuring the phase φ MB Relative to the actual calibration phase φ CB ′, the two-dimensional distribution v of the luminous particle flow velocity measured by the second Doppler coherent imaging system of the same group can be obtained ′ DB .

Images