A helium spectral imaging system suitable for a magnetic confinement fusion device

Abstract

The application discloses a helium spectrum imaging system suitable for a magnetic confinement fusion device, which comprises a jet pipeline, a relay optical path system, a monochromatic gas-filled imaging system, a polychromatic spectrometric system and a high-speed camera system or a photoelectric conversion detector array system. The jet pipeline sprays helium to form a gas cloud object surface, and the monochromatic gas-filled imaging system and the polychromatic spectrometric system respectively image the object surface to a specified region of a photosensitive surface of a high-speed camera. The monochromatic gas-filled imaging system images spectral lines of a specific wavelength in the object surface image to the photosensitive surface of the high-speed camera, and obtains high-time-resolution evolution of the object surface image; the polychromatic spectrometric system images spectral lines of four specific wavelengths in the object surface image to a photosensitive surface of another high-speed camera, and can obtain electron temperature and density in combination with a collision radiation model. The application increases the spectrometric system available for electron temperature and density measurement, and greatly improves the diagnostic capability.

Description

Technical Field

[0001] This invention relates to the field of diagnostics for magnetic confinement fusion plasma, specifically a helium spectral imaging system suitable for magnetic confinement fusion devices. Background Technology

[0002] Magnetic confinement fusion uses a specially configured magnetic field to confine plasma within a specific container. Auxiliary heating is used to increase the plasma temperature, and fuel addition increases its density. Under conditions meeting the Lawson criterion, fusion ignition and self-sustaining combustion can be achieved, generating electricity. Magnetic confinement fusion is a clean energy source, with abundant natural raw materials, and represents a feasible approach to solving humanity's future energy problems. Currently, tokamaks and stellarators are the two most likely devices to achieve controlled magnetic confinement fusion.

[0003] In the boundary plasma of magnetic confinement fusion devices, turbulence is a crucial factor dominating plasma transport, significantly influencing boundary instability and the thermal flux of the scraped layer, and directly impacting the confinement performance of the core plasma. The distribution of electron temperature and density in the boundary plasma determines the nature and amplitude of turbulence, and is a vital physical quantity for understanding and mastering the laws controlling turbulence and its transport. Various diagnostic methods exist for measuring boundary turbulence, such as the Langmuir probe, microwave reflectometer, beam emission spectroscopy, and gas imaging systems (GPI). GPI directly measures the two-dimensional spatial structure and time-varying evolution of boundary turbulence. It involves injecting a neutral gas, such as deuterium or helium, into the boundary plasma to form a gas cloud, then imaging it onto the photosensitive surface of a high-speed camera using an optical path to obtain the two-dimensional intensity distribution and evolution of a spectral line signal at a specific wavelength. Since light intensity is related to the local temperature and density at the object surface, its fluctuations can represent the turbulence intensity in the boundary plasma. Generally, the object surface of a gas imaging system is a two-dimensional spatial surface along the poloidal and radial directions, and its measurement results reflect the two-dimensional structure of the turbulence. Currently, gas-filled imaging systems have been applied in several tokamak devices. Common methods for measuring boundary electron temperature and density include Langmuir probes, charge recombination exchange spectroscopy, and hot helium beam diagnostics. Hot helium beams involve injecting helium gas into the boundary plasma and measuring the intensity of three HeI spectral lines along the radial chord. The ratio of the intensities of two sets of spectral lines is quasi-linearly related to electron density and temperature, respectively. Combined with a collisional radiation model, electron temperature and density can be obtained. Therefore, combining the advantages of both gas-filled imaging systems and hot helium beam diagnostics, developing a helium spectral imaging system to simultaneously measure two-dimensional boundary turbulence, electron temperature, and density distribution is of great significance for understanding boundary turbulent transport mechanisms.

[0004] Internationally, gas-filled imaging systems and hot helium beams typically use imaging fiber bundles or optical fibers to transmit images or optical signals. The coupling of multiple optical elements can cause significant light loss, thus reducing the strength and signal-to-noise ratio of the measurement signal. The helium spectral imaging system of this invention uses a relay optical path directly connected to a high-speed camera (or photoelectric conversion detector array), effectively reducing light loss and improving signal strength and system temporal resolution, which is crucial for conducting high-level physics research. This helium spectral imaging system, based on previous work, adopts a mechanical structure similar to that of the invention patent (application number CN202110616282.8), namely, a separate optical outer cylinder and an optical inner cylinder, with the inner cylinder fixed to the flange at the end of the outer cylinder. Since the structure of this inner and outer cylinder has been described in detail in the invention patent (application number CN202110616282.8), it will not be elaborated upon here. Therefore, this invention focuses on the design and implementation of the monochromatic GPI system and the multicolor spectroscopic system in the helium spectral system. Summary of the Invention

[0005] The purpose of this invention is to provide a helium spectral imaging system suitable for magnetically confined fusion devices, so as to achieve direct measurement of the two-dimensional structural evolution of boundary turbulence, electron temperature and density.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A helium spectral imaging system suitable for magnetic confinement fusion devices includes a jet pipe 1, a relay optical path system 3, a monochromatic gas-filled imaging system 4, a multicolor spectral system 5, a first high-speed camera system 6, and a second high-speed camera system 7. The jet pipe 1 injects helium gas into the boundary plasma through multiple small holes, forming a gas cloud surface 2. The relay optical path system 3 collects the light emitted from the gas cloud surface 2 and converges it into parallel light, which is then guided into the monochromatic gas-filled imaging system 4 and the multicolor spectral system 5 through beam splitters. The monochromatic gas-filled imaging system 4 images specific characteristic spectral lines radiated from the gas cloud surface 2 onto the photosensitive surface of the first high-speed camera system 6, i.e., image plane 25, to obtain the two-dimensional turbulent structure and evolution. The multicolor spectral system 5, through multiple color separation and color combination steps, images the characteristic spectral lines of four wavelengths in the incident light onto the photosensitive surface of the second high-speed camera system 7, i.e., image plane 46, i.e., four wavelength sub-image planes are arranged on one photosensitive surface. Combined with the collisional radiation model, the electron temperature and density on the gas cloud surface 2 are obtained.

[0008] Furthermore, the jet pipe 1 consists of one or more rows of evenly arranged small holes, usually made of 316L stainless steel pipe, and is fixed to the inner wall of the magnetic confinement fusion device by welding or bolting. When needed, helium gas is injected into the plasma boundary to form a gas cloud surface 2.

[0009] Furthermore, the optical tube of the relay optical path system 3 includes a mechanical inner tube and a mechanical outer tube; the observation window 8 is located at the front end of the mechanical outer tube and is used to isolate the vacuum inside and outside the mechanical outer tube. The end flange of the mechanical outer tube is connected to the window flange of the magnetic confinement fusion device to complete the vacuum seal; all other optical lenses are installed and fixed inside the mechanical inner tube. The ends of the mechanical inner tubes corresponding to the monochromatic gas-filled imaging system 4 and the multicolor beam splitting system 5 have internal threads for connecting to the flange with external threads at the bottom. By rotating the threads of the flange, the distances between the first high-speed camera system 6 and the second high-speed camera system 7 and image plane 25 and image plane 46, respectively, can be adjusted and fixed; there is a flange in the middle of the mechanical inner tube, which is connected and fixed to the end flange of the mechanical outer tube.

[0010] Furthermore, the first high-speed camera system 6 and the second high-speed camera system 7 employ commercial high-speed cameras to directly capture graphic information of the gas cloud surface 2, possessing high pixel count and frame rate; or the first high-speed camera system 6 and the second high-speed camera system 7 employ an array of photoelectric conversion detectors to receive image information from the image surface; the first high-speed camera system 6 and the second high-speed camera system 7 are fixed to the flange and support plate at the tail end of the optical barrel, the lower end of the flange has an external thread that connects to the internal thread at the tail end of the barrel, the distance between the photosensitive surface and the image surface can be adjusted through the thread at the lower end of the flange to obtain the clearest image, and the angle of the image surface on the photosensitive surface of the high-speed camera system can be adjusted by rotating the high-speed camera system.

[0011] Furthermore, the relay optical path system 3 includes an observation window 8, a lens, a reflecting prism 9, a right-angle prism, a beam splitter 16, a dichroic prism, a color combining prism, and a filter, which images certain spectral lines emitted by the gas cloud surface 2 onto the photosensitive surface of the high-speed camera system. The observation window 8 is located at the front end of the optical path and is made of quartz glass welded to a stainless steel flange. It is connected to the flange of the mechanical outer cylinder to provide a vacuum seal. The reflecting prism 9 adjusts the incident light to be coaxial with the optical barrel. The light passes sequentially through lens 10, aperture 11, lens 2 12, lens 3 13, lens 4 14, and lens 5 15, which converge the light into parallel light. The beam splitter 16 then splits the light into two parts. One part enters the multicolor beam splitting system 5, and the other part is reflected by the right-angle prism 17 into the monochromatic gas-filled imaging system 4.

[0012] Furthermore, the monochromatic gas imaging system 4 includes lens six 18, lens seven 19, lens eight 20, lens nine 21, lens ten 23, lens eleven 24, and filter one 22. Through the above components, light is gradually converged and imaged onto the photosensitive surface of the first high-speed camera system 6, namely the image plane one 25. The filter one 22 is installed in the slot reserved in the optical barrel of the monochromatic gas imaging system 4. During the experimental interval, by replacing the filter one 22, the two-dimensional structural evolution of different characteristic spectral lines of the gas cloud surface 2 can be obtained.

[0013] Furthermore, the multicolor spectral system 5 extracts the four characteristic spectral lines radiated from the gas cloud surface 2 and images them onto the photosensitive surface of the second high-speed camera system 7. The four sub-image surfaces are closely arranged to form a square image surface 46 located in the central region of the photosensitive surface. After entering the multicolor spectral system 5, the light first passes through the dichroic prism 26, reflecting the characteristic wavelength 1 into the filter 34 and the right-angle prism 30. Then, it passes sequentially through the color combining prism 31, color combining prism 32, and color combining prism 33, and finally converges onto the photosensitive surface of the second high-speed camera system 7 by the lens group. When the light transmitted from the dichroic prism 26 passes through the dichroic prism 27, the characteristic wavelength 2 is... The light reflected from the light enters the third filter 35 and the first color-combining prism 31, and is further reflected through the second color-combining prism 32 and the third color-combining prism 33. Finally, it is converged by the lens group onto the photosensitive surface of the second high-speed camera system. Similarly, the light transmitted from the second color-separating prism 27 passes sequentially through the third color-separating prism 28, the fourth filter 36, the second color-combining prism 32 and the third color-combining prism 33, and the spectral line of the characteristic wavelength 3 can be extracted. Then, it passes through the rear lens group to form an image onto the photosensitive surface of the second high-speed camera system 7. The light transmitted from the third color-separating prism 28 passes sequentially through the fifth filter 37, the second right-angle prism 29 and the third color-combining prism 33, and then passes through the rear lens group to form an image onto the photosensitive surface of the second high-speed camera system 7.

[0014] Furthermore, the second high-speed camera system 7's photosensitive surface receives image plane 46, which includes four sub-image planes. These sub-image planes are closely arranged in the central region of the photosensitive surface, forming a square. The four sub-image planes correspond to images from four different wavelength spectral lines of the gas cloud surface 2. An integrating sphere device is needed to calibrate the correspondence between the absolute intensity of the image of each wavelength spectral line and the measurement signal. By adjusting the angles of dichroic prism 1 26, dichroic prism 27, dichroic prism 3 28, right-angle prism 2 29, right-angle prism 3 30, color combining prism 1 31, color combining prism 2 32, and color combining prism 3 33, the size of each sub-image plane is made the same, and the pixels on the four sub-image planes correspond to the same dot matrix on the gas cloud surface 2.

[0015] Furthermore, the lens group consists of lens 12 38, lens 13 39, lens 14 40, lens 15 41, lens 16 42, lens 17 43, lens 18 44, and lens 19 45.

[0016] The beneficial effects of this invention are as follows:

[0017] This invention proposes a helium spectral imaging system suitable for magnetic confinement fusion devices, comprising a jet pipe system, a relay optical path system, a monochromatic gas-filled imaging system, a multicolor spectral system, and a high-speed camera or photoelectric conversion detector array system. The jet pipe has one or more rows of uniformly distributed small holes, injecting neutral gas to form a gas cloud surface. The relay optical path system includes components such as an observation window, lenses, reflecting prisms, right-angle prisms, beam splitters, dichroic prisms, color combining prisms, and filters, forming the optical paths of the monochromatic gas-filled imaging system and the multicolor spectral system, respectively imaging the gas cloud surface onto designated areas of the high-speed camera's photosensitive surface. The monochromatic gas-filled imaging system images specific wavelength spectral lines from the gas cloud surface image onto the photosensitive surface of the high-speed camera or the photoelectric conversion detector array, obtaining a high-time-resolution image evolution of the surface; the multicolor spectral system images four specific wavelength spectral lines from the surface image onto the photosensitive surface of another high-speed camera or the photoelectric conversion detector array, and combined with a collisional radiation model, the electron temperature and density can be obtained. The helium spectral imaging system of this invention adds a spectroscopic system for measuring electron temperature and density, based on the original gas-filled imaging system, greatly enhancing diagnostic capabilities. Furthermore, this helium spectral imaging system uses a relay optical path to directly image onto the detector, avoiding light loss caused by using imaging fiber bundles. The system has high overall transmittance and light intensity, enabling high time-resolution operation. The optical path system employs a mechanical design with inner and outer cylinders; maintaining the inner cylinder's optical path does not require disassembling the outer cylinder, ensuring high vacuum sealing reliability and stable mechanical performance. Attached Figure Description

[0018] Figure 1 A schematic diagram of the main components of a helium spectral imaging system;

[0019] Figure 2 This is the overall optical path diagram of the helium spectral imaging system;

[0020] Figure 3 This is a monochromatic GPI optical path diagram of a helium spectral imaging system.

[0021] Figure 4 This is the optical path diagram of the multicolor spectral dispersive system of the helium spectral imaging system;

[0022] Figure 5 This is a diagram showing the imaging surface distribution of the multicolor spectral system in a helium spectral imaging system.

[0023] Among them: 1 – jet duct, 2 – gas cloud surface, 3 – relay optical path system, 4 – monochromatic gas imaging system, 5 – multicolor beam splitting system, 6 – first high-speed camera system, 7 – second high-speed camera system, 8 – observation window, 9 – reflecting prism, 10 – lens one, 11 – aperture one, 12 – lens two, 13 – lens three, 14 – lens four, 15 – lens five, 16 – beam splitter, 17 – right-angle prism one, 18 – lens six, 19 – lens seven, 20 – lens eight, 21 – lens nine, 22 – filter one, 23 – lens ten, 24 – Lens 11, 25 – Image plane 1, 26 – Dichroic prism 1, 27 – Dichroic prism 2, 28 – Dichroic prism 3, 29 – Right-angle prism 2, 30 – Right-angle prism 3, 31 – Color combining prism 1, 32 – Color combining prism 2, 33 – Color combining prism 3, 34 – Filter 2, 35 – Filter 3, 36 – Filter 4, 37 – Filter 5, 38 – Lens 12, 39 – Lens 13, 40 – Lens 14, 41 – Lens 15, 42 – Lens 16, 43 – Lens 17, 44 – Lens 18, 45 – Lens 19, 46 – Image plane 2. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0025] like Figure 1 As shown, the helium spectral imaging system of the present invention, applicable to magnetic confinement fusion devices, includes a jet pipe 1, a relay optical path system 3, and a first high-speed camera system 6. The jet pipe 1 injects helium gas into the boundary plasma through multiple small holes, forming a gas cloud surface 2. The relay optical path system 3 collects the light emitted from the gas cloud surface 2 and converges it into parallel light, which is then guided through beam splitters into two branches: a monochromatic gas-filled imaging system 4 and a multicolor beam splitting system 5. The monochromatic gas-filled imaging system 4 images a characteristic spectral line radiated from the gas cloud surface 2 onto the photosensitive surface of the first high-speed camera system 6, obtaining the two-dimensional turbulent structure and its evolution. The multicolor beam splitting system 5, through multiple color separation and color combination steps, images the characteristic spectral lines of four wavelengths in the incident light onto the photosensitive surface of the second high-speed camera system 7, i.e., four wavelength sub-image surfaces are arranged on one photosensitive surface. Combined with a collisional radiation model, the electron temperature and density on the gas cloud surface 2 can be obtained. The entire optical path system has high transmittance and imaging quality.

[0026] The relay optical path system 3 includes a mechanical inner cylinder and a mechanical outer cylinder; the observation window 8 is located at the front end of the mechanical outer cylinder and is used to isolate the vacuum inside and outside the mechanical outer cylinder. The end flange of the mechanical outer cylinder is connected to the window flange of the magnetic confinement fusion device to complete the vacuum seal; all other optical lenses are installed and fixed inside the mechanical inner cylinder. The ends of the mechanical inner cylinders corresponding to the monochromatic gas-filled imaging system 4 and the multicolor beam splitting system 5 have internal threads for connecting to the flange with external threads at the bottom, which can adjust and fix the distance between the high-speed camera system and the image plane; there is a flange in the middle of the mechanical inner cylinder, which can be connected and fixed to the end flange of the mechanical outer cylinder.

[0027] The jet pipe 1 consists of one or more rows of evenly arranged small holes, usually made of 316L stainless steel pipe, and is fixed to the inner wall of the magnetic confinement device by welding or bolting. When needed, it sprays neutral gas, such as helium, into the plasma boundary to form a gas cloud surface 2.

[0028] like Figure 1 As shown, the first high-speed camera system 6 and the second high-speed camera system 7 can be commercial high-speed cameras to directly capture graphic information of the gas cloud surface 2, with high pixel count and acquisition frame rate; or they can be arrayed using photoelectric conversion detectors to receive image information from the image surface; the first high-speed camera system 6 and the second high-speed camera system 7 can be fixed on the flange and support plate at the tail end of the optical barrel. The lower end of the flange has an external thread that connects to the internal thread at the tail end of the barrel. The distance between the photosensitive surface and the image surface can be adjusted by the thread at the lower end of the flange to obtain the clearest image. In addition, the angle of the image surface on the photosensitive surface of the high-speed camera can be adjusted by rotating the high-speed camera system.

[0029] like Figure 2 As shown, the relay optical path system 3 includes components such as an observation window 8, lenses, a reflecting prism 9, a right-angle prism, a beam splitter 16, a dichroic prism, a color combining prism, and filters, which image certain spectral lines emitted by the gas cloud surface 2 onto the photosensitive surface of the high-speed camera system. The observation window 8 is located at the front end of the optical path and is made of quartz glass welded to a stainless steel flange. It is connected to the flange of the mechanical outer cylinder to provide a vacuum seal. The reflecting prism 9 adjusts the incident light to be coaxial with the optical barrel. The light passes through lens 10, aperture 11, lens 2 12, lens 3 13, lens 4 14, and lens 5 15 in sequence, which converges the light into parallel light. The beam splitter 16 splits the light into two parts. One part enters the multicolor beam splitting system 5, and the other part is reflected by the right-angle prism 17 into the monochromatic gas-filled imaging system 4.

[0030] like Figure 3As shown, the monochromatic gas imaging system 4 includes lens six 18, lens seven 19, lens eight 20, lens nine 21, lens ten 23, lens eleven 24 and filter one 22. The above components gradually converge the light and image it onto the photosensitive surface of the first high-speed camera system 6, namely the image surface one 25. The filter one 22 is installed in the slot reserved in the optical barrel. During the experimental interval, the filter one 22 can be replaced to obtain the two-dimensional structural evolution of different characteristic spectral lines of the gas cloud surface 2.

[0031] like Figure 4 As shown, the multicolor spectral system 5 extracts the four characteristic spectral lines radiated from the gas cloud surface 2 and images them onto the photosensitive surface of the second high-speed camera system 7. The four sub-image surfaces are closely arranged to form a square image surface 46 located in the central region of the photosensitive surface. After entering the multicolor spectral system 5, light first passes through the dichroic prism 26, reflecting the characteristic wavelength 1 into the filter 34 and right-angle prism 30. Then, it passes sequentially through the color combining prism 31, color combining prism 32, and color combining prism 33. Finally, a lens group composed of lenses 38 and 45 converges the light onto the photosensitive surface of the second high-speed camera system 7. When light passes through the dichroic prism 26, the characteristic wavelength 2 is reflected into the filter 35 and color combining prism 31, and then further reflected through the color combining prism 32 and color combining prism 33. The lens group composed of lens 38-lens 45 then converges onto the photosensitive surface of the second high-speed camera system 7; similarly, the light transmitted from the dichroic prism 27 passes sequentially through the dichroic prism 38, the filter 4 36, the color combining prism 2 32 and the color combining prism 3 33, and the spectral line of characteristic wavelength 3 can be extracted, and then the image is formed by the rear lens group onto the photosensitive surface of the second high-speed camera system 7; the light transmitted from the dichroic prism 3 28 passes sequentially through the filter 5 37, the right-angle prism 2 29 and the color combining prism 3 33, and then the image is formed by the rear lens group onto the photosensitive surface of the second high-speed camera system 7.

[0032] like Figure 5 As shown, the second high-speed camera system 7 receives image plane 46, which contains four sub-image planes. These sub-image planes are closely arranged in the central region of the photosensitive surface, forming a square. The four sub-image planes correspond to images from four different wavelength spectral lines of the gas cloud surface 2. It is necessary to use equipment such as an integrating sphere to calibrate the correspondence between the absolute intensity of each wavelength image and the measurement signal. By adjusting the angles of dichroic prism 1 26, dichroic prism 27, dichroic prism 3 28, right-angle prism 2 29, right-angle prism 3 30, color combining prism 1 31, color combining prism 2 32, and color combining prism 3 33, the size of each sub-image plane is the same, and the pixels on the four sub-image planes correspond to the dot matrix on the same gas cloud surface 2.

[0033] The parts of this invention not described in detail are well-known in the field.

[0034] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes will be obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A helium spectral imaging system suitable for magnetic confinement fusion devices, characterized in that: The system includes a jet pipe (1), a relay optical path system (3), a monochromatic gas-filled imaging system (4), a multicolor beam splitting system (5), a first high-speed camera system (6), and a second high-speed camera system (7). The jet pipe (1) injects helium gas into the boundary plasma through multiple small holes to form a gas cloud surface (2). The relay optical path system (3) collects the light emitted from the gas cloud surface (2) and converges it into parallel light, which is then guided into the two branches of the monochromatic gas-filled imaging system (4) and the multicolor beam splitting system (5) through beam splitters. The gas imaging system (4) images specific characteristic spectral lines radiated from the gas cloud surface (2) onto the photosensitive surface of the first high-speed camera system (6), i.e., image surface one (25), to obtain the two-dimensional turbulent structure and evolution; the multicolor spectral system (5) images the characteristic spectral lines of four wavelengths in the incident light onto the photosensitive surface of the second high-speed camera system (7), i.e., image surface two (46), i.e., four wavelength sub-image surfaces are arranged on one photosensitive surface, and the electron temperature and density on the gas cloud surface (2) are obtained by combining the collision radiation model.

2. The helium spectral imaging system for magnetic confinement fusion devices according to claim 1, characterized in that: The jet pipe (1) consists of one or more rows of uniformly arranged small holes, usually made of 316L stainless steel pipe, and is fixed to the inner wall of the magnetic confinement fusion device by welding or bolting. When needed, helium is injected into the plasma boundary to form a gas cloud surface (2).

3. The helium spectral imaging system for magnetic confinement fusion devices according to claim 1, characterized in that: The optical tube of the relay optical path system (3) includes a mechanical inner tube and a mechanical outer tube; the observation window (8) is located at the front end of the mechanical outer tube and is used to isolate the vacuum inside and outside the mechanical outer tube. The end flange of the mechanical outer tube is connected to the window flange of the magnetic confinement fusion device to complete the vacuum seal; all other optical lenses are installed and fixed inside the mechanical inner tube. The ends of the mechanical inner tubes corresponding to the monochrome gas-filled imaging system (4) and the multicolor beam splitting system (5) have internal threads for connecting to the flange with external threads at the bottom. The distance between the first high-speed camera system (6) and the second high-speed camera system (7) and image plane one (25) and image plane two (46) can be adjusted and fixed by rotating the threads of the flange. There is a flange in the middle of the mechanical inner tube, which is connected and fixed to the end flange of the mechanical outer tube.

4. The helium spectral imaging system for magnetic confinement fusion devices according to claim 1, characterized in that: The first high-speed camera system (6) and the second high-speed camera system (7) use commercial high-speed cameras to directly capture the graphic information of the gas cloud surface (2), which has high pixel count and acquisition frame rate; or the first high-speed camera system (6) and the second high-speed camera system (7) use photoelectric conversion detectors to form an array to receive the image information of the image surface; the first high-speed camera system (6) and the second high-speed camera system (7) are fixed on the flange and support plate at the tail end of the optical barrel. The lower end of the flange is externally threaded and connected to the internal thread at the tail end of the barrel. The distance between the photosensitive surface and the image surface can be adjusted by the thread at the lower end of the flange to obtain the clearest image. Alternatively, the angle of the image surface on the photosensitive surface of the high-speed camera system can be adjusted by rotating the high-speed camera system.

5. The helium spectral imaging system for magnetic confinement fusion devices according to claim 1, characterized in that: The relay optical path system (3) includes an observation window (8), a lens, a reflecting prism (9), a right-angle prism, a beam splitter (16), a dichroic prism, a color combining prism, and a filter, which images certain spectral lines emitted by the gas surface (2) onto the photosensitive surface of the high-speed camera system. The observation window (8) is located at the front end of the optical path and is made of quartz glass and a stainless steel flange. It is connected to the flange of the mechanical outer cylinder to play a role in vacuum sealing. The reflecting prism (9) adjusts the incident light to be coaxial with the optical tube. The light passes through lens one (10), aperture one (11), lens two (12), lens three (13), lens four (14), and lens five (15) in sequence, which converges the light into parallel light. The beam splitter (16) splits the light into two parts. One part enters the multicolor beam splitting system (5), and the other part is reflected by right-angle prism one (17) into the monochromatic gas-filled imaging system (4).

6. The helium spectral imaging system for magnetic confinement fusion devices according to claim 5, characterized in that: The monochromatic gas imaging system (4) includes lens six (18), lens seven (19), lens eight (20), lens nine (21), lens ten (23), lens eleven (24) and filter one (22). The above components gradually converge the light and image it onto the photosensitive surface of the first high-speed camera system (6), namely image plane one (25). The filter one (22) is installed in the slot reserved in the optical barrel of the monochromatic gas imaging system (4). During the experimental interval, by changing the filter one (22), the two-dimensional structural evolution of different characteristic spectral lines of the gas cloud surface (2) can be obtained.

7. The helium spectral imaging system for magnetic confinement fusion devices according to claim 5, characterized in that: The multicolor spectral system (5) extracts the four characteristic spectral lines radiated from the gas cloud surface (2) and images them onto the photosensitive surface of the second high-speed camera system (7). The four sub-image surfaces are closely arranged to form a square image surface two (46) located in the central area of ​​the photosensitive surface. After the light enters the multicolor spectral system (5), it first passes through the first dichroic prism (26) and reflects the characteristic wavelength one into the second filter (34) and the third right-angle prism (30). Then it passes through the first dichroic prism (31), the second dichroic prism (32), and the third dichroic prism (33) in sequence, and finally converges to the photosensitive surface of the second high-speed camera system (7) by the lens group. When the light transmitted from the first dichroic prism (26) passes through the second dichroic prism (27), the characteristic wavelength two is reflected into the second dichroic prism. The light passing through the third filter (35) and the first color-combining prism (31) is reflected and passed through the second color-combining prism (32) and the third color-combining prism (33), and finally converged by the lens group to the photosensitive surface of the second high-speed camera system. Similarly, the light passing through the second color-separating prism (27) passes through the third color-separating prism (28), the fourth filter (36), the second color-combining prism (32) and the third color-combining prism (33) in sequence, and the spectral line of the characteristic wavelength three can be extracted. Then, the light passes through the rear lens group to form an image to the photosensitive surface of the second high-speed camera system (7). The light passing through the third color-separating prism (28) passes through the fifth filter (37), the second right-angle prism (29) and the third color-combining prism (33) in sequence, and then passes through the rear lens group to form an image to the photosensitive surface of the second high-speed camera system (7).

8. The helium spectral imaging system for magnetic confinement fusion devices according to claim 7, characterized in that: The second high-speed camera system (7) receives image plane two (46) which contains four sub-image planes, which are closely arranged in the central area of ​​the photosensitive surface to form a square. The four sub-image planes correspond to images from four different wavelength spectral lines of the gas cloud surface (2). It is necessary to use an integrating sphere device to calibrate the correspondence between the absolute intensity of the image of each wavelength spectral line and the measurement signal. By adjusting the angles of dichroic prism one (26), dichroic prism two (27), dichroic prism three (28), right angle prism two (29), right angle prism three (30), color combining prism one (31), color combining prism two (32) and color combining prism three (33), the size of each sub-image plane is the same, and the pixels on the four sub-image planes correspond to the dot matrix on the same gas cloud surface (2).

9. The helium spectral imaging system for magnetic confinement fusion devices according to claim 7, characterized in that, The lens group consists of lens twelve (38), lens thirteen (39), lens fourteen (40), lens fifteen (41), lens sixteen (42), lens seventeen (43), lens eighteen (44), and lens nineteen (45).

Images