Plasma magnetic field optical measurement device and method with time and space resolution capabilities

Abstract

This invention discloses a plasma magnetic field optical measurement device and method with temporal and spatial resolution capabilities, comprising: constructing an optical rotation measurement system based on a pulsed laser beam to measure the laser intensity of optical rotation images and shadow images; processing the laser intensity of the optical rotation images and shadow images to obtain the distribution of a proportionality coefficient based on the light intensity distribution; obtaining the distribution of the optical rotation deflection angle based on the mapping relationship between the proportionality coefficient and the optical rotation deflection angle; constructing an interferometric measurement system based on a pulsed laser beam to measure the fringe shift of the interferometric image; and obtaining the evolution of the one-dimensional distribution of the average magnetic field over time based on the optical rotation deflection angle and the fringe shift. This invention adjusts the parameters of the fourth beam splitter and the first analyzer in the optical rotation measurement device to regulate the sensitivity of the optical rotation measurement, thereby achieving a wide-range and highly sensitive measurement of the magnetic induction intensity inside the plasma.

Description

Technical Field

[0001] This invention belongs to the field of magnetic field measurement technology, and relates to a plasma magnetic field optical measurement device and method with time and space resolution capabilities. Background Art

[0002] Magnetic field measurements in a vacuum are primarily performed using contact-type magnetic induction coils. Integrating the induced electromotive force of the coil over time yields the magnetic field distribution at the coil's location. The direct insertion of a magnetic probe into the plasma has two main effects: first, it cools the plasma and disturbs its motion; second, the induced current it generates interferes with the plasma's magnetic field. Furthermore, when the external temperature is too high, the coating on the magnetic probe can be ablated, potentially causing the measurement signal to suddenly exceed the measurable threshold and damage the measuring instrument. Another non-contact measurement method is Faraday rotation, suitable for situations where plasma is present in a vacuum. When a linearly polarized beam of light passes through the plasma, it is deflected, and the deflection angle depends on the electron density and magnetic field distribution along the light propagation path. However, this method is limited by the coordination between the camera and the probe laser, generally achieving only spatial resolution and not temporal resolution.

[0003] In summary, the analysis shows that, among the existing publicly available technologies, how to achieve a diagnostic method that simultaneously possesses temporal and spatial resolution capabilities to study the evolution of plasma magnetic field distribution is a technical challenge that needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that existing Faraday rotation measurements can only achieve spatial resolution but not temporal resolution, and to provide a plasma magnetic field optical measurement device and method with both temporal and spatial resolution capabilities.

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

[0006] A plasma magnetic field optical measurement device with time and space resolution includes: a pulsed laser, a pulsed laser beam, a polarizer, a first beam splitter, plasma, a second beam splitter, a reflector, a third beam splitter, a streak camera, a linear spatial filter, a dispersive prism, and an optical rotation measurement device.

[0007] A pulsed laser emits a pulsed laser beam, which is then split by a polarizer and a first beam splitter. One beam passes through a plasma and a second beam splitter, and is reflected by the second beam splitter before entering a third beam splitter. The other beam passes through a reflector and enters the third beam splitter. The two beams entering the third beam splitter interfere with each other and enter the fringe camera. The pulsed laser beam transmitted through the second beam splitter is filtered by a linear spatial filter plate to form a miniature spot. The miniature spot passes through a dispersive prism and enters the optical rotation measurement device.

[0008] A further improvement of the present invention is that:

[0009] Furthermore, the linear spatial filter plate has several light-transmitting holes, and the number of micro-spots is the same as the number of light-transmitting holes on the linear spatial filter plate.

[0010] Furthermore, the micro-spot includes a first micro-spot and a second micro-spot; the optical rotation measurement device includes a first optical rotation measurement device and a second optical rotation measurement device; after the first micro-spot and the second micro-spot pass through the dispersive prism, the first micro-spot enters the first optical rotation measurement device; the second micro-spot enters the second optical rotation measurement device.

[0011] Furthermore, the first optical rotation measurement device includes: a fourth beam splitter, a first analyzer, a first photodiode, and a second photodiode; the first miniature light spot passes through the fourth beam splitter to split the beam, one beam passes through the first analyzer and the first photodiode, and the other beam enters the second photodiode;

[0012] The second optical rotation measurement device includes: a fifth beam splitter, a second analyzer, a third photodiode, and a fourth photodiode; the second miniature light spot is split by passing through the fifth beam splitter, one beam passes through the second analyzer and the third photodiode, and the other beam enters the fourth photodiode.

[0013] Furthermore, the plasma is located inside the vacuum cavity; the slits of the linear spatial filter plate and the streak camera are positioned at the same location relative to the first and second micro-spots; the polarizer is an optical instrument with p-polarization; and the first and second beam splitters are non-polarized optical instruments.

[0014] Furthermore, the response intensity of the first photodiode, the second photodiode, the third photodiode, and the fourth photodiode is proportional to the energy of the pulsed laser beam.

[0015] Optical measurement methods for plasma magnetic fields with temporal and spatial resolution include:

[0016] An optical rotation measurement system was constructed based on pulsed laser beams to measure the laser intensity in optical rotation images and shadow images;

[0017] The laser intensity of the optical rotation image and the shadow image are processed, and the distribution of the proportional coefficient is obtained based on the light intensity distribution;

[0018] Based on the mapping relationship between the scaling factor and the optical rotation deflection angle, the distribution of the optical rotation deflection angle is obtained;

[0019] An interferometric measurement system based on pulsed laser beams is used to measure the fringe shift of an interferometric image.

[0020] Based on the optical rotation deflection angle and fringe offset, a one-dimensional distribution of the average magnetic field is obtained.

[0021] Furthermore, an optical rotation measurement system is constructed based on pulsed laser beams to measure the laser intensity in optical rotation images and shadow images, specifically:

[0022] A pulsed laser emits a pulsed laser beam. After the pulsed laser beam becomes linearly polarized by a polarizer in the p-polarization direction, it passes through a first beam splitter and, without passing through plasma, sequentially enters a second beam splitter, a linear spatial filter, a dispersive prism, and a first optical rotation measurement device. After being split by a fourth beam splitter in the first optical rotation measurement device, one beam passes through a first analyzer and a first photodiode to obtain the laser intensity I1 of the optical rotation image; the other beam enters a second photodiode to obtain the laser intensity I2 of the shadow image.

[0023] A pulsed laser emits a pulsed laser beam. After the pulsed laser beam becomes linearly polarized by a polarizer in the p-polarization direction, it passes through a first beam splitter and a plasma, and then sequentially enters a second beam splitter, a linear spatial filter, a dispersive prism, and a first optical rotation measurement device. After being split by a fourth beam splitter in the first optical rotation measurement device, one beam passes through a first analyzer and a first photodiode to obtain the laser intensity I′1 of the optical rotation image; the other beam enters a second photodiode to obtain the laser intensity I′2 of the shadow image.

[0024] The polarization planes of the first and second analyzers are at a fixed angle of +β relative to the incident light. Let the energy distribution of the pulsed laser beam be I. Then, the laser intensity I1 in the optical rotation image and the laser intensity I2 in the shadow image are expressed as follows:

[0025]

[0026] In the formula, D1 and D2 represent the reflectivity and transmittance of the fourth beam splitter in the imaging system;

[0027] When plasma is present, assuming the magnitude of the optical rotation deflection angle caused by the plasma is α; and the energy distribution of the pulsed laser beam is I′, then the laser intensity of the optical rotation image is I′1, and the laser intensity of the shadow image is I′2; their expressions are shown in the formula:

[0028]

[0029] The laser intensity of the optical rotation image and the shadow image are processed, and the distribution of the scaling factor is obtained based on the intensity distribution. Specifically, a scaling index I is introduced. F As shown in the formula:

[0030]

[0031] Based on the mapping relationship between the scaling factor and the optical rotation deflection angle, the distribution of the optical rotation deflection angle is obtained, specifically: when β is fixed, the scaling factor I... F It has a mapping relationship with the optical rotation deflection angle α, according to the proportional index I F The value of the optical rotation deflection angle α can be derived from the value of the optical rotation angle α.

[0032] Furthermore, an interferometric measurement system is constructed based on a pulsed laser beam to measure the fringe shift of the interference image. Specifically, a pulsed laser emits a pulsed laser beam, which is then split by a polarizer and a first beam splitter. One beam passes sequentially through a plasma and a second beam splitter, and is reflected by the second beam splitter into a third beam splitter. The other beam passes through a reflecting mirror and enters the third beam splitter. The two beams entering the third beam splitter together enter a fringe camera to form interference fringes. The fringe camera captures the interference fringes, which constitute the interference image. The fringe shift of the interference image is calculated using the formula shown below.

[0033]

[0034] Where y is the distance of the pulsed laser beam from the plasma axis, e is the electron charge, λ is the wavelength of the pulsed laser beam, ε0 is the vacuum dielectric constant, and m e It is the electron mass, c is the speed of light, n e dl is the electron density, and dl is the integral infinitesimal element along the propagation path of the laser beam inside the plasma;

[0035] For the measurement of electron surface density in plasma, the formula is as follows:

[0036]

[0037] Where Δδ represents the fringe offset number; L is the length of the propagation path of the pulsed laser beam in the plasma.

[0038] Furthermore, based on the optical rotation deflection angle and fringe shift, the one-dimensional distribution of the average magnetic field is obtained, specifically:

[0039]

[0040] In the formula, B aα(r) is the average magnetic field strength distributed along the plasma radius, α(r) is the deflection angle at different radii of the plasma, and δ(r) is the offset of the interference fringes at different radii of the plasma.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] This invention obtains an interference image by setting up a polarizer, a first beam splitter, a plasma, a second beam splitter, a reflector, a third beam splitter, and a fringe camera. It then uses a linear spatial filter, a dispersive prism, and an optical rotation measurement device to obtain optical rotation and shadow images. The electron density distribution is measured using the interference image, and the magnitude of the magnetic flux density is finally obtained through Faraday rotation measurement. The spatial range of the measurable magnetic field depends on the size of the probe spot. Furthermore, by adjusting the parameters of the fourth beam splitter and the first analyzer in the optical rotation measurement device, the sensitivity of the optical rotation measurement can be adjusted, thereby achieving a wide-range, high-sensitivity measurement of the magnetic flux density within the plasma. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a structural diagram of a plasma magnetic field optical measurement device with time and space resolution according to an embodiment of the present invention;

[0045] Figure 2 This is a front view of the linear space filter board structure.

[0046] Figure 3 This is a flowchart of a plasma magnetic field optical measurement process with time and space resolution, according to an embodiment of the present invention.

[0047] Wherein, 1-pulsed laser; 2-pulsed laser beam; 3-polarizer; 4-first beam splitter; 5-plasma; 6-second beam splitter; 7-reflector; 8-third beam splitter; 9-streaked camera; 10-linear spatial filter; 11-first micro-spot; 12-second micro-spot; 13-dispersion prism; 14-fourth beam splitter; 15-first analyzer; 16-first photodiode; 17-second photodiode; 18-fifth beam splitter; 19-second analyzer; 20-third photodiode; 21-fourth photodiode; 22-vacuum cavity. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0050] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0051] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0052] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0053] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0054] The present invention will now be described in further detail with reference to the accompanying drawings:

[0055] The theoretical basis of this invention is: the Faraday rotation effect refers to the phenomenon that when a beam of plane-polarized light passes through a magneto-optical medium placed in a magnetic field, the polarization plane of the plane-polarized light rotates with the magnetic field parallel to the direction of the light. When the plasma under test is used as the magneto-optical medium, a beam of linearly polarized light propagating through the medium can be understood as the superposition of two beams of circularly polarized light with opposite rotation directions. Due to the magneto-optical effect, these two beams have different refractive indices and propagation speeds, and therefore have different phase lags after traveling the same distance, thus causing a certain deflection angle of the linearly polarized light passing through the plasma. When using a laser probe of a fixed wavelength for Faraday rotation diagnosis, the Faraday rotation angle is:

[0056]

[0057] Where λ is the wavelength of the pulsed laser beam, and n e is the electron density, B is the component of the magnetic field vector on the pulsed laser beam, and dl is the integral element along the propagation path of the laser beam inside the plasma.

[0058] This method is based on Faraday rotation and interferometric diagnostic techniques. It measures the one-dimensional distribution and evolution of the deflection angle using a long-pulse laser combined with a linear spatial filter and a photodiode. It also measures the one-dimensional distribution and evolution of the electron density using an interferometric image and a fringe camera, thereby ultimately determining the evolution of the magnetic field strength at the plasma's spatial location. The spatial resolution of the measurable magnetic field depends on the size of the apertures on the linear spatial filter. Furthermore, by adjusting the size and number of apertures on the linear spatial filter, the spatial measurement range can be adjusted, while the temporal range depends on the oscilloscope sampling frequency. Therefore, based on this method, it is possible to measure the distribution and evolution of magnetic induction intensity.

[0059] See Figure 1 and Figure 2 The present invention discloses a plasma magnetic field optical measurement device with time and space resolution capability, comprising: a pulsed laser 1, a pulsed laser beam 2, a polarizer 3, a first beam splitter 4, a plasma 5, a second beam splitter 6, a reflector 7, a third beam splitter 8, a streak camera 9, a linear spatial filter plate 10, a dispersive prism 13, and an optical rotation measurement device.

[0060] Pulsed laser 1 emits a pulsed laser beam 2, which passes through polarizer 3 and first beam splitter 4 for beam splitting. One beam passes through plasma 5 and second beam splitter 6 in sequence, and is reflected by second beam splitter 6 into third beam splitter 8. The other beam passes through mirror 7 and enters third beam splitter 8. The two beams entering third beam splitter 8 enter streak camera 9 together. The pulsed laser beam 2 transmitted through second beam splitter 6 enters linear spatial filter plate 10 for filtering, forming a micro spot. The micro spot passes through dispersive prism 13 and enters optical rotation measurement device.

[0061] The linear space filter plate 10 has several light-transmitting holes, and the number of micro-light spots is the same as the number of light-transmitting holes on the linear space filter plate 10.

[0062] The micro-spots include a first micro-spot 11 and a second micro-spot 12; the optical rotation measuring device includes a first optical rotation measuring device and a second optical rotation measuring device; after the first micro-spot 11 and the second micro-spot 12 pass through the dispersive prism 13, the first micro-spot 11 enters the first optical rotation measuring device; the second micro-spot 12 enters the second optical rotation measuring device.

[0063] The first optical rotation measurement device includes: a fourth beam splitter 14, a first analyzer 15, a first photodiode 16, and a second photodiode 17; the first miniature light spot 11 passes through the fourth beam splitter 14 to split the beam, one beam passes through the first analyzer 15 and the first photodiode 16, and the other beam enters the second photodiode 17.

[0064] The second optical rotation measurement device includes: a fifth beam splitter 18, a second analyzer 19, a third photodiode 20, and a fourth photodiode 21; the second miniature light spot 12 passes through the fifth beam splitter 18 to split the beam, one beam passes through the second analyzer 19 and the third photodiode 20, and the other beam enters the fourth photodiode 21.

[0065] Plasma 5 is located inside vacuum chamber 22; the slits of linear spatial filter plate 10 and streak camera 9 are positioned at the same level relative to the first micro spot 11 and the second micro spot 12; polarizer 3 is an optical instrument for p-polarization; first beam splitter 4 and second beam splitter 6 are optical instruments for non-polarization.

[0066] The response intensity of the first photodiode 16, the second photodiode 17, the third photodiode 20, and the fourth photodiode 21 is proportional to the pulsed laser beam 2.

[0067] Vacuum chamber 22 is sealed with steel plate and evacuated to vacuum using a vacuum pump; plasma 5 is generated by applying pulsed current to a metal wire array load, with a peak pulse current of 450kA and a rise time of 400ns;

[0068] See Figure 3This invention discloses a plasma magnetic field optical measurement method with time and space resolution, comprising:

[0069] S101 is an optical rotation measurement system built based on pulsed laser beams to measure the laser intensity of optical rotation images and shadow images.

[0070] Pulsed laser 1 emits a pulsed laser beam 2. After the pulsed laser beam 2 becomes linearly polarized light through the p-polarization polarizer 3, it passes through the first beam splitter 4 and, without passing through the plasma 5, sequentially enters the second beam splitter 6, the linear spatial filter plate 10, the dispersive prism 13, and the first optical rotation measurement device. After being split by the fourth beam splitter 14 in the first optical rotation measurement device, one beam passes through the first analyzer 15 and the first photodiode 16 to obtain the laser intensity I1 of the optical rotation image; the other beam enters the second photodiode 17 to obtain the laser intensity I2 of the shadow image.

[0071] Pulsed laser 1 emits a pulsed laser beam 2. After the pulsed laser beam 2 becomes linearly polarized light through the polarizer 3 in the p-polarization direction, it passes through the first beam splitter 4 and the plasma 5, and then sequentially enters the second beam splitter 6, the linear spatial filter plate 10, the dispersive prism 13 and the first optical rotation measurement device. After being split by the fourth beam splitter 14 in the first optical rotation measurement device, one beam passes through the first analyzer 15 and the first photodiode 16 to obtain the laser intensity I′1 of the optical rotation image; the other beam enters the second photodiode 17 to obtain the laser intensity I′2 of the shadow image.

[0072] The polarization planes of the first analyzer 15 and the second analyzer 19 are at a fixed angle of +β relative to the incident light. Let the energy distribution of the pulsed laser beam be I, then the laser intensity I1 of the optical rotation image and the laser intensity I2 of the shadow image are expressed as formula (1):

[0073]

[0074] In the formula, D1 and D2 represent the reflectivity and transmittance of the fourth beam splitter 14 in the imaging system;

[0075] When plasma 5 is present, assuming the optical rotation deflection angle caused by plasma 5 is α; and the energy distribution of the pulsed laser beam is I′, then the laser intensity of the optical rotation image is I′1, and the laser intensity of the shadow image is I′2; their expressions are shown in formula (2):

[0076]

[0077] S102 processes the laser intensity of the optical rotation image and the shadow image, and obtains the distribution of the scaling factor based on the light intensity distribution.

[0078] Introducing the proportional index I FAs shown in formula (3):

[0079]

[0080] S103, based on the mapping relationship between the scaling factor and the optical rotation deflection angle, obtains the distribution of the optical rotation deflection angle.

[0081] Based on the mapping relationship between the scaling factor and the optical rotation deflection angle, the distribution of the optical rotation deflection angle is obtained, specifically: when β is fixed, the scaling factor I... F It has a mapping relationship with the optical rotation deflection angle α, according to the proportional index I F The value of the optical rotation deflection angle α can be derived from the value of the optical rotation angle α.

[0082] S104 is an interferometric measurement system based on pulsed laser beams, used to measure the fringe offset of interferometric images.

[0083] Pulsed laser 1 emits pulsed laser beam 2, which is split by polarizer 3 and first beam splitter 4. One beam passes through plasma 5 and second beam splitter 6, and is reflected by second beam splitter 6 into third beam splitter 8. The other beam passes through mirror 7 and enters third beam splitter 8. The two beams entering third beam splitter 8 enter fringe camera 9 together to form interference fringes. Fringe camera 9 captures the interference fringes, which is the interference image. The method for calculating the fringe offset of the interference image is shown in formula (4).

[0084]

[0085] Where y is the distance of the pulsed laser beam from the plasma axis, e is the electron charge, λ is the wavelength of the pulsed laser beam, ε0 is the vacuum dielectric constant, and m e It is the electron mass, c is the speed of light, n e dl is the electron density, and dl is the integral infinitesimal element along the propagation path of the laser beam inside the plasma;

[0086] For the measurement of electron surface density in plasma, as shown in Equation (5):

[0087]

[0088] Where Δδ represents the fringe offset number; L is the length of the propagation path of the pulsed laser beam in the plasma.

[0089] S105, based on optical rotation deflection angle and fringe offset, obtains the two-dimensional distribution of the average magnetic field.

[0090]

[0091] In the formula, B aα(r) is the average magnetic field strength distributed along the radius of plasma 5, α(r) is the deflection angle at different radii of plasma 5, and δ(r) is the offset of the interference fringes at different radii of plasma 5.

[0092] The implementation plan includes the following steps:

[0093] Set up a diagnostic device; first, connect the first photodiode 16, the second photodiode 17, the third photodiode 20 and the fourth photodiode 21 to the oscilloscope respectively, and record the laser intensity when there is no plasma 5.

[0094] Specifically, such as Figure 1 As shown, the device includes a pulsed power unit, a Faraday optical rotation diagnostic unit, and a Mach-Zehnder interferometer. A pulsed laser 1 emits a pulsed laser beam 2, which is converted into linearly polarized light by a polarizer 3. The beam is split into two beams by a first beam splitter 4. One beam enters the vacuum cavity 22, passes through the plasma 5, and is reflected by a second beam splitter 6 to form a load beam. The other beam is reflected by a mirror 7 to form a reference beam. These two beams are combined at a third beam splitter 8 to produce an interference image, which is captured by a fringe camera 9. The pulsed laser beam 2 also exhibits optical rotation as it passes through the plasma 5. After being filtered by a linear spatial filter plate 10, the beam is divided into a first micro-spot 11 and a second micro-spot 12, which are spatially separated by a dispersive prism 13. The first micro-spot 11 is measured for optical rotation by a fourth beam splitter 14, a first analyzer 15, a first photodiode 16, and a second photodiode 17. The second micro-spot 12 is measured for optical rotation by a fifth beam splitter 18, a second analyzer 19, a third photodiode 20, and a fourth photodiode 21.

[0095] The specific operating method of this device is as follows:

[0096] Pulsed laser 1 is turned on, and the shadow, optical rotation, and interference information of plasma 5 without plasma 5 are measured as a control. A pulsed current is applied to the load, simultaneously triggering pulsed laser 1 and streak camera 9, thereby measuring the optical rotation and interference information of plasma 5 during the discharge process; the optical rotation and interference information are processed to obtain the optical rotation deflection angle distribution and electron surface density distribution, thereby obtaining the change of magnetic induction intensity distribution over time.

[0097] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A plasma magnetic field optical measurement device with time and space resolution capability, characterized in that, include: Pulsed laser (1), pulsed laser beam (2), polarizer (3), first beam splitter (4), plasma (5), second beam splitter (6), mirror (7), third beam splitter (8), streak camera (9), linear spatial filter (10), dispersive prism (13), and optical rotation measurement device; The pulsed laser (1) emits a pulsed laser beam (2), which is then split by a polarizer (3) and a first beam splitter (4). One beam passes through a plasma (5) and a second beam splitter (6) in sequence, and is reflected by the second beam splitter (6) into a third beam splitter (8). The other beam passes through a reflector (7) and enters the third beam splitter (8). The two beams entering the third beam splitter (8) interfere with each other and enter the fringe camera (9). The pulsed laser beam (2) transmitted through the second beam splitter (6) enters a linear spatial filter plate (10) for filtering, forming a micro-spot. The micro-spot passes through a dispersive prism (13) and then enters the optical rotation measurement device. The optical rotation measuring device includes at least a photodiode and an oscilloscope; The linear spatial filter plate (10) has several light-transmitting holes, and the number of micro-light spots is the same as the number of light-transmitting holes on the linear spatial filter plate (10).

2. The plasma magnetic field optical measurement device with time and space resolution according to claim 1, characterized in that, The micro-spots include a first micro-spot (11) and a second micro-spot (12); the optical rotation measuring device includes a first optical rotation measuring device and a second optical rotation measuring device; after the first micro-spot (11) and the second micro-spot (12) pass through the dispersive prism (13), the first micro-spot (11) enters the first optical rotation measuring device; the second micro-spot (12) enters the second optical rotation measuring device.

3. The plasma magnetic field optical measurement device with time and space resolution according to claim 2, characterized in that, The first optical rotation measurement device includes: a fourth beam splitter (14), a first analyzer (15), a first photodiode (16), and a second photodiode (17); the first micro-spot (11) passes through the fourth beam splitter (14) to split the beam, one beam passes through the first analyzer (15) and the first photodiode (16), and the other beam enters the second photodiode (17). The second optical rotation measurement device includes: a fifth beam splitter (18), a second analyzer (19), a third photodiode (20), and a fourth photodiode (21); the second micro spot (12) passes through the fifth beam splitter (18) to split the beam, one beam passes through the second analyzer (19) and the third photodiode (20), and the other beam enters the fourth photodiode (21).

4. The plasma magnetic field optical measurement device with time and space resolution according to claim 3, characterized in that, It also includes a vacuum cavity (22), in which the plasma (5) is disposed; the slits of the linear spatial filter plate (10) and the streak camera (9) are positioned at the same position relative to the first micro spot (11) and the second micro spot (12); the polarizer (3) is an optical instrument with p-polarization direction; the first beam splitter (4) and the second beam splitter (6) are non-polarized optical instruments.

5. The plasma magnetic field optical measurement device with time and space resolution according to claim 4, characterized in that, The response intensity of the first photodiode (16), the second photodiode (17), the third photodiode (20) and the fourth photodiode (21) is proportional to the energy of the pulsed laser beam (2).

6. A measurement method based on the plasma magnetic field optical measurement device with time and space resolution as described in any one of claims 1-5, characterized in that, include: An optical rotation measurement system was constructed based on pulsed laser beams to measure the laser intensity in optical rotation images and shadow images; The laser intensity of the optical rotation image and the shadow image are processed, and the distribution of the proportional coefficient is obtained based on the light intensity distribution; Based on the mapping relationship between the scaling factor and the optical rotation deflection angle, the distribution of the optical rotation deflection angle is obtained; An interferometric measurement system based on pulsed laser beams is used to measure the fringe shift of an interferometric image. Based on the optical rotation deflection angle and fringe offset, a one-dimensional distribution of the average magnetic field is obtained.

7. The plasma magnetic field optical measurement method with time and space resolution according to claim 6, characterized in that, The optical rotation measurement system based on pulsed laser beams measures the laser intensity of optical rotation images and shadow images, specifically as follows: A pulsed laser (1) emits a pulsed laser beam (2). After the pulsed laser beam (2) becomes linearly polarized light through a polarizer (3) in the p-polarization direction, it passes through the first beam splitter (4) and, without passing through the plasma (5), sequentially enters the second beam splitter (6), the linear spatial filter plate (10), the dispersive prism (13), and the first optical rotation measurement device. After being split by the fourth beam splitter (14) in the first optical rotation measurement device, one beam passes through the first analyzer (15) and the first photodiode (16) to obtain the laser intensity of the optical rotation image. Another beam enters the second photodiode (17) to obtain the shadow image laser intensity. ; A pulsed laser (1) emits a pulsed laser beam (2). After the pulsed laser beam (2) becomes linearly polarized light through a polarizer (3) in the p-polarization direction, it passes through a first beam splitter (4) and a plasma (5), and then sequentially enters a second beam splitter (6), a linear spatial filter plate (10), a dispersive prism (13), and a first optical rotation measurement device. After being split by a fourth beam splitter (14) in the first optical rotation measurement device, one beam passes through a first analyzer (15) and a first photodiode (16) to obtain the laser intensity of the optical rotation image. Another beam enters the second photodiode (17) to obtain the shadow image laser intensity. ; The polarization planes of the first analyzer (15) and the second analyzer (19) are at a fixed angle relative to the incident light. +β Let the energy distribution of the pulsed laser beam be... The laser intensity in the optical rotation image Laser intensity in shadow image ; Its expression is shown in formula (1): In the formula and This represents the reflectivity and transmittance of the fourth beam splitter (14) in the imaging system; When plasma (5) is present, assume that the magnitude of the optical rotation deflection angle caused by plasma (5) is... The energy distribution of the pulsed laser beam is as follows: The laser intensity in the optical rotation image Laser intensity in shadow image ; Its expression is shown in formula (2): The laser intensity of the optical rotation image and shadow image is processed to obtain the distribution of the scaling factor based on the light intensity distribution. Specifically, a scaling index is introduced. As shown in formula (3): The distribution of optical rotation deflection angle is obtained based on the mapping relationship between the scaling factor and the optical rotation deflection angle. Specifically, when the value of β is fixed, the scaling factor... It has a mapping relationship with the optical rotation deflection angle α, according to the proportional index. The value of the optical rotation deflection angle α can be derived from the value of the optical rotation angle α.

8. The plasma magnetic field optical measurement method with time and space resolution according to claim 7, characterized in that, The interferometric measurement system based on pulsed laser beams measures the fringe offset of the interference image. Specifically, a pulsed laser (1) emits a pulsed laser beam (2), which is then split by a polarizer (3) and a first beam splitter (4). One beam passes through a plasma (5) and a second beam splitter (6) in sequence, and is reflected by the second beam splitter (6) into a third beam splitter (8). The other beam passes through a reflector (7) and enters the third beam splitter (8). The two beams entering the third beam splitter (8) enter the fringe camera (9) together to form interference fringes. The fringe camera (9) captures the interference fringes, which is the interference image. The method for calculating the fringe offset of the interference image is shown in formula (4). in, y It is the distance between the pulsed laser beam and the center of the plasma. e It is electron charge. λ It is the wavelength of the pulsed laser beam. ε 0 is the vacuum dielectric constant. m e It is electronic quality. c It's the speed of light. n e It is electron density. dl For the integral infinitesimal element along the propagation path of the laser beam inside the plasma; For the measurement of electron surface density in plasma, as shown in formula (5): Where Δδ represents the fringe offset number; L is the length of the propagation path of the pulsed laser beam in the plasma.

9. The plasma magnetic field optical measurement method with time and space resolution according to claim 8, characterized in that, The method for obtaining a one-dimensional distribution of the average magnetic field based on optical rotation deflection angle and fringe offset is as follows: In the formula, B a (r) is the average magnetic field strength distributed along the radius of the plasma (5). α (r) is the deflection angle of the plasma at different radii (5). δ (r) is the offset of the interference fringes at different radii of the plasma (5).

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