An optical method based plasma local current measurement device and method

Abstract

This invention discloses a plasma local current measurement device and method based on optical methods, belonging to the field of optical measurement technology. The device includes: a high-energy pulsed laser, a beam splitter, a photodiode for triggering an ICCD camera, a beam sampling mirror for providing optical signals to the photodiode, a focusing lens for focusing the high-energy pulsed laser, a pulsed power device for generating Z-pinch plasma, a beam collector, an achromatic lens for collecting scattered light, a reflective grating spectrometer, an ICCD camera, and a Mach-Zehnder interferometer. Electron density distribution, electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity can be simultaneously obtained through plasma interference fringe images and Thomson scattering spectra. The local current at the measurement point is obtained by multiplying the electron density, electron charge, and relative electron-ion drift velocity at the measurement point.

Description

Technical Field

[0001] This invention belongs to the field of optical measurement technology, and relates to a plasma local current measurement device and method based on optical methods. Background Technology

[0002] Z-pinch is currently the most effective means of generating intense pulsed soft X-rays in laboratories, playing a crucial role in radiation environment simulation, materials science research, and inertial confinement fusion. Wire array Z-pinch is the main configuration of Z-pinch loads, and current transfer occurs during its dynamics. Accurate diagnosis of the internal current distribution and transfer process of Z-pinch plasma is of great help in studying the mechanism of Z-pinch plasma dynamics.

[0003] However, due to the high temperature of the Z-pinch plasma (~1×10⁻⁶), 5 The Z-pinch plasma exhibits extreme characteristics such as high voltage (~50kV) and high current (~1mA), short duration (~100ns), rapid change, and operates in an extreme environment. This makes the measurement of local current extremely difficult and challenging. Rogowski coils are the primary method for measuring pulsed current in Z-pinch plasmas, where the electromagnetic induction of the coil is used to measure the current at the positive or negative pole of the pulsed power device's load area. However, Rogowski coils can only measure the overall current magnitude and changes, not the local current distribution within the plasma. Magnetic probe methods can measure local magnetic field changes and calculate the local plasma current magnitude based on Ampere's law. However, the magnetic probe comes into physical contact with the plasma, directly affecting the dynamics of the Z-pinch plasma. Furthermore, the high temperature and high current characteristics of Z-pinch plasmas can directly burn out the magnetic probe. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of the inability to accurately measure the local current density of Z-pinch plasma in the prior art, and to provide a plasma local current measurement device and method based on optical methods.

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

[0006] In a first aspect, the present invention provides a plasma local current measurement device based on an optical method, comprising a high-energy pulsed laser, wherein a first beam splitter is disposed in the output optical path of the high-energy pulsed laser, and the interference laser split by the first beam splitter is incident on a Mach-Zehnder interferometer, and the transmitted light is incident on a Z-pinch plasma in a vacuum cavity to generate Thomson scattered light, which is incident on a Thomson scattering diagnostic device; the Mach-Zehnder interferometer and the Thomson scattering diagnostic device feed back the plasma interference fringe image and the Thomson scattering spectrum to a processing unit, and the processing unit calculates the plasma local current based on the plasma interference fringe image and the Thomson scattering spectrum.

[0007] Furthermore, the Mach-Zehnder interferometer of the present invention includes a first reflecting mirror, the interfering laser is incident on the first reflecting mirror, a second beam splitter is arranged in the reflected light path of the first reflecting mirror, a second reflecting mirror is arranged in the reflected light path of the second beam splitter, the transmitted light is incident on a third reflecting mirror after passing through Z-pinch plasma; a third beam splitter and a digital camera are arranged sequentially in the reflected light path of the second reflecting mirror; the reflected light from the third reflecting mirror is incident on the third beam splitter, and enters the digital camera after being reflected by the third beam splitter.

[0008] Furthermore, the present invention provides a beam sampling mirror in the output optical path of the high-energy pulsed laser. After passing through the beam sampling mirror, the reflected light of the high-energy pulsed laser enters the photodiode to generate a trigger signal, which is then transmitted to the ICCD camera via a transmission line.

[0009] Furthermore, the Thomson scattering diagnostic device of the present invention includes a spectrometer and an ICCD camera; a focusing lens is provided in the transmission light path of the first beam splitter; the Thomson scattered light is input into the slit of the spectrometer through an achromatic lens, and the spectral information of the scattered light is recorded by the ICCD camera.

[0010] Furthermore, the spectrometer of the present invention is a reflection grating spectrometer.

[0011] Furthermore, the high-energy pulsed laser of the present invention, after passing through the Z-pinch plasma, passes through the vacuum cavity and is incident on the beam collector.

[0012] Furthermore, the high-energy pulsed laser of the present invention is connected to a signal generator, so that the triggering time of the high-energy pulsed laser is synchronized with the triggering time of generating Z-pinch plasma.

[0013] Secondly, the present invention provides a plasma local current measurement method based on optical methods, comprising the following steps:

[0014] Step 1: Start the high-energy pulsed laser. The high-energy pulsed laser emits an optical signal to the photodiode through the beam sampling mirror. The photodiode generates a trigger signal, which is transmitted to the ICCD camera via the transmission line.

[0015] Step 2: The high-energy pulsed laser, passing through the beam sampling mirror, is incident on the first beam splitter and split into an interference laser and the remaining high-energy pulsed laser; the interference laser serves as the light source for the Mach-Zehnder interferometer, resulting in a plasma interference fringe image.

[0016] Step 3: The remaining high-energy pulsed laser is incident on the Z-pinch plasma through a focusing lens, generating Thomson scattering. The Thomson scattered light is dispersed by a spectrometer and recorded by an ICCD camera to obtain the Thomson scattering spectrum.

[0017] Step 4: Calculate plasma parameters based on the plasma interferometric fringe image and Thomson scattering spectrum;

[0018] Step 5: Calculate the local plasma current based on the plasma parameters.

[0019] Furthermore, the plasma parameters of the present invention include electron density distribution, electron temperature, ion temperature, plasma velocity, and relative drift velocity between electrons and ions.

[0020] Furthermore, the electron density distribution of the present invention is obtained by taking a plasma stripe offset image, interpolating to obtain the stripe offset of each point in the image, calculating the electron surface density using the stripe offset, and then obtaining it through inverse Abelian transform.

[0021] The ion acoustic wave component of the Thomson scattering spectrum is fitted with the theoretically calculated spectrum. The theoretically calculated spectrum that best matches the shape of the measured spectrum corresponds to the electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity, which are the measured plasma parameters.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention utilizes Thomson scattering and laser interferometry to simultaneously diagnose Z-pinch plasmas. Without affecting the plasma's own motion state, it can simultaneously measure the plasma electron density distribution, electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity. The magnitude of the local current can be calculated using the plasma electron density, electron charge, and relative electron-ion drift velocity, making it suitable for Z-pinch plasma diagnostic research. Attached Figure Description

[0024] 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.

[0025] Figure 1 This is a top view of the experimental apparatus and specific embodiments of the present invention;

[0026] In the diagram: 1-High-energy pulsed laser, 2-Beam sampling mirror, 3-First beam splitter, 4-Focusing lens, 5-Vacuum cavity, 6-Z-pinch plasma, 7-Beam collector, 8-Achromatic lens, 9-Spectrometer, 10-ICCD camera, 11-Photodiode, 12-Transmission line, 13-First reflecting mirror, 14-Second beam splitter, 15-Second reflecting mirror, 16-Third reflecting mirror, 17-Third beam splitter, 18-Digital camera, 19-High-energy pulsed laser, 20-Laser sampling signal, 21-Interference laser, 22-High-energy pulsed laser, 23-Thomson scattering light. Detailed Implementation

[0027] 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.

[0028] 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.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The present invention will now be described in further detail with reference to the accompanying drawings:

[0034] See Figure 1 This invention discloses a plasma local current measurement device based on an optical method, including a high-energy pulsed laser 1. A first beam splitter 3 is arranged in the output optical path of the high-energy pulsed laser 19. The interference laser 21 split by the first beam splitter 3 is incident on a Mach-Zehnder interferometer. The transmitted light is incident on a Z-pinch plasma 6 in a vacuum cavity 5 to generate Thomson scattered light 23. The Thomson scattered light 23 is incident on a Thomson scattering diagnostic device. The Mach-Zehnder interferometer and the Thomson scattering diagnostic device feed back the plasma interference fringe image and the Thomson scattering spectrum to a processing unit. The processing unit calculates the plasma local current based on the plasma interference fringe image and the Thomson scattering spectrum.

[0035] The Mach-Zehnder interferometer includes a first mirror 13, the interfering laser 21 is incident on the first mirror 13, a second beam splitter 14 is arranged on the reflected light path of the first mirror 13, a second mirror 15 is arranged on the reflected light path of the second beam splitter 14, and the transmitted light is incident on the third mirror 16 after passing through the Z-pinch plasma 6; a third beam splitter 17 and a digital camera 18 are arranged sequentially on the reflected light path of the second mirror 15; the reflected light from the third mirror 16 is incident on the third beam splitter 17, and enters the digital camera 18 after being reflected by the third beam splitter 17.

[0036] A beam sampling mirror 2 is provided on the output optical path of the high-energy pulsed laser 19. After passing through the beam sampling mirror 2, the reflected light from the high-energy pulsed laser 19 enters the photodiode 11 to generate a trigger signal. The trigger signal is transmitted to the ICCD camera 10 via the transmission line 12. The Thomson scattering diagnostic device includes a spectrometer 9 and an ICCD camera 10. A focusing lens 4 is provided on the transmission optical path of the first beam splitter 3. The Thomson scattered light 23 is input into the slit of the spectrometer 9 through an achromatic lens 8, and the spectral information of the scattered light is recorded by the ICCD camera 10. The spectrometer 9 is a reflective grating spectrometer.

[0037] The high-energy pulsed laser 19 passes through the Z-pinch plasma 6 and then through the vacuum cavity 5 before being incident on the beam collector 7. A signal generator is connected to the high-energy pulsed laser 1 to synchronize the triggering time of the high-energy pulsed laser 1 with the triggering time of the Z-pinch plasma 6.

[0038] This invention also discloses a method for measuring local plasma current based on optical methods, comprising the following steps:

[0039] Step 1: Start the high-energy pulsed laser 1. The high-energy pulsed laser 19 emits an optical signal to the photodiode 11 through the beam sampling mirror 2. The photodiode 11 generates a trigger signal, which is transmitted to the ICCD camera 10 through the transmission line 12.

[0040] Step 2: The high-energy pulsed laser 19, passing through the beam sampling mirror 2, is incident on the first beam splitter 3 and split into an interference laser 21 and the remaining high-energy pulsed laser 22; the interference laser 21 serves as the light source of the Mach-Zehnder interferometer, and a plasma interference fringe image is obtained.

[0041] Step 3: The remaining high-energy pulsed laser 22 is incident on the Z-pinch plasma 6 through the focusing lens 4, generating Thomson scattering. The Thomson scattered light 23 is dispersed by the spectrometer and recorded by the ICCD camera 10 to obtain the Thomson scattering spectrum.

[0042] Step 4: Calculate plasma parameters based on the plasma interference fringe image and Thomson scattering spectrum; the plasma parameters include electron density distribution, electron temperature, ion temperature, plasma velocity, and relative drift velocity between electrons and ions.

[0043] Step 5: Calculate the local plasma current based on the plasma parameters.

[0044] Example:

[0045] This embodiment provides Z-pinch plasma 6 as the plasma to be diagnosed using a pulsed power device, and combines Thomson scattering diagnostics and a Mach-Zehnder interferometer to measure the plasma electron density, electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity. The embodiment includes the following steps:

[0046] Step 1: Set up the diagnostic optical path;

[0047] Step 2: Set up the signal generator to synchronize the laser trigger time with the pulse power device trigger time, ensuring that Z-pinch plasma 6 has been generated when the laser is triggered;

[0048] Step 3: Evacuate the vacuum chamber of the pulsed power device to a vacuum, trigger the signal generator to generate Z-pinch plasma 6 within the vacuum chamber. Simultaneously, a Mach-Zehnder interferometer captures an image of the plasma interference. A high-energy pulsed laser enters the plasma, generating Thomson scattering. The Thomson scattered light 23 is dispersed by a spectrometer and recorded by an ICCD camera 10. Specifically:

[0049] At the laser exit, a beam sampling mirror 2 is placed to split the high-energy pulsed laser I0 into two beams, I1 and I2. The weaker beam I1 is reflected onto a photodiode 11 to trigger an ICCD camera 10. The I1 < 0.01I0 and the I2 > 0.99I0.

[0050] After beam sampling mirror 2, I2 is split into I3 and I4 by a beam splitter. The weaker light I3 serves as the light source for the Mach-Zehnder interferometer to capture plasma fringe interference images. I3 is approximately 0.01I2.

[0051] Another laser beam I4 is used to inject Z-pinch plasma 6 into the vacuum cavity to generate Thomson scattered light 23, wherein I4 is approximately 0.99I0;

[0052] Laser I4 enters from one side of the vacuum cavity and is focused onto the plasma region by focusing lens 4, generating Thomson scattered light 23 carrying plasma physics information;

[0053] The remaining laser beam is collected by beam collector 7 in the direction in which laser I4 exits the vacuum cavity;

[0054] On the side of the incident direction of the high-energy pulsed laser, an achromatic lens 8 is used to collect Thomson scattered light 23 and focus it at the slit of the spectrometer.

[0055] The optical fiber transmits the Thomson scattered light 23 to the slit of the spectrometer 9. After being dispersed by the spectrometer, the Thomson scattered light 23 is recorded by the ICCD camera 10.

[0056] Step 4: Convert the fringe offset of the interference image into the electron density distribution, fit the measured Thomson scattering spectrum with the theoretically calculated spectrum, and obtain the electron temperature, ion temperature, plasma velocity and relative drift velocity of electrons and ions.

[0057] Step 5: Multiply the electron density, electron charge, and relative drift velocity of electron ions at the measurement point to obtain the current density at the measurement point.

[0058] The principle of this invention:

[0059] like Figure 1As shown, the plasma local current measurement device based on optical methods of the present invention includes a pulse power device, a Thomson scattering diagnostic device, and a Mach-Zehnder interferometer. The pulse power device includes a high-energy pulsed laser 1, which emits a high-energy pulsed laser 19. The sampled laser signal is split off by a beam sampling mirror 2 that provides an optical signal to a photodiode 11 and sent to the photodiode 11 for triggering an ICCD camera 10. The generated trigger signal is transmitted to the ICCD camera 10 through a transmission line 12. The high-energy pulsed laser is then split off by a first beam splitter 3 to form an interference laser 21, which serves as the light source for the Mach-Zehnder interferometer. The Mach-Zehnder interferometer includes a first mirror 13, a second mirror 15, a third mirror 16, a second beam splitter 14, a third beam splitter 17, and a digital camera 18. The remaining high-energy pulsed laser 22 is injected into the vacuum cavity 5 through a focusing lens 4, which is used to focus the high-energy pulsed laser. Thomson scattered light 23 is generated in the Z-pinch plasma 6. The scattered light is collected by an achromatic lens 8 and sent to the slit of the spectrometer 9. The scattered light spectrum information is recorded by the ICCD camera 10. The remaining high-energy pulsed laser passes through the vacuum cavity 5 and is collected by the beam collector 7.

[0060] This invention utilizes a signal generator to trigger a high-energy pulsed laser 1 and a pulsed power device. The laser beam is split into two weaker beams and one stronger beam by a laser sampler and a beam splitter. The two weaker beams are used to trigger an ICCD camera 10 and to capture images using a Mach-Zehnder interferometer, respectively. The stronger beam is focused by a focusing lens 4 onto the plasma region, where Thomson scattering occurs, generating a scattering signal containing plasma parameter information. This signal is then imaged through a lens onto the spectrometer slit and, after dispersion, recorded by the ICCD camera 10. This invention captures plasma interference fringe images using a Mach-Zehnder interferometer and obtains Thomson scattering spectral information using the ICCD camera 10. The electron density is calculated by measuring the offset of the interference fringes at the measurement points. Through spectral fitting, the electron temperature, ion temperature, plasma velocity, and relative drift velocity of electrons and ions are calculated. Multiplying the electron density, electron charge, and relative drift velocity of electrons and ions yields the desired current density.

[0061] Thomson scattering is the elastic scattering of electromagnetic radiation by electrons. Collective Thomson scattering occurs when plasma waves are equal to or greater than the Debye length. In the collective oscillation of plasma, electrons are influenced by other electrons, carrying information about the electron plasma wave, while ions carry information about the ion acoustic wave. Electrons follow the movement of ions, thus carrying information from both. Therefore, the scattering spectrum obtained from the interaction of electromagnetic waves and electrons contains characteristics of both electron plasma waves and ion acoustic waves. The ion acoustic wave portion of the scattering spectrum can simultaneously measure plasma electron temperature, ion temperature, velocity, and relative drift velocity between electrons and ions. Mach-Zehnder interferometers can measure the change in optical path after light passes through a medium by using fringe shifts. The change in optical path in plasma mainly comes from the refractive index changes contributed by electrons and ions. Due to the high ionization of Z-pinch plasma, its refractive index is mainly contributed by electrons and is proportional to the electron density. Therefore, the electron surface density can be directly calculated using the fringe shift. Furthermore, Z-pinch plasma has good axial symmetry, and the plasma electron volume density distribution can be calculated using the inverse Abelian transform. Current can be viewed as the result of the relative motion of negatively charged electrons and positively charged ions. Therefore, the current density can be obtained by multiplying the electron density distribution, electron charge, and relative drift velocity of electrons and ions. An optical method combining Thomson scattering and laser interferometry can accurately measure local plasma current information. Furthermore, this method is non-invasive and does not affect the plasma's own motion state.

[0062] This invention uses an optical method to determine electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity by measuring the spectrum of Thomson scattered light 23. The electron density distribution is simultaneously measured using a Mach-Zehnder interferometer. The current density at the measurement point is calculated using the relative electron-ion drift velocity and the electron density distribution at the measurement point.

[0063] This invention obtains the stripe offset of each point in the image by interpolation from the captured plasma stripe offset image, calculates the electron surface density using the stripe offset, and obtains the electron volume density distribution by inverse Abelian transform.

[0064] This invention fits the ion acoustic wave portion of the Thomson scattering spectrum with the theoretically calculated spectrum. The theoretically calculated spectrum that best matches the shape of the measured spectrum corresponds to the electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity, which are the measured plasma parameters.

[0065] The plasma electron density at the focal point of a high-energy pulsed laser is extracted and multiplied by the relative drift velocity of electron ions obtained from spectral measurements to obtain the local current density.

[0066] The Z-pinch plasma 6 is generated by a metal wire array within the vacuum cavity of a pulsed power device; the Z-pinch plasma 6 has a high average ionization degree, and the fringe shift in the interference image is mainly contributed by electrons; due to its own characteristics, the Thomson scattering generated by the Z-pinch plasma 6 is collective scattering.

[0067] The single-pulse laser energy generated by the high-energy pulsed laser 1 of this invention must be greater than 3J, and it must be vertically polarized light with a pulse width of less than 10ns.

[0068] The direction of the current measured by this invention is the difference between the wave vector of the scattered light and the wave vector of the incident light. The direction of the incident light and the collection direction of the Thomson scattered light 23 can be adjusted according to the direction of the current to be measured.

[0069] 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 local current measuring device based on optical methods, characterized in that, The system includes a high-energy pulsed laser (1), with a first beam splitter (3) set in the output optical path of the high-energy pulsed laser (1). The interference laser (21) split by the first beam splitter (3) of the high-energy pulsed laser (19) is incident on the Mach-Zehnder interferometer. The transmitted light is incident on the Z-pinch plasma (6) in the vacuum cavity (5) to generate Thomson scattered light (23). The Thomson scattered light (23) is incident on the Thomson scattering diagnostic device. The Mach-Zehnder interferometer and the Thomson scattering diagnostic device feed back the plasma interference fringe image and the Thomson scattering spectrum to the processing unit. The processing unit calculates the plasma local current based on the plasma interference fringe image and the Thomson scattering spectrum.

2. The plasma local current measuring device based on optical methods according to claim 1, characterized in that, The Mach-Zehnder interferometer includes a first mirror (13), the interference laser (21) is incident on the first mirror (13), a second beam splitter (14) is arranged on the reflected light path of the first mirror (13), a second mirror (15) is arranged on the reflected light path of the second beam splitter (14), and the transmitted light is incident on the third mirror (16) after passing through the Z-pinch plasma (6); a third beam splitter (17) and a digital camera (18) are arranged sequentially on the reflected light path of the second mirror (15); the reflected light of the third mirror (16) is incident on the third beam splitter (17), and enters the digital camera (18) after being reflected by the third beam splitter (17).

3. The plasma local current measuring device based on optical methods according to claim 2, characterized in that, A beam sampling mirror (2) is provided on the output optical path of the high-energy pulsed laser (19). After passing through the beam sampling mirror (2), the reflected light of the high-energy pulsed laser (19) enters the photodiode (11) to generate a trigger signal. The trigger signal is transmitted to the ICCD camera (10) via the transmission line (12).

4. The plasma local current measuring device based on optical methods according to claim 1, characterized in that, The Thomson scattering diagnostic device includes a spectrometer (9) and an ICCD camera (10); a focusing lens (4) is provided on the transmission light path of the first beam splitter (3); the Thomson scattered light (23) is input into the slit of the spectrometer (9) through an achromatic lens (8), and the spectral information of the scattered light is recorded by the ICCD camera (10).

5. The plasma local current measuring device based on optical methods according to claim 4, characterized in that, The spectrometer (9) is a reflection grating spectrometer.

6. The plasma local current measuring device based on optical methods according to claim 1, characterized in that, The high-energy pulsed laser (19) passes through the Z-pinch plasma (6) and then through the vacuum cavity (5) before being incident on the beam collector (7).

7. The plasma local current measuring device based on optical methods according to claim 1, characterized in that, A signal generator is connected to the high-energy pulsed laser (1) to synchronize the triggering time of the high-energy pulsed laser (1) with the triggering time of the generated Z-pinch plasma (6).

8. A plasma local current measurement method based on an optical method using the apparatus described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Start the high-energy pulsed laser (1). The high-energy pulsed laser (19) emits a light signal to the photodiode (11) through the beam sampling mirror (2). The photodiode (11) generates a trigger signal, which is transmitted to the ICCD camera (10) via the transmission line (12). Step 2: The high-energy pulsed laser (19) passing through the beam sampling mirror (2) is incident on the first beam splitter (3) and is split into an interference laser (21) and the remaining high-energy pulsed laser (22); the interference laser (21) serves as the light source of the Mach-Zehnder interferometer to obtain a plasma interference fringe image; Step 3: The remaining high-energy pulsed laser (22) is incident on the Z-pinch plasma (6) through the focusing lens (4) to generate Thomson scattering. The Thomson scattered light (23) is dispersed by the spectrometer and recorded by the ICCD camera (10) to obtain the Thomson scattering spectrum. Step 4: Calculate plasma parameters based on the plasma interferometric fringe image and Thomson scattering spectrum; Step 5: Calculate the local plasma current based on the plasma parameters.

9. The plasma local current measurement method based on optical methods according to claim 8, characterized in that, The plasma parameters include electron density distribution, electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity.

10. The plasma local current measurement method based on optical methods according to claim 8, characterized in that, The electron density distribution is obtained by interpolating the stripe offset image captured by the plasma stripe image, calculating the electron surface density using the stripe offset, and then performing an inverse Abelian transform. The ion acoustic wave component of the Thomson scattering spectrum is fitted with the theoretically calculated spectrum. The theoretically calculated spectrum that best matches the shape of the measured spectrum corresponds to the electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity, which are the measured plasma parameters.

Images