Measurement method for core impurity density fluctuation of magnetic confinement high-temperature plasma

Abstract

The invention discloses a magnetic confinement high-temperature plasma core impurity density fluctuation measurement method, which comprises the following steps: collecting an active spectrum emitted by a charge exchange reaction between a neutral beam and a high-temperature plasma impurity ion bare nucleus through an active spectrum lens; collecting a passive spectrum of a plasma area without neutral beam injection through a passive spectrum lens; respectively transmitting the active spectrum and the passive spectrum to a characteristic line radiation filtering array, and filtering the active spectrum and the passive spectrum through the characteristic line radiation filtering array; respectively transmitting the active spectrum and the passive spectrum after light filtering processing to a photodiode array for photoelectric conversion, and subtracting the photoelectric signal corresponding to the passive spectrum from the photoelectric signal corresponding to the active spectrum to obtain the photon flux of the active spectrum; and calculating the core impurity density of the magnetic confinement high-temperature plasma according to the photon flux of the active spectrum. According to the invention, the measurement of plasma core impurity density fluctuation can be obtained in an international magnetic confinement fusion device firstly.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic confinement nuclear fusion, and in particular to a method for measuring impurity density fluctuations in a core of a magnetically confined high-temperature plasma. Background Art

[0002] Fluctuations in magnetically confined high-temperature plasmas include electrostatic fluctuations and magnetic fluctuations. The transport coefficient of tokamak plasma is usually greater than the neoclassical transport coefficient. Only inside the boundary transport barrier (ETB) and the internal transport barrier (ITB) can the transport be observed to be close to the neoclassical level, and the corresponding fluctuation level is also greatly reduced. The fluctuation is mainly turbulent, which is driven by various free energies of the plasma and its scale is the order of magnitude of the ion cyclotron radius.

[0003] The turbulence at the boundary of tokamak plasma is usually measured by electrostatic probes, which can obtain the fluctuation characteristics of electron density, temperature and potential. The core fluctuation can be diagnosed by heavy ion probes, Doppler reflectometers, beam emission spectra, laser coherent scattering and other methods. Among them, Doppler reflectometers, beam emission spectra and laser coherent scattering diagnosis measure the fluctuation of core electron density, and heavy ion beam probes can provide core electron density fluctuations and potential fluctuations. Therefore, in the core region of magnetically confined high-temperature plasma, the current diagnosis mainly provides information on core electron fluctuations, while the measurement of core ion fluctuations is scarce. For this reason, it is necessary to study a method that can measure the density fluctuation of impurity ions in the core of magnetically confined high-temperature plasma to provide a new way to measure the ion density fluctuation in the core region. Summary of the invention

[0004] The purpose of the present invention is to provide a method for measuring the density fluctuation of impurities in the core of a magnetically confined high-temperature plasma, in order to address the problem that current diagnostic measurements in the core region of a magnetically confined high-temperature plasma mainly provide information on core electron fluctuations but lack measurements of core ion fluctuations. The method can measure the density fluctuation of impurities in the core of a high-temperature plasma by utilizing a charge exchange composite spectroscopy diagnostic method.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a device for measuring the impurity density fluctuations in the core of a magnetically confined high-temperature plasma, comprising: an active spectral lens, a passive spectral lens, a characteristic line radiation filter array and a photodiode array; the active spectral lens is used to collect the active spectrum emitted by the charge exchange reaction between a neutral beam and the bare cores of impurity ions in the high-temperature plasma; the passive spectral lens is used to collect the passive spectrum of the plasma region without neutral beam injection; the characteristic line radiation filter array is used to filter the collected active spectrum and passive spectrum; the photodiode array is used to perform photoelectric conversion on the active spectrum and passive spectrum after the filtering process.

[0007] As a preferred solution of the present invention, the active spectral lens is arranged near the neutral beam injection window of the vacuum chamber, and the passive spectral lens is arranged on the other side of the vacuum chamber, and the active spectral lens and the passive spectral lens are placed in a centrally symmetrical manner.

[0008] As a preferred solution of the present invention, the sight range of the active spectral lens and the travel path of the neutral beam have an angle of 30° to 60°.

[0009] As a preferred embodiment of the present invention, the characteristic line radiation filter array includes a first row of filter arrays and a second row of filter arrays; the light energy collected by the passive spectrum lens is connected to the first row of filter arrays through a passive spectrum transmission optical fiber; the light energy collected by the active spectrum lens is connected to the second row of filter arrays through an active spectrum transmission optical fiber.

[0010] As a preferred embodiment of the present invention, the active spectrum transmission optical fiber and the passive spectrum transmission optical fiber are optical fiber bundles of the same specification, each optical fiber bundle contains the same number of n optical fibers, which are arranged in one dimension at the optical fiber end, and the optical fiber end face is located at the focal plane of the active spectrum lens and the passive spectrum lens.

[0011] As a preferred embodiment of the present invention, the first row of filter arrays and the second row of filter arrays respectively have n filter units, each of which includes a diverging lens, a filter and a focusing lens arranged in sequence along the optical axis, and the diverging lens and the focusing lens are the same lenses and are symmetrically placed along the optical axis.

[0012] As a preferred solution of the present invention, the photodiode array includes a first row of photodiode arrays and a second row of photodiode arrays, the first row of photodiode arrays receives light energy from the first row of filter arrays, and the second row of photodiode arrays receives light energy from the second row of filter arrays.

[0013] As a preferred solution of the present invention, the first row of photodiode arrays and the second row of photodiode arrays respectively have n detector units, and the detector units are used to collect the transmitted light energy and perform photoelectric conversion.

[0014] In a second aspect, the present invention provides a method for measuring the impurity density fluctuation in the core of a magnetically confined high-temperature plasma, comprising:

[0015] The active spectrum emitted by the charge exchange reaction between the neutral beam and the bare core of the impurity ions in the high-temperature plasma is collected through the active spectrum lens, and the passive spectrum of the plasma region without the injection of the neutral beam is collected through the passive spectrum lens;

[0016] The active spectrum and the passive spectrum are transmitted to the characteristic line radiation filter array respectively, and the active spectrum and the passive spectrum are filtered by the characteristic line radiation filter array;

[0017] The active spectrum and passive spectrum after filtering are respectively transmitted to the photodiode array for photoelectric conversion, and the photon flux of the active spectrum is obtained by subtracting the photoelectric signal corresponding to the passive spectrum from the photoelectric signal corresponding to the active spectrum;

[0018] The impurity density in the core of the magnetically confined high-temperature plasma is calculated based on the photon flux of the active spectrum obtained.

[0019] As a preferred embodiment of the present invention, the impurity density in the core of the magnetically confined high temperature plasma is calculated by the following formula:

[0020]

[0021] Among them, Φ CVI is the photon flux of the active spectrum, is the effective charge exchange recombination radiation rate coefficient corresponding to each neutral beam energy component, N b,k is the chord-integrated neutral beam density of the kth energy component, N b,k Obtained by the neutral beam attenuation procedure, n Z (ρ) is the core impurity density that needs to be calculated.

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

[0023] The present invention collects the active spectrum emitted by the charge exchange reaction between the neutral beam and the bare core of the impurity ions of the high-temperature plasma through an active spectrum lens, collects the passive spectrum of the plasma area without the neutral beam injection through a passive spectrum lens, and then transmits the active spectrum and the passive spectrum to the characteristic line radiation filter array respectively, filters the active spectrum and the passive spectrum through the characteristic line radiation filter array, and then transmits the filtered active spectrum and the passive spectrum to the photodiode array respectively for photoelectric conversion, and subtracts the photoelectric signal corresponding to the passive spectrum from the photoelectric signal corresponding to the active spectrum to obtain the photon flux of the active spectrum, thereby obtaining the impurity density of the core of the magnetically confined high-temperature plasma; the present invention uses the charge exchange composite spectrum diagnostic method to measure the density fluctuation of the impurities in the core of the high-temperature plasma. Through this set of technical solutions, it is possible to take the lead in obtaining the measurement of the density fluctuation of the impurity density in the core of the plasma in the international magnetic confinement fusion device, which will provide necessary physical parameters and experimental data support for further research on the control, transport and internal physical mechanism of the plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0025] Figure 1 It is a schematic diagram of a device for measuring the impurity density fluctuation in the core of a magnetically confined high-temperature plasma in the present invention;

[0026] Figure 2 is a schematic diagram of a filter unit in a characteristic line radiation filter array of the present invention;

[0027] Figure 3 This is a flow chart of the method for measuring the impurity density fluctuation in the core of a magnetically confined high-temperature plasma in the present invention.

[0028] Marks and corresponding parts names in the attached drawings:

[0029] 1. Active spectrum lens, 2. Active spectrum transmission optical fiber, 3. Passive spectrum lens, 4. Passive spectrum transmission optical fiber, 5. Characteristic line radiation filter array, 51. First row filter array, 52. Second row filter array, 6. Photodiode array, 61. First row photodiode array, 62. Second row photodiode array, 7. Diverging lens, 8. Filter, 9. Focusing lens, 10. Transmitting optical fiber head, 11. Collecting optical fiber head. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0032] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0033] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0034] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0035] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0036] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces), unless otherwise clearly and specifically defined.

[0037] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0038] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0039] Please refer to Figures 1 to 3 A device for measuring the impurity density fluctuation of the core of a magnetically confined high-temperature plasma provided in an embodiment of the present application comprises: an active spectral lens 1, a passive spectral lens 3, a characteristic line radiation filter array 5 and a photodiode array 6; the active spectral lens 1 is used to collect the active spectrum emitted by the charge exchange reaction between the neutral beam and the bare core of the impurity ions of the high-temperature plasma; the passive spectral lens 3 is used to collect the passive spectrum of the plasma region without the injection of the neutral beam; the characteristic line radiation filter array 5 is used to filter the collected active spectrum and passive spectrum; the photodiode array 6 is used to perform photoelectric conversion on the active spectrum and passive spectrum after the filtering process.

[0040] According to some embodiments of the present application, the active spectroscopy lens 1 is disposed near the neutral beam injection window of the vacuum chamber, and the passive spectroscopy lens 3 is disposed on the other side of the vacuum chamber, and the active spectroscopy lens 1 is centrally symmetrically placed with the passive spectroscopy lens 3. The line of sight of the active spectroscopy lens 1 collects the active spectrum emitted by the charge exchange reaction between the neutral beam and the bare nuclei of the impurity ions of the high-temperature plasma.

[0041] Since carbon impurities are one of the main impurities in the HL-2A / HL-3 Tokamak plasma, the visible light intensity of carbon ion CVI radiation is strong, which is convenient for observation and measurement. Taking the bare core of carbon impurity ions as an example, the equation for the charge exchange reaction is:

[0042] D 0 +A Z →D + +(A Z-1 ) *

[0043] In this reaction, the neutral beam atom D 0 The electrons are transferred to the bare carbon core A Z , forming a deuterium ion D + With the excited hydrogen-like carbon ion (A Z-1 ) * (A Z-1 ) * The de-excitation process (CVI, n = 8-7) radiates photons to produce a charge exchange composite spectrum. In fact, the CVI spectrum collected by the active spectrum lens 1 observation line of sight includes three parts, namely the active spectrum, the passive spectrum and the edge spectrum. The intensity of the active spectrum is used to calculate the impurity density, and the broadening and frequency shift of the active spectrum are used to calculate the impurity ion temperature and the plasma rotation speed, respectively. The application of this diagnosis benefits from the large charge exchange reaction cross section between the neutral beam atoms and the impurity bare nuclei in the plasma, and it is easy to achieve high time and space resolution measurement. The measurement can cover the core area and the edge area of ​​the plasma.

[0044] Similarly, the passive spectroscopy lens 3 is used to observe the plasma region without neutral beam injection, and the line of sight of the passive spectroscopy lens 3 collects the passive spectrum of the plasma region without neutral beam injection. The line of sight of the passive spectroscopy lens 3 collects two parts of the CVI spectrum, namely the passive spectrum and the edge spectrum.

[0045] According to some embodiments of the present application, the sight range of the active spectral lens 1 has a certain angle with the neutral beam travel path. Preferably, the angle ranges from 30° to 60°.

[0046] According to some embodiments of the present application, the characteristic line radiation filter array 5 includes a first row of filter arrays 51 and a second row of filter arrays 52; the light energy collected by the passive spectrum lens 3 is connected to the first row of filter arrays 51 through the passive spectrum transmission optical fiber 4; the light energy collected by the active spectrum lens 1 is connected to the second row of filter arrays 52 through the active spectrum transmission optical fiber 2.

[0047] According to some embodiments of the present application, the active spectrum transmission optical fiber 2 and the passive spectrum transmission optical fiber 4 are optical fiber bundles of the same specification, each optical fiber bundle contains the same number of n optical fibers, which are arranged in one dimension at the optical fiber end, and the optical fiber end faces are located at the focal planes of the active spectrum lens 1 and the passive spectrum lens 3. Therefore, the measurement device has n spatial measurement channels.

[0048] According to some embodiments of the present application, the first filter array 51 and the second filter array 52 have n filter units, respectively, for respectively receiving light energy from the passive spectrum transmission optical fiber 4 and the active spectrum transmission optical fiber 2. Each of the filter units includes a diverging lens 7, a filter 8 and a focusing lens 9 sequentially arranged along the optical axis, and the diverging lens 7 and the focusing lens 9 are the same lenses and are symmetrically placed along the optical axis.

[0049] Specifically, the divergent lens 7 directs the light emitted from the transmitting fiber head 10 on the passive spectrum transmission fiber 4 or the active spectrum transmission fiber 2 into the filter 8 in parallel, and then the focusing lens 9 images the filtered parallel light to the collecting fiber head 11. The light energy collected by the collecting fiber head 11 finally enters the detector unit of the photodiode array 6 for photoelectric conversion.

[0050] Taking the bare core of carbon impurity ions as an example, the center wavelength of the filter 8 is 529.05nm and the bandwidth is 8.0nm. It should be noted that by changing the center wavelength of the filter 8, the concentration fluctuation measurement of different types of impurity ions can be achieved. For example, HeII uses a filter 8 with a center wavelength of 468.5nm to achieve the concentration fluctuation measurement of helium ions.

[0051] According to some embodiments of the present application, the photodiode array 6 includes a first row of photodiode arrays 61 and a second row of photodiode arrays 62, wherein the first row of photodiode arrays 61 receives light energy from the first row of filter arrays 51, and the second row of photodiode arrays 62 receives light energy from the second row of filter arrays 52.

[0052] According to some embodiments of the present application, the first row of photodiode array 61 has n detector units for collecting light energy from the first row of filter array 51, i.e., passive spectrum; the second row of photodiode array 62 also has n detector units for collecting light energy from the second row of filter array 52, i.e., active spectrum.

[0053] A method for measuring the impurity density fluctuation of the core of a magnetically confined high-temperature plasma provided in an embodiment of the present application, using the above-mentioned measuring device, comprises the following steps:

[0054] The active spectrum emitted by the charge exchange reaction between the neutral beam and the bare core of the impurity ions in the high-temperature plasma is collected through the active spectrum lens 1, and the passive spectrum of the plasma region without the neutral beam injection is collected through the passive spectrum lens 3;

[0055] The active spectrum and the passive spectrum are transmitted to the characteristic line radiation filter array 5 respectively, and the active spectrum and the passive spectrum are filtered by the characteristic line radiation filter array 5;

[0056] The active spectrum and the passive spectrum after filtering are respectively transmitted to the photodiode array 6 for photoelectric conversion, and the photon flux of the active spectrum is obtained by subtracting the photoelectric signal corresponding to the passive spectrum from the photoelectric signal corresponding to the active spectrum;

[0057] The impurity density in the core of the magnetically confined high-temperature plasma is calculated based on the photon flux of the active spectrum obtained.

[0058] Specifically, after intensity calibration, the photoelectric signal collected by the second row of photodiode arrays 62 minus the photoelectric signal collected by the first row of photodiode arrays 61 is the active spectrum component Φ of the three CVI spectrum components of the n spatial channels collected in the active spectrum lens 1. CVI .

[0059] The impurity density in the core of magnetically confined high-temperature plasma is calculated by the following formula:

[0060]

[0061] Among them, Φ CVI is the photon flux of the active spectrum, is the effective charge exchange recombination radiation rate coefficient corresponding to each neutral beam energy component, N b,kis the chord-integrated neutral beam density of the kth energy component, N b,k Obtained by the neutral beam attenuation procedure, n Z (ρ) is the local C that needs to be calculated 6+ Since the photodiode array 6 can achieve a collection frequency of 1 MHz, the above formula can be used to obtain the measurement of the impurity density fluctuation in the core of the magnetically confined high-temperature plasma.

[0062] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for measuring the core impurity density fluctuation of a magnetically confined high-temperature plasma, characterized in that: It includes an active spectral lens, a passive spectral lens, a characteristic line radiation filter array and a photodiode array; The active spectrum lens is used to collect the active spectrum emitted by the charge exchange reaction between the neutral beam and the bare core of the high-temperature plasma impurity ions; The passive spectrum lens is used to collect passive spectra of a plasma region without neutral beam injection; The characteristic line radiation filter array is used to filter the collected active spectrum and passive spectrum; The photodiode array is used for performing photoelectric conversion on the active spectrum and the passive spectrum after the filtered light processing.

2. The device for measuring the core impurity density fluctuation of magnetically confined high temperature plasma according to claim 1, characterized in that: The active spectrum lens is arranged near the neutral beam injection window of the vacuum chamber, and the passive spectrum lens is arranged on the other side of the vacuum chamber. The active spectrum lens and the passive spectrum lens are placed in a centrally symmetrical manner.

3. The device for measuring the core impurity density fluctuation of magnetically confined high temperature plasma according to claim 2, characterized in that: The sight range of the active spectrum lens and the traveling path of the neutral beam have an included angle of 30° to 60°.

4. The device for measuring the impurity density fluctuation of the core of a magnetically confined high temperature plasma according to any one of claims 1 to 3, characterized in that: The characteristic line radiation filter array includes a first row of filter arrays and a second row of filter arrays; the light energy collected by the passive spectrum lens is connected to the first row of filter arrays through a passive spectrum transmission optical fiber; The light collected by the active spectrum lens can be connected to the second row of filter arrays through the active spectrum transmission optical fiber.

5. The device for measuring the core impurity density fluctuation of magnetically confined high temperature plasma according to claim 4, characterized in that: The active spectrum transmission optical fiber and the passive spectrum transmission optical fiber are optical fiber bundles of the same specification, each optical fiber bundle contains the same number of n optical fibers, which are arranged in one dimension at the optical fiber end, and the optical fiber end face is located at the focal plane of the active spectrum lens and the passive spectrum lens.

6. The device for measuring the core impurity density fluctuation of magnetically confined high temperature plasma according to claim 4, characterized in that: The first filter array and the second filter array have n filter units respectively, each of which includes a diverging lens, a filter and a focusing lens arranged in sequence along the optical axis. The diverging lens and the focusing lens are the same lenses and are symmetrically placed along the optical axis.

7. The device for measuring the core impurity density fluctuation of magnetically confined high temperature plasma according to claim 4, characterized in that: The photodiode array includes a first row of photodiode arrays and a second row of photodiode arrays. The first row of photodiode arrays receives light energy from the first row of filter arrays, and the second row of photodiode arrays receives light energy from the second row of filter arrays.

8. The device for measuring the core impurity density fluctuation of magnetically confined high temperature plasma according to claim 7, characterized in that: The first row of photodiode arrays and the second row of photodiode arrays each have n detector units, and the detector units are used to collect the transmitted light energy and perform photoelectric conversion.

9. A method for measuring the impurity density fluctuation in the core of a magnetically confined high-temperature plasma, characterized in that: include: The active spectrum emitted by the charge exchange reaction between the neutral beam and the bare core of the impurity ions in the high-temperature plasma is collected through the active spectrum lens, and the passive spectrum of the plasma region without the injection of the neutral beam is collected through the passive spectrum lens; The active spectrum and the passive spectrum are transmitted to the characteristic line radiation filter array respectively, and the active spectrum and the passive spectrum are filtered by the characteristic line radiation filter array; The active spectrum and passive spectrum after filtering are respectively transmitted to the photodiode array for photoelectric conversion, and the photon flux of the active spectrum is obtained by subtracting the photoelectric signal corresponding to the passive spectrum from the photoelectric signal corresponding to the active spectrum; The impurity density in the core of the magnetically confined high-temperature plasma is calculated based on the photon flux of the active spectrum obtained.

10. The method for measuring the core impurity density fluctuation of magnetically confined high temperature plasma according to claim 9, characterized in that: The impurity density in the core of magnetically confined high-temperature plasma is calculated by the following formula: Among them, Φ CVI is the photon flux of the active spectrum, is the effective charge exchange recombination radiation rate coefficient corresponding to each neutral beam energy component, N b,k is the chord-integrated neutral beam density of the kth energy component, N b,k Obtained by the neutral beam attenuation procedure, n Z (ρ) is the core impurity density that needs to be calculated.

Images