An edge Lyman-alpha-based beam emission spectroscopy(LyBES)diagnostic,using a heating NBI(neutral beam injection)system,is currently under development on the HL-2A tokamak.The 20-channel edge LyBES,which is intended t...An edge Lyman-alpha-based beam emission spectroscopy(LyBES)diagnostic,using a heating NBI(neutral beam injection)system,is currently under development on the HL-2A tokamak.The 20-channel edge LyBES,which is intended to measure the density fluctuation in plasma edge(from R=1960 mm to R=2026 mm)with an improved spatial resolution of 3.3 mm,is a complement to the existing conventional beam emission spectroscopy(BES)diagnostic.In this article,we introduce the progress of LyBES diagnostic,including the collection optics,the monochromator,and the detector system.The reflectance of the collection mirrors is measured to be~82%at 122 nm,and the aberration geometrical radius of the collection optics is tested to be~150μm in the aimed area.The linear dispersion of the LyBES monochromator is designed to be~0.09 nm mm^(-1).The bandwidth of the detector system with the 5×10^(7)V A^(-1)preamplifier gain is measured to be~280 kHz,and the peak-to-peak noise of the detector system is tested to be~16 mV.The finalized design,components development and testing of the LyBES diagnostic have been completed at present,and an overall performance of the LyBES diagnostic is to be confirmed in the next HL-2A campaign.展开更多
The optical design of near-infrared phase contrast imaging(NI-PCI)diagnosis on HL-2A is introduced in this paper.This scheme benefits from the great progress of near-infrared laser technology and is a broadening of tr...The optical design of near-infrared phase contrast imaging(NI-PCI)diagnosis on HL-2A is introduced in this paper.This scheme benefits from the great progress of near-infrared laser technology and is a broadening of traditional phase contrast technology.This diagnostic can work as a keen tool to measure plasma wavenumber spectra by inferring string-integrated plasma density fluctuations.Design of both the front optical path which is the path before the laser transmitting into the tokamak plasma and the rear optics which is the path after the laser passing through the plasma is detailed.The 1550 nm laser is chosen as the probe beam and highprecision optical components are designed to fit the laser beam,in which a phase plate with a 194-nm-deep silver groove is the key.Compared with the conventional 10.6μm laser-based PCI system on HL-2A,NI-PCI significantly overcomes the unwanted phase scintillation effect and promotes the measurement capability of high-wavenumber turbulence with an increased maximal measurable wavenumber from 15 cm^(-1)to 32.6 cm^(-1).展开更多
In this article,the design of a Lyman-alpha-based beam emission spectroscopy(LAB)diagnostic on the HL-2A tokamak has been proposed for the first time.The purpose of this novel diagnostic is to measure density fluctuat...In this article,the design of a Lyman-alpha-based beam emission spectroscopy(LAB)diagnostic on the HL-2A tokamak has been proposed for the first time.The purpose of this novel diagnostic is to measure density fluctuations of tokamak plasma.The light-collection system of LAB,which consists of the first mirror and two groups of coaxial double-mirror telescopes,can realize a twosegmented viewing field ofρ=0–0.2 andρ=0.75–1,which is optimized to measure plasma density fluctuation,not only in the edge transport barrier region but also in the internal transport barrier region,to investigate the underlying physics of turbulence in tokamaks.Spectrometers are developed to separate out the Doppler-shifted target line(122.03 and 122.17 nm)from the background Lyman-alpha line(121.53 nm).Here,30 Core-LAB channels and 30 Edge-LAB channels are under development on the HL-2A tokamak.It has high radial spatial resolutions of about 2.7 mm and 3.3 mm for the core and edge channels,respectively.Taking the high light intensity of this Lyman-alpha line into account,temporal resolution of 200 k Hz can be ensured by broad bandwidth amplifiers.This high spatio-temporal resolution makes LAB a potential keen tool to experimentally investigate tokamak plasma physics.展开更多
A vertical edge Thomson scattering(ETS) diagnostic system on HL-2M tokamak has been designed.The ETS system collects the scattered light from Nd:YAG laser(1064 nm,2 J,30 Hz,15 ns).The laser beam propagates vertically ...A vertical edge Thomson scattering(ETS) diagnostic system on HL-2M tokamak has been designed.The ETS system collects the scattered light from Nd:YAG laser(1064 nm,2 J,30 Hz,15 ns).The laser beam propagates vertically through the plasma region and the polarization is parallel to the toroidal magnetic field.A special designed Galileo-type telescope with long Rayleigh length is applied to focus the laser size and ensure collimation.A group of doubleGaussian collection lenses image the 600 mm vertical scattered region onto rectangular fiber arrays with a spatial resolution of 10 mm.The 2.20 mm × 2.86 mm fiber optic bundle consists of 130 low hydroxyl(OH) 200/220 μm(core/cladding) diameter fibers with numerical aperture NA=0.22,carrying the light to remotely located multi-channel polychromators.Effect of oblique incidence on narrow band filter has been analyzed.The designed electron temperatures range from 5 to 1000 eV and electron densities from 5 × 10^(18) to 1×10^(20) m^(-3).展开更多
Ion temperature, as one of the most critical plasma parameters, can be diagnosed by charge exchange recombination spectroscopy (CXRS). Iterative least-squares fitting is conventionally used to analyze CXRS spectra to ...Ion temperature, as one of the most critical plasma parameters, can be diagnosed by charge exchange recombination spectroscopy (CXRS). Iterative least-squares fitting is conventionally used to analyze CXRS spectra to identify the active charge exchange component, which is the result of local interaction between impurity ions with a neutral beam. Due to the limit of the time consumption of the conventional approach (~100 ms per frame), the Experimental Advanced Superconducting Tokamak CXRS data is now analyzed in-between shots. To explore the feasibility of real-time measurement, neural networks are introduced to perform fast estimation of ion temperature. Based on the same four-layer neural network architecture, two neural networks are trained for two central chords according to the ion temperature data acquired from the conventional method. Using the TensorFlow framework, the training procedures are performed by an error back-propagation algorithm with the regularization via the weight decay method. Good agreement in the deduced ion temperature is shown for the neural networks and the conventional approach, while the data processing time is reduced by 3 orders of magnitude (~0.1 ms per frame) by using the neural networks.展开更多
In this article,we present the optical design of a novel diagnostic on the HL-2A tokamak,i.e.the 20-channel edge Lyman-alpha beam emission spectroscopy,which is a promising solution for edge density turbulence researc...In this article,we present the optical design of a novel diagnostic on the HL-2A tokamak,i.e.the 20-channel edge Lyman-alpha beam emission spectroscopy,which is a promising solution for edge density turbulence research on tokamaks,as it offers the possibility of density fluctuation measurement with a 3.3 mm spatial resolution while maintains a high temporal resolution of 1μs.The optical path,including the reflective collection optics,the high-dispersion spectrometer,and the linear detector array,is carefully optimized to obtain a good image quality and a high throughput.The maximum root mean square radius of the collection optics is 64μm.The detected photon flux is estimated to be about 1011 photons/s/channel.展开更多
基金supported by Sichuan Science and Technology Program(No.2022JDJQ0038)the National Key R&D Program of China(Nos.2022YFE03100002 and 2018YFE0303102)National Natural Science Foundation of China(Nos.12205087 and 12075241)。
文摘An edge Lyman-alpha-based beam emission spectroscopy(LyBES)diagnostic,using a heating NBI(neutral beam injection)system,is currently under development on the HL-2A tokamak.The 20-channel edge LyBES,which is intended to measure the density fluctuation in plasma edge(from R=1960 mm to R=2026 mm)with an improved spatial resolution of 3.3 mm,is a complement to the existing conventional beam emission spectroscopy(BES)diagnostic.In this article,we introduce the progress of LyBES diagnostic,including the collection optics,the monochromator,and the detector system.The reflectance of the collection mirrors is measured to be~82%at 122 nm,and the aberration geometrical radius of the collection optics is tested to be~150μm in the aimed area.The linear dispersion of the LyBES monochromator is designed to be~0.09 nm mm^(-1).The bandwidth of the detector system with the 5×10^(7)V A^(-1)preamplifier gain is measured to be~280 kHz,and the peak-to-peak noise of the detector system is tested to be~16 mV.The finalized design,components development and testing of the LyBES diagnostic have been completed at present,and an overall performance of the LyBES diagnostic is to be confirmed in the next HL-2A campaign.
基金supported by the National Key Research and Development Program of China(Nos.2019YFE03090100 and 2022YFE03100002)National Natural Science Foundation of China(No.12075241)。
文摘The optical design of near-infrared phase contrast imaging(NI-PCI)diagnosis on HL-2A is introduced in this paper.This scheme benefits from the great progress of near-infrared laser technology and is a broadening of traditional phase contrast technology.This diagnostic can work as a keen tool to measure plasma wavenumber spectra by inferring string-integrated plasma density fluctuations.Design of both the front optical path which is the path before the laser transmitting into the tokamak plasma and the rear optics which is the path after the laser passing through the plasma is detailed.The 1550 nm laser is chosen as the probe beam and highprecision optical components are designed to fit the laser beam,in which a phase plate with a 194-nm-deep silver groove is the key.Compared with the conventional 10.6μm laser-based PCI system on HL-2A,NI-PCI significantly overcomes the unwanted phase scintillation effect and promotes the measurement capability of high-wavenumber turbulence with an increased maximal measurable wavenumber from 15 cm^(-1)to 32.6 cm^(-1).
基金supported by the National Key R&D Program of China(Nos.2022YFE03100002,2017YFE0301201 and 2018YFE0303102)Sichuan Science and Technology Program(Nos.2022JDJQ0038 and 2020JDTD0030)National Natural Science Foundation of China(No.12205087)。
文摘In this article,the design of a Lyman-alpha-based beam emission spectroscopy(LAB)diagnostic on the HL-2A tokamak has been proposed for the first time.The purpose of this novel diagnostic is to measure density fluctuations of tokamak plasma.The light-collection system of LAB,which consists of the first mirror and two groups of coaxial double-mirror telescopes,can realize a twosegmented viewing field ofρ=0–0.2 andρ=0.75–1,which is optimized to measure plasma density fluctuation,not only in the edge transport barrier region but also in the internal transport barrier region,to investigate the underlying physics of turbulence in tokamaks.Spectrometers are developed to separate out the Doppler-shifted target line(122.03 and 122.17 nm)from the background Lyman-alpha line(121.53 nm).Here,30 Core-LAB channels and 30 Edge-LAB channels are under development on the HL-2A tokamak.It has high radial spatial resolutions of about 2.7 mm and 3.3 mm for the core and edge channels,respectively.Taking the high light intensity of this Lyman-alpha line into account,temporal resolution of 200 k Hz can be ensured by broad bandwidth amplifiers.This high spatio-temporal resolution makes LAB a potential keen tool to experimentally investigate tokamak plasma physics.
基金supported by the National Key Research and Development Program of China (Nos. 2019YFE0302002, 2017YFE0301203 and 2017YFE0301202)National Natural Science Foundation of China (No. 12175055)。
文摘A vertical edge Thomson scattering(ETS) diagnostic system on HL-2M tokamak has been designed.The ETS system collects the scattered light from Nd:YAG laser(1064 nm,2 J,30 Hz,15 ns).The laser beam propagates vertically through the plasma region and the polarization is parallel to the toroidal magnetic field.A special designed Galileo-type telescope with long Rayleigh length is applied to focus the laser size and ensure collimation.A group of doubleGaussian collection lenses image the 600 mm vertical scattered region onto rectangular fiber arrays with a spatial resolution of 10 mm.The 2.20 mm × 2.86 mm fiber optic bundle consists of 130 low hydroxyl(OH) 200/220 μm(core/cladding) diameter fibers with numerical aperture NA=0.22,carrying the light to remotely located multi-channel polychromators.Effect of oblique incidence on narrow band filter has been analyzed.The designed electron temperatures range from 5 to 1000 eV and electron densities from 5 × 10^(18) to 1×10^(20) m^(-3).
基金supported by National Natural Science Foundation of China(No.11535013)the National Key Research and Development Program of China(Nos.2017YFA0402500,2018YFE0302100)the Users with Excellence Project of Hefei Science Center CAS(No.2018HSC-UE010)
文摘Ion temperature, as one of the most critical plasma parameters, can be diagnosed by charge exchange recombination spectroscopy (CXRS). Iterative least-squares fitting is conventionally used to analyze CXRS spectra to identify the active charge exchange component, which is the result of local interaction between impurity ions with a neutral beam. Due to the limit of the time consumption of the conventional approach (~100 ms per frame), the Experimental Advanced Superconducting Tokamak CXRS data is now analyzed in-between shots. To explore the feasibility of real-time measurement, neural networks are introduced to perform fast estimation of ion temperature. Based on the same four-layer neural network architecture, two neural networks are trained for two central chords according to the ion temperature data acquired from the conventional method. Using the TensorFlow framework, the training procedures are performed by an error back-propagation algorithm with the regularization via the weight decay method. Good agreement in the deduced ion temperature is shown for the neural networks and the conventional approach, while the data processing time is reduced by 3 orders of magnitude (~0.1 ms per frame) by using the neural networks.
基金supported by the National Key R&D Program of China(Nos.2017YFE0301201 and 2018YFE0303102)National Natural Science Foundation of China(Nos.11875124 and 12075241).
文摘In this article,we present the optical design of a novel diagnostic on the HL-2A tokamak,i.e.the 20-channel edge Lyman-alpha beam emission spectroscopy,which is a promising solution for edge density turbulence research on tokamaks,as it offers the possibility of density fluctuation measurement with a 3.3 mm spatial resolution while maintains a high temporal resolution of 1μs.The optical path,including the reflective collection optics,the high-dispersion spectrometer,and the linear detector array,is carefully optimized to obtain a good image quality and a high throughput.The maximum root mean square radius of the collection optics is 64μm.The detected photon flux is estimated to be about 1011 photons/s/channel.
