Table of Content

15 September 2020, Volume 40 Issue 3

Previous Issue    Next Issue

Plasma Physics

Measurement of impurity concentration by relative calibration of the charge exchange recombination spectra and beam emission spectra

HE Xiao-fei, YU De-liang, LIU Liang, WEI Yan-ling, CHEN Wen-jin, ZHONG Wu-lü, HE Xiao-xue, WU Hao

2020, 40(3):  193-199.  DOI: 10.16568/j.0254-6086.202003001

Asbtract ( )   PDF (2618KB) ( )  

References | Related Articles | Metrics

Intensity of the charge exchange recombination spectrum and the beam emission spectrum on the HL-2A tokamak were obtained by numerical simulation method, and the plasma impurity concentrations were obtained by the ratio of these two spectra. The simulation was to validate the possibility and reliability of the method. A three-grating spectrometer system was used in the experiment. Using the same line of sights, simultaneous measurement of carbon (C VI), helium (He II) charge exchange recombination spectrum and neutral beam emission spectrum were obtained for the first time on HL-2A. Absolute concentration profile of C6+ and He2+ ions were obtained synchronously on HL-2A for the first time. The method uses relative intensity calibration instead of complex absolute intensity calibration and avoids neutral beam attenuation calculations.

Development and test of the beam emission spectroscopy diagnostic based on neutral beam injection on HL-2A tokamak

WU Yi-fan1, 2, YU Yi1, 2, KE Rui2, XU Min2, NIE Lin2, WU Ting2, SUN Ai-ping2, LAN Tao1, YUAN Bo-da1, 2, LIU Hao1, 2, GONG Shao-bo1, 2, LONG Ting2, DUAN Xu-ru2, YE Min-you1, HL-2A team2

2020, 40(3):  200-207.  DOI: 10.16568/j.0254-6086.202003002

Asbtract ( )   PDF (4050KB) ( )  

References | Related Articles | Metrics

A 32-channels beam emission spectroscopy (BES) diagnostic system is developed and tested on HL-2A tokamak, which enables the 2D measurements of the long wavelength () electron density fluctuation with both high time and spatial resolutions () in a 2D field zone from radial position r=12~44cm and poloidal position -7.5~+7.5cm. The diagnostic consists of the sets of asymmetric lenses in the vacuum, fibers, high-efficiency detector modules and attached cooler and vacuum pump. In the low frequency (f<100kHz), the photon noise makes the main contribution to the noise level of the whole system, while the e-noise catches the similar level with the photon noise in the higher frequency. During the typical discharge of HL-2A, the signal to noise ratio (SNR) of the whole system is above 3 for the turbulence below 200kHz frequency.

Preliminary experimental study on the characteristics of ion internal transport barrier in EAST H-mode plasmas

ZHOU Yi-xuan1, LI Ying-ying2, JIANG Di2, TAO Wei1, YU Yi1, Lü Bo2, YE Min-you1

2020, 40(3):  208-214.  DOI: 10.16568/j.0254-6086.202003003

Asbtract ( )   PDF (4052KB) ( )  

References | Related Articles | Metrics

In order to investigate the characteristics of ion internal transport barrier (ITB) in EAST H-mode plasmas, the evolution of ion temperature and toroidal rotation velocity is analyzed during the formation and sustainment phase of the ion ITB by charge-exchange recombination spectroscopy (CXRS) diagnostics. The experimental analysis shows that the increase in the ion temperature gradient at R=1.928m associates with the decrease in the ion temperature gradient at R=1.984 during the formation and sustainment phase of the ion ITB and vice versa. Besides, considering that the ion temperature gradient at different radii in core region changes in the same direction before the formation of the ion ITB, the critical value of R/LTi at R=1.984m for characterizing ion ITB can be derived.

The study of plasma shaping effect on edge localized mode

QIN Chen-chen1, MOU Mao-lin1, CHEN Shao-yong1, TANG Chang-jian1, WU Na2

2020, 40(3):  215-221.  DOI: 10.16568/j.0254-6086.202003004

Asbtract ( )   PDF (6488KB) ( )  

References | Related Articles | Metrics

Influence of shaped plasma parameters (elongation and triangularity) on edge localized mode is simulated with the peeling-ballooning three-field module of BOUT++ code. In the linear simulation, the elongation has mainly effect on the ballooning component of the peeling-ballooning mode and suppresses its growth, while the triangularity has effect on both ballooning component and peeling component of the peeling-ballooning mode. In the nonlinear simulation, the elongation leads to larger ELMs energy loss because of the increased boundaryshear rate which forces the positive pressure perturbation to extend to the plasma core, while the triangularity plays an opposite role.

Experimental study on heat load of plasma-facing components by the calorimetry system in the EAST tokamak

ZHUANG Qing1, 2, MING Ting-feng1, YU Yao-wei1, LIU Yu-kai1, 2, ZHOU Fan1, 2, LONG Fei-fei1, 2, YANG Lei1, LI Yi-long1, 2, WANG Yu-min1, LIU Shao-cheng1, LIU Hai-qing1, LI Guo-qiang1, GAO Xiang1, 2

2020, 40(3):  222-226.  DOI: 10.16568/j.0254-6086.202003005

Asbtract ( )   PDF (1822KB) ( )  

References | Related Articles | Metrics

A calorimetry system is developed in the EAST tokamak to monitor the heat load distribution of plasma-facing components, and it is employed to evaluate the heatload exhausted by cooling water via the temperature difference between inlet and outlet of water loops. The results show that about 80% of total input energy is measured by the calorimetry system in an upper single null divertor configuration discharge, in which, about 50% of the heat load is deposited on the upper divertor. Moreover, the change rate of heatload increases with heating power. By fitting the fall-off phase of the measured water temperature, the time constant of thermal decay of cooling system is investigated for the upper and lower divertor, respectively. The former is 13.6s, which is about 10% of that in the later case.

Nuclear Fusion Engineering and Technology

Evaluation of electromagnetic loads on CFETR vacuum vessel mockup under major disruption events for different configurations

YU Zhi-wei1, 2, LU Kun1, GE Jian1, NI Xiao-jun1

2020, 40(3):  227-232.  DOI: 10.16568/j.0254-6086.202003006

Asbtract ( )   PDF (2962KB) ( )  

References | Related Articles | Metrics

Numerical analysis is performed for the electromagnetic loads on China Fusion Engineering Test Reactor (CFETR) vacuum vessel (VV) mockup corresponding to three different current scenarios during the major disruption (MD) event. The influence of plasma equilibrium configuration on the eddy current and electromagnetic force is emphasized. The analysis results show that distributions of eddy current and electromagnetic force on the VV are nearly same for the three different configurations, while the maxima of the axial force and the maxima of the different segments are different. The electromagnetic loads on VV during major disruption acquired from this method provide the data foundation for further checking the local structural strength of the CFETR VV mockup, and play an important role in improving the structural design rationality and operational safety of the VV.

Preliminary structural design and key manufacturing technology pre-research of HL-2M upper divertor

HUANG Yun-cong, CAI Li-jun, YUAN Ying-long, LU Yong, LIU Jian, LIU Yu-xiang, ZHENG Guo-yao

2020, 40(3):  233-240.  DOI: 10.16568/j.0254-6086.202003007

Asbtract ( )   PDF (4536KB) ( )  

References | Related Articles | Metrics

In consideration of the physical target of the HL-2M tokamak, the upper divertor located at the top of the vacuum vessel is designed as a "W" shape modular structure. The single module consists of SS-316L back plate, graphite block, graphite foil and various fasteners, and two ends of the module are only fixed by weft rings and welded studs, which provide more space for the diagnostic components. The finite element method is used to analyze the electromagnetic force, structure and thermal stress of the upper divertor module. By optimizing the support structure and the number of studs, the divertor structure can meet various working conditions. Finally, the pre-research of key manufacturing technologies processes, including welding process, deep hole drilling process, assembly, non-standard fastener development, etc. Those test data indicate that the gap between the final mounting surface of the preform (graphite block profile) and the standard template is less than 1mm, and the gap between adjacent graphites is not more than 0.5mm, the misalignment is between 0.5±0.2mm, and the leak rate of this module is below 2.5′10?10Pa·m3·s?1. These results provide technique support for the formal manufacturing of HL-2M upper divertor.

Development of a W-band multi-channel poloidal correlation reflectometry on EAST

WU Ming-fu1, 2, WEN Fei2, XIANG Hao-ming1, 2, ZHANG Tao2, LIU Zi-xi1, WANG Yu-ming2, LI Gong-shun3, 4, GENG Kang-ning1, 2, ZHONG Fu-bin1, 2, YE Kai-xuan1, 2, HUANG Jia1, 2, HAN Xiang2, ZHANG Shou-biao2 , GAO Xiang1, 2

2020, 40(3):  241-247.  DOI: 10.16568/j.0254-6086.202003008

Asbtract ( )   PDF (4334KB) ( )  

References | Related Articles | Metrics

An X-mode polarized W-band multi-channel correlation reflectometry is installed on EAST tokamak for measuring the density fluctuations in the core of plasma. The diagnostic uses a low loss (<3dB) multiplexer to couple the microwaves of four different frequencies (79.2GHz, 85.2GHz, 91.8GHz and 96GHz) together and then transmit through the same antenna. The reflected wave is received by two antennas separated poloidally with about 5cm, and then heterodyne measurement is achieved by down-conversion technology. The turbulent vertical velocity in the core of plasma can be obtained by doing correlation analysis for the signals received by the two poloidal antennas. Analysis of the 2018 lower confinement mode (L-mode) discharge shows that in plasma heated by the electron cyclotron resonance heating (ECRH), the vertical velocity of the core turbulence is in the direction of the electron diamagnetic drift. The vertical velocity of the core turbulence becomes in the direction of the ion diamagnetic drift after injecting the co-neutral beam.

Mathematical model of HL-2M fast control power supply based on the virtual center current control method

ZHENG Xue, XUAN Wei-min, WANG Ying-qiao, LI Wei-bin

2020, 40(3):  248-253.  DOI: 10.16568/j.0254-6086.202003009

Asbtract ( )   PDF (2668KB) ( )  

References | Related Articles | Metrics

Mathematical model of HL-2M fast control power supply is imitated, which is mainly used for the control of the vertical instability of plasma. The self-inductance and the mutual-inductance are taken full consideration into the mathematical model. The virtual center current control method is innovatively proposed which makes algorithm simpler relatively. The control system uses 2 parameters to control 3 variables benefited from the multiple-input-multiple-output control method. This paper draws up multi-coil coupling voltage based on basic power supply plan and circuit equation based on the fast control power supply topology, then obtains coil voltage mathematical model by combining them. Finally the correctness has been verified with simulations. The results show that the mathematical model is correct, which provides a solid foundation for further calculation.

Simulation of LCC resonant converter applied to glow discharge cleaning power supply

CHEN Jun-hong, WANG Ying-qiao, WANG Ya-li, LI Wei-bin, ZHENG Xue, CHEN Chen, LI Chen

2020, 40(3):  254-261.  DOI: 10.16568/j.0254-6086.202003010

Asbtract ( )   PDF (2738KB) ( )  

References | Related Articles | Metrics

Under the constant current requirement of the power supply after the gas breakdown in the glow discharge cleaning system, a new scheme of LCC resonant converter is proposed to improve the scheme of glow discharge cleaning power supply and increase the reserve of power supply scheme. The software tool is used to select the parameter range, assist to understand the topological characteristics and verify the scheme. The influence of the main parameter quality factor QL and the series and parallel capacitance ratio A in the LCC transfer function on the circuit gain and resonant device stress is analyzed, and the reasonable value is designed. Based on the designed value, MATLAB simulation indicates that the closed-loop output of the power supply reaches the rated value, and the LCC topology meets the requirements of glow discharge cleaning power supply parameters. The current normalization curve of LCC resonant converter shows good constant current characteristics and is suitable for designing as a current source.

Development of spectra analysis software for the space-resolved EUV spectrometer in EAST tokamak

CHENG Yun-xin1, 2, ZHANG Ling1, WU Zhen-wei1, XU Zong3, 4, YANG Xiu-da1, 2, LI Lei1, 2

2020, 40(3):  262-267.  DOI: 10.16568/j.0254-6086.202003011

Asbtract ( )   PDF (5489KB) ( )  

References | Related Articles | Metrics

Interactive interface software is developed based on the MATLAB graphical user interface development environment (GUIDE) for the space-resolved EUV spectrometer in EAST tokamak. The functions of the newly developed software include data reading, wavelength calibration, viewing chord alignment, time synchronization with EAST control center, emission line intensity calculation and profile plotting. The development and application of this newly developed software largely improve the efficiency of data analysis and guarantee the real-time data analysis during the EAST experiment.

Finite element analysis of a valve box structure of ITER fusion power shutdown system

LIU Xi-gang, LI Wei, XIA Zhi-wei, LI Bo, PAN Yu-dong

2020, 40(3):  268-274.  DOI: 10.16568/j.0254-6086.202003012

Asbtract ( )   PDF (5442KB) ( )  

References | Related Articles | Metrics

Calculation and analysis of the stress and strain condition of a valve box structure of ITER fusion power shutdown system (FPSS) under various ITER typical load combinations are performed using ANSYS software. The ASME criterion and ITER related standard are used to evaluate the analysis results, and the evaluation results show that this valve box structure can meet the ITER design requirements.

Neutronics analyses of water-cooled ceramic breeder blanket for the updated CFETR model

LI Xia1, 2, MA Xue-bin3, LU Peng3, ZHENG Yu1, 2, XU Kun1, LIU Song-lin1

2020, 40(3):  275-282.  DOI: 10.16568/j.0254-6086.202003013

Asbtract ( )   PDF (5102KB) ( )  

References | Related Articles | Metrics

Based on a three-dimensional water-cooled ceramic breeder (WCCB) blanket model for the China Fusion Engineering Test Reactor (CFETR), neutronics analyses are performed by utilizing the MCNP5 code and the IAEA Fusion Evaluated Nuclear Data Library FENDL2.1. The results include neutron wall loading (NWL), tritium breeding ratio (TBR), nuclear heating power and radiation damage under 200MW, 500MW, 1.0GW, 1.5GW fusion power. The results show that the neutronics analyses of WCCB meet the design requirements of CFETR.

Non-Fusion Plasma Applications

Multi-field coupling analysis of arc physical properties in micro-plasma welding

CHEN Hao-jie, LIU Hai-hua, LI Liang-yu, ZHAO Tao

2020, 40(3):  283-288.  DOI: 10.16568/j.0254-6086.202003014

Asbtract ( )   PDF (2194KB) ( )  

References | Related Articles | Metrics

A model of micro-plasma arc is established based on the Magnetohydrodynamics equations, which are solved with the finite element analysis software COMSOL. The results show that the temperature distribution of the arc center is in a “brush” shape from the tungsten needle to the workpiece as a whole, where the arc temperature distribution under the nozzle is in a “bell” shape, and the temperature on the workpiece conforms to the Gaussian distribution; the arc plasma has a large velocity inside the nozzle. After leaving the nozzle, its direction gradually changes from vertical downward in the nozzle to the surrounding direction when reaching the workpiece; the current flows out from the surface of the workpiece and flows into the lower end face of the tungsten electrode through the arc column, and the maximum value is obtained near the lower end face of the tungsten electrode; the flux density distribution of the arc is in a “lobes” shape. Finally, the fusion welding test was carried out, and the arc profile captured during the test was basically the same as the simulated arc shape.