Table of Content

15 March 2018, Volume 38 Issue 1

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Plasma Physics

Poloidal rotation driven by turbulent residual stress in the edge of HL-2A plasmas

LONG Ting, NIE Lin, KE Rui, XU Min, WU Yi-fan, GUO Dong, WANG Zhan-hui, YUAN Bo-da, GONG Shao-bo, LIU Hao, HL-2A-Team

2018, 2(1):  1-7.  DOI: 10.16568/j.0254-6086.201801001

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The first measurement of turbulent poloidal residual stress profile in the edge of tokamak plasmas is reported in this article. A specially designed reciprocating Langmuir probe array on the out mid-plane of HL-2A tokamak was used to measure turbulent momentum transport. It is observed that the residual stress is finite and opposite to diffusive stress near last closed flux surface (LCFS). Both of them are about an order of magnitude larger than Reynolds stress. These experimental results indicate that poloidal momentum sources exist at the boundary of plasma and the momentum mainly transports away with diffusion. In the region −2cm<r−r_LCFS<−0.5cm, the negative radial gradient of residual stress serves as an intrinsic torque to drive poloidal rotation.

Fast direct solver for Grad-Shafranov equation based on compact scheme

HU Jin-di, XIAO Bing-jia, LUO Zheng-ping, HUANG Yao

2018, 2(1):  8-14.  DOI: 10.16568/j.0254-6086.201801002

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In the process of iterative computation of plasma equilibrium reconstruction, it is needed to fast solve Grad-Shafranov (G-S) equation. A fourth-order compact scheme was constructed with discrete sine transform (DST) technique to solve G-S equation, and CUDATM was used to realize parallel acceleration. This method will be used in EAST plasma equilibrium reconstruction PEFIT code to fast solve G-S equation based on compact scheme. It turns out that in 65×65 mesh, if the right side current distribution is known, the time needed to solve G-S equation based on GPU is about 34μs.

Development and validation of magnetohydrodynamic solver with projection in OpenFOAM environment

MAO Jie, WANG Hao, LIU Ke, WANG Cheng, Claude B Reed

2018, 2(1):  15-20.  DOI: 10.16568/j.0254-6086.201801003

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Magnetohydrodynamic flow solver with low magnetic Reynolds number in open source CFD environment of OpenFOAM was developed and validated. Four step projection methods were used to solve the momentum equation and the mass conservative equation. The consistent and conservative schemes based on collocated unstructured grid were applied to solve the electric potential Poisson equation, the induced electric current and the Lorentz force. A multi-region technique coupled by the boundary was also developed to solve magnetohydrodynamic flow with electric conducting walls. The solver was verified and validated by simulating duct and pipe flow with conducting walls under uniform magnetic field. Furthermore, the multi-region MHD solver was also validated by simulating liquid metal flows subject to a non-uniform magnetic field in an electrically conducting rectangular duct and pipe. The pressure distribution was compared with the ALEX experimental data. The results show that the solver has a good accuracy and can be used in the numerical study of MHD flows in fusion environment.

Numerical studies on resistive wall mode instability with magnetic shears

CHEN Long-xi, WANG Jin-fang, SUN Zhe, BIAN Zhen-zhu

2018, 2(1):  21-28.  DOI: 10.16568/j.0254-6086.201801004

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The effects of magnetic shear on the resistive wall mode (RWM) are numerically studied in a slab geometry. The most unstable mode is different with different magnetic shear rate . The shear in the magnetic field has an unstable effect on the linear evolution of the RWM. On the other hand, the critical flow velocity for stabilizing the RWM increases with increasing of shear rate . The RWM saturates in the nonlinear phase. The saturation can be attributed to flux piling-up on the resistive wall. The saturation level increases with increasing of shear rate .

Application of symplectic geometric algorithm in calculating propagation trajectory of wave in unmagnetized plasma

YAO Kun

2018, 2(1):  29-33.  DOI: 10.16568/j.0254-6086.201801005

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In order to preserve the symplectic geometric structure of Hamiltonian system, symplectic geometric algorithm is used to solve ray tracing equations. Symplectic geometric algorithm assures that conversion between two steps is symplectic. Symplectic geometric algorithm and Runge-Kutta-Fehlberg method are used to solve ray tracing equations respectively. The accuracy of both methods is fourth order. The results calculated by a simplistic geometric algorithm are in accordance with the analytic solution. In symplectic geometric algorithm, the error of dispersion function value increases with time linearly. The dispersion function value is within high accuracy. The results calculated by Runge-Kutta-Fehlberg method are different with the analytical solution. The calculation results show that the symplectic geometric algorithm has irreplaceable advantages in maintaining propagation trajectory and dispersion function value. Next symplectic geometric algorithm will be applied in magnetized plasma and nonlinear Hamiltonian systems.

Nuclear Fusion Engineering and Technology

Analysis and comparison of the thermal-hydraulic for standard divertor and snowflake-minus divertor of HL-2M tokamak

HUANG Wen-Yu, ZHENG Guo-yao, CAI Li-jun, XUE Lei, LU Yong, LIU Yu-xiang

2018, 2(1):  34-41.  DOI: 10.16568/j.0254-6086.201801006

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The forecast heat flux on the target plates of the standard and the snowflake-minus divertors for HL-2M tokamak, has been simulated with the SOLPS code. Under the condition that the energy flowing into plasma is about 10MW, the temperature distributions of the structures and the cooling water, the deformations and thermal stress distributions of the structures are analyzed with CFX/ANSYS for the two configurations.. Simulation results indicate that, under the same power flowing into plasma edge region, the highest temperature of the target plate of the snowflake-minus divertor is 169℃ lower than that of standard divertor plate. Meanwhile, compared to the standard divertor, the maximum thermal stress and the deformation of the snowflake-minus divertor decrease by a factor of 3/7. Increasing the heat flux in proportion or extending the discharging duration, keeping the distributions of the heat loads on the target plates invariant, temperature rise of the target plate is lower and the cooling water temperature is more balanced for the snowflake-minus divertor. These indicate that the snowflake-minus divertor configuration has a stronger ability to withstand the flowing thermal energy of the divertor region which reduces the requirements of the engineering design.

Beam optics characteristics based on infrared thermography for HL-2M NBI ion source

ZHOU Bo-wen, ZHOU Gui-qing, CAO Jian-yong, WEI Hui-ling, LIU He, ZHOU Hong-xia, HE Feng, YANG Xian-fu, LUO Huai-yu, PAN Chun-hua

2018, 2(1):  42-47.  DOI: 10.16568/j.0254-6086.201801007

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In order to study the optic characteristics of 80kV/40A/5s hot-cathode ion source of neutral beam injector (NBI) on HL-2M tokamak, Charge-coupled Device (CCD) infrared thermography technology was used to measure the temperature distribution caused by the beam bombardment on the calorimetric target and the feature parameter (1/e half width) of beam power distribution was obtained. On the NBI hot-cathode ion source platform, the discharge and extraction parameters of the ion source were scanned, and beam power distributions on the calorimetric target were obtained. The experimental results show that the available perveance range of 80kV/45A ion source on HL-2M NBI system was 0.7~1.5μP. In the same perveance, when the voltage ratio of the gradient electrode to the plasma electrode is higher, the half width of the extraction beam power distribution is smaller.

Neutronics design and analysis of helium cooled solid blanket and shielding for copper conductor CFETR

ZHAO Feng-chao, FENG Kai-ming, CAO Qi-xiang, LI Zai-xin, ZHANG Guo-shu

2018, 2(1):  48-54.  DOI: 10.16568/j.0254-6086.201801008

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According to the design requirement of copper conductor CFETR, the neutronics design and analysis of its helium cooled solid blanket (HCSB) and shielding are conducted. The design of HCSB based on casing pipes is proposed. Neutronics design and analysis show that Tritium Breeding Ratio (TBR) of HCSB with casing pipes reaches 1.25, and meets the tritium self-efficiency requirement, and radiation induced conductivity (RIC) and radiation induced electrical degradation (RIED) effect on insulation of toroidal field coil will not be remarkable in reactor life time.

Design of hardware circuits of solid-state anode high-voltage power supply in electron cyclotron resonance heating system

HUANG Bo, HUANG Mei, CHEN Wen-guang, RAO Jun, FENG Kun, KANG Zi-hua

2018, 2(1):  55-62.  DOI: 10.16568/j.0254-6086.201801008

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The hardware design of solid-state anode high-voltage power supply in electron cyclotron resonance heating system (ECRH) is presented. The anode power supply uses the method that combined high-frequency pulse width modulation (PWM) and phase shift modulation (PSM) control technology. The former in the supply uses the SG3525 to control the IGBT to complete the high frequency invert. The latter is made up of a total of 59 modules connected in series. The output voltage of each module is basically stabilized by feedback of the first stage module output voltage. DSP controls the number of PSM module on and off and the 59th module BUCK circuit duty cycle to achieve the output voltage of the superimposed output, and the output voltage can be adjusted within the full range of 35kV with accuracy less than 0.1kV, the output current up to 200mA, modulation frequency more than 1kHz. The anode power supply has three operating modes, and the rising edge time of the waveform can be adjusted within 3ms. The results tested from dummy load and ECRH experimental platform show that its performance is stable, and the hardware design method is feasible.

Neutronics design and optimization for ITER helium cooled ceramic breeder test blanket module

CAO Qi-xiang, ZHAO Feng-chao, WU Xin-hua, WANG Xiao-yu, FENG Kai-ming, Michael Loughlin

2018, 2(1):  63-68.  DOI: 10.16568/j.0254-6086.201801010

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Considering to reduce the filling factor of Be pebble bed from 80% to 62% in preliminary design phase, preliminary neutronics design and optimization for conceptual design of China ITER helium cooled ceramic breeder test blanket module (HCCB TBM) have been performed and the optimized HCCB TBM design has been proposed with modifying the material and arrangement of TBM inner components. This design has a better neutronics performance and satisfies the safety demand. Calculation results show that the tritium production rate of optimized HCCB TBM design is increased by 0.42mg/FPD comparing with conceptual design, but the total nuclear heating and peak power density are lower than conceptual design. These results can be used as supporting analyses for HCSB TBM preliminary design.

Cooling pipe system of ITER’s poloidal field coil support

XU Wan-yun, LI Peng-yuan, WEI Hai-hong, CHEN Hui, ZHANG Teng

2018, 2(1):  69-73.  DOI: 10.16568/j.0254-6086.201801011

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A series of plans was discussed about the arrangement of the cooling-pipe system on the ITER’s poloidal field coil support, the pipes laid along the width direction of the support was chosen to be simulated and analyzed as an optimum. The temperature and the pressure drop were used as the parameters to judge the results. A pipe arrangement plan was chosen and the numerical simulation result with finite element analysis satisfied the requirements of the ITER Organization.

Modeling and design of control system for ITER neutron flux monitoring

ZHAO Li, WEI Ling-feng, YUAN Guo-liang, LI Yong, YANG Qing-wei

2018, 2(1):  74-81.  DOI: 10.16568/j.0254-6086.201801012

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Based on the measurement and control requirements analysis for neutron diagnostics, the design model of Neutron Flux Monitoring was established on Enterprise Architect platform. According to the ITER Instruments and Control framework, the detailed functional analyses of signal conditioning, operational control, measurement and processing were conducted based on use cases and extended user and system requirements. The automatic operation processes of plasma discharge, equipment maintenance and system acceptance test were adopted by function mapping. The preliminary design of Neutron Flux Monitoring system was finished, whose hardware and software architectures conform to the ITER control, data acquisition and communication specification, and meet the requirement of integration with the ITER central control system.

Development of arc sprayed 3Cr13 coating for ITER poloidal field strut dowel

LUO Rong-rong, LI Peng-yuan, SUN Zhen-chao, CHEN Hui, YANG Kun

2018, 2(1):  82-86.  DOI: 10.16568/j.0254-6086.201801013

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Arc sprayed 3Cr13 coating on the surface of 316LN austenitic stainless steel was developed and investigated to increase the hardness and wear resistant of material for ITER poloidal filed (PF) strut dowel. The bonding strength test shows that the coating has good adhesion with base materials. Micro hardness of the coating is 353MPa, increasing by 23.4% compared to the base material. In addition, the result of friction test shows that the coating has the preferable friction properties at liquid nitrogen temperature (77K) in vacuum, which meet the requirements of ITER PF strut dowel.

Application of experimental physics and industrial control system in HL-2A host centralized control system

XU Jie, DONG Fang-zheng, TIAN Pei-hong, JIE Yan-feng, TANG Fang-qun, CAI Xiao, ZHAO Li, WEI Ling-feng, YANG Qing-wei

2018, 2(1):  87-92.  DOI: 10.16568/j.0254-6086.201801014

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HL-2A host centralized control system development based on Experimental Physics and Industrial Control System (EPICS) is described in detail in this paper. Communication between SoftIOC and PLC was realized using the s7nodave device driver module, and the PLC of the subsystems was integrated to the EPICS control system. Through extension and configuration in relational database and data archive and alarm component of CSS application, real-time communication between OPI layer and each subsystem was realized. HL-2A host measurement and control system parameters centralized successfully on the EPICS platform prepare for the design on the next generation device host centralized measurement and control system.

Design of master control system for poloidal field power supply based on real-time Linux

HE Shi-ying, HUANG Lian-sheng, GAO Ge, SHEN Jun, WANG Guang-hong

2018, 2(1):  93-98.  DOI: 10.16568/j.0254-6086.201801015

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In order to meet extremely requirements of real-time responds for control system of poloidal field power supply, the real-time Linux is choosed as the system platform, an opened-source code, extensible Eclipse based on C/C++ as development tool, and a master control system for poloidal field power supply is designed. This design realized real-time communication and real-time control with 12 sets local controllers of poloidal field power supply system in a control cycle (1ms). A feasibility solution about some key problems of the main controller was presented, such as high-speed communication and real-time control, stability and reliability and so on. The design is evaluated and tested, and it completely meets the real-time requirements of control system for the poloidal field power supply.

Study of equivalent heat conductivity in the Li4SiO4 pebble bed

ZHOU Bing, FENG Yong-jin, WANG Xiao-yu, WU Xin-hua

2018, 2(1):  99-104.  DOI: 10.16568/j.0254-6086.201801016

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The computational fluid dynamics (CFD) simulation of fluid solid coupling heat transfer for the beat transfer properties of Li4Sio4 pebble bed has been performed by referring the actual design parameters in the International Thermonuclear Experimental Reactor (ITER). The thermal hydraulic results under different working conditions are given. Finally, the results of equivalent heat conductivity in pebble bed region obtained with CFD are compared with the related experimental results.

Study of radio frequency inductively coupled plasma diffusion across the transverse magnetic feild

CHEN Hao, LEI Guang-jiu, LI Ming, HUANG Li-ping

2018, 2(1):  105-109.  DOI: 10.16568/j.0254-6086.201801017

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Influence of the transverse magnetic field provided by the external electromagnet on the electron temperature and ion density in the process of radio frequency inductively coupled plasma (ICP) was investigated by using the Langmuir probe which can move axially. The experimental data show that electron temperature dropped rapidly along the axial direction in expansion region in the presence of transverse magnetic field in comparison with non-magnetic field plasma case. In addition, the transverse magnetic field was found to filter the electrons.

Research progress of nano-structured oxide dispersion strengthened steels preparation technology and performance for first wall materials

WU Yu-cheng, WEI Yong, LUO Lai-ma, ZAN Xiang, ZHU Xiao-yong, LUO Guang-nan, CHEN Jun-ling

2018, 2(1):  110-116.  DOI: 10.16568/j.0254-6086.201801018

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Nano-structured oxide dispersion strengthened (ODS) steel was developed in recent years, and because of its excellent high temperature resistance, irradiation resistance, and mechanical properties, it was expected to be used in the structure of first wall materials in the fusion device. This paper briefly describes the research progress of the preparation technology and performance of nano-structured ODS steels.

Non-Fusion Plasma Applications

Nonreciprocal properties of one-dimensional magnetized plasma photonic crystals

XU Zhi-long

2018, 2(1):  117-124.  DOI: 10.16568/j.0254-6086.201801019

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Under ideal conditions, the transmittances of forward and backward waves are calculated by the transfer matrix method under TM wave, which are applied to study the effects of the plasma cyclotron frequency, the plasma frequency, the thickness of plasma layer, the periodic constant and the incident angle on the nonreciprocal properties of one-dimensional magnetized plasma photonic crystals. The results demonstrate that the nonreciprocal properties can be improved by increasing the values of the plasma cyclotron frequency and incident angle. However, the nonreciprocal properties become worse as the value of the plasma frequency and the thickness of plasma layer are blindly increased. Increasing the periodic constant cannot help to improve the nonreciprocal properties, but those can be made better by changing the ways, which are used to introduce the external magnetic field.