Nuclear Fusion and Plasma Physics

Data processing algorithm of three-wave coupling in plasma turbulences by spectral estimation methods

SHEN Yong1, DONG Jia-qi1, 2, SHI Zhong-bing1, ZHAO Kai-jun1

2015, 35(3): 193-197. DOI: 10.16568/j.0254-6086.201503001

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Based on the Ritz method to resolve the waves-coupling equation, the data processing code was developed to investigate the non-linear energy transfer progress in plasma edge turbulence in HL-2A tokamak. The arithmetic principle and the development methods of this code were introduced. By use of this program, the discharge data with relation to zonal flow were processed and studied. The results show that zonal flow was driven by the inverse energy cascade in the plasma turbulence.

Numerical analysis of cold pressure equation of metals

DUAN Yao-yong, GUO Yong-hui, QIU Ai-ci

2015, 35(3): 198-203. DOI: 10.16568/j.0254-6086.201503002

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The cold pressure parameters of q and Q in the Born-Mayer(BM) model for fifty-seven metals equations were calculated by using the Hu-Jing(HJ) method based on isothermal bulk moduli of metal and measured data in shock wave experiments, and at the same time a trial method for computing them by combining Thomas-Fermi model at absolute zero-temperature with low pressure experiment data, is put forward for lack of the sufficient shock wave experiment data. By integrating the Faussurier model for electron thermal pressure, the Cowan model for ion thermal pressure and the above obtained cold pressure fitted formula, the Hugoniot curves of Be, Co and Pb are calculated and compared with experimental data, and then the discrepancies of q value and Q value obtained by HJ method and a comprehensive method are analyzed and interpreted. Furthermore, the precision for the cold pressure equation by HJ method is assessed by comparing the thermodynamic quantities on the Hugoniot curves of Sr, Ba, and Sm with the corresponding measured results and the calculated ones by other models.

Performance test of 4 TH2103A klystrons for HL-2A LHCD system

KANG Zhi-hua, LU Bo, ZENG Hao, RAO Jun, WANG Chao, WANG Ming-wei,WANG Jie-qiong, YAO Tao, LIANG Jun, CHEN Ya-li, FENG Kun, WANG He

2015, 35(3): 204-209. DOI: 10.16568/j.0254-6086.201503003

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A test platform for the TH2103A klystrons and the high power microwave components is developed. The RF driver, four port circulator, RF load and high power cathode power supply are installed on the test bed. A short pulse test is carried out on the test bed. The parameters of the 4 klystrons are optimized by scanning the currents in the 3 focusing coils and the high power microwave transmission components are conditioned. The output power of the 4 klystrons reached 449kW, 417kW, 460kW and 450kW when the pulse duration was 30ms, respectively. The test result is an important reference for the LHCD system on HL-2A tokamak.

Water cooling system design and optimization for HL-2M coils

XIE Yan-feng, LI Guang-sheng, ZHOU Hui, LIU De-quan

2015, 35(3): 210-216. DOI: 10.16568/j.0254-6086.201503004

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Based on one dimension simulations implemented by software and analytical method, the design and calculation of water cooling system for HL-2M TF, PF and CS coils are introduced. The hydraulic parameters for the cooling design is provided. By optimizing available pressure and flow distribution in the cooling system, maximum flow of the subsystems power output is 400m³•h⁻¹ and maximum pressure is 1.8MPa. The optimization results of hydraulic parameters meet the requirement of coils thermal exchange under the maximum velocity 4.5m•s⁻¹.

Welding technology of ITER PF support

LIAO-Min, LI Peng-yuan, SUN Zheng-chao，SHU Run-tao

2015, 35(3): 217-222. DOI: 10.16568/j.0254-6086.201503005

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The manufacturing process and welding technology of PF coil support are introduced, and the taken technical measures to control the deformation stress of welding, to improve low temperature impact toughness and to control the weld ferrite content are explained. The machine accuracy and the quality were improved through post weld stress relief and anti deformation measures.

Application of supper capacitors to power supply for NBI arc discharge

YANG Pu-qiong1, 2, XUAN Wei-min1, WEI Hui-ling1

2015, 35(3): 223-227. DOI: 10.16568/j.0254-6086.201503006

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The structure principle, circuit model and application of the super capacitor were introduced in tokamak experiment. The arc discharge power supply characteristics of high power ion source and the circuit topology of 1MW NBI arc supply for HL-2A tokomak are comprehensively analyzed. An arc discharge power supply circuit for 5MW NBI ion source has been developed by application of super capacitors, which can reduce the load of electric network and has smaller size, higher efficiency, simpler control and quicker response speed. A scheme for 5MW NBI ion source filament power supply using super capacitors supply and constant voltage control has been put forward, and the feasibility and technical advantages of the scheme have also been given. To equalize the voltages of individual super capacitor in energy storage by a numerous super capacitors in series and in parallel, this paper put forward a reliable and efficient voltage balancing circuit.

Numerical simulation and structure selection for rib welding of D-ring patterns in the vacuum chamber module

WANG Ze-ming, TAO Hai-yan, YE Xiao-feng, YU De-huai, WANG Shi-zhong

2015, 35(3): 228-232. DOI: 10.16568/j.0254-6086.201503007

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Based on the finite element analysis software and double ellipsoid heat as the heat source, the ribs welding of D-ring patterns under different ribs in the vacuum chamber module was developed in the 3D dynamic simulation. The transient temperature field distribution, feature points thermal cycling curve and stress-strain curve were obtained. The results showed that the welding temperature field and the feature points thermal cycling curve were consistent. Compared with I-type rib with D-ring structure, the T-type rib had the lower stress-strain and deformation. Thus, it could give priority to the use of T-type rib in the engineering trial process of D-ring patterns of the vacuum chamber module.

Three dimensional electromagnetic analysis of the four strap ICRF antenna for EAST

YANG Hua1, WU Cong-feng1, DONG Sai1, ZHANG Xin-jun2,ZHAO Yan-ping2, SHANG Lei1

2015, 35(3): 233-239. DOI: 10.16568/j.0254-6086.201503008

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The performance of the four strap ion cyclotron range of frequency (ICRF) antenna in EAST was studied by three dimensional electromagnetic code CST MWS. The coupling impedance with various frequencies, the distribution of current on straps and the power spectra for the three types of phases were calculated. The voltage breakdown and ICRF-related impurity were also studied. Simulation results show that the coupling impedance and power spectrum of the antenna design were reasonable, however, highest electric field, which is 3.61MV•m⁻¹ for (0, 0, 0, 0) toroidal phasing at the local area, exceeds the empirical value of breakdown. After the structure size was optimized, the maximum of E-field was below the breakdown value, the results also show that the high radio frequency (RF) potential was close to the antenna limiter, the RF potential along total B-field in front of Faraday screens 10mm for (0, π, π, 0) phasing was one-third of that for (0, 0, π, π) phasing.

Design and FE analysis for the welding process of vacuum vessel support in KTX

WANG Zhen1, YANG Qing-xi1, SONG Yun-tao1, XU Hao1, WAN Shu-de2, LIU Wan-dong2

2015, 35(3): 240-245. DOI: 10.16568/j.0254-6086.201503009

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The welding process of KTX vacuum vessel support was designed and then the distributions of welding temperature field and residual stress field were calculated through FE method. The strength of welding joints was assessed by a method combining the theoretical analysis and FE analysis. The analysis results verified the reliability of the welding structure and provided theoretical basis for the welding process of vacuum vessel support structures.

Comparative analysis of two-dimensional and three-dimensional models for poloidal magnetic field calculation in tokamak with iron core

CHENG Ji, CHEN Zhi-peng, YU Wen-zhao, LI Fu-ming,RAO Bo, TAN Hao, WANG Zhi-jiang, ZHUANG Ge

2015, 35(3): 246-252. DOI: 10.16568/j.0254-6086.201503010

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For simplifying the calculation the magnetic distribution on tokamak, some two-dimensional analytic models including the effect of the iron core were established, such as the infinite long iron core model and the spool model. The assumptions of these two-dimensional analytic models lead to different results with the actual magnetic field due to the distinctive boundary condition. In order to accurately calculate the three-dimensional magnetic field distribution in the tokamak with iron core, a three-dimensional numerical finite element model was established based on J-TEXT tokamak. In two conditions, where the total toroidal current is nonzero or zero respectively, more comparison were carried out between the derived results of two-dimensional models and the results at different toroidal positions in three-dimensional models. Furthermore, the toroidal asymmetry of the magnetic field distribution of the three-dimensional model of tokamak with iron core was investigated. The results indicate that the three-dimensional construction of iron core causes the toroidal asymmetric poloidal magnetic field and the difference between the two- and three-dimensional models in the condition with total current of nonzero. However, in the condition with total current of zero, the intensity of toroidal asymmetric is reduced and the difference between the two- and three-dimensional models is smaller.

Experimental study of heat transfer with hyper-vapotron for high heat flux components

CHU De-lin1, PAN Bao-guo1, MEI Luo-qin1, ZHANG Qiang-hua1,JIANG Hai-yan2, WANG Wei-hua1

2015, 35(3): 253-258. DOI: 10.16568/j.0254-6086.201503011

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An experimental study of heat transfer was carried out in the hyper-vapotron loop-Ⅰ(HVL-Ⅰ) test facility. Phenomena of subcooling were observed using the techniques of planar laser induced fluorescent (PLIF), high speed photography, particle image velocimetry, etc. The flow and condition parameters were as follows: (1) CuCrZr alloy material, (2) triangle and rectangle fin structures, (3) inlet subcooling temperature of 296K, (4) Rhodamine solution flow velocity of 0.3~0.5m•s⁻¹. It was found that the heat transfer coefficient (HTC) of rectangle fin is 1.3～1.5 times higher than the triangle fin under the same tested conditions. Furthermore, the heat transfer efficiency is extraordinary dependent on the maintain time of vortex forming between the fins.

Electromagnetic analysis for blanket of fusion reactor under plasma disruption

CHEN Ming-feng1, LIU Su-mei1, 2, SUN Peng-fei1, LEI Ming-zhun2, WANG Zhong-wei2

2015, 35(3): 259-264. DOI: 10.16568/j.0254-6086.201503012

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In a fusion reactor, the blanket is one of the core components inside the vacuum vessel, it is directly facing the plasma, and the working environment is very harsh. In this paper, the induced eddy current and suffered electromagnetic force in the blanket of China Fusion Engineering Test Reactor (CFETR) has been calculated by the vector electromagnetic method of ANSYS in the major plasma disruption or the vertical displacement event. The modeling, the current source loading, boundary conditions setting, solving and calculated results are presented. This will provides the necessary reference data and method for future detailed design and optimization of the blanket components.

Design and analysis of optical coupling isolation amplifier for J-TEXT tokamak

PAN Ming-jun1, 2, ZHANG Ming1, 2, LI Ting-ting1, 2, ZHENG Wei1, 2, RAO Bo1, 2, ZHUANG Ge1, 2

2015, 35(3): 265-271. DOI: 10.16568/j.0254-6086.201503013

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A wideband optical coupling isolation amplifier is presented. Experimental results showed that the presented isolation amplifier can transmit an analog signal from dc to 2.7MHz with good linearity and low propagation delay. Effects of the compensation capacitor on the frequency characteristics of the isolation amplifier was studied by simulation analysis. Meanwhile the mathematical model of the circuit was established with parts of the parasitic parameters taken into consideration. The linearity and frequency characteristics of the circuit was studied, combining theoretical analysis, simulation and test. At last, the availability of the presented isolation amplifier was verified in the Langmuir probe floating potential measurement system on J-TEXT tokamak.

Voltage balance control and simulation for high magnetic chain-type active power filter

LIU Jia1, WU Ping-zhi1, LIU Xiao-ning2, CHENG Si-ming2

2015, 35(3): 272-277. DOI: 10.16568/j.0254-6086.201503014

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Aiming at the program planning for chained high-voltage active power filter system in superconducting magnet power of stabilized intense magnetic fields, combing with the non-linear characteristics of active power filter system, a method adopting the fractional-order PI controller instead of ordinary PI controller was proposed to realize three capacitive equalizing control method, and based on the improved Oustaloup algorithm, the solution of fractional calculus was achieved. Through simulation and experimental comparison, the running effects of fractional-order PI controller and conventional PI controller was analyzed. According to simulation and experiment, this fractional-order PI controller is correct.

Simulation of cooling efficiency in test device of liquid lithium

ZHU Zhi-chuan1, GOU Fu-jun2, MIAO Feng1, WANG Jian-qiang2,YANG Dang-xiao3, ZHANG Chuan-wu1

2015, 35(3): 278-283. DOI: 10.16568/j.0254-6086.201503015

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Using commercial software CFX, the effect of velocity of liquid lithium, heat flux, velocity and temperature of water on temperature of the free flow liquid lithium and cooling efficiency of water under the action of thermal load was calculated. Results indicate that temperature of liquid lithium will decrease with the increase of velocity of liquid lithium. When heat flux is less than 2MW·m^-2, water cooling can meet the requirements of the temperature control of liquid lithium, however, cooling capacity of water is insufficient when heat flux is much higher. Increasing the velocity of cooling water is the effective way to decrease temperature of liquid lithium and improve cooling efficiency. The temperature of water has a little impact on temperature of liquid lithium and cooling efficiency.

Numerical simulation on focused state of strong current ion beam

ZHANG Feng-juan, ZHANG Chao-hai

2015, 35(3): 284-288. DOI: 10.16568/j.0254-6086.201503016

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The ion beam focused state is studied theoretically by combining the schematic of the charge lens in space and the magnetohydrodynamics equation of the ion beam. The theory applies laminar flow of non-collision model to calculate a series of parameters, such as the initial radius, the emergence angle, the focal length and the minimum radius of the focal spot. The effects of energy divergence and dispersion differs on the minimum radius of the focal spot are analyzed theoretically. Finally, in line with the principles of the conservation of energy and angular momentum, the maximum radius of the beam in view of different incidence angles of the ion beam are calculates. The results show that with the increase of incident angle, the confluence angle and the minimum radius of the focal spot will reduce, and the focal length will increase. Besides, when beam radius increases, the parameters above will increase. The minimum focal spot radius, within the smooth area, is in close relationship to the energy divergence and the divergence. The larger energy divergence and the divergence become, the larger the focal length will be. Besides, beam divergence with the same incidence angle will show common character on the maximum radius.

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