Nuclear Fusion and Plasma Physics

Calibrations of ECE measurement systems on HL-2A tokamak

HUANG Xian-li, SHI Zhong-bing, SUN Hong-juan, LIU Ze-tian, CUI Zheng-ying, DING Xuan-tong

2011, 31(3): 193-199.

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In the heterodyne measurement of electron cyclotron emission (ECE) on the HL-2A tokamak, in order to realize the absolute measurement of electron temperature profile, the two-temperature and the magnetic scanning methods are employed to relatively calibrate the frequency-scanning and the multi-channel ECE measurement systems respectively. The relative calibration coefficients between the channels are obtained. The absolute calibrations of ECE measurement systems are conducted by using the center electron temperature measured by Thomson scattering. The results show that both methods provide reliable calibration. The differences between the two methods are also compared and discussed.

The method of inversion of magnetic island two-dimensional structure by magnetic probes and its application on HL-2A tokamak

SUN Teng-fei, LIU Yi, JI Xiao-quan, XU Yuan, FENG Bei-bin

2011, 31(3): 200-206.

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The new method that reconstructs the polar two-dimensional structure of the magnetic island using magnetic pickup coils data is introduced on HL-2A tokamak and dynamic analysis method that set up based on it for tearing mode is also introduced. In this experiment, the perturbation current which is the source of the perturbation magnetic field can be determined using the data measured by magnetic probes. Superimposing the perturbation flux and equilibrium flux reconnected by EFIT, the structure and the width of the magnetic islands can be obtained. Then two-dimensional structure maps are set up chronologically and recorded in turn. After that these maps are revealed in turn and magnetic island can be analyzed dynamically. This method is applied to analyzing tearing mode. The conclusion that magnetic island rotating direction is in accordance with electronic diamagnetic drift direction is reached. The relationship between the magnetic island width and the magnetic perturbation field is proved and the suppression of magnetic island by ECRH is also verified. It shows the immediacy of the method of inversion of magnetic island structure by magnetic probes and it is very useful for watching and controlling MHD instability.

Molecular dynamics simulation of beryllium bombardment with C⁺

SUN Wei-zhong, ZHAO Cheng-li, ZHANG Jun-yuan, CHEN Feng, PAN Yu-dong, GOU Fu-jun

2011, 31(3): 207-212.

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Molecular dynamic simulations were performed to study the effect of the incident energy on the interreaction of C⁺ ion with Be sample surface. The simulated results show that with increasing C⁺ incident energy, the C⁺ implantation depth increases and the sputtering yield of Be increases near-linearly. However, the retention rate of C in the sample slightly changes. During the initial stage of the C⁺ bombarding Be sample, the sputtering yield of Be in sample increases sharply. With increasing exposure to C⁺, the sputtering yield of Be decreases and reaches saturation gradually. It is found that the formation of a carbon-rich layer near the sample surface region can protect beryllium sample from sputtering.

Study on the loss of neutral beam injected fast ions in EAST

LI Ji-bo, DING Si-ye, WANG Jin-fang, WU Bin, HU Chun-dong

2011, 31(3): 213-218.

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By means of classical guiding center orbit code ORBIT and combining with equilibrium code EFIT, as well as transport code TRANSP, the loss of neutral beam injected fast ions in EAST is calculated. 29% and 31% of the injected neutral beam ions were lost, with the beam power and energy given by 4MW (80keV) and 2MW (50keV), respectively, and the lost fast ions are strongly localized.

Development of a consistent and conservative scheme on a staggered grid for liquid metal MHD flows

LI Jun-feng, NI Ming-jiu

2011, 31(3): 219-223.

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A consistent and conservative scheme has been extended and developed on a staggered grid system for liquid metal MHD flow at a low magnetic Reynolds number by solving electrical potential Poisson equation based on the Ohm’s law and the charge conservation law. The consistent scheme is used to ensure the calculated current density conserves the charge, and the divergence formula of the Lorentz force is used to ensure the momentum conservation. Simulation of liquid metal flows in a three-dimensional straight channel is conducted and compared with the analytical solutions from Shercliff’s and Hunt’s. The numerical results are in good agreement with analytical solutions for the Hartmann numbers from 50 to 5000. A fully conservative scheme on a staggered grid, which can conserve mass, momentum and kinetic energy and charge, is then developed with the central-symmetrical scheme for the convective term and the pressure term and with the consistent and conservative scheme for the calculation of the current density and the Lorentz force. A fully conservative scheme can be a good tool for numerical analysis of MHD flow instability, large eddy simulation (LES) and direct numerical simulation (DNS) of MHD turbulence.

Out-of-pile tritium release experiments of lithium orthosilicate pebbles

XIAO Cheng-jian, CHEN Xiao-jun, KANG Chun-mei, GAO Xiao-ling, LIU Jun, GU Mei, LUO Yang-ming, WANG Xiao-lin

2011, 31(3): 224-227.

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Lithium orthosilicate (Li₄SiO₄) pebbles are considered as the candidate tritium breeders of Chinese helium cooled solid breeder test blanket module (CH HCSB TBM). The post-irradiation annealing experiments of lithium orthosilicate ceramic pebbles, made by freezen-sintering process, have been performed in CAEP. The samples were purged with 100mL/min mixed gas of He +1% H₂, heated at a constant rate of 5K•min^-1 in a reactor tube. The results showed that tritium was released mainly as tritium gas (HT+T₂), the proportion was about 70% except that in free tritium released out before annealing, and there were two tritium release peaks from 400℃~700℃. On the other hand, percentage of tritiated water (HTO+T₂O) was less than 20%, and released at lower temperature region of 300℃~500℃. Tritium remained in the pebbles was less than 1% after 800℃ in annealing experiments, so Li₄SiO₄ pebbles made by freezen-sintering process have favorable tritium release performance, and have potential application in fusion reactor solid blanket system.

The system design of CXRS diagnostic on HL-2A tokamak

HAN Xiao-yu, DUAN Xu-ru, YANG Li-mei, YU De-liang, ZHONG Wu-lv, FU Bing-zhong

2011, 31(3): 228-234.

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In order to obtain the important plasma parameters such as ion temperatures, rotate velocity and their profiles, a CXRS (charge exchange recombination spectroscopy) diagnosis was developed in HL-2A tokamak. In order to get the diagnostics signals with enough signal-to-noise ratio, the EMCCD detector suitable for the weak signal and the dedicated optical collection system converging light flux effectively were utilized. The experiment result proved that the design was feasible.

Thermo-hydraulic and neutronics calculation for the blanket of HCSB-DEMO

WU Xin-hua, ZHAO Feng-chao, ZHAO Zhou, LI Zai-xin, ZHANG Guo-shu, FENG Kai-ming

2011, 31(3): 235-240.

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Through thermo-hydraulic and neutronics iterative computation and optimization for the blanket sub-module on HCSB-DEMO, the preliminary structure layout under separate cooling circumstance has been designed, which meet several important requirements from thermo-hydraulics and neutronics. Each material’s temperature is below its limit value, outlet temperature of coolant has reached 500℃, and pressure drop of coolant has also meet the engineering requirement, meantime TBR has reached 1.30, regardless of the complicated structures. Using the final structure layout mentioned above, there were still some discussions about the sympathetic cooling circumstance, considering that the first wall is a special component with high heat flux, it is suggested that separate cooling circumstance should be taken.

Safety analysis for CH TBM tritium system in the design phase

FU Wan-fa, LUO De-li, TANG Tao, CHEN Chang-an

2011, 31(3): 241-245.

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A layout of TBM tritium system was designed and analyzed according to safety conception of multiple containment. Function and material of TBM tritium system were analyzed based on safety analysis. Four safety states of TBM tritium system were divided, according to operating states or possible dangers of tritium system, different emergency level was ascertained, and different safety measures should be taken for each emergency level. At last, on the basis of above analysis, PHA of tritium release for three containment systems was completed, accidental cause and harmful consequence were analyzed, and safety measures resisting tritium release were given.

Design of the movable structure for the EAST ICRF antenna

YANG Qing-xi, SONG Yun-tao, CHEN Yong-hua, CHENG Dao-lin

2011, 31(3): 246-251.

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On the basis of the physics experiment requirements of EAST, the ion cyclotron range of frequency (ICRF) antenna has been designed with the capacity of moving back and forth along the rail in the radial direction of EAST by the hydraulic drive. With the aim of demonstrating the feasibility of the movable structure, the analysis has been carried out for the support components of the ICRF antenna movable structure by applying the formulas and the finite element method, analysis results satisfy the design requirements. In addition, the mechanical analysis have been performed for the ICRF antenna, and the engineering commissioning have been done for the assembled ICRF antenna movable structure, results of mechanical analysis are shown that the ICRF antenna can move stably as well as results of commissioning meet what was expected.

Structure design of ITER PF in-cryostat-feeder

CHENG Wang, LIU Zheng-shi, SONG Yun-tao, LIU Su-mei

2011, 31(3): 252-255.

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According to the ITER performance requirement of poloidal field in-cryostat-feeder, and considering the complexity of the position and particularity working environment, the conceptual design of overall structure of the poloidal field in-cryostat feeder is processed with CATIA. Some important points are emphasized，such as the BUSBAR, cooling pipes, instrumentation pipes, the inside and outside supports. The conceptual design of PF ICF already has been approbated by ITER international group, and the paper is an important reference to the feeder design for other superconducting magnet system.

Buckling analysis and preliminary design of semi-prototype test for gravity support of ITER toroidal field

HOU Bing-lin, SUN Zhen-chao, HAN Shi-lei, LI Peng-yuan, PAN Chuan-jie

2011, 31(3): 256-259.

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The 3-D finite element model of the gravity support (GS) for ITER toroidal field was built by ANSYS software according to the new designed GS characteristics. The eigenvalues of the GS system under several load cases were solved using the Block Lanczos method. The results of buckling analysis show that the GS buckling doesn’t occur and the GS structure is secure. In order to ensure the GS reliability, a preliminary semi-prototype with full size is designed and will be used to engineering test for the new designed GS structure.

ITER GIS experiment platform control system

ZHANG Yu-xian, LI Bo, LI Wei

2011, 31(3): 260-265.

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The work is mainly focused on the design and implementation of a control and measuring system with GE PLC as its control center on the distributed experiment platform. With integration of industrial Ethernet, CAN bus and RS485, etc, the system ensures ITER GIS safety running control and enables remote control and real-time status-monitoring.

Design of alternant integrator based on DSP

MIAO Jing, JI Zhen-shan, WANG Yong

2011, 31(3): 266-271.

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Based on the algorithm of DSP deducting slope, we designed a new type of alternate integrator. This new integrator makes use of DSP for logic control to make two analog integrator work by turn, and this will reduce integration time of two integrator, which effectively overcome the errors caused by capacitance and temperature drift, thus the signal integration for a long time is realized. At the same time, we also use fixed-point processor Iqmath library functions to achieve real-time compute to improve the precision, it is convenient to achieve integration of real-time and accurate processing.

Optimized design for filter-fluorescer spectrometer for suprathermal electron diagnostication

ZHAO Xue-feng, JIANG Gang, WU Zhuang, LI San-wei, WANG Chuan-ke, KUANG Long-yu, LI Chao-guang

2011, 31(3): 272-277.

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According to fluorescence response and scatter response function, the thicknesses of profilters, postfilters and fluorescers of the filter-fluorescer spectrometer have been optimized with data interpolation. The least signal-to-noise and the optimize thicknesses of prefilters, postfilters and fluorescers are obtained. The filter-fluorescer spectrometer apply the optimize thicknesses of prefilters, postfilters and fluorescers for decreasing influence of high-octane to the signal of detector and gaining more available spectrum of hard X-ray, sequentially calculating available information of suprathermal electron.

The study of field and density cavition in the near wake region of a space vehicle

LUO Qing1, WANG Jing1, HU Tao-ping2

2011, 31(3): 278-282.

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Under the static limit, using the method of Fourier transformation, the non-steady, nonlinear interactions between plasma and field in the near wake region of a space vehicle are investigated. Numerical calculations are performed and the results show that there are the formation of the electromagnetic soliton and density caviton in the near wake region of the space vehicle, which can be detected due to the collapse of electric field. Therefore, we can trace out the space vehicle by means of observing the structure and intensity of the density caviton and electromagnetic soliton although the space vehicle may be have a disguised characteristic.

Experimental system design of liquid lithium-lead alloy bubbler for DFLL-TBM

XIE Bo, LI Jun-ge, XU Shao-mei, WENG Kui-ping

2011, 31(3): 283-288.

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The liquid lithium-lead alloy bubbler is a very important composition in the tritium unit of Chinese Dual-Functional Lithium Lead Test Blanket Module (DFLL-TBM). In order to complete the construction and run of the bubbler experimental system, overall design of the system, main circuit design and auxiliary system design have been proposed on the basis of theoretical calculations for the interaction of hydrogen isotope with lithium-lead alloy and experiment for hydrogen extraction from liquid lithium-lead alloy by bubbling with rotational jet nozzle. The key of this design is gas-liquid exchange packed column, to achieve the measurement and extraction of hydrogen isotopes from liquid lithium-lead alloy.

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