Table of Content

15 June 2010, Volume 30 Issue 2

Previous Issue    Next Issue

Plasma Physics

Experimental results from SDD soft X-ray PHA array on the HL-2A tokamak

ZHANG Yi-po,LIU Yi,YANG Jin-wei,SONG Xian-ying,LI Xu,YUAN Guo-liang,PAN Chan-hon

2010, 30(2):  97-102. 

Asbtract ( )   PDF (2266KB) ( )  

References | Related Articles | Metrics

The time evolution of electron temperature (T_e) profile and electron velocity distribution can be obtained by means of the new soft X-ray pulse height analysis(PHA) array system. Preliminary experimental results obtained from the PHA system show that the T_e profile during ohmic heating (OH) phase is correspondingly flat, and close to the analogical parabola form of 1.0×[1-(r/a)²]²; the T_e profile become peaking during near-axis ECRH (0.8 MW), the T_e in the plasma center (z＝0) increase 0.6 keV, however, the increment of T_e in the plasma edge (z＝30cm) is only 0.1keV, a mass of high-energy electrons are generated during ECRH phase, therefore, the electron velocity distribution is changed evidently during ECRH; both the number and energy of the high-energy electrons is larger in plasma center (z＝0) than that in plasma edge (z＝30cm), the energy of high-energy electrons in plasma center can extend to 17keV. It can be concluded from the experimental results that heating effect of ECRH is very obvious, the energy of ECW is mainly deposited in the plasma center during near-axis ECRH (B_t＝1.3T) discharges, and the electron velocity distribution changes from Maxwellian to non-Maxwellian normally.

Primary experimental results of the dichroic filters on FIR laser interferometer

ZHENG Ling, ZHOU Yan, DENG Zhong-chao, YI Jiang, LI Yong-gao, LI Lian-cai

2010, 30(2):  103-107. 

Asbtract ( )   PDF (1692KB) ( )  

References | Related Articles | Metrics

One kind of dichroic filters for protecting the detectors of FIR laser interferometer on HL-2A tokamak is introduced. The geometry of dichroic filters was optimized. The dichroic filters were used on HL-2A FIR laser interferometer system for the first time. The experimental results show that the dichroic filters can effectively isolate the interference from ECRH and make the HCN laser signals keep high transmittance.

Preliminary study of energy confinement data with a statistical analysis system in HL-2A tokmak

XU Yuan,CUI Zheng-ying,O J W F Kardaun,JI Xiao-quan,DONG Chun-feng,YANG Qing-wei

2010, 30(2):  108-114. 

Asbtract ( )   PDF (1408KB) ( )  

References | Related Articles | Metrics

Taking advantage of the HL-2A experimental data, an energy confinement database facing ITERL DB2.0 version has been originally established. As for this database, a world widely used statistical analysis system(SAS) has been adopted for the first time to analyze and evaluate the confinement data from HL-2A and the research on scaling laws of energy confinement time corresponding to plasma density is developed, some preliminary results having been achieved. Finally, through comparing with both ITER scaling law and previous ASDEX database, the investigation about L-mode confinement quality on HL-2A and influence of temperature on Spitzer resistivity will be discussed.

A real-time algorithm of spatial inversion for the line- integral signals and its application in HT-7 Tokamak

YANG Jian-hua,GAO Xiang,HU Li-qun,WU Zhen-wei

2010, 30(2):  115-121. 

Asbtract ( )   PDF (2397KB) ( )  

References | Related Articles | Metrics

A new algorithm is introduced to reconstruct the parameters of plasma from line-integral data. This method is based on the Radon inversion theory. The series expansion and least-square methods are employed to get the Radon inversion of the plasma parameter on the minor cross-section of tokamak. Then the plasma parameter can be given by the Radon inversion formula. This algorithm is introduced to study the asymmetric phenomenon between the positive and negative current plasma of the X-ray emission in HT-7 tokamak.

Experimental investigation on MHD effects due to different FCI’s structures and conductivities

XU Zeng-yu, PAN Chuan-jie, ZHANG Xiu-jie, ZHAO Li, ZHANG Jian, YANG Guo-ji

2010, 30(2):  122-126. 

Asbtract ( )   PDF (2376KB) ( )  

References | Related Articles | Metrics

The experimental investigation of the MHD effects for the flow channel inserter (FCI) due to the different structures and the different conductivities of the FCIs is presented. The FCIs are electric insulator / electric conductivity with the pressure equalization holes (PEH) / the pressure equalization slot (PES). The experimental results showed that there are a significant different on the velocity distribution and MHD pressure drop for the different structures and the different conductivities of the FCIs. It is also indicated that FCI with PEH is better than with PES on reducing MHD pressure drop and controlling velocity distribution in the duct with FCI. FCI MHD effects can be understood with the secondary flow MHD effect (short in “S-MHD”). The S-MHD effects also can be used to control the fluid structure and MHD pressure drop. These experimental data is useful for understanding the mechanism of FCI to reduce MHD pressure drop and for supplying the technical reference of liquid metal blanket system design.

Influence of Compton scattering on the relation between laser energy and photo-acoustic signal intensity in solid

HAO Xiao-fei, YAO Qiao-ge, HAO Dong-shan

2010, 30(2):  127-130. 

Asbtract ( )   PDF (436KB) ( )  

References | Related Articles | Metrics

The photo-acoustic theory，relativity quantum theory and the model of the nonlinear Compton scattering between an electron and a multi-photon group is adopted to study the influence of Compton scattering on laser energy and photo-acoustic signal intensity in impure solid. The results show that when the nonlinear Compton scattering between the an electron and a photon group is taken place in the impure solid and the changing of the photo-acoustic transfer effect and the contribution of the crystal lattice to dielectric function are ignored，the coupling laser energy and its magnetic induction intensity are the two key factors to the changing of the photo-acoustic intensity. In these factors，the magnetic induction intensity takes key effect. Under Compton scattering，the photo-acoustic signal intensity will quickly be increased along with the increase of the coupling magnetic induction intensity and laser energy. There is a logarithm linear relation between the energy and the sound pressure of the photo-acoustic signal，but their relation will be lower than that before Compton scattering.

PIC/MC simulations of transition between conventional and micro hollow cathode discharge in nitrogen

ZHANG Lian-zhu, MENG Xiu-lan, TIAN Zhong-tao, GAO Shu-xia, ZHAO Shu-xia

2010, 30(2):  131-137. 

Asbtract ( )   PDF (3601KB) ( )  

References | Related Articles | Metrics

A two-dimensional PIC/MC model is developed for a hollow cathode discharge in nitrogen. The transition of potential and electric field from conventional hollow cathode discharge to the micro hollow cathode discharge in N₂ is studied. The results showed that the distributions of electric potential and electric field in different sizes of hollow cathode discharge are almost similar, but the electric field linear increases approximately with the hollow cathode diameter decrease and the pressure increase; The electric field in typical micro hollow cathode discharge is about 3 orders of magnitude bigger than in the conventional hollow cathode discharge; The electron, nitrogen molecular ions and nitrogen atoms ion density in the micro hollow cathode discharge is about 3 orders of magnitude bigger than in conventional hollow cathode discharge, and the N₂⁺ density is above 8 times than the N⁺ density in the micro hollow cathode discharge.

Application of asymptotic preserving PIC method in the plasma particle simulation

SUN An-bang, MAO Gen-wang, Degond P, Deluzet F, Navoret L, Vignal M-H

2010, 30(2):  138-142. 

Asbtract ( )   PDF (1031KB) ( )  

References | Related Articles | Metrics

The existing problem of multi-scale parameters in the quasi-neutral Vlasov-Poisson system was studied, using asymptotic preserving scheme to induce a Poisson equation coupled with Vlasov equation. One dimensional plasma expansion in vacuum was simulated, the asymptotic preserving PIC and classical PIC results were compared. The simulated results show that two methods have a good agreement while satisfying the smaller scale constraint, and the asymptotic preserving scheme still simulates correctly the physics behavior of plasma while free of the smaller scale constraint, the calculated time is saved intensely.

Nuclear Fusion Engineering and Technology

Design of the 3-dB power splitter for LHCD antenna on HL-2A

ZENG Hao,BAI Xin-yu,CHEN Gang-yu,LU Bo

2010, 30(2):  143-147. 

Asbtract ( )   PDF (1645KB) ( )  

References | Related Articles | Metrics

The even-odd mode theory, wave superposition and impedance matching are used to design the 3-dB power splitter, then the structure and the parameters of the power splitter are simulated by HFSS cord. Finally the optimistic results are acquired: reflection loss in input port 1 is -41.42dB; isolation between the port1 and 4 is -44.86dB; power splitting in output port 2, 3 are -3.02 dB, -3.01 dB；input VSWR is 1.017.

Test of ITER superconduct strand's mechanical properties

LIU Bo,WU Yu,LIU Fang,LONG Feng

2010, 30(2):  148-151. 

Asbtract ( )   PDF (1024KB) ( )  

References | Related Articles | Metrics

Design theory of the Pacman equipment was introduced and characteristic curves of critical current and strain of Nb₃Sn strands processed by the OST company with internal tin were described. The Nb₃Sn strands were measured in the axial strain range from -0.8%～+0.6% at 4.2K and 12T by the Pacman equipment. The scaling law between critical current and axial strain was simulated with the improved deviatoric scaling model. The relation between n value and the axial strain was analyzed, and the Nb₃Sn strands’ sensitivity to strain was concluded.

Electromagnetic and mechanical analysis of ITER TF superconducting busbar

WANG Zhi-bin,SONG Yun-tao,WANG Zhong-wei,LI Chang-chun,JI Xiang

2010, 30(2):  152-156. 

Asbtract ( )   PDF (1553KB) ( )  

References | Related Articles | Metrics

The structure of ITER TF superconducting busbar was introduced. The electromagnetic and mechanical analysis of busbar under operating conditions was performed by means of finite element method, and then the stress and deformation of busbar was checked. The analysis results proved that the structural of busbar and its supports was reliable and safe.

Lower hybrid wave current drive efficiency study on EAST tokamak

LI Wen-ke,DING Bo-jiang,LI Miao-hui,ZHA Wen-qing,HU Huai-chuan

2010, 30(2):  157-161. 

Asbtract ( )   PDF (1351KB) ( )  

References | Related Articles | Metrics

The relationship between the residual loop voltage and the power of lower hybrid wave is investigated to obtain the lower hybrid wave current drive efficiency on EAST tokamak. The power of lower hybrid wave is normalized by plasma current，electron density，the major radius of the plasma and the effective ion charge number，so lower hybrid current drive efficiency can be calculated in one curve with different plasma parameters. The obtained lower hybrid current drive efficiency varies between 0.5 and 1.3×10¹⁹ A•m^-2•W^-1，a fully lower hybrid current drive is obtained as long as 3s at a plasma current of 277kA and lower hybrid wave power of 681kW.

Conceptual design of current leads for dipole superconducting magnet for collector ring of FAIR

ZHU Yin-feng, WU Wei-yue, LIU Chang-le

2010, 30(2):  162-165. 

Asbtract ( )   PDF (1581KB) ( )  

References | Related Articles | Metrics

The basic principle of current leads for superconducting magnet of collector ring(CR) of Facility for Antiproton and Ion Research(FIAR) are introduced in brief. The main parameters of the current leads and its preliminary design scheme are done. In order to reduce the heat leakage, using composite materials and structure optimization are brought out. Furthermore, the heat leakage was analyzed and calculated based on the heat transfer performance of current leads, then the feasibility of conceptual design is verified by the experiment.

Analysis study on the bursting disc of overpressure venting device for vacuum vessel of EAST

SHENG Dao-lin, WU Song-tao, ZHU Yin-feng

2010, 30(2):  166-168. 

Asbtract ( )   PDF (1142KB) ( )  

References | Related Articles | Metrics

The bursting disc was set on the vacuum vessel system. The bursting disc and the bracket were analyzed based on the finite element code, ANSYS. The results are in accord with the experimental results. All of the results provided a valuable reference to the design of similar overpressure venting devices.

Non-Fusion Plasma Applications

Properties of plasma frequency spectrum of the unbalanced magnetron sputtering

MU Zong-xin, MU Xiao-dong, JIA Li, ZHANG Peng-yun, LIU Sheng-guang, DONG Chuang

2010, 30(2):  169-172. 

Asbtract ( )   PDF (696KB) ( )  

References | Related Articles | Metrics

Langmuir probe and fast Fourier transformation (FFT) were used to study the stand wave resonance frequency spectrum features of the plasma electrostatic oscillation of the unbalanced magnetron sputtering. The width of the frequency band was 0~300kHz. The range of resonance eigenfrequency change of the probes 2cm and 10cm in front of the magnetron sputtering under the typical discharge condition was respectively 10~50kHz and 1~10kHz. The impacts of the coil current, pressure and the discharge power on the resonance eigenfrequency were studied. The two potential trap structures causing the stand wave resonance of the plasma electrostatic oscillation in the unbalanced magnetron sputtering were identified and the stand wave resonance mechanism was proposed to explain the characteristic frequency occurred. The electron temperature calculated by the stand wave resonance mechanism conformed to the experiment results.

Study of generation and investigation of nanosecond pulsed plasma jet

ZHU Hai-long,REN Chun-sheng,LV Xiao-gui,NIE Qiu-yue,WANG De-zhen,MA Teng-cai

2010, 30(2):  173-177. 

Asbtract ( )   PDF (977KB) ( )  

References | Related Articles | Metrics

Three atmospheric nanosecond pulsed plasma jets are studied based on three different configurations. The first consists of an injection needle placed inside a hollow dielectric tube, while the second employs a ring electrode wrapped around a dielectric tube. The third is a hybrid of the first two configurations. The characteristics of the jets are diagnosed by optical and electrical methods, and the mechanism is studied. For these three plasma jets, the rotational temperature are all 295K, while the vibration temperature are 1900K, 2000K, and 2100K, respectively. The results above demonstrate that plasmas generated by these three nanosecond pulsed plasma jets are of the state of nonequilibrium. Furthermore, the investigation suggests that the hybrid jet with both the needle and the ring electrode connecting to the high-voltage has a better performance, for which a uniform and stable discharge with low temperature and higher reactive species is achieved. It is conceivable that the cold atmospheric nanosecond pulsed plasma jets have a great potential of application in the area of material processing，plasma chemistry and plasma medicine, etc.

Study on the techniques with using of RF induction plasma for tungsten powders spheroidization

GU Zhong-tao,YE Gao-ying,LIU Chuan-dong,TONG Hong-hui

2010, 30(2):  178-182. 

Asbtract ( )   PDF (2387KB) ( )  

References | Related Articles | Metrics

Spherical tungsten particles were obtained by the process of heating irregularly shaped tungsten powders under radio frequency induction plasma (RF induction plasma) condition. The effect of feed rate and different disperse ways on spheroidization efficiency was studied. The efficiency of the spheroidization is evaluated through measurements of the percentage of powder spheroidized based on sweep electron microscopic SEM observations. After detection of the XRD of spheroidized tungsten powder, non-oxidation and no other impurity are verified in the preparation process. During the short flight of the tungsten particles in the plasma flow, about the order of a few milliseconds, the individual particles of the tungsten powder are heated and melted forming a spherical liquid droplet which upon freezing gives rise to the formation of a perfectly dense spherical solid particle.

Hydrogen extraction from liquid lithium-lead alloy by bubbling with rotational jet nozzle

XIE Bo, YANG Tong-zai, GUAN Rui, WENG Kui-ping

2010, 30(2):  183-188. 

Asbtract ( )   PDF (1202KB) ( )  

References | Related Articles | Metrics

The technology of tritium extraction from lithium-lead alloy has been simulated, hydrogen extraction from lithium-lead alloy by bubbling with rotational jet nozzle being used to simulate tritium in the study based on the introduction of fluid dynamics to establish algebraic model. The results show that the higher than lithium-lead melting temperature, the higher cumulative hydrogen extraction efficiency, and gas holdup of bubble column is little affected by the impeller diameter. Gas holdup when using small aperture is slightly higher when using large aperture only at a high helium flow rate, but the smaller the aperture, the greater the bubble surface area, and a marked increase in intensity of flow circulation for liquid lithium-lead with the increase of helium flow rate, hydrogen extraction rate increases too. Moreover, influence of the jet rotational velocity on hydrogen extraction is limited.

The effect of pulsed plasma duty cycle on the characters of porous silica films

YANG Qin-yu, LIU Lei, DING Ke, ZHANG Jing, WANG Qiang-rui

2010, 30(2):  189-192. 

Asbtract ( )   PDF (1483KB) ( )  

References | Related Articles | Metrics

Porous silica films were prepared on the glass substrate by plasma enhanced chemical vapor deposition (PECVD) system modulated by pulse negative bias voltage and silane as precursor gas. During duty cycle increased from 0.162 to 0.864 maintaining bias voltage of deposition region at -350V in the reaction process, the configuration, composition and microstructure of the samples were investigated intensively. The scanning electron microscope (SEM) revealed that the size of silica particles became smaller and silica films got more porous and fleecy when the duty cycle increases. The Raman spectra and Fourier transform infrared spectra (FTIR) revealed that amorphous silicon and Si-H bonds weakened till vanished at higher duty cycle. The proportions of Si-O-Si bridge bonds enhanced while the duty cycle increasing.