检索结果-南通市图书馆

Forced-flow gas cooled current leads for SCQ magnets in BEPCⅡ

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin institute of technology(New Series) 2007年第1期14卷 64-68页

作者：张小斌王莉贾林祥 institute of cryogenics and superconductivity technology Harbin Institute of Technology Brookhaven National Laboratory Upton

Current leads are used to connect the superconducting magnets in cryogenic temperature to the power station in room temperature. It is the main source of heat leak into the eryostat of magnets on static operation. This paper presents the optimized methods of the leads for BEPC Ⅱ , and the effects of different cross section ar- ea on the heat leak, temperature profile as well as the voltage drop of the leads. The multi-tube structure is adopted and improved for the leads. The results of numerical simulation using CFD software package Fluent6. 0 for the muhi-tube-structure leads are presented, which can be used to improve the design of the leads.

关键词： current leads BEPCII numerical simulation Fluent6. 0

Analyses of an Improved Double-Absorber Absorption Refrigeration System at Low Temperatures

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2019年第4期28卷 705-713页

作者： HE Yijian CHEN Guangming Key Laboratory of Refrigeration and cryogenics technology of Zhejiang Province Institute of Refrigeration and Cryogenics Zhejiang University

An auto-cascade absorption refrigeration(ACAR)system could achieve a-60℃ refrigeration temperature by low-grade *** an ACAR system,its performance is mainly affected by energy and mass coupling of the auto-cascade processes.A novel ACAR system with double-absorber was proposed to get higher-efficient refrigeration as low as-60℃ in this context,which used R23-R134 a-DMF(N,N-Dimethylformamide)as its working *** calculation and analyses were conducted under different working *** the calculated results,the new system gained a COP value 20%higher than that of an ACAR system with single-absorber under the same generating,condensing,absorbing and refrigerating *** of a refrigerant mixture showed key influences on energy and mass coupling of the auto-cascade processes,and an optimal composition of the mixed refrigerants was obtained for the new ACAR *** addition,it was clearly found that absorbing processes of the new system had great effects on energy and mass coupling of the auto-cascade *** on the difference of absorbing characteristics among R23,R134 a and DMF,the absorbing processes were intensified under the different absorbing *** a result,an optimal matching pressure was obtained for the new ACAR *** and mass coupling of the auto-cascade processes were further optimized,and the highest COP value was *** theoretical analyses showed that performance of the innovative ACAR system could be superior to that of an ACAR system with single-absorber at a refrigeration temperature from -55℃ to -60℃.

关键词： absorption refrigeration auto-cascade refrigeration low refrigeration temperature double-absorber

Low-frequency oscillations in Hall thrusters

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2015年第5期24卷 117-126页

作者：魏立秋韩亮于达仁郭宁 Laboratory of Plasma Propulsion Harbin Institute of Technology Science and technology on Vacuum & cryogenics technology and Physics Laboratory

In this paper, we summarize the research development of low-frequency oscillations in the last few decades. The findings of physical mechanism, characteristics and stabilizing methods of low-frequency oscillations are discussed. It shows that it is unreasonable and incomplete to model an ionization region separately to analyze the physical mechanism of low-frequency oscillations. Electro-dynamics as well as the formation conditions of ionization distribution play an important role in characteristics and stabilizing of low-frequency oscillations. Understanding the physical mechanism and characteristics of low- frequency oscillations thoroughly and developing a feasible method stabilizing this instability are still important research subjects.

关键词： low-frequency oscillations plasma discharge Hall thrusters

Superconducting magnetic energy storage for stabilizing grid integrated with wind power generation systems

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 400-411页

作者： Poulomi MUKHERJEE V. V. RAO Applied superconductivity Laboratory Cryogenic Engineering Centre Indian Institute of TechnologyKharagpur

Due to the interconnection of various renewable energies and adaptive technologies, voltage quality and frequency stability of modern power systems are becoming erratic. Superconducting magnetic energy storage(SMES),for its dynamic characteristic, is very efficient for rapid exchange of electrical power with grid during small and large disturbances to address those *** addition,SMES plays an important role in integrating renewable sources such as wind generators to power grid by controlling output power of wind plant and improving the stability of power *** application of SMES in various power system operations depends on the proper location in the power system, exact energy and power ratings and appropriate controllers. In this paper, an effort is given to explain SMES device and its controllability to mitigate the stability of power grid integrated with wind power generation systems.

关键词： Power fluctuation Power quality Low voltage ride through Superconducting magnetic energy storage Superconductors Wind energy

Comparison study of the charge density distribution induced by heavy ions and pulsed lasers in silicon

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2010年第1期34卷 148-151页

作者：田恺曹洲薛玉雄杨世 Lanzhou institute of Physics National Laboratory of Vacuum & Cryogenics Technology and Physics

Heavy ions and pulsed lasers are important means to simulate the ionization damage effects on semiconductor materials. The analytic solution of high-energy heavy ion energy loss in silicon has been obtained using the Bethe-Bloch formula and the Kobetich-Katz theory, and some ionization damage parameters of Fe ions in silicon, such as the track structure and ionized charge density distribution, have been calculated and analyzed according to the theoretical calculation results. Using the Gaussian function and Beer＇s law, the parameters of the track structure and charge density distribution induced by a pulsed laser in silicon have also been calculated and compared with those of Fe ions in silicon, which provides a theoretical basis for ionization damage effect modeling.

关键词： heavy ion pulsed laser charge density distribution

Evaluation and prediction of the degradation of space Si solar cells induced by a low-earth-orbit radiation environment

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2012年第9期36卷 900-904页

作者：高欣杨生胜冯展祖张雷 Science and technology on Vacuum&cryogenics technology and Physics Laboratory Lanzhou Institute of Physics

Space-graded silicon solar cells are evaluated by 1 MeV and 2 MeV electron-irradiation. The mean degradation of the maximum power （Pmax） is presented and anMyzed. The degradation at both electron energies has been correlated with the displacement damage dose （Dd）. A good linearity between the electron Dd and the mean Pmax degradation is obtained. The concept of Dd has Mso been used to predict the Si solar cell response in a low-earth-orbit （Altitude 799 km, Inclination 99~） radiation environment, considering the shielded effect of a 120 ~m-thick silica coverglass on reducing the radiation. Compared with the on-orbit data from a Si solar array of a Chinese satellite （duration from April 2007 to July 2010）, a good match can be found between the on-orbit data and the predicted results using Dd methodology, indicating the method is appropriate for evaluating the radiation damage of the solar cells, and also to provide a new technique for studying radiation effects on the optoelectronic detectors used in many high energy physics applications, where harsh radiation environments produce damage in optoelectronic device materials.

关键词： radiation displacement damage dose Si solar cell LEO

Effects of electron radiation on shielded space triple-junction GaAs solar cells

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2009年第11期18卷 5015-5019页

作者：高欣杨生胜薛玉雄李凯李丹明王鹢王云飞冯展祖 National Key Laboratory of Vacuum & cryogenics technology and Physics Lanzhou Institute of PhysicsChinese Academy of Space Technology

The displacement damage dose methodology for analysing and modelling the performance of triple-junction InGaP2/GaAs/Ge solar cells in an electron radiation environment is presented. Degradations at different electron energies are correlated with displacement damage dose （Dd）. One particular electron radiation environment, relative to a geosynchronous earth orbit （GEO）, is chosen to calculate the total Dd behind the different thicknesses coverglasses to predict the performance degradation at the end of the 15-year mission.

关键词： nonionizing energy loss displacement damage dose solar cell

Particle-in-Cell Simulation Study on the Floating Potential of Spacecraft in the Low Earth Orbit

在线全文

学校读者我要写书评

暂无评论

Plasma Science and technology 2015年第4期17卷 288-293页

作者：汤道坦杨生胜郑阔海秦晓刚李得天柳青赵呈选杜杉杉 Science and technology on Vacuum & cryogenics technology and Physics Laboratory Lanzhou Institute of Physics DFH SATELLITE CO. LTD.

In order to further understand the characteristics of the floating potential of low earth orbit spacecraft,the effects of the electron current collection area,background electron temperature,photocurrent emission,spacecraft wake,and the shape of spacecraft on spacecraft floating potential were studied here by particle-in-cell simulation in the low earth *** simulation results show that the electron current collection area and background electron temperature impact on the floating potential by changing the electron current collection of *** increasing the electron current collection area or background electron temperature,the spacecraft will float at a lower electric potential with respect to the surrounding ***,the spacecraft wake affects the floating potential by increasing the ion current collected by *** emission of the photocurrent from the spacecraft surface,which compensates for the electrons collected from background plasma,causes the floating potential to *** shape of the spacecraft is also an important factor influencing the floating potential.

关键词： spacecraft floating potential PIC electron current collection area electron temperature photocurrent emission spacecraft wake spacecraft shape

Two-port network model and startup criteria for thermoacoustic oscillators

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2009年第2期54卷 335-343页

作者： HU XingHua ZHANG XiaoQing WANG HuiLing SHU ShuiMing institute of Refrigeration and cryogenics Huazhong University of Science and Technology Wuhan 430074 China

The startup process of a thermoacoustic engine is a self-excited oscillation process generated in inhomogeneous acoustic media. To reveal these coupling relations between various influential factors is an important task of basic research on thermoacoustics. In this paper thermoacoustic engines are regarded as thermoacoustic oscillators consisting of the active network and the passive network. Accordingly, the two-port Y-parameter for relevant component is derived, and standing wave and traveling wave thermoacoustic engine are described by the negative-resistance and feedback model, respectively. The relevant two-port network topology is given as well. The startup criteria for thermoacoustic oscillators are obtained by using Nyquist instability criterion. The model prediction of startup parameters, particularly, startup frequency and mode characteristic are in agreement with that of experimental results reported in the literature. Moreover, with topological graphs it is verified that standing wave engines would start up in a negative-resistance state and there would exist high frequency modes in thermoacoustic-Stirling engines. By investigating into the frequency response of thermoacoustic system, this method proposed can achieve such an objective that these effects of operating and structural parameters of engine on startup modes and startup temperature can be revealed in an analytical way. Thus this approach to test and check thermal stability can be provided in a design phase, instead of using empirical frequency to design thermoacoustic systems.

关键词：振荡器标准网状模型研究