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1.
HT-7U是一个先进的等离子体稳态托卡马克装置.它的环向磁场(TF)和极向磁场(PF)系统,均采用超导磁体,所有超导磁体均由CICC导体制成.为了获得PF和TF磁体运行的的安全裕度,需要对这些超导线圈进行严谨的热工水力特性分析,研究超导磁体在正常运行条件下所能承受的最大扰动.稳定裕度的分析充分考虑了多种不同的扰动.本文的分析均基于修改的Gandalf程序,即考虑超导CICC磁体系统之间(匝间、层间、不同的冷却通道之间)的热耦合,研究了HT-7U超导托卡马克系统的TF和PF超导线圈在不同运行条件下的稳定裕度和失超传播特性.这些分析将为HT-7U超导磁体系统的运行提供参考.  相似文献   

2.
失超传播速度v_(nzp)和最小失超能量E_(mq)是超导磁体的失超保护设计的重要参数。对由YBCO制成的单长导体、平行并联双导体和堆叠并联双导体进行实验,测试和分析了液氮温度下三种不同结构样品的失超传播速度和最小失超能量,监测了并联结构受到局部热干扰时的带材分流情况,及带材分流对于失超特性的影响。结果表明,分流现象导致失超传播速度降低,最小失超能量升高;通流比相同时,堆叠并联结构相比单根带材,失超传播速度约下降14%,最小失超能量约上升13%。  相似文献   

3.
在液氮(77K)环境下对YBCO涂层导体的交、直流失超传播特性进行了研究。测量了交、直流情况下的失超传播速度以及最小失超能量;分析了超导带材的失超传播速度与传输电流的关系;推导了一维模型下的失超传播速度计算公式。结果表明,当带材的传输电流交流(有效值)与直流相同时,交、直流失超传播速度基本一致,交流的最小失超能略小,且随着传输电流的增大最小失超能间的差距加大。  相似文献   

4.
采用双线圈闭合电路法研究了未包漆Nb-Ti复合线的失超动态过程. 测出了超导材料的正常区最小触发能量~8m,在不同的背景场强及工作电流下正常区的传播速度v以及I_pI_ml各参量.发现漆膜对失超过程的V-l特性曲线的形态及各特征参量有显著的影响. 当单位导体长度上的释热功率高于某一临界值时,正常区从一维传播过渡到二维传播. 实验表明,双线圈闭合电路法可以预测超导材料的运行特性以及简单地给出超导磁体失超过程的各种信息.它有助于大型磁体工作点的选取和在一定幅度的热脉冲条件下的稳定性分析,有可能作为超导材料的一种常规检测方法加以推广.  相似文献   

5.
高性能高温超导带材在大型超导磁体装置上的应用已成为一种趋势,由于存在失超传播速度缓慢、失超检测信号微弱等不足,对失超保护设计提出很大挑战。本文基于液氮浸泡式双保护层的高性能ReBCO带材失超传播特性,采用一维热平衡方程建立失超传播速度的数学模型,通过增加失超源,检测热点温度与电压信号,探究液氮浴环境下的ReBCO带材在传输电流等不同参数下失超传播速度和最小失超能量的变化规律。结果显示:相同条件下,高温超导带材的失超传播速度与传输电流成正相关,最小失超能量与传输电流成负相关,且相比无保护层的普通高温超导带材,具有双保护层的高性能ReBCO临界电流和触发裕度均有提升。  相似文献   

6.
利用FEM软件ANSYS对德国GSI的FAIR项目的超导二极铁的超导线进行了失超模拟.该模拟形象地给出导线的失超过程,通过APDL编程可以得到失超传播速度,失超时导体的端电压随时间的变化.文章还进一步研究了导线的最小失超传播区域MPZ,失超段初始温度和电流对失超传播速度的影响.  相似文献   

7.
利用FEM软件ANSYS对德国GSI的FAIR项目的超导二极铁的超导线进行了失超模拟. 该模拟形象地给出导线的失超过程, 通过APDL编程可以得到失超传播速度, 失超时导体的端电压随时间的变化. 文章还进一步研究了导线的最小失超传播区域MPZ, 失超段初始温度和电流对失超传播速度的影响.  相似文献   

8.
低温/高温复合超导体的热稳定性的数值模拟研究   总被引:2,自引:0,他引:2  
本文提出了一种高温超导体与低温超导体直接复合成混杂结构的复合超导体的导体模型.针对NbTi/Bi2223复合超导体的热稳定性进行了初步的理论模拟研究,结果表明低温/高温复合超导体的最小失超能远大于低温超导体,失超传播速度介于纯低温超导体和高温超导体之间,对于超导磁体的热稳定和保护具有重要参考价值.  相似文献   

9.
对一种YBCO涂层的高温超导带材及其单饼线圈进行了失超传播特性的实验测试与分析。实验测试在77K温度的液氮环境下进行,给带材通入恒定直流电流,使用加热丝给带材上一点提供脉冲热扰动,主要测量了超导带材及单饼线圈失超传播过程中的最小失超能和失超传播速度。实验结果表明YBCO超导带材及其线圈的失超传播速度随电流升高而增大,最小失超能随电流升高而减小,线圈中径向传播速度要远小于纵向传播速度。  相似文献   

10.
张婕  邵海成  吴锐  李海涛  邵慧 《低温与超导》2012,40(6):25-28,63
文中对超导带材的失超产生机理进行了详细分析,建立了其失超传播的计算模型。在此基础上,对Bi-2223/Ag高温超导带材失超传播进行了实验研究,用四引线法测得不同条件下其失超传播的U-t曲线,由此计算出Bi-2223/Ag超导带材的失超传播速度为0.4cm/s~1.98cm/s。实验结果表明:带材的失超传播速度与载流大小有关,与触发失超的能量无关,带材载流越大,失超传播得越快。  相似文献   

11.
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.  相似文献   

12.
A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.  相似文献   

13.
The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.  相似文献   

14.
A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.  相似文献   

15.
16.
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.  相似文献   

17.
A transient suppression method for piezoelectric ceramic transducer is presented. By adding some special pedestal pulses to the original transmitted signal, the transient effects in the output of the transducer can be just precisely transmission by use of a narrowband transducer. canceled, thereby achieving the broadband The experimental results show that the transient responses of the sinusoid pulses and coded signals are suppressed successfully and the acoustic waveforms radiated into the surrounding water are improved significantly.  相似文献   

18.
We experimentally demonstrate amplitude squeezed soliton utilizing intensity-dependent self-phase modulation in an asymmetric Sagnac interferometer.The system.whose components are connected via ferrule connector/physical connection(FC/PC)fiber connectors,constitutes all-fiber configuration to generate squeezed soliton.Soliton amplitude reduction measured by homodyne detection is near 4.0 dB below the shot-noise level.Optimal squeezing fields in both simple and compact all-fiber configuration are obtained.  相似文献   

19.
The(2 1)-dimensional nonlinear Schr(o)dinger(NLS)equation with spatially inhomogeneous nonlinearities is investigated,which describes propagation of light in(2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities.New types of optical modes and nonlinear effects in optical media are presented numerically.The results reveal that the regular split of beam can be obtained in (2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities,by adjusting the guiding parameter.Furthermore,the stability of beam regular split is discussed numerically,and the results reveal that the beam regular split is stable to the finite initial perturbations.  相似文献   

20.
In the real-world application of face recognition system, owing to the difficulties of collecting samples or storage space of systems, only one sample image per person is stored in the system, which is so-called one sample per person problem. Moreover, pose and illumination have impact on recognition performance. We propose a novel pose and illumination robust algorithm for face recognition with a single training image per person to solve the above limitations. Experimental results show that the proposed algorithm is an efficient and practical approach for face recognition.  相似文献   

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