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交流损耗是影响超导电力装置运行稳定性和成本的关键因素之一.本文提出了一种基于电压补偿法的大载流超导单元交流损耗测量方法,通过串联在回路中的大电流补偿线圈,抵消超导单元的感性电压来实现.在系统设计上,通过数据采集卡和运动控制器,获取超导单元、补偿线圈的电压信号,同时控制步进电机拖动补偿线圈.通过相位的对比计算,实现精确定位补偿,从而测量超导单元的交流损耗.最后,在不同频率下,测量了0.2 m长、110 kV/1.5 kA的高温超导电缆样缆的交流损耗,得出的交流损耗曲线与计算结果基本吻合.实验结果表明,采用补偿线圈的交流损耗测量系统具有自动检测、定位和测量功能,可以实现具有大电流容量超导单元交流损耗的准确测量. 相似文献
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超导线圈交流损耗的测量,能为研究超导线圈交流损耗提供重要方法,并对应用中超导线圈的优化提供重要依据。通过测量电流电压得到功率、再对时间积分的方法,来计算交流损耗,实验中可采用电容补偿降低电源功率负荷,电感补偿降低采集信号噪音,调整采样周期进一步提高采集效率和信噪比等方法来进行。将超导单带在88 Hz及小线圈在90 Hz的实验结果,与理论公式、经典锁相放大器测试结果对比,实验结果中交流损耗从小电流到大电流的差别为17%~1%,证明用该方法测量超导线圈交流损耗,准确、合理。 相似文献
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本文研究了使用Bi-2223/Ag超导带材制备超导闭合线圈的工艺及超导闭合线圈中电流衰减的特性.在闭合线圈焊接点的制作上,分别采用了超导焊接和普通焊锡焊接两种不同方法.通过测量闭合线圈中心点的磁场衰减过程,观察了这两种闭合线圈中电流衰减的特性.实验发现,使用超导焊接技术制备的闭合线圈,电流衰减与时间的自然对数成线性关系,在线圈局部受损伤的情况下,上述关系仍然成立;使用普通焊锡焊接方法制备的闭合线圈,电流衰减不存在上述关系,但也不是时间的e指数函数. 相似文献
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本文研究了使用Bi-2223/Ag超导带材制备超导闭合线圈的工艺及超导闭合线圈中电流衰减的特性.在闭合线圈焊接点的制作上,分别采用了超导焊接和普通焊锡焊接两种不同方法.通过测量闭合线圈中心点的磁场衰减过程,观察了这两种闭合线圈中电流衰减的特性.实验发现,使用超导焊接技术制备的闭合线圈,电流衰减与时间的自然对数成线性关系,在线圈局部受损伤的情况下,上述关系仍然成立;使用普通焊锡焊接方法制备的闭合线圈,电流衰减不存在上述关系,但也不是时间的e指数函数. 相似文献
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王恩耀 《核聚变与等离子体物理》1982,(4)
超导线短样品的临界电流是表征超导线材重要的基本参数之一。由于目前采用的测量方法不同,标准不一样,使测量的结果很难进行比较。为此有必要建立标准的测量方法。 本文对目前超导线短样品测量中经常遇到的几个问题如:临界点判据,测量误差和样品过热等做了分析。叙述了解决这些问题的办法,以便在实验中加以应用,不断提高测量精度,为建立标准方法做些工作。 相似文献
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为表征超导线圈低/变温环境热膨胀系数,首先基于细观力学有限元方法建立了超导线圈代表性体积元模型,并利用多项式函数赋予材料属性进一步完成低/变温环境热膨胀系数有限元预测,通过复合律公式计算出理论值验证了有限元模型的准确性。其次,基于应变片测量热膨胀系数的原理,搭建了超导线圈低/变温热膨胀系数测量系统,最后,针对常规材料热膨胀系数进行了实验测量,验证了搭建系统的可靠性。进一步地,基于上述基础表征研究,开展了超导线圈相关低温测量的实验研究,得到了极端低/变温环境下超导线圈热应变、热膨胀系数与温度之间明显的非线性关系,且实验测试结果与理论值吻合良好。该数值模型、实验方法与测试系统的成功发展一方面丰富了极端环境下材料热膨胀系数的表征方法,另一方面,将为我国各类大型超导磁体结构设计、制备与实验提供重要参数与热-力学基础测试平台。 相似文献
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临界电流密度(J_c)是超导材料的重要特征参数之一,精确的测量临界电流密度对研究超导材料特性及超导器件稳定性具有重要意义.本文介绍了一种基于经典电磁感应理论和超导技术理论测量YBCO超导薄膜临界电流密度的方法和测试装置.研究显示,在液氮环境下,将超导薄膜加入初级线圈和次级线圈中间会明显影响次级线圈的接收效果.我们根据此测量方法搭建了一种测量YBCO薄膜临界电流密度的实验装置.在分析实验测量误差后,通过实验的对比,得到了加入超导薄膜对次级线圈的感应电压的影响,并分析感应电压与线圈互感之间的关系,从而算出超导薄膜的临界电流密度.实验通过噪声抑制和数据校正,准确地测量了超导薄膜的临界电流密度. 相似文献
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Malveau C Grandclaude D Canet D 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,150(2):214-218
T(2) images are obtained by two interleaved B(1)-gradient imaging experiments preceded by CPMG trains of different lengths. The method is assessed by means of a phantom involving compartments of different, though relatively close, T(2) values. T(1) images arise from a previously published procedure also based on two interleaved B(1)-gradient imaging experiments involving different evolution of the longitudinal magnetization. Both types of image appear to be useful in view of the structural characterization of polymer samples through the T(2) and T(1) distribution of a solvent embedded in the material. 相似文献
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利用溶胶-凝胶法制备了一系列的La0.8Sr0.2Co1-xFexO3样品.通过研究在不同外加磁场下磁化强度和温度变化的关系发现,在较高的外场下La0.8Sr0.2Co1-xFexO3样品的磁性反转现象没有被观察到;在低场下La0.8Sr0.2Co1-xFexO3系统磁性反转现象被实现.这说明Fe的掺杂引起了La0.8Sr0.2Co1-xFexO3样品中铁磁和反铁磁之间的竞争,导致了La0.8Sr0.2Co1-xFexO3样品磁性反转;同时外加磁场的强弱影响了La0.8Sr0.2Co1-xFexO3系统磁性反转现象的发生,外加磁场增大使得在La0.8Sr0.2Co1-xFexO3样品中Co离子的自旋平行趋势更强,在铁磁和反铁磁之间的竞争中铁磁耦合占主导优势,因此在较高的外场下磁性反转现象没有被观察到. 相似文献
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F. Klose J. Thiele A. Schurian O. Schulte M. Steins O. Bremert W. Felsch 《Zeitschrift für Physik B Condensed Matter》1993,90(1):79-82
Multilayers of Ce and Fe show a low Curie temperature and saturation magnetization below a critical thickness of the individual Fe layers where amorphous growth occurs. We have studied on a series of such multilayers with different modulation lengths prepared by ion-beam sputtering the impact of hydrogen absorption on their magnetic properties. Hydrogenation was performed during film growth either reactively by introducing hydrogen gas into the UHV chamber or by irradiation with a beam of low-energy hydrogen ions. Hydrogen is absorbed only in the Ce layers, with a concentration near CeH2. For suitable modulation lengths, the Curie temperature and saturation magnetization are considerably enhanced with respect to the non-hydrided multilayers. This is correlated with the changes in structure and the quality of the interfaces induced by hydrogenation: the irradiation process itself reduces the critical thickness for amorphous growth of Fe, and the chemical interaction of hydrogen causes a considerable sharpening of the interfaces. 相似文献
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The saturation magnetization of MnBi films in the low-temperature phase and the quenched high-temperature phase was measured
at room temperature by a new method recently described. The measurements were performed with samples of varying thickness
and composition (ratio Mn:Bi). The results obtained show no dependence either on film thickness or on composition. Hence,
the different magnetization values given in the literature for bulk and thin film samples of the quenched high-temperature
phase must not be attributed to a thickness dependence of the samples or to stoichiometric variations.
This work has been supported by the data processing program of the Federal Department of Research and Technology of the FRG.
The authors alone are responsible for the contents. 相似文献
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In this paper we present a study of the separation of phases in multi-phase alloys. The proposed technique is based on the hyperbolic model of magnetization. By using this model it is possible to decompose the magnetic phases of alloys and determine their magnetic properties separately. Experimental verification was carried out on a transformer-like setup, constructed from layered samples representing the various magnetic phases. The samples were constructed from elements of strongly different magnetic properties. The results given by the model are in an excellent agreement with the experimental results, giving justification for the proposed method of decomposition. The proposed method is the first step towards the recognition and the separation of magnetic constituencies of different magnetic properties in an alloy by analytical means. 相似文献