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电流引线是连接超导低温装置室温电源与超导单元的桥梁,其漏热直接关系到低温系统的运行稳定与运行成本.本文对传统的气冷电流引线分段计算方法做了一定的改进,提出了气冷变截面电流引线优化设计方法.应用此方法为一个YBCO高温超导带材临界电流特性测试装置设计了变截面电流引线.通过对电流引线的温度场分布进行实验测量,并与设计值进行比较,结果吻合较好,证明了气冷变截面电流引线设计方法的有效性和实际优化效果.本文的设计方法及相关实验研究为变截面电流引线在超导低温装置中的实际应用提供了一定的参考. 相似文献
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气冷电流引线被广泛的应用于许多大型超导磁体及其它一些超导装置中.由于引线实际制作过程中的差异或者超导装置本身的一些问题,正负两个引线之间或者同一引线的不同流道之间都存在着冷却气流分配上的不均衡.超导装置中除电流引线外的其他低温热源也可能使流经引线的冷却气流处于非正常状态.所有这些都会使电流引线的实际工作状况偏离最优化设计.本文用数值模拟的方法对非最优化冷却气流条件下的电流引线运行状况进行了研究,分析了冷却气流偏离最优化程度与引线实际运行参数之间的影响关系. 相似文献
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气冷电流引线被广泛的应用于许多大型超导磁体及其它一些超导装置中.由于引线实际制作过程中的差异或者超导装置本身的一些问题,正负两个引线之间或者同一引线的不同流道之间都存在着冷却气流分配上的不均衡.超导装置中除电流引线外的其他低温热源也可能使流经引线的冷却气流处于非正常状态.所有这些都会使电流引线的实际工作状况偏离最优化设计.本文用数值模拟的方法对非最优化冷却气流条件下的电流引线运行状况进行了研究,分析了冷却气流偏离最优化程度与引线实际运行参数之间的影响关系. 相似文献
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低温装置的最佳气冷电流引线 总被引:7,自引:0,他引:7
本文提出了一种计算低温装置气冷电流引线的最佳尺寸比和最小热流的方法,并按照这一方法计算了铜、德银和不锈钢电流引线的最佳尺寸比和最小热流.计算结果发现,当液氦的蒸发率较大时,由具有最佳尺寸比的电流引线流入低温装置的最小热流与电流强度的平方成正比,与液氦的蒸发率成反比,而与引线材料几乎无关.所以,为减小电流引线漏热,材料的选择是无关紧要的,关键是选取最佳尺寸比. 相似文献
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EAST装置15kA高温超导电流引线研发 总被引:5,自引:0,他引:5
低温超导磁体采用高温超导电流引线能显著降低制冷系统的造价和运行费用.正在建造中的大型超导托卡马克核聚变试验装置(EAST)需要一对16kA和12对15kA电流引线.所研发的电流引线采用美国超导(AMSC)公司提供的Bi-2223/Ag-Au带材, 每5条超导带组成单元叠,与不锈钢支撑圆筒表面50个槽软钎焊成超导段.支撑筒两端铜接头,温端与铜电流引线段丝扣连接并低温钎焊;冷端与100根NbTi/Cu超导线直接锡铅钎焊.冷端采用4K超临界氦流冷却;温端正常运行温度为78K,用液氮冷却.设计要求在此冷却条件下的临界电流大于16kA.78~290K铜电流引线采用3头螺旋槽换热器,冷氮气冷却.为提高电流引线的安全性,在高温超导段温端贮存适量液氮作为热沉,大大增加电流引线被烧毁的时间常数. 相似文献
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横跨低温到室温温区的电流引线是连接电源和超导装置的部件,是超导装置的主要漏热源之一.因此减小由于电流引线导致超导低温系统的漏热对低温系统的稳定运行和运行效率至关重要.在传统铜电流引线的室温端插入热电材料碲化铋(Bi_2Te_3)形成的珀尔帖电流引线(Peltier current lead,以下简称PCL)可以有效地减小由于电流引线造成的漏热.珀尔帖电流引线将漏热从纯铜引线的42.4W/kA降低到30.470W/kA.在本文中采用有限元法对PCL进行优化,得到PCL的最优几何参数.改变PCL中铜引线和热电材料碲化铋的横截面面积,并计算改变横截面面积时PCL的漏热.仿真结果显示改变PCL中铜引线的横截面面积时对电流引线的漏热影响不大,而在改变PCL中热电材料的横截面,可以将PCL的漏热从30.470 W/kA降低到27.36 W/kA. 相似文献
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电流引线是室温电源电缆与低温磁体之间的电连接部件.高温超导材料在液氮温度下具有零电阻率和低热导率的特性,用它做成的电流引线可以大大减小低温系统的热负荷,从而减少制冷设备投资及系统运行费.高温超导电流引线可以分为阻性换热器段和高温超导段两部分(其中还包括各部件间的连接部分).高温超导段的分流器设计关系到冷端热负荷大小以及超导段失超后的安全问题.为了研究国际热核聚变试验堆(ITER)电流引线高安全性能,专门设计、试验了68kA引线的1/90实验样品.本文通过对比全CuBe(cu-2%Be)分流器、全不锈钢分流器和二元分流器的失冷故障(LOFA)实验结果,证明二元分流器能够克服安全性和冷端漏热矛盾,可以满足ITER高安全性的要求. 相似文献
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N.A. Bogolyubov 《Physica C: Superconductivity and its Applications》2010,470(7-8):361-364
Our experiments performed earlier have shown that, when an external magnetic field is absent, the transport critical current in 3-d superconducting ceramics is a homogeneous function of the sample transverse sizes. The transport critical current density and magnetic field induced by the current are homogeneous functions of a point on the sample cross-section. Using these experimental results equations describing the induced magnetic field pattern in ceramic sample have been derived. The distributions of the transport critical current density and induced magnetic field in the samples having polygonal, diamond-shaped cross-sections illustrate the results. 相似文献
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The actual form of the resistive section of the AC current–voltage curve (CVC) is determined experimentally. It is found that the CVC is shaped both by the electrical properties of the superconducting layer and by the thermomechanical properties of layers in the tape structure. The specific features of CVC behavior in different current ranges are determined. It is demonstrated that small amounts of heat released in stabilizing and superconducting layers do not affect the CVC shape below the critical current. Above the critical current, combined heat releases in stabilizing and superconducting layers raise the temperature and the resistance of an HTS tape in the resistive state. It is found that the stabilizing layer has a critical thickness. Below this critical level, the current in the resistive state flows primarily along the HTS layer, and its slight overheating initiates the transition of the sample to the normal state due to the thermal instability of heat removal to liquid nitrogen. In tapes with thicker copper layers, the current in the resistive state is distributed between stabilizing and HTS layers, and the transition to the normal state occurs near the critical temperature of the superconductor at zero current. The dependence of critical voltages characterizing different damage levels of HTS tapes on the thickness of the copper layer is determined. It is found that the breakdown occurs at higher voltages if step voltage is applied. 相似文献
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The effect of transverse geometries of the slab of composite high-Tc superconductors on their stable and unstable thermal and electrodynamics transient states in the incomplete and complete penetration modes during the current charging are discussed. The transient period when the electric field that is induced by the charged current becomes more homogeneous during the initial stage of the complete penetration mode in the sub-critical voltage range is studied. In the over-critical voltage range, the cross-section shape of the slab affects its stable and unstable temperature variation. As a result, the current instability condition is not identical for high-Tc superconducting composite tapes that have the same cross-sectional area with various shapes of the cross-section. The condition depends on their thickness: the less thickness, the more stable the current distribution in the composite superconductors with the same cross-sectional area. This feature is a result of the unavoidable reduction of the current-carrying capacity of a high-Tc superconducting composite by the temperature increase. This reduction is caused by the relevant temperature dependence of electrodynamics states of the composite. This temperature dependence happens even during a stable stage of the current charging. These mechanisms must be considered during experiments at which the critical or quenching currents are defined. 相似文献
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V-Ga-Al alloys containing 68–82 at.-% vanadium can be easily worked mechanically in the A2 phase and transformed into the
superconducting A15 phase by subsequent heat treatment. The preparation, critical temperature and critical current density
of the A15 phase are described. The critical current density, which at 5 Tesla is in the 104 to 105 A/cm2 range, is compared with values of technically used superconductors. Ternary V-Ga-Al alloys are suitable for superconducting
shielding devices for high fields. 相似文献