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设计并搭建了一套高精度的磁场测量和补偿系统,并结合中国科学院高能物理研究所(IHEP)的2K超导腔垂直测试平台对1.3 GHz单加速间隙超导腔的磁通排出效应开展了实验研究:利用研制的磁场测量和补偿系统能够精密地测量超导腔赤道位置磁场,并能够将磁场补偿至小于5.0×10-8 T;并对超导腔不同表面温度梯度下的磁通排出效应进行了测量分析;对钉扎了磁场的超导腔进行了射频性能测试,研究了超导腔电阻对磁通钉扎的敏感度,以及在不同电场梯度下超导腔的表面电阻变化情况。结果表明,研制的高精度磁场测量和补偿系统能够满足超导腔磁通排出研究的需求;高的超导腔表面温度梯度有利于磁通的排出;磁通钉扎电阻的敏感度随着加速电场梯度的增加而增大,导致超导腔的性能下降。此实验研究也为后续超导腔的研制奠定了一定基础。 相似文献
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Tl—Ba—Ca—Cu氧化物超导体的低场磁性 总被引:1,自引:0,他引:1
我们测量了 T1-Ba-Ca-Cu-O 高温超导样品在低磁场下的磁化率和电阻与温度的关系;观察到样品具有两个超导主相,T_c 分别为117K 与104K;估算出该样品在77K 下的下临界场H_(c1)大约为480G.样品的迈斯纳效应和磁屏蔽的测量结果表明,该样品的磁屏蔽效应很小.在外加低磁场下测量了样品的临界电流,研究了,I_c-H 关系,发现在30G 以下磁场范围内的实验结果与超导颗粒之间是无规并联的约瑟夫森弱连接的理论结果符合较好. 相似文献
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超导腔的静态热负荷和无载品质因数是表征超导腔低温恒温器以及超导铌腔性能好坏的最重要参数.BEPCⅡ超导腔采用的是液氨浸泡冷却方式,对两个超导腔在测试站分别进行了降温调试,在超导腔达到超导状态并稳定运行后,对其静态热损耗进行了测定.此外,超导腔Q_0的测量主要是采用热力学的方法测量其高频损耗然后经计算得出Q_0.介绍了BEPCⅡ超导腔静态热负荷和无载品质因数的测量原理及方法,并且给出了两个超导腔在不同高频加速电压下的测试结果.此测试结果已作为BEPCⅡ超导腔验收测试的重要依据. 相似文献
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超导腔的静态热负荷和无载品质因数是表征超导腔低温恒温器以及超导铌腔性能好坏的最重要参数.BEPCⅡ超导腔采用的是液氦浸泡冷却方式,对两个超导腔在测试站分别进行了降温调试,在超导腔达到超导状态并稳定运行后,对其静态热损耗进行了测定.此外,超导腔Qo 的测量主要是采用热力学的方法测量其高频损耗然后经计算得出Qo.介绍了BEPCⅡ超导腔静态热负荷和无载品质因数的测量原理及方法,并且给出了两个超导腔在不同高频加速电压下的测试结果.此测试结果已作为BEPCⅡ超导腔验收测试的重要依据. 相似文献
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超导腔的静态热负荷和无载品质因数是表征超导腔低温恒温器以及超导铌腔性能好坏的最重要参数. BEPCⅡ超导腔采用的是液氦浸泡冷却方式, 对两个超导腔在测试站分别进行了降温调试, 在超导腔达到超导状态并稳定运行后, 对其静态热损耗进行了测定. 此外, 超导腔Q0的测量主要是采用热力学的方法测量其高频损耗然后经计算得出Q0. 介绍了BEPCⅡ超导腔静态热负荷和无载品质因数的测量原理及方法, 并且给出了两个超导腔在不同高频加速电压下的测试结果. 此测试结果已作为BEPCⅡ超导腔验收测试的重要依据. 相似文献
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A mutual inductance bridge to measure low frequency magnetic susceptibilities of magnetic materials has been constructed.
Salient features of the bridge, which uses a variable mutual inductance simulated using operational amplifiers, the cryostat
and the coil assembly are described in this paper. The apparatus has been employed for accurate measurement of superconducting
transition temperatures and for sensitive detection of magnetic ordering transitions in liquid helium and liquid nitrogen
temperature ranges respectively. The bridge has been calibrated to determine the static susceptibility of magnetic materials
as a function of temperature. 相似文献
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中国科学院近代物理研究所自主研发的ADS注入器Ⅱ第一代高频低电平(LLRF)控制系统,工作频率为162.5 MHz;LLRF系统是由基于I/Q采样的正交解调技术构成的全数字闭环反馈控制系统,其主要功能是实现超导腔腔体电压幅值稳定控制、相位稳定控制与腔体谐振频率控制;LLRF控制系统在液氦温区超导腔上进行了系统稳定度和性能的在线测试,根据实验数据计算得超导腔体电压幅度稳定度为±3.4‰,相位稳定度为±0.3°,腔体表面峰值电场(Epk)能长时间稳定在25.1 MV/m。通过实验测试,检验了LLRF控制系统的性能,并对测试过程中出现的问题进行了分析,为将来超导腔LLRF控制系统运行积累了经验。 相似文献
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在合肥先进光源(HALF)建设中,由低温超导材料组成的真空部件被大量使用,尤其是超导高频腔。超导腔以高加速梯度、低束流阻抗、高无载品质因数和低运行成本等特点,成为21世纪国际上拟建的大型加速器的首选。而超导腔和低温真空室内表面的二次电子发射可能会引发电子云(EC)现象。超剂量的二次电子倍增功率沉积会引起低温区域热负载增加、超导腔失超等现象,因此降低超导高频腔内二次电子发射成为合肥先进光源设计过程中的巨大挑战。在常温材料二次电子产额(SEY)测试系统的基础上,作者自主研发设计低温样品架结构,使液氦流经样品台并通过热传导冷却样品,计算漏热来反推所需要的制冷量和液氦的消耗速率。在系统集成调试后进行降温性能测试,搭建了低温材料二次电子测试系统。 相似文献
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It has been recently reported that the three-dimensional Bose-Einstein condensation of the quasi-particles is valid for the
mercury cuprates at liquid helium temperature. In this study, the validity of the interlayer theory in three dimensions has
been investigated for optimally oxygen-doped mercury cuprates at the temperature interval of 0–15 K. Furthermore, some thermodynamic
and electrodynamics parameters of mercury cuprates have been calculated for both the under-doped and the over-doped samples
at the vicinity of 4.2 K. Moreover, it has been determined that the superconducting system behaves as a terahertz wave cavity
regardless of the oxygen doping concentration. 相似文献
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D. R. Cohn L. Bromberg W. Halverson B. Lax P. P. Woskov 《International Journal of Infrared and Millimeter Waves》1987,8(12):1503-1524
Conventional superconducting materials used at liquid helium temperatures have been employed to greatly reduce ohmic power loss in microwave cavities. If suitable high temperature superconductor surfaces can be developed, it could be possible to alleviate constraints due to relatively low energy gaps and limits due to critical fields, and operate at more convenient temperatures with larger thermal margins. These features could be used to improve performance of present superconducting microwave cavity devices. They may also facilitate new applications and device designs at millimeter-wave and far infrared frequencies. Possible cavity and waveguide applications are described. Sensitivity of RF surface resistance to boundaries and nonaligned grains in the material and to small amounts of nonsuperconducting material may be an obstacle to development. Moreover, critical RF fields can be limiting for high power applications. An additional problem is the adverse effect of D.C. magnetic fields.Supported by Department of Energy No. ET-51013-227. Reproduction, translation, publication, use and disposal in whole or in part, by or for the United States government is permitted. 相似文献
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A magnetic flux has been generated within a hollow toroidal cavity whose walls consisted of superconducting indium and lead. The origin of the flux is attributed to a thermoelectric transport effect induced by a temperature gradient in the toroid. The flux was found to diverge rapidly near the transition temperature of indium and to be several orders of magnitude larger than predicted by existing theory. 相似文献
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A numerical and analytical investigation of thermodynamic properties of a magnetized superconducting quantum cylinder has been carried out. The dependence of the difference in the magnetizations of the superconducting and normal phases on the parameters of the nanotube, temperature, and magnetic field has been analyzed. The jump in the heat capacity of the superconducting and normal states at the critical temperature has been calculated. The fluctuation contribution to the thermodynamic properties of the nanotube at a temperature above the transition point has been studied. 相似文献