A study on the microwave responses of YBCO and TBCCO thin films by coplanar resonator technique

YBa₂Cu₃O₇(YBCO) thin films have been prepared by thermal coevaporation on LaAlO₃(LAO) substrates, and Tl₂Ba₂CaCu₂O₈(TBCCO) thin films are synthesized by magnetron sputtering method on LAO substrates. The transition temperature T_c is 90\,K for YBCO/LAO and 104\,K for TBCCO/LAO. Microwave responses of the films are studied systematically by coplanar resonator technique. Energy gaps of the films obtained are {\it\Delta}₀=1.04k_BT_c for YBCO films and ${\it\Delta}_0=0.84k_BT_c for TBCCO films by analysing the temperature dependence of resonant frequencies of coplanar resonator. Penetration depth at 0\,K \lambda ₀=198nm for YBCO films and \lambda₀ =200nm for TBCCO films could also be obtained by using the weak coupling theory and two fluid theory. Results of penetration depth and energy gap confirm the weak coupling properties of the films. In addition, microwave surface resistances R_s of YBCO/LAO and TBCCO/LAO are also investigated by analysing the quality factor and insert loss of the coplanar resonator. Surface resistance of TBCCO/LAO is less than that of YBCO/LAO, so that TBCCO/LAO films may have more potential applications.     

适用于雷达接收系统的高温超导窄带滤波器的研制

本文介绍一种为某专用雷达设计制作的工作于L波段的高温超导窄带带通滤波器.该滤波器为10阶微带谐振器级联(CQ)滤波器,引入两个交叉偶合构成一对传输零点形成准椭圆函数传输特性来增加带外陡度.为减小非近临谐振器间寄生耦合对滤波器传输特性的影响,对所采用的谐振器结构进行了精心选择.整个滤波器制作在一块2英寸的MgO衬底YBCO片上,封装后滤波器的整体尺寸为60mm×30mm×18mm.滤波器带宽为5MHz(FBW小于0.4%).实测滤波器带边陡度超过100dB/MHz,在中心频率(3MHz以外频域抑制好于-60dB,滤波器宽带抑制好于-80dB,滤波器最小插损0.3dB.     

基于相位恢复的光学元件面形检测技术研究

利用标量衍射的角谱理论,研究了基于两幅光强分布的相位恢复算法,并将此算法应用到光波的波前及光学元件面形的检测中。实验研究了球面光波波前的相位恢复及面形检测,给出了恢复波前与理想波前之间的偏差,采用求Zernike系数的广义逆矩阵的方法,用程序实现了光学元件面形的Zernike拟合。     

The microwave response of MgB2 /Al2O3 superconducting thin films

Microwave characteristics of MgB2/Al2O3 superconducting thin films were investigated by coplanar resonator technique. The thin films studied have different grain sizes resulting from different growth techniques. The experimental results can be described very well by a grain-size model which combines coplanar resonator theory and Josephson junction network model. It was found that the penetration depth and surface resistance of thin films with smaller grain sizes are larger than those of thin films with larger grain sizes.     

同位素内标-液相色谱-串联质谱法测定动物源性食品中氯霉素残留

加入氯霉素同位素内标的动物源性样品(龙虾、肠衣)经乙酸乙酯提取浓缩、正己烷去脂后,采用液-液萃取,水相经0.45μm滤膜过滤后,用液相色谱-串联质谱定量.在0.1、0.2,0.3μg/kg3个浓度水平上进行添加回收试验.回收率为71.8%～90.0%,检出限为0.05μg/kg.该法简化了前处理操作步骤,缩短了检测时间...     

CFETR低杂波电流驱动数值模拟研究

利用射线追踪和福克-普朗克方程,研究了CFETR上驱动电流和功率沉积对低杂波注入位置和耦合波谱的依赖关系,讨论了边界非线性效应对电流驱动与功率沉积的影响,给出了低杂波平行折射率和低杂波注入位置的一个优化值。初步数值计算表明：边界非线性效应会导致驱动电流降低;不考虑低杂波非线性效应时,驱动电流的差异约为6%左右,小于考虑该效应时的差异(~25%)。     

钢动静态强度计算的电子理论模型

价电子结构对物性具有本质的影响,以固体与分子经验电子理论为基础,结合材料动态力学过程,构建了计算钢静动态强度的新模型.该模型预测的多种成分钢的静(动)态强度与实验值符合得较好.首次把价电子结构参数引入了材料动态性能的预测模型中.     

气相色谱法测定活泥鳅中硫丹及其硫酸盐残留

建立了检测活泥鳅中α-硫丹、β-硫丹及硫丹硫酸盐残留量的气相色谱法.泥鳅样品经过正己烷-丙酮混合液提取后,转溶至乙腈中,冷冻去脂,再经中性氧化铝小柱净化处理,用丙酮-正己烷(体积比1:2)洗脱,洗脱液用气相色谱-电子捕获检测器检测,外标法定量.标准曲线的线性范围为10～100 ng/mL,相关系数不小于0.998,硫丹定量限为3.3 μg/kg,检出限为1.0 μg/kg.进行4.0,8.0和10.0 μg/kg 3个浓度水平的加标回收试验,回收率为91.3％～105.4％.该方法分析成本低,测定结果准确,能满足常规检测及食品安全监控的需要.     

不同速率热解焦低温氧化增重现象及反应动力学

利用固定床热解反应装置和美国CDS-2500快速热解仪对胜利褐煤裂解,制得不同速率热解焦。借助热重分析技术,采用Achar微分法计算热解焦低温氧化增重特性及反应活化能。实验结果表明,快速热解焦的氧化增重量高于慢速热解焦。一级化学反应动力学模型可以很好地描述胜利褐煤焦的氧化增重反应,快速热解焦的氧化活化能较慢速焦低,快速焦更易发生低温氧化反应。