U.S.-Federal Republic of Germany Cooperative Research in High-Temperature Superconductivity

该奖项支持加州大学伯克利分校的Alan M. Portis教授与伍珀塔尔大学物理系的Helmut Piel教授在高温超导方面的合作研究。他们对开发高质量的高温超导体薄膜和涂层有共同的兴趣，这些薄膜和涂层可用于各种应用，包括在微波频率下工作的粒子加速器腔。这些材料的质量在高微波功率下恶化。他们与洛斯阿拉莫斯国家实验室的d·w·库克博士一起，正在开发一个详细的微波通量穿透和表面阻力的理论模型，并对这两种现象进行了仔细的测量。粒子加速器微波腔的开发主要是由Piel博士和他的学生领导的。在其他地方没有类似的经验。波蒂斯博士在高温超导体的微波特性方面为合作带来了杰出的专业知识。他们的目标是确定损耗过程并努力消除损耗，以便获得在高微波功率水平下保持其质量的材料。验证超导体中的微波临界状态将具有重要的科学和技术效益。这将表明，超导体中的微波过程比人们认为的要快得多，这就需要重新审视我们对II型超导体中通量渗透的一些想法。它还将通过确定高温超导体表面电阻中观察到的功率依赖性的起源，提高高功率下的表面质量。如果损耗机制确实持续到微波频率范围内，那么很可能有机会将这些材料用于高频信号处理。因此，给粒子加速器制造问题的机制可能在一个完全不同的领域提供机会。

This award supports Professor Alan M. Portis of the University of California at Berkeley for collaborative research on high temperature superconductivity with Professor Helmut Piel, Department of Physics, University of Wuppertal. They share an interest in the development of high quality films and coatings of high temperature superconductors for a variety of applications including particle accelerator cavities operating at microwave frequency. The quality of these materials deteriorates at high microwave power levels. Together with Dr. D. W. Cooke of the Los Alamos National Laboratory, they are developing a detailed theoretical model of microwave flux penetration and surface resistance and are also undertaking careful measurements of both phenomena. The development of microwave cavities for particle accelerators has largely been led by Dr. Piel and his students. There is no comparable experience anywhere else. Dr. Portis brings to the collaboration outstanding expertise in the microwave properties of high temperature superconductors. Their goal is to identify the loss processes and to work for their elimination, so as to obtain materials that maintain their quality at high microwave power levels. Verification of a microwave critical state in superconductors would have important scientific and technological benefits. It would indicate that microwave processes in superconductors are much faster than has been thought possible, requiring reexamination of some of our ideas of flux penetration into type II superconductors. It would also improve surface quality at high power by identifying the origin of the observed power dependence in surface resistance in high temperature superconductors. If the loss mechanism does persist into the microwave frequency range, there may well be opportunities for using these materials for high frequency signal- processing. Thus a mechanism that creates a problem for particle accelerators may provide opportunities in an entirely different domain.