演讲人：Thomas T. Y. Wong（伊利诺工学院教授）
时间：3月15日上午9：00-10:00
地点：光华楼东主楼1101
Abstract
A coaxial power coupler for a superconducting multicell cavity resonator at 3.9 GHz has been developed. The cavity is intended to be employed as an accelerator to provide enhanced electron beam quality in a free-electron laser. Due to cryogenic, high vacuum and high power requirements, special provisions for two windows and two bellows were implemented. A transition from rectangular waveguide to a coaxial line is employed to receive the power from the microwave source. The windows and bellows are embedded with the coaxial structure, which is interfaced with the cavity resonator by a probe arrangement. Simulation tool was employed to optimize the coupler structure for low reflection of incident power and dissipation while restraining the field at critical locations to prevent material breakdown. Procedures for testing the coupler on its own and integrated with the superconducting cavity are described and the measurement results are presented. The coupler-cavity assembly was tested to exceed the requirement of 9.3 kW input power and axial field intensity of 14.5 MV/m in the cavity. Coupler return loss and insertion loss were estimated to be 21 dB and 0.2 dB, respectively.
Biography
Thomas T. Y. Wong received the B.Sc. (Eng.) degree from the University of Hong Kong, and the M.S. and Ph.D. degrees from Northwestern University, all degrees being in electrical engineering. He joined the faculty at the Illinois Institute of Technology in 1981 and is currently a professor with the Department of Electrical and Computer Engineering (ECE). He has conducted research in microwave measurement and applied electromagnetics. In collaboration with national laboratories, he has contributed to the development of dielectric-loaded accelerators and nanoscale instrumentation. He served as the ECE graduate program director at IIT from 1987 to 1995, the chair of the Faculty Council in the 1998 academic year, and the chairman of the ECE Department from 2001 to 2005. He is a former chair of the IEEE AP-MTT Joint Chapter in Chicago and served as organizing committee member of several international conferences. He is the author of Fundamentals of Distributed Amplification (Artech, 1993), coauthor of Electromagnetic Fields and Waves (Higher Education Press, 2006) and has several patents in the areas of microwave electronics and wireless system design