报告题目：Energy Chirp Control in a Linac-Based X-Ray FEL using a Corrugated Structure: Theory and Experiment at the Linac Coherent Light Source
报 告 人：Karl Bane (SLAC)
报告时间：2016年5月19日(星期四)10:00
报告地点：张江办公楼101会议室

报告内容：
Two corrugated plates can be used as a passive device for removing residual energy chirp at the end of a linac-based, X-ray free electron laser (FEL). When a short, high energy beam passes between two such plates—that comprise a device that we call a “dechirper”—wakefields will be induced that generate a negative chirp, i.e. one with the tail of the beam at lower energy than the head. Recently the so-called RadiaBeam/LCLS dechirper was installed and tested in the Linac Coherent Light Source (LCLS) at SLAC. This was the first time a dechirper has been tested at high energies (4.4 - 13.3 GeV), with short bunches (10’s of fs), and on an operating FEL.　In my talk I will discuss the theory of the dechirper and present results from the commissioning studies at the LCLS. Time-resolved measurements of both longitudinal and transverse wakefields were performed and compared with simulations.　In addition, we demonstrated flexible control of the LCLS FEL bandwidth for hard and soft X-rays. Finally, taking advantage of the strong transverse wakes of the dechirper, novel methods were devised for operating the FEL in self-seeding and two color modes.

报告人简介：
Karl Bane Studied undergraduate at Tufts University, graduate at Stanford. Worked from 1973—present at SLAC. Started working on wakefield/impedance calculations with Perry Wilson and Bruno Zotter. Accomplishments: Linac wakefields for short bunches, microwave instabilities in storage rings, optical model of short bunch wakes, corrugated structures　for dechirping and THz generation　(some together with G. Stupakov, I. Zagorodnov). Projects worked on: Stanford Linear Collider, Next Linear Collider, Linac Coherent Light Source, LCLS-II.