报告题目：Electron beam sources and beam manipulation using passive structures at PSI
报 告 人：PAOLO CRAIEVICH
Head of the RF System 2 (RF linacs) Group in the Large Research
Facilities Division (GFA) at the Paul Scherrer Institute (PSI), Switzerland.
报告时间：2018年9月21日15:00-16:00
报告地点：清华大学刘卿楼302
主 持 人：杜应超 副教授
报告摘要：
RF photoinjectors are used to generate high-brightness electron beams for a wide range of applications. Because of their outstanding beam quality, they are particularly well-suited as sources for X-ray free-electron lasers (FELs). To fulfill the beam quality and operational requirements of the SwissFEL project a new RF photocathode gun for the electron source was designed and manufactured in house. A 2.6 cell S-band gun operating with near-perfect rotationally symmetric RF field was designed to operate with a 100MV/m cathode field at a repetition rate of 100Hz. The emitted dark current was also measured during the high-power tests and the charge within the RF pulse was measured as a function of the peak cathode field. The beam emittance, which is significantly influenced by the intrinsic emittance of the cathode, is fundamental for FELs, since it has a strong impact on the lasing performance and
it defines the length and cost of the facility. Measurements of the intrinsic emittance as afunction of the rf field for a copper and cesium telluride photocathode were also performed comparing the performance of metal and semiconductor cathodes under the same conditions.
Furthermore, several possibilities of manipulating the electron beam using sources of wakefield are being explored. Wakefield have been successfully used to remove or enhance the energy chirp residual from the magnetic compression to control the free electron laser bandwidth (dechirper), to linearize the compressed beam (linearizer), to generate more bunches to produce two color mode, and to retrieve the temporal distribution. At the SwissFEL injector we are installing 2 m long system to accommodate sources of wakefield with different periodicities, each of them associated with one of the discussed beam manipulation.

报告人简介：
Paolo CRAIEVICH is the head of the RF System 2 (RF linacs) Group in the Large Research Facilities Division (GFA) at the Paul Scherrer Institute (PSI), Switzerland. He is a RF engineer and accelerator physicist working in the RF group for the SwissFEL project and for the Swiss Light Source synchrotron storage ring. His research interests include microwave applications to accelerators, such as cavities and traveling wave accelerating structures, rf photo and thermionic guns, wake-field, instability and coupling impedance. He has more than 130 publications. Over 50 of them are peer reviewed journal articles.