Time-resolved Measurement of Quadrupole Wakefields in Corrugated   Structures
  Corrugated structures have recently been widely used for manipulating electron beam longitudinal phase space and for producing THz radiation. Here we report on time-resolved measurements of the quadrupole wakefields in planar corrugated structures. It is shown that while the time- dependent quadrupole wakefield produced by a planar corrugated structure causes significant growth in beam transverse emittance, it can be effectively canceled with a second corrugated structure with orthogonal orientation. The strengths of the time-dependent quadrupole wakefields for various corrugated structure gaps are also measured and found to be in good agreement with theories. Our work should forward the applications of corrugated structures in many accelerator based scientific facilities. 
Chao Lu, Feichao Fu, Tao Jiang, Shengguang Liu, Libin Shi, Rui Wang,   Lingrong Zhao, Pengfei Zhu, Zhen Zhang, and Dao Xiang
physics.acc-ph