• H. Suk, D. Jang, D. Jang, M. Kim, S. Oh
  APRI-GIST, Gwangju

In recent years, the laser-driven plasma wakefield acceleration has attracted much attention as it has a much higher acceleration gradient (>100 GeV/m) compared with the RF-based conventional accelerators. In the past, the supersonic gas jet method for plasma wakefield acceleration was widely used, but this method has a limitation in acceleration distance and energy because the focused laser beam is diffracted severely over a very short distance (~ a few mm range). To avoid the diffraction problem, a capillary plasma source can be used, where a high power laser beam can be guided over a long distance (~ a few cm range) by a parabolic plasma density profile in the capillary plasma channel. We have developed a gas-filled capillary plasma source for generation of GeV-level electron beams in collaboration with the University of Oxford team. In this presentation, the detailed test results and the near-future experimental plan for GeV-level e-beam generation are shown.

• I. Hwang, C. Kim, K.R. Kim, M. Kim, S.H. Nam, S.J. Park, S. Shin
  PAL, Pohang, Kyungbuk
• J. Hou, L.G. Liu
  SINAP, Shanghai

The measurement and the control of the coupling is essential to maximize synchrotron performance. Small coupling is required for small vertical size and high brightness. The Pohang Light Source has a 2.5 GeV storage ring and its coupling constant is measured as about 1%. In addition to errors at quadrupole or sextupole, the condition varying of the insertion device affects the coupling. The coupling for various condition is measured by the resonance and the response matrix and compared with the beam size and the lifetime. The correction and the control of the coupling is presented.