Kim, C. Kang, H.-S. Kim, G. Ko, I.S. Ko, J.H. JACoW Publishing Geneva, Switzerland 978-3-95450-201-1 10.18429/JACoW-IBIC2018-WEPA16 English 404-406 WEPA16 radiation electron bunching laser linac Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-IBIC2018-WEPA16 http://jacow.org/ibic2018/papers/wepa16.pdf A direct method was developed to measure the micro-bunching instability in the X-ray Free Electron Laser (XFEL). The micro-bunching instability comes from the interaction between the electron beam and the coherent synchrotron radiation (CSR), and the FEL intensity can be affected significantly by the micro-bunching instability. However, no effective method had been introduced to monitor the micro-bunching instability, so that we installed a CCD camera to measure the micro-bunching instability after the bunch compressor. The CCD camera showed the micro-bunching instability successfully, and more interesting features of the micro-bunching instability were revealed from it.