Malyutin, D. Matveenko, A.N. JACoW Geneva, Switzerland 978-3-95450-177-9 10.18429/JACoW-IBIC2016-MOPG53 English 179-182 MOPG53 electron diagnostics synchrotron simulation gun Contribution to a conference proceedings 2017 2017-02 http://dx.doi.org/10.18429/JACoW-IBIC2016-MOPG53 http://jacow.org/ibic2016/papers/mopg53.pdf A low energy electron beam can be used to characterize the high energy ultra-relativistic bunches. This technique allows one to obtain the bunch transverse profiles as well as the bunch length within a non-destructive single shot measurement. In this paper the bunch length measurement technique based on the interaction of the low energy electron beam with an ultra-relativistic bunch is described. Results of numerical simulations of measurements related to BESSY II are presented. A possible setup of such diagnostic system for BESSY II and in future for BESSY VSR is proposed.