Beam instability and microbunching due to coherent synchrotron radiation

A beam microwave instability induced by the coherent radiation of the density fluctuations is studied theoretically in this paper. We consider the case when coherent synchrotron radiation of a bunch as a whole is suppressed by screening and is caused by microstructures with longitudinal dimensions small compared to the bunch length. In this case, we can simplify consideration studying stability of a coasting beam with the line density equal to the local line density of the bunch.