Longitudinal space charge-driven microbunching instability in the TESLA Test Facility linac

In this paper, we study a possible microbunching instability in the TESLA Test Facility linac. A longitudinal space charge is found to be the main effect driving the instability. Analytical estimates show that initial perturbations of beam current in the range 0.5–1 mm are amplified by a factor of a few hundred when the beam passes two bunch compressors. A method to suppress the instability is discussed.