  In future normal-conducting linear colliders, the beams will be delivered in
short bursts with a length of the order of 100 ns. The pulses will be separated
by several ms. In order to maintain high luminosity, feedback is necessary on a
pulse-to-pulse basis. In addition, intra-pulse feedback that can correct beam
positions and angles within one pulse seem technically feasible. The likely
performances of different feedback options are simulated for the NLC (Next
Linear Collider) and CLIC (Compact Linear Collider).
