Wake field excitation in plasma by a relativistic electron pulse with a controlled number of short bunches

The excitation of wake fields in plasma by a train of relativistic electron bunches was studied both theoretically and experimentally. It follows from the theoretical analysis that the amplitude and spatial structure of the electric field of wake waves excited by either a high particle density single pulse or by a train of relatively low particle density bunches should be approximately equal if the total charge in both cases remains the same. It was shown experimentally that a very high electric field is excited in plasma by a train of short relativistic bunches if the bunch repetition rate coincides with the electron Langmuir frequency. 19 refs., 13 figs., 1 tab