Technique for the measurement of the amplitude and phase velocity of a slow space charge wave on a relativistic electron beam

A technique is described for the measurement of the axial electric field of a slow space charge wave. The measurement employs a double probe arranged to give an output proportional to the rate of change of magnetic flux linking the probe loop. This output may be related to the electric field of the wave. Two such probes used in an interferometer arrangement allow for the measurement of the phase velocity of the wave.