NAVAL RESEARCH LAB WASHINGTON DC
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An analytic solution is presented for the longitudinal density modulation of a bending magnet with a transverse scanning electron beam. The analysis is carried out for the cases with and without a guiding magnetic field. Dependence of the electron bunching on various design parameters is clarified in both cases. In the case without a guide field, the beam focusing properties, and the effects of energy spread and self-field are studied. The focusing conditions are determined and a condition for cancelling the effect of energy spread is found. It is shown, moreover, that the self-field enhances electron bunching in the bending magnet due to the negative mass effect. In the case with a guide field, a resonant excitation in the modulation cavity is considered in order to enhance the transverse modulation. A configuration with a half cusp field has also been considered to avoid the difficulty in scanning modulation in the presence of the guide field.
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