Self-magnetic cusp limit of a finite sized bunched relativistic annular electron beam

Summary form only given. We show the existence of a self-magnetic cusp which forms in a highly bunched (zero bunch length) annular electron beam as the average beam current approaches a critical current limit. The self-magnetic cusp is calculated within the framework of a fluid equilibrium model for periodic azimuthally symmetric relativistic bunched disk beams propagating in a perfectly conducting cylindrical pipe with a uniform magnetic focusing field. In certain parameter regimes, magnetic cusp formation plays an important role in determining the operational current limit of high-current bunched annular beam experiments. We also discuss how finite bunch length affects the formation of the self-magnetic cusp.