Extended Theory of Beam Loading in Electron Linac

A new class of disk-loaded traveling-wave structures is proposed. This class is derived from direct generalization of conventional structures, and contains the constant-impedance (CZ) and constant-gradient (CG) structures as members. A beam-loading theory extended for this class implies that within the class, there exists a structure better than the conventional structures in field uniformity and other aspects, when a large-current beam is accelerated. A structure, taken as an example for the case of 10-MeV acceleration of a 1-A beam, is 12% shorter in dimension and 7% more efficient in microwave-to-beam power conversion than the constant-gradient structure.