A Small Diameter Standing Wave Linear Accelerator Structure

A compact, small diameter, standing-wave linear accelerator structure suitable for industrial and medical applications is presented. The novel structure utilizes a new type of coaxial cavity as the coupling cavity for π/2 mode, standing-wave operation. This structure offers a significant reduction in overall diameter over the side-coupled, annular ring, and existing coaxial coupled structures, while maintaining a high shunt impedance and large nearest neighbor coupling (high group velocity). A prototype 4 MeV, 36 cm long, S-band accelerator incorporating the new structure has been built and tested. Theoretical accelerator design parameters, as well as experimental results, are presented.