Abstract
A new class of accelerating structures employing a
uniformly twisted waveguide is considered. Such a twisted helical
structure can be designed to have a specified longitudinal cross section.
The design of twisted accelerating structures is discussed with
regard to particle velocity and strength of the accelerating field. It
is shown how to choose a cross section and twist rate in order to
produce a slow wave with a given velocity. With two representative
structures, obtained wave velocities range from the speed of
light, , down to 61% the speed of light, while values of over
1,000 Ohms/m have been achieved. A novel two dimensional finite difference
based solver is employed to analyze the twisted structures
considered. Two twisted cavity prototypes are fabricated and measured,
and good agreement is obtained between measured and predicted
dispersion curves.