Slow wave structure having offset projections comprised of a metal-dielectric composite stack

A traveling wave amplifier circuit to receive an RF wave and an electron sheet beam and to effect synchronized interaction therebetween. The circuit includes a wave guide having at least a first wall and a second wall opposite the first wall. The first wall and the second wall are connected to define an axis of propagation and a rectangular wave guide cross-section that is normal to the axis of propagation. The circuit further includes a plurality of first projections located on an interior surface of the first wall of the wave guide, the first projections being pitched in a direction of the axis of propagation. The circuit further includes a plurality of second projections located on an interior surface of the second wall of the wave guide, the second projections being pitched in a direction of the axis of propagation. A number of the second projections are located on the interior surface of the second wall in a staggered configuration in a direction of the axis of propagation relative to a number of corresponding first projections located on the interior surface of the first wall.