Close-coupled rf power systems for linacs

Abstract

A close-coupled rf power system provides high peak rf power for a linear accelerator, or 'linac', and other charged particle systems. The linac operates in a vacuum housing. Low level rf power is coupled inside of the vacuum housing by a conventional rf feedthrough connector. An input resonator cavity mounts on the side of the linac within the vacuum housing. The resonator cavity couples rf power to one or more amplifier assemblies, each including at least one planar triode mounted directly on the linac housing, proximate one end of the resonator cavity. The planar triode, in turn, generates a high power rf current at its respective anode. The high power rf current couples to the linac through a conductive loop operating at the anode potential. Anode cooling is provided by pumping a suitable fluid, such as de-ionized water, through the conductive loop. The high power rf current in the loop generates magnetic fields in the linac required for its operation. After passing through the loop, the rf current is shunted to ground through an integral rf-bypass capacitor. Many components of conventional rf power systems, such as rf output resonators, transmission lines, and vacuum windows, are not needed. Peak rf power of up to 1 megawatt is achievable by using clusters of planar triodes in each amplifier assembly, and by using multiple amplifier assemblies.