Technical Paper Abstract

A New Linac Structure for the BNCT Application

Donald A. Swenson,
Linac Systems, L.L.C.

A new rf-focused drift tube linac structure, which may have a role in the optimum linac configuration for the BNCT application, is described. It resembles a drift tube linac with rf focusing incorporated into each drift tube. It has the superior focusing properties of the radio frequency quadrupole (RFQ) linac structure and the superior acceleration properties of the drift tube linac (DTL) structure, hence the name Rf Focused DTL, or RFD. The motivation for developing this new linac structure was to find ways to extend the exceptional performance of RFQ linacs to higher energies. The resulting structure may become the structure of choice to follow the highly successful RFQ linac structure for many ion beam applications. In fact, it may tend to reduce the energies to which we push RFQ linacs by offering a superior alternative, at lower energies, to its magnetically focused counterpart, the conventional DTL. It lends itself to miniaturization better than the conventional DTL and, hence, is amenable to higher frequency operation. This new linac structure does not replace the conventional RFQ linac, but rather, provides a graceful way to accelerate the small diameter, tightly bunched beams that come from RFQ linacs to higher energies. A very attractive configuration for the BNCT application would be a short, 350-MHz RFQ linac to 0.5 MeV followed by a short 700-MHz RFD linac to 2.5 MeV.