BRIDGE COUPLED DRIFT-TUBE LINACS

Modern linac designs for treating radioactive waste achieve high proto n currents through funneling at low energy, typically around 20 MeV. T he resulting switch to a high-frequency accelerating structure poses s evere performance and fabrication difficulties below 100 MeV. Above 10 0 MeV, proven coupled-cavity linacs (CCLs) are available. However, at 20 MeV one must choose between a high-frequency drift-tube linac (DTL) or a coupled-cavity linac with very short cells. Potential radiation damage from the CW beam, excessive RF power losses, multipactoring, an d fabricability all enter into this decision. At Los Alamos, we have d eveloped designs for a bridge-coupled DTL (BCDTL) that, like a CCL, us es lattice focusing elements and bridge couplers, but that unlike a CC L, accelerates the beam in simple, short, large aperture DTL modules w ith no internal quadrupole focusing. Thus, the BCDTL consumes less pow er than the CCL linac without degrading beam performance and is simple r and cheaper to fabricate in the 20 to 100 MeV range.