Physics Division Research Highlights
Reduced-Beta Cavities for High-Intensity Compact Ion Accelerators
The Argonne Physics Division is carrying out fundamental research in development of high-gradient reduced-beta superconducting resonators. In March 2012, a cavity designed, built, processed and tested at Argonne reached record accelerating gradients. The cavity, a quarter-wave resonator designed for beta = 0.077 ions, operates at 72 MHz and can provide more than 7.4 MV of accelerating voltage at the design beta, with peak surface fields of 166 mT and 117 MV/m. Operation was limited to this level not by RF surface defects but by our administrative limits on x-ray production, this cavity did not quench. A similar goal is being pursued in the development of a half-wave resonator designed for beta = 0.29 ions which will be tested in 2013. It is expected that the HWR will produce similar accelerating voltage of ~7 MV.
Figure 1: The measured performance of the 72-MHz cavity. Shown is the accelerating gradient as a function of cavity unloaded quality factor Q.
Figure 2: The halfwave cavity design (Left, cross section of cavity) and fabrication status (Right, cavity has only 2 welds left to do). This cavity will be processed and tested in 2013.