Impact of the RFI Linac Structure on Accelerator Technology

The RFI linac structure represents an effective combination of the interdigital linac structure, used for many low frequency, heavy ion applications, and the rf electric quadrupole focusing used in the RFQ and RFD linac structures. The interdigital format results in relatively small diameter structures with very high rf efficiencies, while the rf focusing results in relatively small diameter beams. Together, these features promise significant reductions in the size, cost, and complexity of linac systems for scientific, medical, industrial, defense, and homeland security applications.

The small diameter feature of the interdigital format results in modest-sized structures even for the relatively low frequencies typically used for heavy-ion acceleration. The RFI structure can be configured as compact, relatively low frequency, very high efficiency, high performance accelerating structure for protons, light ions, and heavy ions.

This new linac structure provides a graceful way to accelerate the small diameter, tightly bunched beams of proton or heavier ions that come from RFQ linacs to higher energies. We believe that this new structure will become the structure of choice to follow RFQ linacs in many applications. The performance of the RFI is much less energy dependent than magnetically focused structures. It can perform well at much lower energies. Consequently, the transition energy between RFQs and RFIs can be as low as 0.5 to 1.0 MeV.

The RFI structure could be as revolutionary to accelerator technology as the conventional RFQ was on its introduction to the world in 1980. This new linac structure will lead to the development of a new breed of ion linac systems for a whole host of ion beam applications. These new linac systems will enhance the reliability, reduce the cost, and reduce the complexity of these sources of radiation. Applications, which formerly were out of range for linacs, may now find that they are within the range of practical linac-based systems. This represents a significant commercial business opportunity with both domestic and foreign market potential.