Design of a Hybrid Single Cavity With a Novel Coupled-Window Structure

In recent decades, significant advancements have been made in accelerator technology, particularly with the hybrid single cavity (HSC). The HSC structure combines a radio frequency quadrupole (RFQ) and a drift tubes linac (DTL) within a unified interdigital H-type (IH) structure, resulting in greater compactness and system simplification. However, this design poses two fundamental challenges: reduced beam transmission efficiency and the concentration of electromagnetic (EM) fields at the matching section between RFQ and DTL sections. To address these issues, a novel coupled-window structure (CWS) has been devised to mitigate the EM fields effects. This paper explores the design and optimization of a 100 MHz HSC for high-intensity applications. The new HSC cavity is engineered to accelerate 20 mA C6+beams from 20 keV/u to 4 MeV/u within a distance of 4.4 m, achieving a total transmission efficiency of 91%. These outcomes are attainable through the implementation of CWS, which effectively mitigates the challenges associated with matching dynamic fields between the RFQ and DTL sections.