Design and Optimization of A 750 MHz IH-DTL for Medical Isotope Production

For the efficient production of the 211 At isotope, a 750 MHz interdigital drift tube linac operating at a 2% duty factor has been designed by the Institute of Modern Physics (IMP). The accelerator is capable of accelerating He 2+ beam from 1.75 MeV/u to 7 MeV/u with a peak beam current of 2.5 pmA. The cavity has an overall length of approximately 2.15 m and achieves an average accelerating gradient of 4.88 MV/m. The sparking coefficient limit was determined through prototype cavity power tests. Furthermore, Radio frequency simulations conducted with CST Studio Suite established the maximum axial electric field boundary. Multiphysics analysis verified the thermal stability of the cell model under the 2% duty factor. Within these boundary conditions, longitudinal dynamics were designed using the LORASR code, and transverse dynamics designs employing external PMQ Doublet and Triplet focusing schemes were compared by TraceWin. Evaluation of beam envelope, transmission efficiency, and emittance growth led to the selection of the external PMQ Doublet scheme as the preferred focusing approach. Finally, error analysis and an End-to-End simulation from the 750 MHz RFQ exit to the IH-DTL exit were performed. This paper comprehensively describes the design process and presents the resulting performance.