We present the design of three types of multi-beam interdigital H-mode radio frequency quadrupoles (IH-RFQs), which can be used in ion implantation applications. The first type of cavity enables the simultaneous acceleration of boron (B) and phosphorus (P) ions within a single cavity. In order to increase the beam current, two additional types of cavities were designed to accelerate B or P ions individually. The key advantages of the three cavities include minimal footprint, capability to simultaneously accelerate beams with different charge-to-mass ratios, and ability to double output beam current. Four channels, each independently optimized, are capable of providing beams at different output energies while ensuring at least 97% transmission for each. The replacement of the modulation structure results in the configuration of the four beam channels to accelerate the same element (B or P) with different output energies. This approach simplifies the laser-ion-source system and effectively doubles the peak beam current for the same ions. Initially, the beam dynamics of B and P were designed. Subsequently, the RF design was carried out. The resonance frequency and the Q factor of the RFQ were found to be approximately 81.25 MHz and 3090, respectively. Additionally, a simulation was conducted to assess the distribution of the electric field and its associated error analysis. The unflatness of quadrupole field was mainly maintained within ±3%, and the dipole remained within ±4% (an acceptable level). Finally, a comprehensive multiphysics analysis was conducted to enhance the cavity's long-term stability and reliability.
Long et al. (2026) studied this question.