Passive higher-harmonic RF cavity simulations for bunch lengthening in the NSLSII-U

In this study, we present a comparative analysis of passive higher-harmonic cavity (HHC) simulations with beam loading compensation using the particle tracking codes ELEGANT and SPACE. By cross-verifying results from both codes, we assess their accuracy in modeling beam dynamics under passive HHC operation for different filling patterns. Our findings demonstrate consistent outcomes between ELEGANT and SPACE, validating their effectiveness in simulating passive HHC systems with beam loading compensation. This work provides valuable insights for optimizing beam stability and performance in storage rings with HHCs.