IPAC'25 - the 16th International Particle Accelerator Conference

Comprehensive study of Robinson instability in active and passive higher harmonic cavities for bunch lengthening

TUAN3

3 Jun 2025, 10:10

20m

Hall 201 (TICC)

Contributed Oral Presentation MC5.D05 Coherent and Incoherent Instabilities Theory, Simulations, Code Development TUAN :Beam Dynamics and EM Fields (Contributed)

Speaker

Youngmin Park (Pohang University of Science and Technology)

Description

Higher harmonic cavities (HHCs) play a critical role in storage rings by extending the bunch length, thus mitigating beam instability and increasing the beam lifetime. This study investigates the influence of Robinson instability on the bunch lengthening performance for both active and passive HHCs. A detailed comparison is conducted to analyze the Robinson instability thresholds and the parameters of the HHCs* that govern the onset of instability. Simulation results and theoretical analysis are combined to provide guidelines for optimizing HHCs configurations to balance effective bunch lengthening with stability requirements. As illustrative examples, we consider an active normal-conducting HHC for Korea-4GSR , and a passive superconduting HHCs for PLS-II.

Footnotes

T.He et al., Mode-zero Robinson Instability in the presence of passive superconducting harmonic cavities.
*A. Gamelin et al., Beam dynamics with a superconducting harmonic cavity for the soleil upgrade.