Note: matching index technique for avoiding Higher Order Mode resonance in accelerators: INDUS-2 accelerator as a...

Area of Science:

• Accelerator Physics
• Particle Accelerators
• Electromagnetism

Background:

• Coupled-bunch instabilities in accelerators arise from resonances between circulating beam frequencies and Radio Frequency (RF) cavity Higher Order Modes (HOMs).
• Mitigating these instabilities by shifting HOM frequencies is crucial for accelerator performance and stability.

Purpose of the Study:

• To introduce a quantitative measure, the matching index (IM), for assessing the proximity of HOMs to beam modes.
• To establish criteria for classifying operating scenarios as safe or unsafe based on the IM.
• To apply this methodology to the accelerating cavities of the INDUS-2 accelerator.

Main Methods:

• Development of the matching index (IM) to quantify the closeness of HOM frequencies to beam frequencies.
• Analysis of RF cavity HOMs in the INDUS-2 accelerator.
• Classification of operating scenarios using the IM to determine safe and unsafe conditions.

Main Results:

• Introduction of the matching index (IM) as a novel tool for evaluating HOM-beam resonance risks.
• Demonstration of IM's utility in the INDUS-2 accelerating cavities.
• Establishment of a clear classification system (safe/unsafe) based on IM values.

Conclusions:

• The matching index (IM) provides a quantitative and effective method for managing HOM-induced instabilities in accelerators.
• This approach aids in optimizing accelerator operation by identifying and mitigating resonance conditions.
• The study offers a practical framework for future accelerator design and operational adjustments.