RF system of the SPring-8 storage ring.

Area of Science:

• Accelerator Physics
• Particle Accelerators
• Synchrotron Radiation Technology

Background:

• Coupled-bunch instabilities in storage rings limit stored current and beam stability.
• Existing radio frequency (RF) systems may not adequately suppress these instabilities.
• SPring-8 storage ring requires an upgraded RF system for enhanced performance.

Purpose of the Study:

• To report the construction and commissioning of three new RF stations for the SPring-8 storage ring.
• To detail a design strategy focused on mitigating coupled-bunch instabilities.
• To ensure stable high-current operation and reliable synchrotron radiation output.

Main Methods:

• Designed bell-shaped RF cavities to minimize higher-order mode (HOM) coupling impedance.
• Systematically trimmed cavity dimensions to distribute HOM frequencies.
• Implemented precise control of cavity cooling water temperature (within 0.02 K) and constant water flow.
• Installed movable tuners in each cavity for fine frequency adjustment.

Main Results:

• Successfully constructed and commissioned three new RF stations.
• The new RF system effectively suppresses coupled-bunch instabilities.
• Achieved stable operation at higher stored currents than previously possible.
• Demonstrated reliable performance of the synchrotron radiation beam.

Conclusions:

• The newly constructed RF stations effectively address coupled-bunch instabilities in the SPring-8 storage ring.
• The design, featuring bell-shaped cavities and precise environmental controls, ensures a stable and high-current electron beam.
• This advancement enhances the capability of SPring-8 for synchrotron radiation research.