Development of a scintillator-based optical soft x-ray (OSXR) diagnostic system for KSTAR tokamak

Area of Science:

• Plasma Physics
• Fusion Energy
• Diagnostic Systems

Background:

• KSTAR tokamak requires advanced diagnostic systems for plasma instability monitoring.
• Limited vacuum-port access presents challenges for traditional soft x-ray detection methods.

Purpose of the Study:

• To develop and validate a novel scintillator-based optical soft x-ray (OSXR) diagnostic system for KSTAR.
• To overcome vacuum-port limitations in KSTAR using an innovative optical system design.

Main Methods:

• Utilized fiber optic faceplates, mm-size lens arrays, and fiber bundles for optical system construction.
• Selected P47 (Y2SiO5) scintillator material for its fast response time (7 ns rise, 100 ns decay).
• Integrated lens arrays and optical fibers to collect scintillation towards a photodetector system.

Main Results:

• Successfully constructed a novel OSXR system adaptable to KSTAR's constraints.
• Demonstrated validity of OSXR data through consistency with other KSTAR diagnostics during the 2022 campaign.
• Observed capture of magnetohydrodynamic activities, including sawtooth oscillations.

Conclusions:

• The developed OSXR system is effective for diagnosing plasma instabilities in KSTAR.
• The system provides valuable data for disruption mitigation studies, particularly with shattered pellet injection.
• This novel diagnostic enhances KSTAR's capability for fusion plasma research.