Simulation of vibration-induced effect on plasma current measurement using a fiber optic current sensor

Area of Science:

• Plasma physics
• Optical sensing technologies
• Fusion energy research

Background:

• Accurate plasma current measurement is crucial for tokamak magnetic equilibrium control.
• Fiber Optic Current Sensors (FOCS) are proposed for ITER, but susceptible to vibration-induced birefringence.
• Vibrations can compromise FOCS performance and measurement accuracy.

Purpose of the Study:

• To investigate the impact of vibrations on plasma current measurement accuracy.
• To evaluate FOCS performance under ITER-relevant operational conditions.
• To assess the viability of FOCS for ITER's current diagnostics requirements.

Main Methods:

• Simulations were conducted to model FOCS performance under vibration.
• Investigated a specific FOCS reflection scheme incorporating spun fiber and a Faraday mirror.
• Analyzed the induced error due to time-dependent parasitic birefringence.

Main Results:

• Simulation results indicate that vibration effects were analyzed under ITER-relevant conditions.
• The chosen FOCS reflection scheme demonstrated resilience to vibration-induced errors.
• The error induced by vibrations was found to be within acceptable limits for ITER.

Conclusions:

• The investigated FOCS configuration, utilizing spun fiber and a Faraday mirror, is suitable for ITER.
• This FOCS design effectively mitigates vibration-induced errors in plasma current measurements.
• The findings support the implementation of FOCS technology for ITER's current diagnostics.