Real-time processing system of a two-color CO2 laser interferometer for density feedback control in JT-60SA

Area of Science:

• Plasma Physics
• Fusion Energy Engineering
• Optical Diagnostics

Background:

• The JT-60SA tokamak requires precise electron density monitoring for effective plasma control.
• Traditional interferometry systems can be susceptible to disruptions from off-normal events.

Purpose of the Study:

• To develop and implement a robust real-time processing system for a two-color CO2 laser interferometer on JT-60SA.
• To enhance density feedback control by accurately detecting and mitigating off-normal events.

Main Methods:

• Development of a real-time processing system for a two-color CO2 laser interferometer.
• Implementation of fringe jump detection logic with a threshold of π/2 to identify off-normal events.
• Utilizing the system as a density monitor for real-time feedback control.

Main Results:

• The system successfully detects fringe jumps caused by beam displacement and wavelength changes.
• Off-normal events trigger the abort of real-time feedback control, preventing data corruption.
• Electron density (NL) was controlled at 16.8% ± 6.6% lower than the reference value.

Conclusions:

• The developed real-time processing system enhances the reliability of density feedback control on JT-60SA.
• The novel fringe jump detection capability effectively mitigates disruptions from off-normal events.
• This system serves as a crucial density monitor for advanced fusion plasma operations.