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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.