A new dispersion interferometer on HL-2A

Area of Science:

• Plasma physics
• Fusion energy research
• Optical diagnostics

Background:

• High plasma density and pellet injection can cause fringe jumps in interferometers.
• Accurate real-time plasma density measurement is crucial for fusion device control.

Purpose of the Study:

• To design and commission a new CO2 dispersion interferometer for HL-2A.
• To achieve reliable average line-density measurement and density feedback control.
• To mitigate fringe jumps and phase shifts caused by plasma conditions and vibrations.

Main Methods:

• Utilized a CO2 dispersion interferometer with second harmonic technology.
• Implemented a digital phase comparator for real-time signal processing.
• Conducted experiments to characterize system performance, including stability and resolution.

Main Results:

• Achieved a density measurement resolution better than 8 × 10^17/m^3.
• Demonstrated effective tracking of rapid plasma density evolution on HL-2A.
• Confirmed system stability against mechanical vibrations and phase shifts.

Conclusions:

• The new CO2 interferometer successfully addresses fringe jump issues.
• The system provides accurate and stable plasma density measurements for feedback control.
• This diagnostic is valuable for advancing fusion energy research on HL-2A.