High-sensitivity far-forward collective scattering diagnostic on HL-2A tokamak

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Diagnostic Techniques

Background:

• Understanding electron density fluctuations is crucial for controlling plasma behavior in fusion devices.
• Previous diagnostic limitations hindered detailed observation of small-scale fluctuations.

Purpose of the Study:

• To develop and implement a novel diagnostic system for measuring far-forward collective scattering.
• To investigate electron density fluctuations caused by plasma energetic particles and turbulence in the HL-2A tokamak.

Main Methods:

• Utilized a multichannel formic acid (HCOOH) laser interferometer and Faraday-effect polarimeter.
• The system operates at a wavelength of 432.5 µm.
• Measured line-integrated electron density fluctuations across eight channels, covering wave numbers up to k⊥ < 1.6 cm⁻¹.

Main Results:

• Successfully established a far-forward collective scattering system on the HL-2A tokamak.
• Routinely observed density fluctuations attributed to energetic particles and plasma turbulence.
• Provided detailed measurements of electron density fluctuations within the specified wave-number range.

Conclusions:

• The developed diagnostic system is effective for studying plasma turbulence and energetic particle effects.
• This advancement enables routine observation and analysis of critical plasma phenomena in tokamak experiments.
• The findings contribute to a better understanding of plasma dynamics relevant to fusion energy.