An eight-channel Doppler backscattering system in the experimental advanced superconducting tokamak

Area of Science:

• Plasma physics
• Fusion energy research
• Advanced diagnostics

Background:

• Density turbulence significantly impacts plasma confinement in fusion devices.
• Accurate measurement of turbulence properties is crucial for understanding and controlling plasma behavior.
• Existing diagnostic systems may have limitations in spatial resolution or dynamic range.

Purpose of the Study:

• To introduce a new eight-channel Doppler backscattering system for the EAST.
• To detail the hardware design, optical system, and capabilities of the new diagnostic.
• To present preliminary experimental results demonstrating the system's performance.

Main Methods:

• Installation of an eight-channel Doppler backscattering system on the EAST.
• Utilizing quasi-optical components including corrugated waveguides and parabolic mirrors.
• Employing ray tracing simulations to determine scattering locations and wavenumbers.
• Operating with eight fixed frequencies ranging from 55 to 75 GHz.

Main Results:

• Simultaneous probing of eight radial plasma locations.
• Capability to measure perpendicular velocity and fluctuation amplitude of density turbulence.
• Wavenumber range of 2-15/cm with resolution Δk/k≤0.21.
• Demonstrated dynamic range of up to 40 dB in the EAST.

Conclusions:

• The new eight-channel Doppler backscattering system is a valuable addition to EAST diagnostics.
• The system enables detailed characterization of intermediate wavenumber density turbulence.
• Preliminary results confirm the system's effectiveness for plasma turbulence studies.