A method for determining poloidal rotation from poloidal asymmetry in toroidal rotation (invited)

Area of Science:

• Plasma physics
• Fusion energy research
• Diagnostic development

Background:

• Understanding plasma rotation is crucial for magnetic confinement fusion.
• Existing diagnostics have limitations in spatial resolution and atomic physics dependence.
• Impurity poloidal rotation influences plasma stability and transport.

Purpose of the Study:

• To introduce and validate a novel diagnostic for measuring impurity poloidal rotation.
• To overcome limitations of previous measurement techniques.
• To investigate core plasma rotation dynamics in DIII-D.

Main Methods:

• Development of a new diagnostic utilizing tangential charge exchange (CX) viewchords on the DIII-D tokamak.
• Measurement of poloidal asymmetry in toroidal angular rotation velocity.
• Utilizing co- and counter-current neutral beams to eliminate atomic physics calculations.

Main Results:

• Successful implementation of the diagnostic on DIII-D, covering the core plasma region (r/a < 0.6).
• Achieved improved spatial resolution compared to the vertical CX system.
• Observed poloidal rotation measurements that significantly deviate from neoclassical predictions.

Conclusions:

• The new diagnostic provides accurate measurements of impurity poloidal rotation in the tokamak core.
• This tool enhances our understanding of plasma rotation physics beyond neoclassical theory.
• The diagnostic is a valuable addition to fusion research, enabling new physics investigations.