Fast ion D-alpha measurements using a bandpass-filtered system on EAST

Area of Science:

• Plasma physics
• Fusion energy research
• Atomic and molecular physics

Background:

• Fast ions play a crucial role in magnetic confinement fusion energy research.
• Understanding fast ion transport is essential for controlling plasma instabilities.
• Existing fast ion D-alpha (FIDA) methods require enhancements for improved signal detection.

Purpose of the Study:

• To extend fast ion D-alpha (FIDA) measurements using a novel filtered approach (f-FIDA).
• To investigate the interaction between plasma instabilities and fast ion transport.
• To detail the hardware specifications and performance of the f-FIDA system.

Main Methods:

• Utilized a charge exchange reaction between fast ions and a neutral beam.
• Employed a bandpass filter (651 nm to 654 nm) coupled with a photomultiplier tube (PMT) for enhanced spectral selection.
• Implemented f-FIDA measurements in the EAST tokamak with vertical and tangential viewing geometries.

Main Results:

• Successfully detected active signals from reneutralized beam ions.
• Demonstrated the capability of f-FIDA to capture Doppler-shifted Balmer-alpha light.
• Acquired preliminary data showcasing the system's performance in tokamak conditions.

Conclusions:

• The f-FIDA system represents a significant advancement in fast ion measurement techniques.
• The preliminary results validate the effectiveness of the filtered approach for studying fast ion dynamics.
• Further analysis of f-FIDA data will provide deeper insights into plasma behavior and instability interactions.