Gas puff imaging on the TCV tokamak.

Area of Science:

• Plasma physics
• Fusion energy research
• Diagnostic techniques

Background:

• Turbulence in the plasma edge and Scrape-Off-Layer (SOL) significantly impacts fusion device performance.
• Understanding plasma dynamics is crucial for achieving stable and efficient fusion reactions.
• The Tokamak à Configuration Variable (TCV) requires advanced diagnostics to study these phenomena.

Purpose of the Study:

• To design, operate, and characterize a suite of Gas Puff Imaging (GPI) diagnostic systems on the TCV.
• To enable simultaneous 2D imaging of plasma dynamics across multiple critical regions of the tokamak.
• To investigate plasma edge turbulence and SOL behavior with high spatial and temporal resolution.

Main Methods:

• Installation and operation of multiple Gas Puff Imaging (GPI) diagnostic systems.
• Development and implementation of an innovative control system for deuterium and helium gas injection.
• Utilizing detection systems including avalanche photodiodes and high-speed CMOS cameras.
• Collecting poloidal 2D images of plasma dynamics at various locations (midplane, X-point, HFS/LFS SOL, divertor).

Main Results:

• Successful operation of GPI diagnostic systems on TCV.
• Acquisition of poloidal 2D images of plasma dynamics with spatial resolution up to ≈2 mm and temporal resolution of 0.5 µs.
• Characterization of an innovative gas injection control system.
• Demonstration of GPI's capability to image diverse plasma regions.

Conclusions:

• The new GPI diagnostic suite offers unprecedented capabilities for studying plasma edge and SOL turbulence on TCV.
• The advanced gas injection control system is a key innovation for TCV diagnostics.
• Future upgrades will further enhance the diagnostic capabilities for fusion research.