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Coaxial pellets for metallic impurity injection on the large helical device
X L Huang1, S Morita1, T Oishi1
1Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu, Japan.
The Review of Scientific Instruments
|November 29, 2014
Summary
Using polyethylene tubes for tungsten pellets prevents plasma collapse in the Large Helical Device, enabling successful spectroscopic analysis. Graphite carbon tubes cause undesirable plasma disruptions.
Area of Science:
- Plasma physics
- Materials science
Background:
- Tungsten is crucial for fusion energy research.
- Effective tungsten injection methods are needed for plasma studies.
Purpose of the Study:
- Compare tungsten pellets in graphite carbon vs. polyethylene tubes.
- Analyze tungsten deposition and spectroscopic profiles.
- Identify methods to avoid plasma collapse during tungsten injection.
Main Methods:
- Coaxial pellet injection into the Large Helical Device.
- Pellet ablation spectroscopy for deposition analysis.
- Spectroscopic observation of tungsten emission.
Main Results:
- Tungsten pellets with carbon tubes induced plasma collapse.
- Tungsten pellets with polyethylene tubes ablated smoothly.
- Carbon tube pellets penetrated the core plasma, causing collapse.
- Polyethylene tube pellets allowed successful radial tungsten spectrum observation.
Conclusions:
- Polyethylene tubes are superior for tungsten pellet injection in the Large Helical Device.
- This method enables detailed tungsten spectroscopic studies without plasma disruption.