JET divertor diagnostic upgrade for neutral gas analysis

Area of Science:

• Nuclear Fusion Engineering
• Plasma Physics
• Materials Science

Background:

• The Joint European Torus (JET) tokamak underwent a major upgrade with the installation of an ITER-like wall.
• Characterizing neutral gas behavior in the sub-divertor region is crucial for understanding plasma-wall interactions and material performance.

Purpose of the Study:

• To implement and validate a new diagnostic system for measuring neutral gas pressure and composition.
• To investigate the retention and outgassing properties of the new metallic first wall in JET.
• To analyze neutral gas dynamics under diverse plasma operational scenarios.

Main Methods:

• Installation of two magnetically shielded diagnostic systems in the JET sub-divertor region.
• Utilized sensitive capacitance manometers for absolute pressure measurements (10^-5 - 10^-1 mbar).
• Employed residual gas analyzers for gas composition analysis (1-200 amu) during plasma operation.

Main Results:

• Successfully deployed advanced diagnostics capable of real-time measurements during plasma operations.
• Collected data on neutral gas pressure and composition within the sub-divertor region.
• Provided initial characterization of neutral gas behavior influenced by the new metallic wall.

Conclusions:

• The new diagnostic upgrade provides essential data for understanding plasma-wall interactions in fusion devices.
• The system enables detailed characterization of metallic first wall performance regarding gas retention and outgassing.
• This diagnostic capability is vital for optimizing future fusion reactor designs, such as ITER.