Langmuir probe electronics upgrade on the tokamak à configuration variable

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Diagnostic Instrumentation

Background:

• Langmuir probes are essential for plasma characterization in fusion devices.
• Previous generations of Langmuir probe electronics at TCV (Tokamak à Configuration Variable) had limitations in probe connectivity and amplifier count.
• The TCV divertor upgrade necessitated an expansion of diagnostic capabilities.

Purpose of the Study:

• To detail the upgrade of Langmuir probe electronics for the TCV tokamak.
• To increase the number of simultaneously connectable Langmuir probes for comprehensive plasma monitoring.
• To present technical improvements and address potential issues in the new amplifier circuitry.

Main Methods:

• Detailed description of the new Langmuir probe amplifier circuitry.
• Comparison of the third-generation amplifiers with previous generations (1993/1994 and 2012/2013).
• Successful operation of the upgraded system for over a year, monitoring plasma events.

Main Results:

• The number of amplifiers increased from 48 to 120, allowing simultaneous connection to 114 Langmuir probes.
• An additional 108 amplifiers are ready for installation to support 80 new probes.
• The new amplifiers have performed successfully, but silicon power transistors showed susceptibility to damage during off-normal plasma events.

Conclusions:

• The Langmuir probe electronics upgrade significantly enhances TCV's plasma diagnostic capabilities.
• The new system supports a greater number of probes for detailed plasma analysis.
• Mitigation strategies for transistor damage during off-normal plasma events are under investigation.