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A magnetic diagnostic suite for the Pegasus-III experiment
J A Reusch1, M W Aslin1, M W Bongard1
1Department of Nuclear Engineering and Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
The Review of Scientific Instruments
|September 11, 2024
Summary
Pegasus-III installed new magnetic diagnostics for solenoid-free startup studies in spherical tokamaks. The system achieves high accuracy despite significant electrical noise, crucial for fusion energy research.
Area of Science:
- Fusion Energy Research
- Plasma Physics
- Magnetic Confinement Fusion
Background:
- Spherical tokamaks require precise magnetic field measurements for plasma control.
- High-field side diagnostics face challenges due to limited space and electromagnetic interference.
- Solenoid-free startup methods are critical for compact fusion reactor designs.
Purpose of the Study:
- To introduce and validate a new magnetic diagnostic suite for the Pegasus-III spherical tokamak.
- To enable accurate magnetohydrodynamic (MHD) mode analysis during solenoid-free startup.
- To overcome significant noise challenges in a confined diagnostic environment.
Main Methods:
- Installation of a new magnetic diagnostic suite with differential signal paths and EMI shielding.
- High-speed digitization (1 MHz) and filtering (200 kHz Butterworth) to mitigate noise.
- Ex-vessel calibration and physics-based modeling for stray toroidal field correction.
Main Results:
- Successful measurement of magnetic fields in a high-noise environment with <0.5% calibration uncertainty.
- Achieved agreement between corrected measurements and modeling within 1.3% on average.
- Demonstrated measurement accuracy within the 1.5% required for fast boundary and equilibrium reconstruction.
Conclusions:
- The new magnetic diagnostic suite on Pegasus-III is effective for solenoid-free startup studies.
- The system successfully overcomes severe electromagnetic interference for accurate plasma measurements.
- This advancement is vital for comparative studies and the development of future fusion devices.
