Energetic ion loss detector on the Alcator C-Mod tokamak.

Area of Science:

• Nuclear Fusion Science
• Plasma Physics
• Tokamak Diagnostics

Background:

• Understanding energetic ion behavior is crucial for controlling fusion reactions.
• Ion cyclotron resonance heating (ICRH) can lead to significant energetic ion losses in tokamaks.
• Effective diagnostic tools are needed to measure these losses.

Purpose of the Study:

• To commission a novel scintillator-based energetic ion loss detector on the Alcator C-Mod tokamak.
• To characterize the phase space distribution of lost ions during ICRH.
• To investigate the correlation between ion losses and ICRH operational parameters.

Main Methods:

• A scintillator probe was designed and installed below the outer midplane of the Alcator C-Mod tokamak.
• The probe utilizes a collimating aperture to direct ions based on gyroradius and pitch angle.
• Four fiber optic cables provide phase space resolution by viewing different scintillator regions.

Main Results:

• The energetic ion loss detector was successfully commissioned and operated.
• The detector captured ions with energies up to 2 MeV.
• Measured loss levels evolved during ICRH, showing dependence on individual antenna operation.

Conclusions:

• The scintillator-based detector is a compact and effective diagnostic for measuring energetic ion losses.
• The probe provides valuable data on ion energy and pitch angle distributions.
• This diagnostic capability enhances the understanding and control of fusion plasma behavior during ICRH.