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Controlled optimization of mode conversion from electron Bernstein waves to extraordinary mode in magnetized plasma
B Jones1, P C Efthimion, G Taylor
1Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA.
Physical Review Letters
|May 7, 2003
Summary
Efficient conversion of electron Bernstein waves to X mode was achieved in the CDX-U spherical torus. Controlling electron density scale length optimized wave conversion, supporting heating and current drive applications.
Area of Science:
- Plasma physics
- Fusion energy research
Background:
- Electron Bernstein waves are a key component of plasma emissions.
- Efficient conversion to the X mode is crucial for plasma diagnostics and heating.
Purpose of the Study:
- To investigate the conversion efficiency of electron Bernstein waves to the X mode in a spherical torus.
- To determine the optimal conditions for maximizing this wave conversion process.
Main Methods:
- Utilized the CDX-U spherical torus.
- Employed Thomson scattering for electron temperature measurements.
- Controlled electron density scale length (L(n)) using a local limiter.
Main Results:
- Achieved approximately 100% conversion of electron Bernstein waves to the X mode.
- Demonstrated agreement between radiation temperature and Thomson scattering electron temperature profiles.
- Shortened L(n) to the theoretically required value for optimal conversion.
Conclusions:
- The study confirms efficient wave conversion in the CDX-U spherical torus.
- The method of controlling L(n) is effective for optimizing wave conversion.
- Results strongly support prospects for efficient coupling in heating and current drive scenarios.
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