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Neoclassical transport caused by collisionless scattering across an asymmetric separatrix
Daniel H E Dubin1, C F Driscoll, Yu A Tsidulko
1Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
Physical Review Letters
|January 15, 2011
Summary
Apparatus asymmetries enhance plasma loss in magnetic confinement. Asymmetric separatrix structures allow particles to move between trapped and passing states without collisions, significantly increasing plasma transport.
Area of Science:
- Plasma physics
- Magnetic confinement fusion
- Astrophysical plasma dynamics
Background:
- Plasma loss due to asymmetries is a significant challenge in magnetic plasma confinement devices.
- Standard theories describe plasma transport based on collisional scattering between trapped and passing particle populations.
- The presence of a separatrix partitions these particle populations, influencing their response to asymmetries.
Purpose of the Study:
- To investigate the enhanced plasma transport mechanisms in magnetic confinement systems with asymmetric separatrix structures.
- To analyze the behavior of trapped and passing particles under asymmetric conditions.
- To explore the impact of collisionless transitions between particle orbits on overall plasma loss.
Main Methods:
- Theoretical analysis of particle orbits in asymmetric magnetic fields.
- Application of superbanana orbit theory to model transport regimes.
- Investigation of particle scattering and transit phenomena across the separatrix.
Main Results:
- Asymmetric separatrix structures lead to enhanced plasma transport beyond standard collisional regimes.
- Particles can transition between trapped and passing states collisionlessly when the separatrix is asymmetric.
- This collisionless transit significantly amplifies plasma loss compared to systems with symmetric separatrix.
Conclusions:
- Asymmetric separatrix design is a critical factor influencing plasma confinement efficiency.
- Understanding collisionless particle dynamics across asymmetric separatrix is crucial for mitigating plasma loss.
- The findings have implications for optimizing magnetic confinement fusion reactor designs and astrophysical plasma models.
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