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Nonlocal magnetic-field generation in plasmas without density gradients
1Plasma Physics Group, Blackett Laboratory, Imperial College, London SW7 2BZ, United Kingdom.
Physical Review Letters
|January 22, 2002
Summary
Spontaneous magnetic field generation in collisional plasmas can occur due to nonuniform heating, challenging existing theories. This finding, revealed by a 2D Fokker-Planck code, highlights the role of nonlocal effects in plasma physics.
Area of Science:
- Plasma Physics
- Laser-Plasma Interactions
- Magnetohydrodynamics
Background:
- Standard theories link magnetic field generation in laser-driven plasmas to density gradients or anisotropic pressure.
- Previous models often employed local approximations, potentially overlooking crucial physical mechanisms.
Purpose of the Study:
- To investigate spontaneous magnetic field generation in collisional plasmas under conditions not typically predicted by conventional theories.
- To explore the role of nonlocal effects in laser-plasma interactions.
Main Methods:
- Utilized the first two-dimensional Fokker-Planck code capable of self-consistently including magnetic fields.
- Simulated a collisional plasma subjected to nonuniform heating.
Main Results:
- Demonstrated spontaneous magnetic field generation even with uniform density (delta n = 0) and isotropic pressure.
- Observed magnetic fields strong enough to significantly influence plasma transport.
- Identified nonlocal effects as the driving mechanism for this spontaneous generation.
Conclusions:
- Nonlocal effects in collisional plasmas can drive spontaneous magnetic field generation, independent of density gradients or anisotropic pressure.
- The findings necessitate a revision of existing local theories for magnetic field generation in laser-produced plasmas.
- The generated magnetic fields have significant implications for understanding and controlling transport processes in plasmas.
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