Coherent four-wave scattering in plasmas: application to plasma diagnostics
An explicit solution for the third-order nonlinear transverse susceptibility and for the scattered power in a collisionless unmagnetized plasma is presented. We show that a consistent second-order approximation of the Vlasov equation that treats on equal footing the electric and the magnetic fields of the electromagnetic waves produces a ponderomotive force term that drives various plasma excitations. In analogy with Thomson scattering from thermal fluctuations, the wavevector and frequency dependence of the scattered power is dominated by the first-order longitudinal susceptibilities of the plasma. Even though the Landau damping may be considerable and the plasma resonances may not be well defined, the coherent nature of this four-photon process produces a considerably enhanced scattered power within a narrow scattering cone. These features make this technique well suited for plasma diagnostics. These techniques are a close counterpart of the coherent anti-Stokes Raman spectroscopy and the Raman-induced Kerr effect spectroscopy used with Raman active transitions in gas, liquid, and solid spectroscopy.
- Research Organization:
- Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- OSTI ID:
- 5723798
- Journal Information:
- Appl. Phys. Lett.; (United States), Vol. 35:10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PLASMA
ELECTROMAGNETIC RADIATION
BOLTZMANN-VLASOV EQUATION
ELECTRIC FIELDS
EXCITATION
FREQUENCY DEPENDENCE
LANDAU DAMPING
MAGNETIC FIELDS
MAGNETIC SUSCEPTIBILITY
MATHEMATICAL MODELS
NONLINEAR PROBLEMS
RESONANCE
SCATTERING
THOMSON SCATTERING
DAMPING
DIFFERENTIAL EQUATIONS
ENERGY-LEVEL TRANSITIONS
EQUATIONS
INELASTIC SCATTERING
MAGNETIC PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
700108* - Fusion Energy- Plasma Research- Wave Phenomena