Nonlinear radial propagation of drift wave turbulence
Linear and nonlinear radial propagation of drift-wave energy in an inhomogeneous plasma was studied. The drift mode excited in such a plasma is dispersive in nature. The drift-wave energy spreads out symmetrically along the direction of inhomogeneity with a finite group velocity. To study the effect of the nonlinear coupling on the propagation of energy in a collision free plasma, the Hasegawa-Mima equation is solved as a mixed initial boundary-value problem. Solutions of the linearized equation are used to check the reliability of the numerical calculations. Additional checks are also performed on the invariants of the system. Results reveal that a pulse gets distorted as it propagates through the medium. The peak of the pulse propagates with a finite velocity that depends on the amplitude of the initial pulse. The polarity of propagation depends on the initial parameters of the pulse. Also studied was drift wave propagation in a resistive plasma. The Hasegawsa-Wakatani equations are used to investigate this problem. Results of the numerical calculations show that the resistive drift wave grows as it propagates through the medium. For spatially dependent resistivity, the peak of the pulse propagates in the direction of decreasing resistivity. Polarity of propagation is independent of the phases of the initial pulse. Results of the calculations are explained framework of weak turbulence theory. These results provide qualitative insights into the phenomenon of drift wave turbulence observed in tokamak plasmas.
- OSTI ID:
- 6956960
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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