摘要:

Analytic results are presented for the laser beam deflection rate in the case of spatial and temporal smoothing by induced spatial incoherence (ISI). It is shown that for flow perpendicular to the beam propagation direction with Mach number M, temporal smoothing decreases the beam deflection rate forM>1, but may increase it forM<1and weak acoustic wave damping. ©1997 American Institute of Physics. 

ISSN:1070-664X    

DOI:10.1063/1.872609

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The nonlinear destabilization of pressure driven (ballooning) modes by internal kink modes during sawtooth cycles was found in the Tokamak Fusion Test Reactor (TFTR) [Park &etal;, Phys. Rev. Lett.75, 1763 (1995)]. It is shown by a numerical parameter study, including aspect ratio and magnetic shear profile effects, that in ideal magneto-hydrodynamics (MHD), this nonlinear destabilization occurs in plasma equilibriaclose to marginal stabilityto linear sub-harmonics of the internal kink with toroidal mode numbern⩾3. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872610

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A new theoretical model for the study of the surface-wave–particle interactions in a plasma column in the presence of a constant external magnetic field has been developed. The model is based on the linear resolution of the Vlasov equation by the method of characteristics, with the specular reflection hypothesis at the wall. The expression obtained for the rate of increase of kinetic energy per electron permits the analysis of the influence of the critical parameters in this transference process. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872579

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Linear evolution of electrostatic perturbations in an unmagnetized electron–ion plasma shear flow is studied. New physical effects, arising due to the non-normality of linear dynamics are disclosed. A new class ofnonperiodic collective modewith vortical motion of ions, characterized by intense energy exchange with the mean flow, is found. It is also shown that the velocity shear induces extraction of the mean flow energy by ion-sound waves and that during the shear-induced evolution the ion-sound waves turn eventually into ion plasma oscillations. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872580

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A theory of plasma response to electromagnetic perturbations has been developed based on the full solution to the Fokker–Planck equation in highZplasmas without electron–electron collisions. For the first time the transverse electron susceptibility has been calculated for the entire range of frequencies and wave numbers including the quantitative description of the weakly collisional regime where the wave frequency is comparable to the electron–ion collision frequency and the wave number is comparable to the inverse electron mean free path. The results have been compared to approximate expressions for the electron conductivity based on the Drude model showing discrepancy by a factor of few in regions where the spatial dispersion is important. The theory is applied to the calculation of laser light absorption in solid density plasmas. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872581

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

For an arbitrary monotonic charging function, the dynamics of a dust grain is dissipative and energy is a Liapunov function. In an arbitrary external potential two types of equilibria exist. The first type, with uncharged grain, is always unstable. The second type of equilibrium, admitting states of both positive and negative charge, can be marginally stable; stability depends on the local potential. Under spatially uniform (constant or time-dependent) potentials, motion is free while the charge adapts to the potential. For a spatially oscillating potential, the phase space is that of the simple pendulum with one additional degree of freedom, the charge. Dissipation in the charging process forbids periodic behavior and ensures the existence of attractors: A grain is at stable equilibrium only when charged positively and trapped in a potential well, or when charged negatively on top of a hill. The small oscillations near a stable equilibrium decay weakly, and the grain charge oscillates at twice the oscillation frequency. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872582

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The kinetic theory of transport in an impure, partially ionized, edge plasma is developed. It is found that the thermal force between bulk ions and impurities is enhanced by the presence of neutral atoms, but the dynamical friction is not affected by the neutrals. When the neutral viscosity is large, an additional force on the impurities also arises. This force is parallel to the magnetic field, and is proportional to the shear of the parallel plasma velocity and the perpendicular ion density and temperature gradients. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872583

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The spatiotemporal evolution of near-forward stimulated Brillouin scattering (SBS) is studied in detail. For large scattering angles SBS grows and saturates as a three-wave instability. For small scattering angles SBS begins to grow as a three-wave instability, then continues to grow and saturates as a four-wave instability. Expressions for the saturation time and steady-state gain exponent of SBS are derived for large and small scattering angles. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872584

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The effect of ion and electron drifts on the existence of arbitrary amplitude solitary waves is studied using Sagdeev’s pseudopotential method. It is found that if the electron drift velocityu0is finite, solitary waves may exist for relatively large values ofv0/c,wherev0is the ion drift velocity andcis the velocity of light. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872585

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The problem of nonlinear Burger equation in a plasma contaminated with heavy dust grains has been revisited. As discussed earlier [C. B. Dwivedi and B. P. Pandey, Phys. Plasmas2, 9 (1995)], the Burger equation originates due to dust charge fluctuation dynamics. A new alternate mathematical approach based on a simple traveling wave formalism has been applied to find out the solution of the derived Burger equation, and the method recovers the known shock-wave solution. This technique, although having its own limitation, predicts successfully the salient features of the weak shock-wave structure in a dusty plasma with dust charge fluctuation dynamics. It is emphasized that this approach of the traveling wave formalism is being applied for the first time to solve the nonlinear wave equation in plasmas. ©1997 American Institute of Physics.

ISSN:1070-664X    

DOI:10.1063/1.872586

出版商:AIP    

年代:1997

数据来源: AIP