摘要:

By means of the cold electron plasma equations, we have shown that surface soliton solutions can exist in semi‐infinite plasmas.

ISSN:0031-9171    

DOI:10.1063/1.863852

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The two‐dimensional dynamics of nonlinear ion‐acoustic waves in plasmas are considered. A new nonlinear equation is found which is valid for unmagnetized as well as magnetized plasmas. For exactly vanishing magnetic fields, the Kadomtsev–Petviashvili equation is recovered; for weak magnetic fields, however, the dynamics are qualitatively different from that equation, depending on amplitude. With increasing magnetic field, the new equation becomes similar (but not identical) to the Zakharov–Kuznetsov equation which was derived for very strong magnetic fields. The stability behavior of plane solitons propagating along the magnetic field is also discussed. The transition from stable to unstable behavior and some quantitative new results for the instability growth rates are presented.

ISSN:0031-9171    

DOI:10.1063/1.863853

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Scattering of waves in the ion cyclotron range of frequencies by low‐frequency fluctuations is analyzed in the weak turbulence approximation. Finite‐ion‐Larmor radius, multi‐ion species, ion‐drift motion, and electromagnetic terms are included in the wave kinetic equation. Conditions for significant scattering have been identified for the fast wave as well as for externally launched ion Bernstein waves. Implications for the ion cyclotron range of frequency heating in tokamak plasmas are discussed.

ISSN:0031-9171    

DOI:10.1063/1.863861

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The effects of plasma waves on the electron runaway production rate is studied. For a wave packet with a one‐dimensional spectrum directed along the electric field and with a phase velocity range containing the critical velocityvcfor runaway, the runaway production rate is found to be enhanced by many orders of magnitude. For an isotropic wave spectrum, however, the runaway production rate is reduced because of the wave‐enhanced pitch angle scattering.

ISSN:0031-9171    

DOI:10.1063/1.863834

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Electric field and plasma density fluctuations have been observed in the range 0.2⩽k⊥ &rgr;⩽15 in association with a long wavelength naturally occurring plasma instability. The observed spectral form and amplitude of the waves is in excellent agreement with predictions for drift waves.

ISSN:0031-9171    

DOI:10.1063/1.863854

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A study is made of the effects of curvature of the magnetic field on the drift‐dissipative instability of a nonuniform plasma. It is found that inward curvature of the static magnetic field stabilizes the drift instability produced by the particle collisions.

ISSN:0031-9171    

DOI:10.1063/1.863855

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Energy equations are derived from kinetic theory for plasmas in a bumpy torus. It is shown that the work done by the poloidal electric field on the precession motion of the particles should not appear in the energy equation. Both finite‐ and low‐&bgr; cases are examined.

ISSN:0031-9171    

DOI:10.1063/1.863856

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The discrete nature of the toroidal magnetic field coils spoils the symmetry of the tokamak and creates small modulations of the toroidal field called ripples. Particles trapped in the ripple well drift off the flux surface and enhance both particle and heat fluxes. In the usual ripple transport calculations, the derivative of the perturbed particle distribution function in velocity space is discontinuous at the boundary between the ripple trapped and untrapped regions. To smooth out the particle distribution across the boundary, the particle distribution in the boundary layer is calculated by using the Wiener–Hopf technique. The correction to the ripple‐trapped particle distribution function away from the boundary layer and the ripple transport associated with it are obtained. It is found that the particle diffusion and heat conduction coefficients are increased by about a factor of 2 and scale like &ngr;−1/2as (&ngr;eff/&ohgr;b&dgr;)1/2→1. Even for very collisionless plasmas, &ngr;eff/&ohgr;b&dgr;= 10−2, the corrections are still non‐negligible and are about 15%.

ISSN:0031-9171    

DOI:10.1063/1.863857

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A kinetic ballooning mode equation retaining full finite ion Larmor radius and ion magnetic drift resonance effects is derived by employing the highnballooning mode formalism. It is found that the critical &bgr; is smaller than the ideal magnetohydro‐dynamic critical &bgr;, except that when &eegr;i=O(&eegr;i≡d ln Ti/d ln N), that are identical. The finite Larmor radius effects reduce the growth rate but do not stabilize the mode. The ion magnetic drift resonance effects are destabilizing.

ISSN:0031-9171    

DOI:10.1063/1.863858

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The nonlinear development of magnetic reconnection in an isolated current‐sheet system is studied numerically. The reconnection processes develop from an initial small disturbance under different sets of typical boundary conditions. The following distinct macroscopic characteristics are shown. In a situation where plasma can freely flow out of or into the system, the fast reconnection mechanism by which the stored magnetic energy can explosively be released is set up. The magnitude of the initial disturbance influences the onset time of the fast reconnection but has little effect on the established configuration of fast reconnection. Also, even in the presence of impermeable walls placed at the top and bottom boundaries, the fast reconnection is eventually available, so that the fast reconnection process is regarded as a gross instability inherent to the system itself. On the other hand, in the tearing‐type field geometry with impermeable walls, plasma confinement in magnetic islands prevents the fast reconnection from taking place and finally leads to an oscillation on the nonlinear saturation level.

ISSN:0031-9171    

DOI:10.1063/1.863859

出版商:AIP    

年代:1982

数据来源: AIP