摘要:

A kinetic formalism of sideband excitation at the multiples of bounce and cyclotron frequencies of electrons trapped in the ponderomotive potential well and a guide field is developed. A positive (negative) slope of the distribution function with parallel energy is necessary for the excitation of upper (lower) sidebands of the bounce frequency. The cyclotron harmonic sideband excitation requires large perpendicular energy; the latter, however, tends to lower the growth rate of bounce harmonic sidebands. In either case the growth rate falls off rapidly with the harmonic number.

ISSN:0031-9171    

DOI:10.1063/1.866847

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The evolution of large scale vortices as coherent structures in a free shear layer and the corresponding energetics in Fourier space are investigated numerically. The results confirm that vortex pairing as a result of selective energy transfer directly to the subharmonic is a rare event when other instability modes are present with random phases. For this naturally perturbed shear flow, vortices are observed to coalesce locally and intermittently in a manner that leaves isolated vortices between paired states. The spatial and temporal intermittency results in a gradual energy transfer from the linearly unstable mode to larger length scales.

ISSN:0031-9171    

DOI:10.1063/1.866848

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A simple model is presented that yields analytical expressions for the heating efficiency of beat‐wave excitation in a plasma with a linear density profile. The effect of self‐consistent Landau damping by tail electrons is included without recourse to WKB approximations.

ISSN:0031-9171    

DOI:10.1063/1.866849

出版商:AIP    

年代:1988

数据来源: AIP

ISSN:0031-9171    

DOI:10.1063/1.867029

出版商:AIP    

年代:1988

数据来源: AIP