摘要:

The three wave equations in the limit where the waves at the upper two frequencies are undamped and the lowest frequency mode is heavily damped so that its dynamic equation becomes &ggr;3a3=K*a1a2,are considered.These equations are solved (by quadrature) in two dimensions and time subject to arbitrary initial and boundary conditions. Illustative examples arising in tokamak heating by lower hybrid waves are presented.

ISSN:0031-9171    

DOI:10.1063/1.861772

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The nonlinear Schro¨dinger equation, with complex coefficients that describe growth and damping, is considered. An exact stationary soliton solution is found for arbitrary growth and damping strength.

ISSN:0031-9171    

DOI:10.1063/1.861773

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A numerical solution of the damped nonlinear Schro¨dinger equation is compared to analytical predictions that assume invariance of the soliton shape. The agreement is fair for the damping laws of the form &ggr;k∞‖k‖b. Good agreement is found for &ggr;k∞k2, and this case is studied analytically including second order effects of the damping.

ISSN:0031-9171    

DOI:10.1063/1.861774

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The steady‐state temperature profiles in a magnetically confined cylindrical plasma obtained by balancing Ohmic power input and thermal diffusion are shown to exhibit a bifurcation as a function of the applied electric field. A linear stability analysis predicts that the upper (high temperature) branch is unstable and that the lower branch is stable. These results agree with those of a transport code that uses the steady‐state profiles as initial conditions. The transport calculation reveals that the upper solution decays to the lower solution with a growth rate that is in agreement with the linear stability computation.

ISSN:0031-9171    

DOI:10.1063/1.861775

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The simultaneous presence of tearing modes of different helical pitches leads to the destruction of magnetic surfaces, which has been suggested as the mechanism leading to the onset of the disruptive instability in tokamaks. For current profiles in which them=2 mode is unstable, but them=3 is stable, the coupling of them=3 to them=2 through the poloidal variation of the toroidal field can drive them=3 amplitude &psgr;3to order &psgr;2times the inverse aspect ratio. Detailed calculations, including nonlinear effects, have been performed for two models for the equilibrium andm=2 mode structure. A slab model and incompressiblem=3 perturbations are assumed. Them=3 amplitude increases with shear, up to a point, showing that as the current channel shrinks, overlap of resonances becomes more likely. Our results also apply qualitatively to otherm,m±1 interactions.

ISSN:0031-9171    

DOI:10.1063/1.861776

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The local linear dispersion relation for the hot ion cyclotron beam‐whistler mode instability near the leading edge of parallel shock waves is generalized into a WKB eigenvalue problem. Its solution reveals the existence of stationary eigen growth modes capable of generating turbulence in the leading edge region.

ISSN:0031-9171    

DOI:10.1063/1.861741

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A highly turbulent beam plasma steady state which completely annihilates the beam has been studied experimentally. A large fraction of the entering beam power appears in a wideband spectrum of longitudinal electrostatic waves. A scaling law relating power spectral density to velocity space particle flux has been derived and applied to this interaction. Its predictions are in excellent agreement with experimental behavior.

ISSN:0031-9171    

DOI:10.1063/1.861777

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Measurements of strong absorption of high frequency (&ohgr;≃&ohgr;c, &ohgr;/2&pgr;=2.45 GHz electromagnetic waves in a plasma (&ohgr;p2/&ohgr;2=2.7) are reported. The absorption is almost complete; the transmitted power is less than 0.1% and the reflected power is less than 5%. Coincident with the onset of strong absorption is the appearance of microwave energy in the plasma in two frequency bands, and an increase in the electron temperature (from 6 to 10 eV). One frequency band is close to the plasma frequency (&ohgr;p/2&pgr;≃4 GHz); the second is a low frequency band below 2 GHz. These modes are identified as being of the Gould–Trivelpiece type. Wave amplitude, combined with transmitted and reflected power measurements, suggest that 95% or more of the incident energy may be converted into the low frequency modes which are trapped in the plasma and thus can be dissipated via resistive absorption.

ISSN:0031-9171    

DOI:10.1063/1.861778

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

An asymptotic solution is given for the ion‐drift‐kinetic equation with a full Fokker–Planck term for the limiter‐scrape‐off layer in a tokamak. In this layer, the plasma is assumed to consist of hot, collisionless ions, and cold, collisional electrons. From the solution of the boundary‐layer problem, ion and electron particle and energy losses to the limiter are calculated. Limiter load profiles due to ions are explicitly given as functions of the poloidal angle.

ISSN:0031-9171    

DOI:10.1063/1.861779

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A study of the Be´nard problem under the influence of a random gravitational field. It is shown that under these conditions the fluid may be slightly destabilized.

ISSN:0031-9171    

DOI:10.1063/1.861715

出版商:AIP    

年代:1977

数据来源: AIP