摘要:

The continuous magnetohydrodynamic spectrum is investigated for axially symmetric equilibria in which the plasma rotates toroidally in a purely poloidal magnetic field. The flow continuum is given by a simple algebraic expression, while the Alfve´n‐ and cusp continua (which are coupled through the Coriolis force) are given by the eigenvalues of a fourth‐order non‐self‐adjoint problem in ordinary differential equations along magnetic field lines. It is shown that these continua are stable if the entropy does not increase along the field lines away from the rotation axis, but that the cusp continuum may turn unstable otherwise.

ISSN:0031-9171    

DOI:10.1063/1.862655

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An investigation of equilibrium, stability, and space‐charge‐ limiting current of a solid relativistic beam propagating along a finite external magnetic field has been carried out and compared with experiments. The concept of a rigid‐rotor equilibrium is only approximately valid when the beam current is much less than the Alfve`n critical current. Typically, low‐voltage beams rotate fastest at the beam edge whereas high‐voltage beams rotate fastest near the beam axis. A limited investigation of the rigid rotor stability condition indicates, at worst, a weak instability may be present if the rigid‐rotor equilibrium is artificially imposed, and no instability at all for a self‐consistent equilibrium. Numerical solutions for the space‐charge limiting current and relativistic factor on axis are presented and compared with two‐dimensional, cylindrical, space‐ and time‐dependent simulations. Analytical expressions for the limiting current are valid for &ohgr;c/&ohgr;b≳5, where &ohgr;cis the cyclotron frequency and &ohgr;bis the beam frequency. For external magnetic field strengths below this level, the limiting current increases monotonically with decreasing field strength until the beam collides with the drift tube. Expressions for foil scattering are also presented. The results are in good agreement with experiments.

ISSN:0031-9171    

DOI:10.1063/1.862633

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The general form of the quasi‐linear equation is derived for plasmas in which there is a finite amplitude pump wave. Electrostatic turbulence is considered and the pump wave is treated in the dipole approximation. Appropriate number, momentum, and energy moment constraints are shown to be computable from the diffusion equation. The derivation of anHtheorem indicates that the quasi‐linear diffusion of parametric instabilities always tends to an accessible asymptotic steady state.

ISSN:0031-9171    

DOI:10.1063/1.862656

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The dissipative trapped electron instability is observed in the linear multi‐mirror experiment. This instability is observed in two forms, one driven by the electron temperature gradient, and one driven by finite Larmor radius effects. The experimental results are in reasonable agreement with the theoretical predictions of the linear dispersion relation.

ISSN:0031-9171    

DOI:10.1063/1.862657

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The general form of the scattered spectrum from a plasma in which the electrons and ions are allowed to have Maxwellian velocity distribution functions with temperatures in the three major directions unequal is calculated. The general structure is shown annd the possibility of measuring the direction of anisotropy in a plasma using this structure is discussed.

ISSN:0031-9171    

DOI:10.1063/1.862634

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A Newtonian liquid was observed to climb up a rotating shaft whose tip was initially just in contact with the liquid surface. This phenomenon occurred when the rotation speed was increased above a certain threshold. An energy transfer mechanism is suggested as a possible explanation.

ISSN:0031-9171    

DOI:10.1063/1.862658

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Experimental observations of a fully developed round jet entering a second, less dense, immiscible liquid reveal that cocurrent flow of the outer fluid can eliminate instabilities. Both helical and axisymmetric disturbances were observed.

ISSN:0031-9171    

DOI:10.1063/1.862659

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Beyond a critical shear rate, laminar flows of polymer solutions display an excess pressure drop, &Dgr;Pe, localized at the capillary tube entrance and linearly shear dependent. The measured pressure drop represents the viscous contribution and the elastic effects &Dgr;Pe. The relative apparent viscosity is therefore determined.

ISSN:0031-9171    

DOI:10.1063/1.862660

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Nozzle flows are investigated assuming either a strong or a weak vibrational nonequilibrium. The corresponding vibrational temperature evolutions are found to be in disagreement due to the fact that both methods are probably not appropriate for computing the entire flow.

ISSN:0031-9171    

DOI:10.1063/1.862661

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

By means of a variational approach using trial functions, approximate analytical solutions are found for strongly nonlinear one‐dimensional Schro¨dinger equations, in good agreement with numerical results.

ISSN:0031-9171    

DOI:10.1063/1.862626

出版商:AIP    

年代:1979

数据来源: AIP