摘要:

The curvature‐driven flute instability in an axisymmetric mirror was stabilized by an annular line‐tied plasma blanket. A significant temperature difference was maintained between core and blanket. Theoretical calculations support the experimental observations.

ISSN:0031-9171    

DOI:10.1063/1.863931

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Observations are reported on a nonlinear, three‐wave interaction process occurring during high‐power electron cyclotron heating in the Versator II tokamak. The measured spectra and the threshold power are consistent with a model in which the incident power in the extraordinary mode of polarization decays at the upper‐hybrid resonance layer into a lower‐hybrid wave and an electron Bernstein wave.

ISSN:0031-9171    

DOI:10.1063/1.863932

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

It is demonstrated that the free energy associated with the sheared flow induced by the parallel variations of drift frequencies can provide a new destabilizing term. In particular, we show the existence of a magnetohydrodynamic‐like instability which may occur in the mirror end plugs or thermal barrier region of a tandem mirror fusion device.

ISSN:0031-9171    

DOI:10.1063/1.863933

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

By considering the effect of finite aspect ratio, the neoclassical ion thermal conductivity has been found to be significantly larger than reported by Hazeltine, Hinton, and Rosenbluth. A simple correction to the expression of Hinton and Hazeltine is suggested.

ISSN:0031-9171    

DOI:10.1063/1.863934

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Measurements are presented for the drag on a torus moving along its axis of rotational symmetry at low Reynolds number. IfDis the outside diameter of the torus, anddis the thickness in the axial direction, then the measurements cover the ranges0= 1 (the closed torus) tos0= 135, wheres0≡(D/d)−1. The effect of a coaxial cylindrical boundary (diameterH) is taken into account by an empirical correlation. The values of drag obtained by extrapolating to a fluid of infinite extent are in good agreement with the exact solution obtained by Majumdar and O’Neill. When &pgr;d(s0)1/2≪H, the empirical boundary correlation is consistent with the result of Brenner for a particle of arbitrary shape. Measurements with outer boundaries of square and circular cross section indicate that the relative effect of the two boundary shapes on the drag is the same for the torus as that found by Happel and Bart for a sphere. Empirical results are presented for the case in which the torus is strongly influenced by a coaxial cylindrical boundary.

ISSN:0031-9171    

DOI:10.1063/1.863935

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The mean field equations, which contain no explicit Prandtl number dependence, are shown to provide reasonably accurate predictions of average heat transport for Rayleigh numbers from 2000 to 18000 over a wide range of Prandtl numbers, provided physically observed wavenumbers are used in the calculations. It is concluded from this that the physical significance of Prandtl number in Be´nard convection is principally in setting the ’’preferred’’ wavenumber, i.e., the size of the convection cell.

ISSN:0031-9171    

DOI:10.1063/1.863936

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

This paper reports an experimental study of the nonaxisymmetric flow of a fast liquid jet discharging into the atmosphere. The nonaxisymmetric shape of the jet was photographed and subjected to a wavelength analysis. The results of the wavelength analysis demonstrate that the jet shape is governed by a narrow band of wavelengths associated with a characteristic value &lgr;maxwhich scales with the jet diameterD. It is shown that the experimental observations are in agreement with predictions based on hydrodynamic stability theory and buckling theory.

ISSN:0031-9171    

DOI:10.1063/1.863937

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The validity of kinematic wave theory for linear waves with small dissipation propagating through a homogeneous medium is examined with the aid of the higher‐order theory of Chin. It is shown that both for nondissipative and weakly‐dissipative waves the kinematic theory holds with errors of order &egr;2for times of order &egr;−1times the wave period, where &egr; is a measure of the nonuniformity of the wave train. For longer times, of order &egr;−2times the period, secular terms arise, which makes the theory invalid when wave dispersion becomes vanishingly small. By selecting a complex wavenumber chosen such as to make the group velocity real, it is possible to remove the first‐order secular terms and thus produce a modified theory uniformly valid within the longer time period. This modification is also applied to wave trains propagating in a nonhomogeneous medium. General solutions are presented for wave trains or packets of arbitrary initial conditions.

ISSN:0031-9171    

DOI:10.1063/1.863930

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

This paper continues an earlier study by S. A. Maslowe of inviscid asymmetric disturbances to flow with rotation along a pipe. It is shown that there is a class of neutral modes with a critical layer near the wall of the pipe when the azimuthal wavenumber is large and negative. Analytic and numerical properties of these modes are studied and found to lead to consistent results, notable among which is the severe singularity in the disturbance velocity at the critial level. Some of the properties of the most unstable modes are also examined.

ISSN:0031-9171    

DOI:10.1063/1.863938

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A nonlinear analysis is presented for the case of second‐harmonic resonant interactions on the interface of a liquid film and a supersonic gas stream. The analysis takes into account the effects of the gas viscosity and mean profiles. Moreover, the extent of the gas disturbance layer is not restricted to the region in which the mean profiles are linear. Self‐sustained oscillations are calculated for low and intermediate liquid Reynolds numbers. The present solution is compared with available experimental data. The predicted and observed wave amplitudes, wavenumbers, and frequencies are in good agreement for intermediate liquid Reynolds numbers. The calculated amplitudes overpredict the observed values by about a factor of three for low liquid Reynolds numbers.

ISSN:0031-9171    

DOI:10.1063/1.863939

出版商:AIP    

年代:1982

数据来源: AIP