摘要:

Spatial localization of bursts of the drift cyclotron loss cone instability in a mirror machine is caused by asymmetric motion of the background plasma. The dynamic behavior of the plasma determines the appearance of the instability

ISSN:0031-9171    

DOI:10.1063/1.865405

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Some discrepancies are pointed out for kinetic and fluid dispersion relations of low‐frequency electrostatic modes in tokamaks. It is shown that both electrons and ions contribute to the ballooning term, which is subject to finite ion Larmor radius correction.

ISSN:0031-9171    

DOI:10.1063/1.865002

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The absorption of electron cyclotron waves in a hot, dense tokamak plasma is investigated for the case of the extraordinary mode for outside launching. It is shown that, for electron temperaturesTe≥5 keV, strong absorption occurs for oblique propagation at frequencies significantly below the electron gyrofrequency at the plasma center. A new density dependence of the wave absorption is found which is more favorable for plasma heating than the familiarn−1escaling.

ISSN:0031-9171    

DOI:10.1063/1.865003

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A rigorous proof is presented which shows that the classical Young–Laplace equation cannot predict a continuous liquid layer inside a spherical‐shell container. An augmented Young–Laplace equation is in turn derived to describe the equilibrium profiles of a continuous liquid hydrogen layer inside a spherical‐shell inertial fusion target. The augmentation is achieved by adding to the total free energy a term originating from the attractive intermolecular forces of the van der Waals type.

ISSN:0031-9171    

DOI:10.1063/1.865004

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Shape oscillation and fission of drops of an oil in water were studied photographically. Novel theoretical results are also presented concerning the resonance response of drops. The initial radii of the drops observed were typically between 1 and 2 mm. Two‐lobed oscillations of moderate amplitude were driven by the temporally modulated radiation pressure of an ultrasonic wave. The tendencies for drops to elongate and break are discussed qualitatively. The oil is more compressible than water. Radiation stresses repel the oil from pressure nodes of the ultrasonic standing wave. The excitation of a transient deformation that appears to run around the drop’s surface is noted.

ISSN:0031-9171    

DOI:10.1063/1.865005

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The wave height and wavelength of wavy Taylor vortices have been measured in a fluid column of aspect ratio 31 and radius ratio 0.88. The fluid was either water or 10 cS silicone oil. The wave height as well as the wavelength were found to increase with Reynolds number until 1.8Rcfor a state with 15 pairs of vortices and four azimuthal waves. Subsequent changes in the wave height and azimuthal wavenumber seem to be primarily caused by changes in the number of vortices which are caused by the increase of the wavelength.

ISSN:0031-9171    

DOI:10.1063/1.865006

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The numerical continuation and bifurcation methods of Keller [H. B. Keller, inApplicationsofBifurcationTheory(Academic, New York, 1977), pp. 359–384] are used to study the variation of some branches of axisymmetric Taylor vortex flow as the wavelength in the axial direction changes. Closed ‘‘loops’’ of solutions and secondary bifurcations are determined. Variations with respect to Reynolds number show the same phenomena. The results presented here show that Taylor vortices with periodic boundary conditions exist in a wider range of wavelengths, &lgr;, than observed in the Burkhalter/Koschmieder experiments [Phys. Fluids17, 1929 (1974)]. They also show that there is possibly a &lgr; subinterval within the neutral curve of Couette flow such that there are no Taylor vortex flows with smallest period in this interval.

ISSN:0031-9171    

DOI:10.1063/1.865007

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The Kelvin–Helmholtz stability problem is studied by employing the variational method. With the restriction to a single dominant spatial mode, a set of fully nonlinear evolution equations is derived. The limiting states of these evolution equations are discussed and their stability is analyzed. It is found that at the critical point for the linear stability problem, another stable limiting state with finite amplitude appears. A nonlinear sinusoidal wave state is also found. The nonlinear dispersion relation for this wave is derived. The wavenumber of the dominant spatial mode and its evolution with time can also be determined with the aid of the variational method.

ISSN:0031-9171    

DOI:10.1063/1.865008

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The method of multiple scales is used to determine three partial differential equations describing the modulation of the amplitude and complex wavenumbers of three‐dimensonal (3‐D) waves propagating in two‐dimensional (2‐D) heated liquid layers. These equations are solved numerically along the characteristics subject to the condition that the ratio of the complex group velocities in the streamwise and transverse directions be real. A new criterion for the most dangerous frequency is proposed. For annfactor of 9,F=25×10−6is found to be the most dangerous frequency for the Blasius flow. Three‐dimensional waves yield lowernfactors than 2‐D waves, irrespective of the heating distribution. For a power‐law heating distribution of the formT=Te+AxN, one cannot make a general statement on the effect ofNon the stability. Numerical results are presented that show thenfactor to increase with an increase or a decrease inN.

ISSN:0031-9171    

DOI:10.1063/1.865009

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Axisymmetric contoured Laval nozzles have been calculated in order to obtain uniform supersonic flow. For nitrogen and oxygen gases the calculation uses only similarity techniques, but for helium, complete calculations of the isentropic core and the boundary layer were performed for two sets of boundary conditions. Experimental testing has shown that the nitrogen or oxygen flows exhibit a good uniformity but that the helium flow was uniform only for one set of boundary conditions. The purpose of this work is to provide flow reactors for studies of ion‐molecule reactions in the real temperature range of interstellar clouds (T<80 °K).

ISSN:0031-9171    

DOI:10.1063/1.865010

出版商:AIP    

年代:1985

数据来源: AIP