摘要:

Measurements are reported of the thermal diffusion factor for mixtures of carbon dioxide with argon, with krypton, and with xenon. For the first, the thermal diffusion factor passes through a positive minimum value, and Waldmann's conclusion, from his study of the diffusion thermo‐effect, that the thermal diffusion factor increases with decreasing temperature in the range 400–200°K is confirmed. For the other mixtures, the thermal diffusion factor becomes negative as the temperature decreases, and there is no indication of a minimum value in the accessible temperature range.

ISSN:0031-9171    

DOI:10.1063/1.1711393

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Measurements of the thermal conductivity of SO2by the line source method over the range 295°–887°K are presented. These measurements are compared with existing experimental data and theoretical results using the modified‐Eucken equation. Values of the collision number for rotation relaxation are obtained using the heat conductivity theory of Mason and Monchick for polyatomic gases.

ISSN:0031-9171    

DOI:10.1063/1.1711394

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

A transformation is derived from first principles to reduce the boundary‐layer equations for a general compressible two‐dimensional flow to incompressible form. For the case of boundary‐layer flow of a Newtonian fluid past a smooth wall, but with no other restrictions, it is shown that the combination (&rgr;∞&mgr;∞/&rgr;w&mgr;w)CfRe&thgr;is an invariant of the transformation. This result is called the law of corresponding stations. In order to apply the transformation to the problem of the turbulent boundary layer on a smooth wall, it is assumed that the sublayer Reynolds number is unaffected by compressibility or heat transfer provided the density and viscosity are evaluated at a mean sublayer temperature defined by the transformation. Explicit formulas are obtained for the effect of Mach number and heat transfer on surface friction when the fluid is a perfect gas, the pressure is constant, and the stagnation temperature is constant or linear in the velocity. An appendix contains a brief critical discussion of the mean‐temperature hypothesis, the laminar‐film hypothesis, and other analytical ideas related to the idea of a transformation.

ISSN:0031-9171    

DOI:10.1063/1.1711395

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The investigation of idealized detonations in a two‐reaction A&rlarr2;B, A&rlarr2;C medium is extended to consideration of the one‐dimensional piston problem for cases in which strictly steady flows are not possible. On easing the steady‐state assumption so as to allow two (steady) waves of different velocity, the weak detonation can no longer be excluded on the basis of ``structural stability''. For the parallel‐reaction case in which both reactions are exothermic but the first is at least twice as energetic as the second, the weak detonation solution is proposed when the second reaction is sufficiently slow. Slight overdrive is shown to yield two‐wave detonations involving either a diffuse shock or a second detonation wave following the weak detonation. At sufficient overdrive the two waves merge into a strong detonation. The regimes of relative rate and piston velocity appropriate to the various situations are given numerically for several values of the other parameters.

ISSN:0031-9171    

DOI:10.1063/1.1711396

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Langmuir‐type probes consisting of a flat‐headed circular cylinder with a collecting electrode at the stagnation point are placed in a shock tube and exposed to supersonic ionized air flow at ion mass fractions less than 10−4and initial shock tube pressure of 1 cm Hg. Stagnation point measurements of ion current density are obtained using negative electrode potentials. The exact gasdynamic stagnation point boundary layer equations and the one‐dimensional Poisson equation are solved for an axially symmetric blunt body and ion mass fractions less than 10−2. Calculations of the ion‐electron flow in the stagnation point boundary layer are presented for negative electrode potentials. The measurements and calculations agree within the experimental accuracy and the precision to which the physical constants are known.

ISSN:0031-9171    

DOI:10.1063/1.1711397

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Reflection measurements have been made of very low power X‐band microwaves, axially incident on shock‐produced xenon and krypton plasmas. The electron density profile at the advancing shock front was measured with a special high‐resolution transverse 60‐kMcps interferometric probe. On comparison with free space exponential plasma‐microwave interaction theory, the measured reflection coefficients were always found to be very significantly lower than the theoretical values, the greatest disagreement being at the lowest plasma densities.

ISSN:0031-9171    

DOI:10.1063/1.1711398

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Plasma rotation in a &thgr;‐pinch is analyzed theoretically on the basis of the mechanism proposed by Haines. The torque on the plasma is assumed to be due to the interaction of an axial Hall current with a weak transverse magnetic field component normal to the plasma axis. Such a transverse magnetic field is present when multipole fields of Ioffe type are used to prevent radial plasma drift. The Hall currents arise from the interaction of the main &thgr; current with the transverse magnetic field. The problem is simplified by ignoring radial and axial plasma motion and assuming the plasma to be incompressible. The resistive decay of the plasma currents and the distortion of the initial transverse magnetic fields by the Hall currents are shown to be of primary importance in determining the characteristic growth time of rotation and the maximum rotational velocity. The condition for the appearance of flute instabilities as a result of plasma rotation is briefly discussed.

ISSN:0031-9171    

DOI:10.1063/1.1711399

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The stability properties of a semi‐infinite inhomogeneous electron plasma in a uniform positive background are examined by using the Vlasov approximation. It is assumed that the perfect absorbing plane atx= 0 is a cathode emitting electrons. It is shown that equilibrium solutions with an electron excess everywhere in the half plane are stable, whereas those solutions which exhibit a positive space charge are unstable provided the maximum accelerating potential is roughly greater than 5kT. The growth rates are on the order of (1/2&pgr;)(4&pgr;e2N/m)½.

ISSN:0031-9171    

DOI:10.1063/1.1711400

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Plasma with a density gradient supported in a strong, nearly uniform magnetic field is liable to resistive, gravitationally (g‐) driven instability and short‐wave drift instability. Waves associated with both propagate almost perpendicular to the field lines. Only a lowg, and low density plasma are considered, for which these flutelike perturbations remain quasi‐electrostatic, so that dispersion relations are readily found. When the magnetic‐field lines are sheared the localized perturbations which arise are treated by a phase‐integral approximation and growth rates appear as eigenvalues of certain standard equations. The ions are treated throughout by the Vlasov equation so that fine‐scale features such as finite ion Larmor radiusaiand Hall current are correctly included. The results for the resistive, gravitational instability are compared with those based on fluid equations and are valid if the perturbation is not localized withinai.

ISSN:0031-9171    

DOI:10.1063/1.1711401

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The properties of a nonadiabatic magnetic system for trapping and confining charged particles are derived. The trapping mechanism is a helical perturbation that matches the gyrations of an incoming particle beam. These particles, in resonance with the structure, convert their axial energy into transverse energy even in the absence of a magnetic mirror. By the same scheme, a spiraling beam could be straightened out. The best injection system is a four‐conductor set, which is analyzed in detail. Once confined, the particles experience small and almost random nonadiabatic perturbations in their motion; they diffuse in both real and velocity space. A linear operator that governs this diffusion is presented; it is applicable to a uniform magnetic field with small perturbations. The velocity‐space diffusion in a magnetic mirror is calculated for a general perturbation and in particular for a helical perturbation. For this last case, the injected particles can be confined for several hundred axial transits. If the charged particles are modified after being initially trapped (e.g., dissociation of molecular ions), the loss in physically realizable systems can be made virtually negligible compared with charge transfer and other conventional losses.

ISSN:0031-9171    

DOI:10.1063/1.1711402

出版商:AIP    

年代:1964

数据来源: AIP