摘要:

This paper aims at removing certain sources of confusion in plasma theory by deriving a complete set of macroscopic equations based on the ionic theory. Relativistic and quantum effects are usually neglected, and an approximation equivalent to that of the macroscopic theory of irreversible processes is adopted. But there is no other approximation, and in particular multiple interactions are fully accounted for. The theory of the dielectric constant and permeability of plasmas is sketched, and there follows an ionic derivation of the equations of continuity, and of energy and momentum transport, based on an exact separation of the long‐range and short‐range forces. It is shown how the short‐range forces contribute to the pressure, the energy flux, and the flux of entropy. The ionic basis of the theory of irreversible processes is discussed, and its relevance to the generalization of Ohm's law. In an appendix, the formal statistical thermodynamics of plasmas is developed in a way which avoids certain difficulties associated with the long‐range interactions.

ISSN:0031-9171    

DOI:10.1063/1.1724403

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The mean energy of the charged particles of a plasma which is confined in a magnetic field may be increased by increasing the magnitude of the magnetic field in a time which is short with respect to the ion relaxation time (magnetic compression). It is shown that the necessary stored energy can be reduced and the efficiency greatly increased if the magnetic compression is performed in several stages, such that the plasma is compressed and transferred to successively smaller volumes. The predicted transfer behavior has been confirmed by studying the plasma movement in a three‐stage system. In the course of the investigation a plasma source has been developed which provides bursts of plasma of 1016to 1018ions with an average velocity of the order of 107cm/sec.

ISSN:0031-9171    

DOI:10.1063/1.1724404

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A necessary and sufficient condition is derived for a magnetic differential equationB·▿r= 0 to have a single‐valued solutionr, whereBis the field of a magnetohydrostatic equilibrium state or, more generally, and field with a system of toroidal magnetic surfaces.

ISSN:0031-9171    

DOI:10.1063/1.1724405

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A theoretical discussion is given of the propagation of weak hydromagnetic discontinuities (e.g., weak shocks) in an infinitely conducting, perfect, compressible fluid. The undisturbed flow is assumed to be steady and isentropic. As in geometrical optics, the wave fronts evolving from a given initial manifold‐there will be six of them, in general‐are constructed by means of rays. In addition, formulas are derived describing the variation of the discontinuity ``strength'' of a given propagating mode along rays associated with that mode. These results are employed to obtain an explicit solution of a simple mixed initial, boundary‐value problem that has been designed to illustrate, (1) a method of producing hydromagnetic disturbances, and (2) the fact that an initial disturbance gives rise, in general, to several propagating waves.

ISSN:0031-9171    

DOI:10.1063/1.1724406

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The cyclotron emission from a hot, completely ionized, magnetically confined plasma has been estimated by computing the absorption of an incident plane wave. The harmonics of the fundamental cyclotron frequency, which are emitted perpendicular to the magnetic field direction, were summed over and also treated individually. Because of the Doppler effect and the relativistic variation in mass the behavior of the electrons and the electromagnetic properties of the medium are functions of electron velocity.Assuming a Maxwell‐Boltzmann distribution in electron velocity, the polarization of the plasma was computed by integrating over electron velocity. Solution of Maxwell's equations yielded the absorption of an incident wave, and thus, from Kirchhoff's relation, the emission of the plasma was determined. The entire calculation was carried out nonrelativistically to first order inv2/c2, and at temperatures too low for fluctuations to play a dominant role.

ISSN:0031-9171    

DOI:10.1063/1.1724407

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

An electromagnetic wave having its wave vector parallel to the direction of the steady magnetic fieldHˆis attenuated in plasma very effectively when the frequency &ohgr; is equal to the ionic resonance frequency &OHgr;gof the plasma. A small localized periodic disturbance initiated in a plasma in thermodynamic equilibrium att= − ∞ and having frequency &ohgr; = &OHgr;gproduces along the direction of the magnetic field a wave motion characterized by a complex wave vectork∼ (&OHgr;0&OHgr;g/c2u0i)⅓(√3 +i) where &OHgr;0is the Langmuir frequency andu0iis the mean thermal velocity of the ions in the plasma. The attenuation per wavelength at the resonance frequency is substantial since Imk/Rek= 1/√3. However, the attenuation per unit of length is not at maximum at ionic resonance since it increases for increasing frequencies when &ohgr; passes through the resonance. This is shown by the fact that for &ohgr; = &OHgr;gwe have Im(dk/d&ohgr;) > 0 since at resonance Im(dk/d&ohgr;) =K1/u0i+ (K2/u02ui0)⅓whereK1andK2are appropriate positive constants andu0is the velocity of the magnetohydrodynamic wave.

ISSN:0031-9171    

DOI:10.1063/1.1724408

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Extension of Rayleigh's problem to magnetohydrodynamics is investigated for a perfectly conducting plate with a transversely applied magnetic field. Induced electric and magnetic fields are both included in the analysis. Results obtained show that along the plate an electromagnetic body force will actinthe direction of fluid motion. The results are found to be the same whether the applied magnetic field is fixed‐in‐space or attached to the moving plate. A comparison of these results with those of Rossow (magnetic field fixed with fluid) shows opposite trends in the velocity profile. Such discrepancies are discussed. Rossow's second case (magnetic field fixed with plate) is also discussed.

ISSN:0031-9171    

DOI:10.1063/1.1724409

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The problem considered is the steady flow of an electrically conducting, incompressible fluid, in the annular space between two infinitely long circular cylinders, under a radially impressed magnetic field. The general magnetohydrodynamic equations are simplified by the conditions of the problem to three equations in pressure, velocity, and magnetic field. One equation gives the pressure variation in the radial direction; the other two are coupled equations for the velocity and magnetic field, which are functions of the radial variable only and may be solved for in closed form. In the limiting case where the radii of the annulus become infinite, but their difference remains finite, the solution converges on the expression for magnetohydrodynamic flow between infinite planes under a transverse magnetic field.

ISSN:0031-9171    

DOI:10.1063/1.1724410

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A cylindrical Pyrex beaker of internal radius 0.318 cm containing He II was rotated about its principal axis at angular velocities ranging from 4 to 220 radians per second. The film flow rate during rotation was compared with the stationary rate by observing the rate of fall of the meniscus in rotation and at rest. No change in film flow rate greater than the scatter of individual runs (±4%) was observed over the entire range of rotation speeds. Deliberate introduction of contamination increased the creep rate but did not otherwise alter the above conclusion. A number of subsidiary experiments necessary to confirm the main conclusions are discussed.

ISSN:0031-9171    

DOI:10.1063/1.1724411

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The question of the range of ejected liquid streams is connected with the relation of the stability of the jet motion to an initial infinitesimal disturbance. This is investigated as a theoretical problem for the planar and cylindrical cases neglecting any fluid viscosity. In addition, the stabilizing influence of either a surface or ``body tension'' is calculated. Comparison of the theory with some published data is found to yield qualitative and semiquantitative agreement. The possibility of applying this theory to the measurement of dynamic surface tensions is suggested.

ISSN:0031-9171    

DOI:10.1063/1.1724412

出版商:AIP    

年代:1959

数据来源: AIP