摘要:

Nonlinear constant‐profile Alfve´n waves are studied in an ionized gas in which thermal motions are negligible. The system of differential equations possesses numerous integrals, and can be solved up to a single quadrature. Many properties of the waves can be inferred without performing any numerical integrations. The waves necessarily involve nonzero magnetic field components in both directions perpendicular to the direction of propagation, and plane polarized waves are impossible except in the special case of equal mass particles. Circularly polarized modes are also a special case, and, unlike the more general solutions, involve neither longitudinal electric fields nor compression of the gas.

ISSN:0031-9171    

DOI:10.1063/1.1705958

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Experiments were carried out with two magnetic field configurations ahead of the shock front, the first with a magnetic field ahead of the shock front in the direction of motion of the shock. In the second configuration the magnetic field ahead of the shock had its principal component in the plane of the shock front and a small component in the direction of the shock motion. The continuum radiation emitted by the shock‐heated plasma was measured with photomultipliers. Use of probes to measure the change in the local magnetic field in the shock front was investigated. With the second configuration, shock velocities in excess of 4 × 107cm/sec were measured in hydrogen. For these high‐speed shock waves, shock thicknesses, obtained from measured rise times of the emitted visible radiation, are thinner than the mean free path in the shock‐heated plasma, an observation which agrees with a theoretical prediction.

ISSN:0031-9171    

DOI:10.1063/1.1705959

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The magnetic annular shock tube uses a magnetic field to drive a shock wave through an annular region, producing a very high‐temperature plasma [cf. R. M. Patrick, Phys. Fluids 2, 589 (1959)]. It is shown that this particular configuration allows a fairly precise calculation of the flow parameters. Numerical calculations of the significant flow properties for a complete range of the initial field strength and orientation have been made and are presented graphically.

ISSN:0031-9171    

DOI:10.1063/1.1705960

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

By introducing a spiral in the return conductor of a conical discharge tube with a hollow electrode, a magnetic multipole has been observed propagating down a cylinder extending out from the hollow electrode. This magnetic field appears to have an extremely complicated internal structure when observed with small magnetic probes; when observed by an external loop, the net axial leakage flux shows a structure consistent with the characteristics of a shock produced deuterium plasma.

ISSN:0031-9171    

DOI:10.1063/1.1705961

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Temperatures ranging from 10 000 to 25 000°K have been measured spectroscopically in thermal plasmas of atmospheric pressure argon arcs at currents in the range of 200 to 800 amp. Electrical properties of the plasmas have been derived from measured radial temperature distributions using Spitzer's theory for the temperature dependence of electrical conductivity of a completely ionized gas. Existence of local thermal equilibrium has been demonstrated by the agreement between excitation temperatures determined from both atomic and ionic spectral line intensities. Agreement between values of electrical quantities obtained by direct measurement and those derived from measured temperatures based on the assumption of thermal equilibrium demonstrates the internal consistency of the experimental and analytical methods.

ISSN:0031-9171    

DOI:10.1063/1.1705962

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The static boundary problems of line currents and dipoles immersed in a perfectly conducting static fluid are considered first. The perturbing effect of moving fluid on the magnetostatic boundary about an isolated line current is then investigated. In this case, the initial circular boundary is distorted into an ellipse with major axis transverse to the direction of flow.

ISSN:0031-9171    

DOI:10.1063/1.1705963

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

An incompressible electrically conducting fluid is contained in a torus of rectangular cross section. A uniform magnetic field is maintained along the polar axis of the tube. A radial electric field is suddenly applied, causing the fluid to flow through the tube. Over‐all properties such as the time required to reach steady state, resistance and capacitance are calculated, and an equivalent electrical circuit is given.

ISSN:0031-9171    

DOI:10.1063/1.1705964

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Propagation of magnetohydrodynamic waves is investigated in a fluid bounded by a cylindrical surface of constant, but not necessarily circular, cross section. The fluid is assumed to be nonviscous and perfectly conducting with a constant magnetic field applied parallel to the walls of the cylinder. It is shown that the following types of waves can propagate in such a wave guide: (1) transverse waves propagating without dispersion with the velocity of Alfve´n waves; (2) a longitudinal wave, identical with the wave of the principal mode for an acoustic wave guide; (3) waves having both longitudinal and transverse components propagating with a dispersion, their group and phase velocity being close to the respective velocities for an acoustic wave guide; (4) waves having both longitudinal and transverse components propagating with a small dispersion, their group and phase velocity being close to the velocity of Alfve´n waves. When the applied frequency is too low, damping of certain modes appears for waves of type (3), only; the cut‐off frequencies turn out to be slightly higher than the corresponding cut‐off frequencies for an acoustic wave guide.

ISSN:0031-9171    

DOI:10.1063/1.1705965

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The production of ion drag pressure under dynamic conditions, i.e., with the carrier medium in motion, is theoretically investigated. It is shown that for constant applied voltage the pressure increases with increasing velocity of the carrier fluid. This can lead to instability of the system which is theoretically discussed and experimentally demonstrated.

ISSN:0031-9171    

DOI:10.1063/1.1705966

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A particle treatment is used to determine the potential distribution about an ion moving subsonicly through a plasma. A fore‐aft asymmetry is obtained which has the effect of producing a drag on the ion. This asymmetry is the most important difference between the results of this treatment and those obtained for the subsonic case by the linearized treatment of the electrohydrodynamic equations.

ISSN:0031-9171    

DOI:10.1063/1.1705967

出版商:AIP    

年代:1959

数据来源: AIP