摘要:

Kinetic theory principles are used to study one‐dimensional steady‐state vapor condensation phenomena in the presence of a noncondensable gas. The results have been fitted to an interpolation formula describing the condensation flux that reduces to the one obtained by Labuntsov and Kryukov [Int. J. Heat Mass Transfer22, 989 (1979)] in the limit of no noncondensable gas.

ISSN:0031-9171    

DOI:10.1063/1.865607

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The equations governing the motion and thermodynamic state of a gas that absorbs energy from an electromagnetic field, interfering with itself within that gas, are linearized and solved in closed form. The dependence of the solution on the geometrical configuration of the gas enclosure, on the polarization state of the incident electromagnetic field, and on the various time constants of the system are derived. The relevant time constants of the system include the pulse duration of the electromagnetic field, the characteristic times for photon absorption, and for transfer of the absorbed energy into translational energy modes, the times associated with the diffusion of heat and vorticity, and the time required for pressure pulses to transit the distance between the laser‐induced grating planes. The space and time variations of the mass density of a mixture of gaseous ammonia and nitrogen resulting from energy absorbed from a pulsed carbon dioxide laser are calculated to illustrate the characteristics of the solution.

ISSN:0031-9171    

DOI:10.1063/1.865608

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Previous calculations of hole growth in a one‐dimensional electron–ion plasma are extended to a greater range of parameter space including the region around linear instability. The effect of the ion‐acoustic resonance on hole growth is analyzed and the relationship to linear instability is discussed. Agreement with computer simulations is much improved. Energy and momentum conservation are discussed and proved for both holes and waves.

ISSN:0031-9171    

DOI:10.1063/1.865609

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Earlier work [Phys. Fluids25, 277 (1982); Phys. Fluids26, 2460 (1983)] on the structure and growth of phase space density holes for &psgr;=−qi&fgr;/Ti<1 is extended to &psgr;>1. As in the &psgr;<1 case, it is found that reflecting electrons cause the ion holes to decelerate and grow, although the details are quite different. The reflected electrons cause the formation of a so‐called ‘‘double layer.’’ It is shown that isolated (intermittent) ion holes or wave packets can grow to much larger amplitudes than that predicted by the conventional quasilinear plateau limitation or Manheimer’s [Phys. Fluids14, 579 (1971)] trapping criteria.

ISSN:0031-9171    

DOI:10.1063/1.865610

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The nonlinear equations describing drift‐Alfve´n solitary vortices in a low &bgr;, rotating plasma are derived. Two types of solitary vortex solutions along with their corresponding nonlinear dispersion relations are obtained. Both solutions have the localized coherent dipolar structure. The first type of solution belongs to the family of the usual Rossby or drift wave vortex, while the second type of solution is intrinsic to the electromagnetic perturbation in a magnetized plasma and is a complicated structure. While the first type of vortex is a solution to a second‐order differential equation the second one is the solution of a fourth‐order differential equation intrinsic to the electromagnetic problem. The fourth‐order vortex solution has two intrinsic space scales in contrast to the single space scale of the previous drift vortex solution. With the second short scale length the parallel current density at the vortex interface becomes continuous. As special cases the rotational electron drift vortex and the rotational ballooning vortex also are given.

ISSN:0031-9171    

DOI:10.1063/1.865611

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Parametric decay instability of an extraordinary electromagnetic wave into a magnetized electron plasma wave and a whistler wave propagating at an angle with respect to the static magnetic field has been considered. Application of the present investigation to tandem mirrors and tokamaks has been pointed out. For example (i) for the tandem‐mirror parameters at the second harmonic cyclotron resonance in the thermal barrier minimum, the convective threshold ∼100 W/cm2, (ii) for tokamak parameters when the extraordinary mode is launched from outside the torus, the convective threshold ∼1 kW/cm2for this decay process.

ISSN:0031-9171    

DOI:10.1063/1.865612

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A theory of unstable magnetic‐drift waves was first discussed by Krall and Rosenbluth [Phys. Fluids6, 254 (1963)]. However, the growth rate is exceedingly small and, therefore, the instability seems to be unimportant. It is found in the present analysis that a weak electron temperature anisotropyT⊥<T∥can lead to a much stronger instability. When there is no temperature gradient, the conditions of the new instability are (c2k2/&ohgr;2e+1)(T⊥/T∥)−1 <0, &egr;n/&egr;B>0, where &egr;n=(1/n)(∂n/∂x) and &egr;B=(1/B)(∂B/∂x). In this case, the instability is attributed to wave–electron interactions, whereas the case discussed by Krall and Rosenbluth [Phys. Fluids6, 254 (1963)] attributes the instability to wave–ion interactions. A general discussion including a temperature gradient is presented with the usual local approximation which is justifiable whenk&egr;n>1.

ISSN:0031-9171    

DOI:10.1063/1.865613

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A Korteweg–de Vries equation that is applicable to both the nonlinear magnetosonic fast and slow waves is derived from a two‐fluid model with finite ion and electron pressures. As in the cold plasma theory, the fast wave has a critical angle &thgr;c. For propagation angles greater than &thgr;c(quasiperpendicular propagation), the fast wave has a positive soliton, whereas for angles smaller than &thgr;c, it has a negative soliton. Finite  &bgr; effects decrease the value of &thgr;c. The slow wave has a positive soliton for all angles of propagation. The magnitude of resonant ion acceleration (thevp×Bacceleration) by the nonlinear fast and slow waves is evaluated. In the fast wave, the electron pressure makes the acceleration stronger for all propagation angles. The decrease in &thgr;cresulting from finite  &bgr; effects results in broadening of the region of strong acceleration. It is also found that fairly strong ion acceleration can occur in the nonlinear slow wave in high  &bgr; plasmas. The possibility of unlimited acceleration of ions by quasiperpendicular magnetosonic fast waves is discussed.

ISSN:0031-9171    

DOI:10.1063/1.865614

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

For a collisionless, relativistic electron fluid, conditions on the velocity field are formulated which are necessary for the maintenance of pressure isotropy in the local fluid rest frame. A complete characterization of all velocity fields which satisfy these conditions is worked out in the nonrelativistic limit, and a few simple examples are given in the relativistic case.

ISSN:0031-9171    

DOI:10.1063/1.865999

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A dispersion functional for the Vlasov‐fluid model is derived as a finite‐Larmor‐radius (FLR) expansion in which the eigenfrequency is not assumed to be small compared to the ion gyrofrequency and secularities in the gyrophase angle never occur. The expansion is carried out in the localE0×B0drift frame. Use of the dispersion functional for calculating the small‐signal response of a plasma is compared to using an approximate dispersion differential equation. The linearized Vlasov‐fluid model is examined with particular reference to the questions of treating the initial‐value problem correctly and specifying a generally valid gauge condition. Calculational details for applying the dispersion functional to a general linear screw pinch are presented.

ISSN:0031-9171    

DOI:10.1063/1.865615

出版商:AIP    

年代:1986

数据来源: AIP