摘要:

The role of water, initially mixed with air, upon the properties of shock compressed air has been investigated using a thermodynamic equilibrium computer program. The principal effect of the inclusion of water in the computation of the shock parameters of air is to reduce the temperature of the products. This reduction in temperature results in a reduction in the equilibrium electron concentration by reducing the ionization of NO. The maximum effect occurs at shock velocities of 4.0 to 4.3 km/sec. A procedure is presented for estimating the effect of the addition of water.

ISSN:0031-9171    

DOI:10.1063/1.1693613

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Radiatively and collisionally structured, normal shock waves in a monatomic, nonequilibrium, ionizing gas are solved for waves in which the emission‐convection ratio varies from a small value in the preshock flow to a very large value in the postshock flow. The gas model adopted for the mixture allows nonequilibrium ionization and spectral radiative emission and absorption. Two sequential regions are identified: (1) One which displays far upstream an abrupt isothermal “ionization front” and then subsequent heating and adjustment, and next (2) a uniform asymptotic region in which occurs a thick, hot, unusual precursor, a frozen and adiabatic discontinuity, and a very thin tail. The second region permits asymptotic simplifications leading to rational uncoupling of precursor and tail and simplification of spectral difficulties. The first region affords no spectral simplification, and nonrational spectral approximations are employed.

ISSN:0031-9171    

DOI:10.1063/1.1693614

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Solutions of nitromethane in acetone which are too dilute to support a self‐sustained detonation can be forced to react by a strong booster. In such cases the wave front is composed of an induction zone followed by a turbulent reaction zone and a region of turbulence decay. As the nitromethane concentration is increased, the induction zone disappears and reaction appears to begin at the wave front. At the highest concentrations no wave structure could be resolved and the reaction time may be subnanosecond with the booster system used.

ISSN:0031-9171    

DOI:10.1063/1.1693615

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Methods are discussed for determining both the density gradient at the surface and the free‐stream density of charged particles in a weakly ionized flowing gas by means of flush electrostatic probes. It is shown that the values of the density gradients of the ions and electrons at the surface can be determined by current‐voltage characteristics. The determination of the free‐stream charged‐particle density is studied by means of an analysis in the sheath region which, for highly negative probe potentials, gives sufficient boundary conditions to, in general, overspecify the density solution in the quasineutral region. This overspecification makes possible the determination of the boundary of the quasineutral region for a large class of continuum model equations describing the region. Using this information, current‐voltage characteristics can be drawn for various values of free‐stream charged‐particle density, and the density thus determined by comparison with experiment. These characteristics are drawn for two models.

ISSN:0031-9171    

DOI:10.1063/1.1693616

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A comparison was made of plasma density measurements obtained using cylindrical Langmuir probes and a high‐sensitivity microwave interferometer in magnetic fields between 1 and 7 kG. The experiment was carried out in a current‐free stream of ionized hydrogen with electron densities ranging from3×109to4×1011 cm−3. A set of probes of different sizes was used so that the ratio of probe diameter to ion gyroradius2rp/&rgr;icovered the critical range from 0.2 to 5 or more. It was found that (1) the shape of the probe characteristics was not affected very much by the presence of the strong magnetic field; (2) the electron temperature derived from the slope seemed to be the true temperature; but (3) the apparent ion density inferred from the characteristic using Laframboise's calculation, which applies in the absence of magnetic fields, was consistently low by a factor which depended primarily on the ratiorp/&rgr;iand seemed nearly independent of the Debye length. This reduction factor was considerably larger in the streaming plasma than in a stationary one, presumably because of the wake or “shadow” cast by the probe whenrp/&rgr;iis not negligible.

ISSN:0031-9171    

DOI:10.1063/1.1693617

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Measurements of externally excited moving striations in a low‐pressure (0.005‐0.03 Torr) argon discharge are presented. The wave propagates with little radial structure, and corresponds to the lowest radial mode. A theory which uses the Boltzmann equation for the electron motion, and fluid equations for the ions gives results in agreement with the experiment. Included in this model are the effects of ion inertia, and of depletion of the high‐energy tail of the electron distribution function due to loss of electrons to the tube walls. Results indicate that both effects are important at low pressure. A simple model, which uses fluid equations for electrons and ions, shows the relationship between moving striations and ion acoustic waves.

ISSN:0031-9171    

DOI:10.1063/1.1693618

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

In a cold plasma, finite magnetosonic disturbances lead to the familiar steady‐state solitary pulse of Adlam and Allen. Leading effects of finite plasma pressure on these disturbances are considered using both linear and nonlinear analyses. Earlier limitations imposed by adiabatic considerations have been removed. Within a regime of limited disturbance strength the inclusion of finite temperature leads to a singular perturbation scheme. The nature of pulse distortions due to these effects is discussed both analytically and numerically.

ISSN:0031-9171    

DOI:10.1063/1.1693619

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The existence and structure of large amplitude, stationary, longitudinal plasma oscillations are studied for the case of a simple waterbag distribution of electrons and an immovable background of ions. The analysis employs the one‐dimensional Vlasov equation for a plasma of infinite spatial extent. An expression for the maximum amplitude of the oscillations is derived. This maximum amplitude decreases monotonically as the ratio of the electron thermal velocity to the wave phase velocity increases. The structure of the oscillations is expressed analytically in terms of hyperelliptic integrals.

ISSN:0031-9171    

DOI:10.1063/1.1693620

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The equations for the equilibrium density and temperature profiles and the self‐consistent electric potential are derived for mirror‐contained collisional distributions. The equations are solved in two limiting cases: (a) The normal mirror reactor equilibrium where the electrons are contained by the electrostatic potential(e&phgr;≫12mVe2);(b) electron heated plasmas wheree&phgr;≪12mVe2. The critical magnetic field scale length in the mirror throat necessary for plasma wave absorption in case (a) is found to beLT>ai[(Te/Ti)(Mi/Me)]1/2 exp (2e&phgr;/3mVe2), and in case (b)LT>ai[(Te/Ti)(Mi/Me)]1/2(R0−1)−1/2. Neither of these conditions should pose a serious problem for the design of mirror reactors.

ISSN:0031-9171    

DOI:10.1063/1.1693621

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Nonlinear damping of electromagnetic waves propagating along a uniform magnetic field has been calculated by computing nonlinear trajectories for trapped and resonant untrapped particles while using linear theory to describe the rest. This procedure parallels O'Neil's calculation for electrostatic modes, and the results are qualitatively similar. After an initial linear damping, amplitude oscillations set in and the amplitude quickly approaches a finite constant value. The frequency of the amplitude oscillations is temperature dependent. Phase mixing results from the spread in both parallel and perpendicular velocities, giving rise to a more rapid approach to the asymptotic amplitude than for electrostatic modes.

ISSN:0031-9171    

DOI:10.1063/1.1693622

出版商:AIP    

年代:1971

数据来源: AIP