Atmospheric excitation and ionization by ions in strong auroral and man-made electric fields
Excitation and ionization cross sections of atmospheric molecular species by low energy ions in strong auroral and man-made electric fields
Cole, K. D.↗
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Coherence theory of the strong ignition limit
Coherence theory of strong shock induced explosive gas ignition limit
Meyer, J. W.↗
An Implicit Finite Difference Solution to the Viscous Radiating Shock Layer with Strong Blowing
An implicit finite difference scheme is developed for the fully coupled solution of the viscous radiating stagnation line equations, including strong blowing. Solutions are presented for both air injection and carbon phenolic ablation products injection into air at conditions near the peak radiative heating point in an earth entry trajectory from interplanetary return missions. A detailed radiative transport code that accounts for the important radiative exchange processes for gaseous mixtures in local thermodynamic and chemical equilibrium is utilized.
Garrett, L. B.↗
The interaction of moderately strong shock waves with thick perforated walls of low porosity
A theoretical prediction is given of the flow through thick perforated walls of low porosity resulting from the impingement of a moderately strong traveling shock wave. The model was a flat plate positioned normal to the direction of the flow. Holes bored in the plate parallel to the direction of the flow provided nominal hole length-to-diameter ratios of 10:1 and an axial porosity of 25 percent of the flow channel cross section. The flow field behind the reflected shock wave was assumed to behave as a reservoir producing a quasi-steady duct flow through the model. Rayleigh and Fanno duct flow theoretical computations for each of three possible auxiliary wave patterns that can be associated with the transmitted shock (to satisfy contact surface compatibility) were used to provide bounding solutions as an alternative to the more complex influence coefficients method. Qualitative and quantitative behavior was verified in a 1.5- by 2.0-in. helium shock tube. High speed Schlieren photography, piezoelectric pressure-time histories, and electronic-counter wave speed measurements were used to assess the extent of correlation with the theoretical flow models. Reduced data indicated the adequacy of the bounding theory approach to predict wave phenomena and quantitative response.
Grant, D. J.↗
Dispersion discontinuities of strong collisionless shocks
Linear fluid equations are used to estimate wave train properties of strong collisionless shocks. Fast shocks exhibit several dispersion changes with increasing Mach number. For perpendicular propagation into a finite-beta plasma, an ion cyclotron radius trailing wave train exists only for (M sub F)2 is smaller than 2. Oblique fast shocks have a leading ion inertia wave train if M sub A is smaller than root of M(+)/M(-) cos theta/2 and a trailing electron inertia train if M sub A is greater than root of M(+)/M(-) cos theta/2. If the downstream sound speed exceeds the flow speed, linear wave theory predicts a trailing ion acoustic structure which probably resides within the magnetic shock. For a turbulent shock model in which an effective electron-ion collision frequency exceeds the lower hybrid frequency, ions decouple from the magnetic field; the shock wave train now trails with electron inertia and electron gyroradius lengths. Comparisons of this turbulent model and observations on the earth's bow shock are made.
Coroniti, F. V.↗
Kubo conductivity of a strongly magnetized two-dimensional plasma.
The Kubo formula is used to evaluate the bulk electrical conductivity of a two-dimensional guiding-center plasma in a strong dc magnetic field. The particles interact only electrostatically. An ?anomalous' electrical conductivity is derived for this system, which parallels a recent result of Taylor and McNamara for the coefficient of spatial diffusion.
Montgomery, D.↗
Transient, compressible heat and mass transfer in porous media using the strongly implicit iteration procedure.
Coupled nonlinear partial differential equations describing heat and mass transfer in a porous matrix are solved in finite difference form with the aid of a new iterative technique (the strongly implicit procedure). Example numerical results demonstrate the characteristics of heat and mass transport in a porous matrix such as a charring ablator. It is emphasized that multidimensional flow must be considered when predicting the thermal response of a porous material subjected to nonuniform boundary conditions.
Curry, D. M.↗
Origin of strong magnetic fields.
A possible mechanism by which extremely strong magnetic fields in neutron stars and white dwarfs could originate involves the existence of thermodynamic equilibrium states (LOFER states) of an electron gas. The essence of the stability theory of a LOFER state is discussed. The extended electronic system considered is in contact with a thermal bath in the presence of an external magnetic field. It is found that it is not necessary to require absolute stability in order to realize a LOFER state in nature.
Canuto, V.↗
Numerical study of strong plasma shock waves produced in an electromagnetic shock tube.
A set of two-fluid Navier-Stokes equations with classical physical transport coefficients is used to compute the evolution and structure of collisional plasma shock waves in an electromagnetic shock tube. Shock speeds up to 200 cm/microsec and shocked-plasma temperatures of the order of kilovolts are studied. A strong transverse bias magnetic field is employed, which significantly alters the size and shape of the shock profiles, when compared with the zero bias field case. The wave structure is different from that of a two-fluid gasdynamic shock without transverse magnetic field. Especially significant is the effect of the small ion Larmor radius in reducing the gasdynamic shock thickness by at least an order of magnitude in the transverse shock case, which permits collisional shocks to have thicknesses much smaller than the post-shock mean free path. These collisional shock waves produce very hot ions, the ion temperature increasing with shock speed, although the formation time and distances also increase substantially with shock speed.
Schneider, S. H.↗
Three-dimensional plasma diffusion in a very strong magnetic field.
The thermal equilibrium coefficient of spatial diffusion transverse to a strong uniform dc magnetic field is calculated for a fully ionized plasma. The particles are assumed to move transverse to the field only as a consequence of the E x B drift, but to move freely parallel to it. The particles interact only electrostatically. The calculation is done at large, but fixed and finite, plasma volume. It is shown that, as magnetic field density approaches infinity, the leading term of the coefficient of transverse spatial diffusion falls off in a prescribed manner, but contains a multiplicative factor which goes to zero as the plasma volume becomes infinite. The method of calculation fails for unbounded plasmas.
Montgomery, D.↗
Resonant diffusion in strongly turbulent plasmas.
The effect of turbulent fluctuations on plasma particles is considered, and equations are derived which describe the evolution of macroscopic properties such as temperature and flow speed of the turbulent plasma. Initially, a diffusion equation for a single-particle distribution function averaged over an ensemble of plasmas is derived for an unmagnetized plasma. For the resonant diffusion in strongly turbulent plasmas, an ensemble of three-dimensional plasmas is considered with an approximately homogeneous and stationary distribution of random electromagnetic fluctuations. For each realization, the single-particle distribution function satisfies the Vlasov equation.
Birmingham, T. J.↗
Anomalous motion of radiating particles in strong fields.
The effect of radiative reaction on the motion of particles is evaluated for pulsars with electromagnetic fields as strong as 10 to the twelfth power G, assuming that the pulsars are sources of high-energy particles. The analysis is limited to the specific motion of the particles. A simple method of solution, suitable for solving other similar problems, is proposed. The significance of particle motion to astronomical problems is examined.
Jaffe, J.↗
An implicit finite-difference solution to the viscous shock layer, including the effects of radiation and strong blowing
An implicit finite-difference scheme is developed for the fully coupled solution of the viscous, radiating stagnation-streamline equations, including strong blowing. Solutions are presented for both air injection and injection of carbon-phenolic ablation products into air at conditions near the peak radiative heating point in an earth entry trajectory from interplanetary return missions. A detailed radiative-transport code that accounts for the important radiative exchange processes for gaseous mixtures in local thermodynamic and chemical equilibrium is utilized in the study. With minimum number of assumptions for the initially unknown parameters and profile distributions, convergent solutions to the full stagnation-line equations are rapidly obtained by a method of successive approximations. Damping of selected profiles is required to aid convergence of the solutions for massive blowing. It is shown that certain finite-difference approximations to the governing differential equations stabilize and improve the solutions. Detailed comparisons are made with the numerical results of previous investigations. Results of the present study indicate lower radiative heat fluxes at the wall for carbonphenolic ablation than previously predicted.
Garrett, L. B.↗
Pressure signatures for the Apollo command module and the Saturn 5 launch vehicle with a discussion of strong shock extrapolation procedures
Wind tunnel pressure signatures measured at Mach 10.1 for model of the Apollo Command Module and at Mach numbers from 3.01 to 7.91 for two models of the Saturn launch configuration are presented. The signatures for the command module were obtained at roll angles ranging from 0 deg to 180 deg. A brief discussion of the extrapolation of strong pressure signatures is included in the report.
Hicks, R. M.↗
Ionizing gas breakdown waves in strong electric fields.
A previous analysis by Albright and Tidman (1972) of the structure of an ionizing potential wave driven through a dense gas by a strong electric field is extended to include atomic structure details of the background atoms and radiative effects, especially, photoionization. It is found that photoionization plays an important role in avalanche propagation. Velocities, electron densities, and temperatures are presented as a function of electric field for both negative and positive breakdown waves in nitrogen.
Klingbeil, R.↗
Pair annihilation into neutrinos in strong magnetic fields.
Among the processes that are of primary importance for the thermal history of a neutron star is electron-positron annihilation into neutrinos and photoneutrinos. These processes are computed in the presence of a strong magnetic field typical of neutron stars, and the results are compared with the zero-field case. It is shown that the neutrino luminosity Q(H) is greater than Q(O) for temperatures up to T about equal to 3 x 10 to the 8th power K and densities up to 1,000,000 g/cu cm.
Canuto, V.↗
A computer program to calculate radiating viscous stagnation streamline flow with strong blowing
A computer program (program LEE) has been developed to calculate the fully coupled solution of the radiating viscous stagnation streamline flow with strong blowing. The report describes the digital computer program, including FORTRAN IV listing, flow charts, instructions for the user, and a test case with input and output. Program LEE is available through COSMIC.
Smith, G. L.↗
Two-demensional analysis of heat and mass transfer in porous media using the strongly implicit procedure
Numerical results of the heat and mass transfer in a porous matrix are presented. The coupled, nonlinear partial differential equations describing this physical phenomenon are solved in finite difference form for two dimensions, using a new iterative technique (the strongly implicit procedure). The influence of the external environment conditions (heating and pressure) is shown to produce two-dimensional flow in the porous matrix. Typical fluid and solid temperature distributions in the porous matrix and internal pressure distributions are presented.
Curry, D. M.↗