Steady radiation fronts behind windows

1969 ◽  
Vol 47 (16) ◽  
pp. 1709-1721 ◽  
Author(s):  
Boye Ahlborn ◽  
William W. Zuzak
Keyword(s):  
Shock Wave ◽  
Rarefaction Wave ◽  
Ionized Gas ◽  
Constant Intensity ◽  
Neutral Gas ◽  
Jouguet Point ◽  
Radiation Induced ◽  
Reduced Density

If radiation of constant intensity W ionizes a gas of density ρ1 behind a window, a steady radiation front may be established and the gas will be heated, accelerated, and compressed. The properties of such radiation-induced waves are discussed as a function of the external parameters W and ρ1. With high absorber density ρ1 the radiation front acts like a "leaky piston" accelerating and compressing the neutral gas ahead, and leaving plasma of reduced density behind. This leads to the formation of a precursing shock wave travelling at vshock α (W/ρ1)1/3. The shock develops as a sharp spike near the Jouguet point which requires a sonic speeds a4 α (W/ρ1)J1/3in the ionized gas. With lower absorber density, the radiation front propagates as vr α W/ρ1 and accelerates and compresses the ionized gas at its rear. This plasma is then brought to rest and expanded in a subsequent rarefaction wave.

scholarly journals On the Propagation and Structure of Ionization Fronts

1958 ◽  
Vol 8 ◽  
pp. 1062-1068
Author(s):  
F. A. Goldsworthy
Keyword(s):  
Shock Wave ◽  
Ionizing Radiation ◽  
Atomic Hydrogen ◽  
Hydrogen Gas ◽  
Ionization Front ◽  
Ionized Gas ◽  
Hii Region ◽  
Ionization Fronts ◽  
Neutral Gas ◽  
Gravitational Equilibrium

The problem discussed here is that of determining the motion of a cloud of neutral atomic hydrogen gas, when it is subjected to ionizing radiation from a star embedded in it. Initially the gas is in gravitational equilibrium at a constant temperature of about 100°K. It is supposed that at time t=0 the star suddenly begins to radiate with a certain intensity, which remains constant thereafter. Part of the surrounding gas will be ionized and an ionization front (separating the ionized gas from the neutral gas) will move outwards into the neutral gas. A shock wave may also propagate ahead of the ionization front into the neutral gas. There will therefore be two regions to consider—a region of ionized gas (HII region) and a region of neutral gas (HI region) in which there may be a shock.

Magnetogasdynamic deflagration and detonation waves with ionization

1963 ◽  
Vol 16 (2) ◽  
pp. 243-261 ◽  
Author(s):  
J. B. Helliwell
Keyword(s):  
Shock Wave ◽  
Electromagnetic Field ◽  
Combustion Wave ◽  
Detonation Waves ◽  
Ionized Gas ◽  
One Dimensional ◽  
Jouguet Point ◽  
Electric And Magnetic Fields ◽  
The Waves ◽  
Steady Detonation

The propagation of a one-dimensional combustion wave into a non-ionized gas at rest in the presence of an electromagnetic field is considered when ionization of the gas occurs across either the combustion wave or a preceding shock wave. The electric and magnetic fields in the undisturbed gas ahead of the waves are mutually perpendicular and orthogonal to the direction of wave propagation. It is shown that steady detonation occurs at a point which is analogous to the Chapman-Jouguet point of ordinary gasdynamic combustion theory. Numerical calculations are made of the state of the gas between and behind the waves in two particlar models, in both of which the upstream electric field is zero. The models are then equivalent to magnetogasdynamic phenomena in a perfectly conducting gas. First, the case of steady detonation is studied. Secondly, steady deflagration in a tube, closed at one end, is discussed.

Switch-shock wave structure in a magnetized partly-ionized gas

1975 ◽  
Vol 14 (2) ◽  
pp. 333-346 ◽  
Author(s):  
N. F. Cramer
Keyword(s):  
Magnetic Field ◽  
Shock Wave ◽  
Wave Structure ◽  
High Resistivity ◽  
Shock Wave Structure ◽  
Ionized Gas ◽  
Heavy Particles ◽  
Neutral Gas ◽  
Shock Transition ◽  
The Magnetic Field

The effect of the interaction of plasma and neutral gas on the structure of switchtype shock waves propagating in a partly-ionized gas is studied. These shocks, in which the magnetic field is perpendicular to the shock front either upstream or downstream, exhibit a spiralling behaviour of the magnetic field in the shock transition region, if the Hall term is important in the Ohm's law. Observation of this behaviour for shocks propagating into a plasma with a residual neutral content of ~ 15 % has implied an anomalously high resistivity of the plasma. We show that this can be partly explained by considering the collisions of ions with the neutral atoms in a magnetic field. We show that the extra dissipation due to the increase in resistivity goes primarily to the ions and neutrals. Thus even in the absence of viscous dissipation within each species, the heavy particles can be appreciably heated in a shock propagating into a partly-ionized gas in a magnetic field.

Effects of lateral rarefaction wave on phase transition of PZT-95/5 ceramics under shock wave

2001 ◽  
Vol 254 (1) ◽  
pp. 329-335 ◽  
Author(s):  
Du Jinmei ◽  
Yuan Wanzong ◽  
Dong Qingdong ◽  
B. O. Sokol
Keyword(s):  
Phase Transition ◽  
Shock Wave ◽  
Rarefaction Wave

scholarly journals Is there any pristine gas in nearby starburst galaxies?

2008 ◽  
Vol 4 (S255) ◽  
pp. 278-282
Author(s):  
Vianney Lebouteiller ◽  
Daniel Kunth
Keyword(s):  
Chemical Composition ◽  
Starburst Galaxies ◽  
Lower Threshold ◽  
Ionized Gas ◽  
Neutral Gas

AbstractWe derive the chemical composition of the neutral gas in the blue compact dwarf (BCD) Pox 36 observed with FUSE. Metals (N, O, Ar, and Fe) are underabundant as compared to the ionized gas associated with H ii regions by a factor ~7. The neutral gas, although it is not pristine, is thus probably less chemically evolved than the ionized gas. This could be due to different dispersal and mixing timescales. Results are compared to those of other BCDs observed with FUSE. The metallicity of the neutral gas in BCDs seems to reach a lower threshold of ~1/50 Z⊙ for extremely-metal poor galaxies.

scholarly journals On the mathematical model of combined rarefaction and compression waves in condensed matter

2021 ◽  
Vol 50 ◽  
pp. 104-107
Author(s):  
Alexander Alexandrovitch Samokhin ◽  
Pavel Aleksandrovich Pivovarov
Keyword(s):  
Shock Wave ◽  
Rarefaction Wave ◽  
Condensed Matter ◽  
Steady State Regime ◽  
Compression Waves ◽  
Momentum Fluxes ◽  
State Regime ◽  
The Mathematical Model ◽  
The Waves ◽  
Nonmetal Transition

Two waves model where shock wave is combined with rarefaction wave appearing in laser ablation due to metal-nonmetal transition effect is investigated using conservation laws for mass and momentum fluxes for the steady-state regime of the process. This approach permits to obtain the relation between front velocities of the waves which shows that the rarefaction wave can be rather slow compared with the generated shock wave.

Shock waves in a liquid containing gas bubbles

1958 ◽  
Vol 243 (1235) ◽  
pp. 534-545 ◽  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Rarefaction Wave ◽  
Temperature Rise ◽  
Compression Wave ◽  
Liquid Mixture ◽  
Propagation Speed ◽  
Plane Wall ◽  
Shock Propagation ◽  
Wide Range

Considerations of continuity, momentum and energy together with an equation of state are applied to the propagation of plane shock waves in a gas + liquid mixture. The shock-wave relations assume a particularly simple form when the temperature rise across a shock, which is shown to be small for a very wide range of conditions, is neglected. In particular, a simple relation emerges between the shock propagation speed and the pressure on the high-pressure side of the shock, the density of the liquid and the relative proportions, by mass and volume, of gas and liquid in the mixture. It is shown from entropy considerations that a rarefaction wave cannot propagate itself without change of form, and it is argued that a compression wave can be expected to steepen into a shock wave. Consideration of the collision between two normal shock waves, moving in opposite directions, suggests that the strengths of the two shocks are unaltered by the interaction between them. This implies, in particular, that, when a shock impinges normally on a plane wall, the pressure ratio across the reflected shock is equal to that across the incident shock. When the mass ratio of gas to liquid in the mixture is allowed to tend to infinity, the various shock-wave relations for a mixture, derived with the temperature rise across the shock neglected, assume the same limiting form as the corresponding relations for a perfect gas when the ratio of specific heats tends to unity. The theoretical discussion has been illustrated by experiments with a small gas + liquid mixture shock tube. Samples of the records, obtained when the passage of a shock changes the amount of light transmitted through the mixture to a photoelectric cell, illustrate the steepening of a compression wave and the flattening of a rarefaction wave. Measurements confirm the theoretical relation for the propagation speed of shock waves. Reasonably good experi­mental confirmation is also reported of the theoretical predictions for the pressure which arises following the normal impact of a shock wave on a plane wall.

scholarly journals Turbulence in the diffuse magneto-ionized medium: observational aspects

2015 ◽  
Vol 11 (A29B) ◽  
pp. 720-722
Author(s):  
Marijke Haverkorn
Keyword(s):  
Magnetic Fields ◽  
Milky Way ◽  
Turbulent Energy ◽  
Spectral Lines ◽  
Observational Methods ◽  
Interstellar Gas ◽  
Ionized Gas ◽  
Neutral Gas ◽  
Velocity Information ◽  
Gas Component

AbstractTurbulence in the interstellar medium is ubiquitous. The turbulent energy density in the gas is significant, and comparable to energy densities of magnetic fields and cosmic rays. Studies of the turbulent interstellar gas in the Milky Way have mostly focused on the neutral gas component, since various spectral lines can give velocity information. Probing turbulent properties in the ionized gas, let alone in magnetic fields, is observationally more difficult. A number of observational methods are discussed below which provide estimates of the maximum scale of fluctuations, the Mach number and other turbulence characteristics.

Sign in / Sign up

Export Citation Format

Share Document