Nonequilibrium Ionization Behind Shock Waves in Argon PDF Download

Author: R. L. Alpert
Publisher:
ISBN:
Category :
Languages : en
Pages : 256

View

Book Description

Author: Claire Edwin Chapin
Publisher:
ISBN:
Category : Ionization
Languages : en
Pages : 134

View

Book Description
Radiation energy transfer and ionization rates in the mixture of atoms, ions and electrons produced by a normal shock wave propagating in cold argon gas are examined. It is shown the gas may be regarded as a combination of two gases, one composed only of electrons and one composed of both atoms and ions. Temperature differences between the electron gas and the atom-ion gas significantly affect radiation and ionization rates in the shock wave. The analysis uses the ionization rates due to both atom-atom collisions and electron-atom collisions. In addition, photoionization, which is responsible for precursor ionization, is included. (Author).

Author: K. Terao
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

View

Book Description
The electron temperature, the density and the ion temperature in argon gas behind reflected shock waves were measured by a laser light scattering method, while the gas temperature was measured by the spectroscopic method. The values of these three temperatures are different from each other during a certain period after arrival of the reflected shock front. Both the electron and ion temperatures are much higher than the theoretical gasdynamic temperature. The ionization rate is also much higher than that in the equilibrium state, but the measured gas temperature is lower than the theoretical one. These results suggest that the argon gas is in a non-equilibrium state during the first period.

Author: Harry Petschek
Publisher:
ISBN:
Category :
Languages : en
Pages : 72

View

Book Description
Previous work on strong shock waves in argon has shown that the degree of ionization reaches thermodynamic equilibrium for shock speeds greater than about ten times the speed of sound in room temperature argon. The degree of ionization reaches about 25% at the highest shock strengths available in an ordinary shock tube. This paper reports a detailed theoretical and experimental study of the approach of high temperature argon to this equilibrium degree of ionization. The mechanism for the approach to equilibrium can be divided into two stages. The first, which accounts for about 10% of the final ionization, is apparently controlled by impurities present in the gas even after considerable care is taken to insure high purity. In the second stage ionization by electron-atom collisions becomes dominant. The rate of ionization by this process is limited by the rate of energy transfer to electrons by elastic collisions with the atoms and ions in the gas and is relatively independent of the inelastic ionization crosssection. This rate is calculated and is in agreement with experimental measurements making use of (1) the visible continuum radiation from the gas, and (2) the electrostatic potentials in the gas due to the diffusion of electrons. (Author).

Author: Harry Petschek
Publisher:
ISBN:
Category : Argon
Languages : en
Pages : 98

View

Book Description

Author: Harry Ewald Petschek
Publisher:
ISBN:
Category : Ionization
Languages : en
Pages : 260

View

Book Description

Author: William Henry Foley
Publisher:
ISBN:
Category :
Languages : en
Pages : 48

View

Book Description
Ionizing shock waves in helium and argon are structured by nonequilibrium radiative and inelastic collisional transitions. The model atom of the monatomic gas has three electronic energy levels. The monatomic gas is not in local equilibrium with respect to population, and local translational equilibrium between the heavy species present and the electron gas is not assumed either. For the flow conditions studied the physics and morphology of the shock is further developed on a continuum basis from previous work, and the shock is found to consist of a far precursor due to radiative excitation, a near precursor due to radiative ionization, an embedded transport shock, an inelastic and thermal collisional relaxation zone, and an equilibrium radiating tail. Of particular interest in the results are the heating of the electron gas in the precursor by the said radiative and the associated de-exciting collisional mechanisms and the subsequent, electron-triggered collisional relaxation zone which is optically transparent to radiation; thus, nonequilibrium radiative and collisional processes are locally uncoupled throughout the shock. A family of numerical examples are displayed diagrammatically for an upstream temperature of 300 degrees K and upstream pressures bbetween 1/1000 and 1/100,000 atmospheres. Selected were those accompanying downstream temperatures giving nominal equilibrium degrees of ionization of either 0.8 or 0.95. (Author).

Author: Norman T. Grier
Publisher:
ISBN:
Category : Argon
Languages : en
Pages : 60

View

Book Description

Author: Dennis Martin Phillips
Publisher:
ISBN:
Category :
Languages : en
Pages : 44

View

Book Description

Author: Ozer Igra
Publisher:
ISBN:
Category : Argon
Languages : en
Pages : 131

View

Book Description
Experiments using a 15-degree corner-expansion flow of ionized argon, induced by a normal shock wave in a 4 in x 7 in hypervelocity shock tube, have yielded values of the recombination rate constant as a function of temperature and the variation of the plasma flow quantities with distance from the corner. The data were obtained by using mainly a Mach-Zehnder interferometer which had a nine inch diameter field of view. The interferometer had a dual frequency laser light source and was driven by either a ruby or neodymium rod. The theoretically predicted values for three-body, electron-ion-electron collisional recombination rate are in good agreement with those measured gasdynamically in a well defined flow. The measured flow quantities substantiate a previous analysis based on the method of characteristics. (Author).