Ionizing shocks in argon. Part I: Collisional-radiative model and steady-state structure

A detailed collisional-radiative model is developed and coupled with a single-fluid, two-temperature convection model for the transport of shock-heated argon. The model is used in a systematic approach to examine the effects of the collision cross sections on the shock structure, including the relaxation layer and subsequent radiative-cooling regime. We present a comparison with previous experimental results obtained at the University of Toronto’s Institute of Aerospace Studies and the Australian National University, which serve as benchmarks to the model. It is shown here that ionization proceeds via the ladder-climbing mechanism, in which the upper levels play a dominant role as compared to the metastable states. Taking this into account, the present model is able to accurately reproduce the metastable populations in the relaxation zone measured in previous experiments, which is not possible with a two-step model. Our numerical results of the radiative-cooling region are in close agreement with experime...

[1]  Harold Mirels,et al.  TEST TIME IN LOW PRESSURE SHOCK TUBES , 1963 .

[2]  D. Bershader,et al.  Thermal equilibration behind an ionizing shock , 1966, Journal of Fluid Mechanics.

[3]  A. J. Kelly.  Atom—Atom Ionization Cross Sections of the Noble Gases—Argon, Krypton, and Xenon , 1966 .

[4]  P. Wojciechowski,et al.  Multistep initial ionization behind strong shock waves in argon , 1974 .

[5]  I. I. Glass,et al.  Effects of hydrogen impurities on shock structure and stability in ionizing monatomic gases. Part 1. Argon , 1978, Journal of Fluid Mechanics.

[6]  R. Shreffler,et al.  Boundary Disturbances in High‐Explosive Shock Tubes , 1954 .

[7]  T. McLaren,et al.  Initial Ionization Rates and Collision Cross Sections in Shock‐Heated Argon , 1968 .

[8]  Harold Mirels,et al.  Flow Nonuniformity in Shock Tubes Operating at Maximum Test Times , 1966 .

[9]  J. Vlček,et al.  A collisional-radiative model applicable to argon discharges over a wide range of conditions. I. Formulation and basic data , 1989 .

[10]  A Roe scheme for the Bi-temperature model of magnetohydrodynamics , 2001 .

[11]  P. Vervisch,et al.  Influence of Ar(2)+ in an argon collisional-radiative model. , 2002, Physical review. E, Statistical, nonlinear, and soft matter physics.

[12]  M. Mitchner,et al.  Partially ionized gases , 1973 .

[13]  J. Bittencourt.  Fundamentals of plasma physics , 1986 .

[14]  G. Ben-Dor,et al.  Ionization behind strong normal shock waves in argon , 1986 .

[15]  M. Kapper.  A High-Order Transport Scheme for Collisional-Radiative and Nonequilibrium Plasma , 2009 .

[16]  H. Drawin,et al.  Transition probabilities for argon(I). , 1980 .

[17]  Y. Enomoto.  Wall Boundary Layer Effects on Ionizing Shock Structure in Argon , 1973 .

[18]  H. Petschek,et al.  Approach to equilibrium lonization behind strong shock waves in argon , 1957 .

[19]  K. Bartschat,et al.  B-spline calculations of oscillator strengths in neutral argon , 2006 .

[20]  T. Märk,et al.  Theoretical determination of absolute electron-impact ionization cross sections of molecules , 2000 .

[21]  T. Märk,et al.  Calculated cross sections for the electron-impact ionization of excited argon atoms using the DM formalism , 2004 .

[22]  P. Haugsjaa,et al.  Ionization and metastable excitation in low- energy collisions of ground state argon atoms , 1970 .

[23]  E. J. Morgan,et al.  IONIZATION RATES BEHIND SHOCK WAVES IN ARGON , 1965 .

[24]  E. J. Morgan,et al.  Total Ionization Times in Shock‐Heated Noble Gases , 1970 .

[25]  R. J. Sandeman,et al.  On the population of the metastable states behind unstable shock waves in ionizing argon , 1986, Journal of Fluid Mechanics.