Abstract
Calculated thermophysical properties of nitrogen plasmas in and out of thermal equilibrium are presented. The cutoff of the partition functions due to the lowering of the ionization potential has been taken into account, together with the contributions from different core excited electronic states. The species composition and thermodynamic properties are determined numerically using the Newton–Raphson iterative method, taking into account the corrections due to Coulomb interactions. The transport properties including diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are calculated using the most recent collision interaction potentials by adopting Devoto’s electron and heavy particle decoupling approach, expanded to the thirdorder approximation (secondorder for viscosity) in the framework of Chapman–Enskog method. Results are presented in the pressure range of 0.1 atm–10 atm and in electron temperature range from 300 to 40 000 K, with the ratio of electron temperature to heavyparticle temperature varied from 1 to 20. Results are compared with those from previous works, and the influences of different definitions of the Debye length are discussed.
This work was supported by the Chinese Government Scholarship program for postgraduates and Dual Collaborative Ph.D. Degree Program between Xi’an Jiaotong University and University of Liverpool.
I. INTRODUCTION
II. PARTITION FUNCTIONS AND PLASMA COMPOSITION
A. Evaluation of partition functions
B. Determination of plasma composition
III. DETERMINATION OF THERMODYNAMIC PROPERTIES
IV. TRANSPORT COEFFICIENTS AND COLLISION INTEGRALS
A. Determination of transport coefficients
B. Evaluation of collision integrals
1. Neutral–neutral interactions
2. Ion–neutral interactions
3. Electron–neutral interactions
4. Charged species interactions
V. RESULTS AND COMPARISONS
A. Partition function and equilibrium composition
B. Thermodynamic properties
C. Transport properties
1. Diffusion coefficients
2. Viscosity
3. Thermal conductivity
4. Electrical conductivity
D. The influence of pressure on properties
VI. CONCLUSIONS
Key Topics
 Plasma temperature
 57.0
 Ionization
 38.0
 Thermal conductivity
 37.0
 Photon density
 25.0
 Thermodynamic properties
 24.0
Figures
(Color online) Temperature dependence of internal partition functions of nitrogen molecular (a) and its ion (b) (straight line and symbols: this work; symbols: the work of Drellishak et al. in Ref. 43).
(Color online) Temperature dependence of internal partition functions of nitrogen molecular (a) and its ion (b) (straight line and symbols: this work; symbols: the work of Drellishak et al. in Ref. 43).
Numerical computation flow chart.
Numerical computation flow chart.
(Color online) Internal partition function of nitrogen atom under different degrees if nonLTE (solid line with symbols: using Debye length from only electrons; dashed line with symbols: Debye length from electrons and ions).
(Color online) Internal partition function of nitrogen atom under different degrees if nonLTE (solid line with symbols: using Debye length from only electrons; dashed line with symbols: Debye length from electrons and ions).
(Color online) As Fig. 3, but for the monatomic nitrogen ion N^{+}.
(Color online) As Fig. 3, but for the monatomic nitrogen ion N^{+}.
(Color online) Temperature dependence of the number density of different species in nitrogen plasmas under different degrees of nonequilibrium at atmospheric pressure (solid line and symbols: Debye length including only electrons; dashed line and symbols: Debye length including electrons and ions). (a) N_{2}, (b) N, (c) electron, (d) N^{+}, and (e) N^{++}.
(Color online) Temperature dependence of the number density of different species in nitrogen plasmas under different degrees of nonequilibrium at atmospheric pressure (solid line and symbols: Debye length including only electrons; dashed line and symbols: Debye length including electrons and ions). (a) N_{2}, (b) N, (c) electron, (d) N^{+}, and (e) N^{++}.
(Color online) Temperature dependence of mass density of nitrogen plasmas under different degrees of nonequilibrium; symbols as in Fig. 5.
(Color online) Temperature dependence of mass density of nitrogen plasmas under different degrees of nonequilibrium; symbols as in Fig. 5.
(Color online) Temperature dependence of enthalpy of nitrogen plasmas under different degrees of nonequilibrium (solid line and symbols: this work, Debye length including only electrons; dashed line and symbols: this work, Debye length including electrons and ions; open symbols: Colombo et al. (Ref. 23)).
(Color online) Temperature dependence of enthalpy of nitrogen plasmas under different degrees of nonequilibrium (solid line and symbols: this work, Debye length including only electrons; dashed line and symbols: this work, Debye length including electrons and ions; open symbols: Colombo et al. (Ref. 23)).
(Color online) Temperature dependence of internal energy of nitrogen plasmas under different degrees of nonequilibrium; symbols as in Fig. 5.
(Color online) Temperature dependence of internal energy of nitrogen plasmas under different degrees of nonequilibrium; symbols as in Fig. 5.
(Color online) Temperature dependence of specific heat at constant pressure of nitrogen plasmas under different degrees of nonequilibrium as Fig. 7. (a) Specific heat of electrons at constant pressure. (b) Specific heat of heavy particles at constant pressure. (c) Total specific heat at constant pressure.
(Color online) Temperature dependence of specific heat at constant pressure of nitrogen plasmas under different degrees of nonequilibrium as Fig. 7. (a) Specific heat of electrons at constant pressure. (b) Specific heat of heavy particles at constant pressure. (c) Total specific heat at constant pressure.
(Color online) Temperature dependence of electron thermal diffusion coefficients of nitrogen plasmas under different degrees of nonequilibrium; symbols as in Fig. 5.
(Color online) Temperature dependence of electron thermal diffusion coefficients of nitrogen plasmas under different degrees of nonequilibrium; symbols as in Fig. 5.
(Color online) Temperature dependence of viscosity of nitrogen plasmas under different degrees of nonequilibrium; symbols are as in Fig. 7.
(Color online) Temperature dependence of viscosity of nitrogen plasmas under different degrees of nonequilibrium; symbols are as in Fig. 7.
(Color online) Temperature dependence of total thermal conductivity of nitrogen plasmas in LTE. Straight line and symbols: this work using collision integrals mentioned here; symbols: this work using collision integrals described by Capitelli et al. (Ref. 61) and the work of Murphy and Arundell (Ref. 18).
(Color online) Temperature dependence of total thermal conductivity of nitrogen plasmas in LTE. Straight line and symbols: this work using collision integrals mentioned here; symbols: this work using collision integrals described by Capitelli et al. (Ref. 61) and the work of Murphy and Arundell (Ref. 18).
(Color online) Temperature dependence of translational thermal conductivity (λtr) of nitrogen plasmas under different degrees of nonequilibrium; symbols are as in Fig. 7.
(Color online) Temperature dependence of translational thermal conductivity (λtr) of nitrogen plasmas under different degrees of nonequilibrium; symbols are as in Fig. 7.
(Color online) Temperature dependence of reactive thermal conductivity of nitrogen thermal plasmas under different degrees of nonequilibrium; symbols are as in Fig. 5. (a) Reactive thermal conductivity of electrons. (b) Reactive thermal conductivity of heavy particles. (c) Total reactive thermal conductivity.
(Color online) Temperature dependence of reactive thermal conductivity of nitrogen thermal plasmas under different degrees of nonequilibrium; symbols are as in Fig. 5. (a) Reactive thermal conductivity of electrons. (b) Reactive thermal conductivity of heavy particles. (c) Total reactive thermal conductivity.
(Color online) Temperature dependence of components of the thermal conductivity of nitrogen plasmas for θ = 3; symbols are as in Fig. 5. λ_{tot}: total thermal conductivity; λ_{trh} and λ_{tre}: translational components due to heavy particles and electrons. respectively; λ_{re}: reactive component; λ_{in}: internal component.
(Color online) Temperature dependence of components of the thermal conductivity of nitrogen plasmas for θ = 3; symbols are as in Fig. 5. λ_{tot}: total thermal conductivity; λ_{trh} and λ_{tre}: translational components due to heavy particles and electrons. respectively; λ_{re}: reactive component; λ_{in}: internal component.
(Color online) Temperature dependence of total thermal conductivity of nitrogen plasmas under different degrees of nonequilibrium; symbols are as in Fig. 5.
(Color online) Temperature dependence of total thermal conductivity of nitrogen plasmas under different degrees of nonequilibrium; symbols are as in Fig. 5.
(Color online) Temperature dependence of electrical conductivity of nitrogen plasmas under different degrees of nonequilibrium; symbols are as in Fig. 7.
(Color online) Temperature dependence of electrical conductivity of nitrogen plasmas under different degrees of nonequilibrium; symbols are as in Fig. 7.
(Color online) Influence of pressure on electron mole fraction (a), specific heat at constant pressure (b), electron thermal diffusion coefficients (c), viscosity (d), thermal conductivity (e), and electrical conductivity (f) of nitrogen plasmas under different pressures 0.1 atm, 1 atm, 2 atm, 3 atm, 5 atm, 10 atm for θ = 3, respectively. Symbols are as in Fig. 5.
(Color online) Influence of pressure on electron mole fraction (a), specific heat at constant pressure (b), electron thermal diffusion coefficients (c), viscosity (d), thermal conductivity (e), and electrical conductivity (f) of nitrogen plasmas under different pressures 0.1 atm, 1 atm, 2 atm, 3 atm, 5 atm, 10 atm for θ = 3, respectively. Symbols are as in Fig. 5.
Tables
Chemical reaction energy changes and the reaction excited temperature.
Chemical reaction energy changes and the reaction excited temperature.
States of the atoms considered in our calculation of the internal partition function of nitrogen atom.
States of the atoms considered in our calculation of the internal partition function of nitrogen atom.
Parameters for ionneutral interaction potentials.^{64}
Parameters for ionneutral interaction potentials.^{64}
Internal thermal conductivity and its percentage contribution to the total thermal conductivity, for θ = 10.
Internal thermal conductivity and its percentage contribution to the total thermal conductivity, for θ = 10.
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