Simplified theoretical expressions for the transport properties of ionized gas mixtures are derived within the framework of the Chapman—Enskog—Burnett method. The properties of equilibrium partially ionized argon are then computed with these expressions and compared with values obtained with the exact theory. Agreement is satisfactory.

The electrical conductivity, translational and reactive thermal conductivity and viscosity have been computed for ionized argon in thermodynamic equilibrium at pressues from 0.001-1000 atm and temperatures to 35 000°K. Comparison of the values with experiments shows reasonable agreement.

Expressions are developed with the Chapman-Enskog-Burnett method for the third and fourth approximations to the thermal conductivity and the diffusion coefficients, and for the second approximation to the viscosity of multicomponent gas mixtures. Special forms of these expressions are then derived for application to ionized gas mixtures, in particular to the partially ionized gas. Convergence of the approximations is checked by computing the properties of fully ionized hydrogen and of several other mixtures where the molecules interact with inverse-power repulsive potentials. From the results for hydrogen, it is seen that at least the third approximation should be used for the thermal conductivity and thermal diffusion coefficient, and the second approximation for the electrical conductivity and viscosity of ionized gases. These results contrast with those for un-ionized gases where one lower level of approximation is generally adequate.

The complete Chapman-Enskog-Burnett expressions for the transport coefficients of multicomponent gas mixtures are applied to the computation of the properties of partially ionized argon. Studies of the rate of convergence of the approximations to the coefficients show that the third approximation to the thermal conductivity and the second to the viscosity are adequate at all degrees of ionization. The ordinary ambipolar diffusion coefficient is given to excellent accuracy by twice the binary ion-atom diffusion coefficient but, at low ionization, apparently not even the fourth approximation to the electrical conductivity has converged to the true value. The computed electrical and thermal conductivities are compared with experimental measurements.

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A simulation model for current drive by lower hybrid slow waves has been generalized to accommodate elongated plasma cross-sections. Toroidal ray trajectories are computed from the magnetic field, density and temperature distributions obtained from a numerical, free boundary solution of the Grad-Shafranov equation. A numerical solution of a relativistic Fokker-Planck equation is used to compute the absorbed power and the driven current. This lower hybrid model has been incorporated into the ACCOME code which iterates between solutions of the Grad-Shafranov equation and computation of the driven current until a self-consistent solution is obtained. Current driven by neutral beams, neoclassical effects and an Ohmic electric field in addition to lower hybrid waves is included. The model is applied to the proposed ITER design under steady state, non-inductive operation

Transport coefficients are given in tabular form for partially ionized helium in chemical equilibrium at several pressures and for temperatures up to 35000 °K. Simplified theoretical expressions, derived with the Chapman—Enskog—Burnett method, were used for the computations. The convergence of the approximations to the electrical conductivity was also studied. It was found that the first approximation was within 17% of the true value at low ionization in contrast to recent results for argon where it could not be determined if even the fourth approximation had converged to the true value.

Transport coefficients have been computed for partially ionized hydrogen at pressures of 0·01, 0·1, 1 and 10 atm and temperatures up to 50,000 °K. Theoretical expressions containing accurate collision integrals for charged particles were employed for the calculations. The electrical and thermal conductivities are compared with recent measurements in the wall-stabilized electric arc. Generally satisfactory agreement is noted for the electrical conductivity to 19,000 °K, but the computed thermal conductivity is considerably lower than that measured.