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The effects of magnetization on an expanding high-enthalpy plasma jet in argon are studied with a non-LTE model. The magnetic field is taken into account with a complete approach where the calculation of diffusion velocities, the electromagnetic field and the flow field are self-consistently coupled via the current density. Results of the simulations show that inside the plasma source there are no significant changes due to the magnetic field. However, in the expansion the magnetic field completely changes the appearance of the jet. Due to the magnetic field, shockwaves disappear and power dissipation not only takes place inside the source but also in the expansion region.

Abstract. In partially ionized, magnetically confined plasmas, the diffusive fluxes of the different species are coupled. Additionally, the fluxes are directionally coupled as well due to the Lorentz force. The challenge in modelling of multicomponent, magnetized plasmas is to take care of this coupling in the numerical method. In this paper, a complex form of the Stefan-Maxwell equations is used, to account for the coupling between the flow directions. To handle the coupling between the species fluxes in the finite volume method, a generalised, coupled form of the exponential scheme is used. The presented numerical method is applied to a magnetically confined hydrogen jet. The results show that the numerical method is capable of describing typical characteristics of magnetized plasmas, such as anisotropic diffusion and the presence of a pressure gradient sustained by the Lorentz force.

The cascaded arc hydrogen plasma of Pilot-PSI is studied in a non-LTE model. We demonstrate that the effect of vibrationally excited molecules on the heavy-particle-assisted dissociation is crucial for obtaining thermal constriction. To the best of our knowledge, thermal constriction has not been obtained before in a non-LTE simulation. Probably, realistic numerical studies of this type of plasma were hindered by numerical problems, preventing the non-LTE simulations to show characteristic physical mechanisms such as thermal constriction. In this paper we show that with the help of appropriate numerical strategies thermal constriction can be obtained in a non-LTE simulation. To this end, a new source term linearization technique is developed, which ensures physical solutions even near chemical equilibrium where the composition is dominated by chemical source terms. Results of the model are compared with experiments on Pilot-PSI and show good agreement with pressure and voltage measurements in the source.