NUMERICAL SIMULATION OF TRANSONIC SUPER-ALFVENIC MHD FLOWS WITH ACCELERATION IN NARROW COAXIAL CHANNELS IN THE PRESENCE OF A LONGITUDINAL MAGNETIC FIELD

The article is devoted to numerical studies of dense hot plasma flows in coaxial channels of plasma accelerators. Plasma is considered as a continuous electrically conducting medium, the behavior of which is described in terms of magnetic hydro dynamics (MHD). The work uses a mathematical model with nonstationary equations of “ideal” single-fluid magnetic hydro dynamics, obtained in a quasi-one-dimensional approximation. The purpose of the work is to study the influence of the geometry of the accelerator channel in the form of a nozzle and the external longitudinal magnetic field on the parameters of steady-state transonic super-Alfvénic acceleration MHD flows, which are of the greatest applied interest in the development of plasma engines. It has been demonstrated that a longitudinal magnetic field causes rotation of the flow and slightly reduces the acceleration characteristics of the channel. It has been established that the location of the “waist”, where the minimum cross-section of the channel is achieved, has practically no effect on the input and output flow values, but significantly affects the flow parameters inside the channel area. It is shown that the channel geometry affects the value of the critical longitudinal magnetic field corresponding to the boundary of the super-Alfvénic flow regime.

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