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Description
The simplicity of the magnetic plasma confinement in a dipolar configuration makes such plasma quite attractive for the application to magnetic fusion [1-5]. However, it has a significant downside – the necessity to levitate the coil producing the dipolar magnetic field to avoid plasma-material interactions. Whereas such a drawback of the dipolar plasma confinement is manageable for small-scale experiments, it can result in a severe issue for a large-scale fusion reactor.
Recently [6], a novel dipole-like symmetric magnetic configuration suitable for a fusion plasma confinement was suggested. In this configuration, the dipolar-like magnetic field is formed by the combination of the magnetic field provided by structurally supported current-carrying coils and the plasma diamagnetic current. As a result, a separatrix disconnects the plasma-occupied magnetic flux surfaces from the rest of the magnetic field lines. Therefore, plasma is “free” and not wrapped around any coil as it does in the original dipolar configuration[1-5]. We notice that the vacuum magnetic field studied here is produced by three coils with different settings and has a triple-X point.
In this work, we assess the possibility of plasma initiation in the FREED device by the electric breakdown of the gas, filling the chamber, in the vicinity of the X-point with an inductive electric field. We perform numerical simulations of the electron dynamics in the vacuum magnetic and inductive electric fields. Different settings of the coils producing a vacuum magnetic field were considered. The results obtained will be used for the design of the FREED device.