Physics Issues

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Low Temperature Magnetized Plasmas - EXB plasmas

 

In EXB plasma devices an external magnetic field is typically placed perpendicular to the discharge current in a cylindrical geometry. This results in a large EXB electron current (or Hall current or closed drift current).

Because electrons are strongly magnetized while ions are not or are only weakly magnetized, the physics of EXB plasmas is very specific and different from that of fusion plasmas. This distinct area of basic plasma physics has been poorly explored and is not well understood but is within the reach of current analytical and numerical capabilities as well as powerful modern diagnostics tools. Improving our qualitative and quantitative understanding of these plasmas is critical for important technologies such as electric propulsion and  material processing.

Turbulent current across the magnetic field is due to azimuthal fluctuations. These fluctuations can be triggered by various physical mechanisms including the large EXB electron drift, density gradients, ionization, neutral depletion etc… Unstable fluctuations across different time and length scales as well as self-organized coherent structures are ubiquitous in EXB devices  The origin and interactions of fluctuations transport and structures are not clear but have a dramatic effect on the regimes and performance of these devices.