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Physics Colloquium - Dr. Saikat Chakraborty Thakur
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Dr. Saikat Chakraborty Thakur, Auburn University, Title: Explorations in plasma turbulence, self-organization and structure formation in magnetized plasmas
Abstract:
Plasmas are ubiquitous in Nature and depending on the specific circumstances, plasmas can sustain various kinds of instabilities leading to turbulence. In addition, presence of an external magnetic field can reduce the effective dimensionality of plasma transport, thus closely resembling classical 2-D turbulence, which can in turn lead to self-organization and pattern formation. In this talk, we will learn about two such examples related to plasma turbulence and self-organization. In the Controlled Shear De-correlation eXperiment (CSDX), a high-density helicon plasma device, we show the existence of simultaneously present, radially separated, multiple plasma instabilities. At a certain magnetic field threshold, we observe a global, self-organized transition to a more coherent plasma state, which has important implications to the physics of the helicon blue core formation and axial plasma detachment. In the Magnetized Dusty Plasma eXperiment (MDPX), a low density, low temperature, capacitively coupled plasma device, immersed in a high magnetic field (up to 4 Tesla), we observe the formation of field aligned plasma filaments of various shapes as the ions also get magnetized. Recent studies shed light on the properties of these filaments and show that they emerge as self-organized structures from the background plasma turbulence in MDPX.
Sponsored by: Physics