Numerical Analysis Seminars: Transport Driven Magnetothermal Instability in Laser-Produced Plasmas
23 November 2012 14:00 in CM105
Accurate prediction of electron transport phenomena, such as the flow heat and advection of magnetic field, is essential to the success of long-pulse (100ps-10ns) laser-plasma experiments, including those aimed at achieving controlled, self-sustained nuclear fusion. Typically such plasmas are modelled by magneto-hydrodynamic fluid equations, themselves closed using `classical transport theory', which yields equations for both the heat-flux (the heat-flow equation) and local electric field (generalised Ohm's Law). Classical theory predicts strong coupling between thermal transport and magnetic ï¬eld dynamics in laser-plasmas; for example, fields are carried with the thermal flux (via the `Nernst effect'), while simultaneously deflecting it (giving rise to a `Righi-Leduc heat-ï¬‚ow').
In this seminar we briefly review the classical theory, and show how electron transport can drive a new kind of instability---the magnetothermal instability---when heat flows perpendicular to a magnetic field (Bissell et al., Phys Rev. Lett., 105, 175001 ). Produced by transport phenomena alone, the magnetothermal instability is of particular interest because it acts to destabilise plasmas in the absence of more usual mechanisms, such as those arising from bulk hydrodynamic motion (Bissell et al., Phys Plas., 19, 052107 ). Given the potential importance of the instability when a high degree of symmetry or control of heat transport is needed, or where uniform magnetic fields are applied for a specific purpose, we also discuss a forthcoming experiment (early 2013) aimed at its detection.
Contact David.Bourne@durham.ac.uk for more information