Department of Physics and Astronomy

Plasma and Fluids

Home > Research > Plasma and Fluids

Plasma and Fluids

Research in the physics of plasmas and fluids is carried out by Professors David Montgomery and Barrett Rogers, and includes studies of nonlinear magnetohydrodynamics and turbulence in plasmas and fluids, investigations of magnetic reconnection, the physics of fusion devices, analytical dynamics, computational physics, plasma simulation, and plasma theory. The department also has a large vacuum calibration and test system for quantifying the response of particle detectors flown on auroral sounding rockets to the space environment, including a plasma source. Further details are described under Professor Kristina Lynch's rocket lab.

Through the efforts of an an international fusion research program, dramatic progress has been made in recent years toward the goal of confining a fusion-grade plasma in the laboratory using intense magnetic fields. The performance of these fusion devices is typically limited by a host of instabilities, which produce turbulence and degrade the confinement of particles and thermal energy. Research on this topic at Dartmouth (Rogers and Montgomery) is focused on understanding the physics of these instabilities as well as the turbulence and transport that they produce. This work relies heavily on both analytic methods as well as state-of-the-art massively parallel numerical simulations.

Professor Montgomery's recent activities have included studies of:(1) the effect of an externally-imposed dc magnetic field's partial or total suppression of turbulent magnetohydrodynamic (MHD) dynamo action (see, e.g., D.C. Montgomery et al, Phys. Plasmas 9, 1221 (2002) and 6, 2727 (1999)); (2) the mass flows which necessarily arise in steady-state toroidal confinement devices for magnetic fusion plasmas (see, e.g., L.P. Kamp and D.C. Montgomery, Phys. Plasmas 10, 157 (2003)). The two figures below are taken from a 2004 Kamp/Montgomery paper, and show field lines (magnetic and mechanical streamlines) inside a toroid that is being Ohmically driven when viscous and resistive boundary conditions are being imposed. Both toroidal and poloidal flows necessarily result (see Kamp and Montgomery, J. Plasma Phys, 70, 113 (2004)) even in the laminar steady state; (3) together with P.D. Minninni (Buenos Aires) and L. Turner (Cornell), three-dimensional, spectral-method, magnetohydrodynamic computations of dynamos inside spherical shells have been carried out, with particular reference to the role that magnetic and mechanical helicity might play in the generation of planetary magnetic fields (the figure at the top of this page shows some computer graphics displaying typical evolving computed energy densities and field lines for mechanical and magnetic driven helical flows in the interior of the sphere (Mininni et al, New Journal of Physics 9, 303 (2007)); (4) maximum entropy predictions for the evolution of two-dimensional turbulent vortices both in a Malmberg-Penning electron trap and in numerical solutions of the neutral fluid dynamical equations have been in progress with an experimental group from the University of Delaware (e.g., see D.J. Rodgers et al, Phys. Rev. Letters 102, 244501 (2009)), and also in the completely unbounded case where the Oseen vortex has been shown to be the relaxed long-time state of a compact vorticity distribution with circulation in the absence of boundaries (D.C. Montgomery and W.H. Matthaeus, Phys. Fluids 23, 075104 (2011).

For more information, visit Prof. Montgomery's and Prof. Roger's home page.

Recent Publications

D. J. Rodgers,1 S. Servidio, W. H. Matthaeus,1 D. C. Montgomery, T. B. Mitchell,* and T. Aziz, "Hydrodynamic Relaxation of an Electron Plasma to a Near-Maximum Entropy State" Phys. Rev. PRL 102, 244501 (2009).

D. J. Rodgers,1 S. Servidio, W. H. Matthaeus,1 D. C. Montgomery, T. B. Mitchell,* and T. Aziz "Nonlinear Magnetohydrodynamics by Galerkin-method Computation" Phys. Rev. PRL 102, 244501 (2009).

P.D. Mininni, D.C. Montgomery, and L.Turner "Hydrodynamic and magnetohydrodynamic computations inside a rotating sphere" New J. Phys. 9, 303(25 pages), 2007.

D.C. Montgomery and W.H. Matthaeus, "Oseen vortex as a maximum entropy state in a two dimensional fluid," Phys. Fluids 23, 075104 (2011)