Speaker: Troy Carter, University of California, Los Angeles

Title: Plasma wave studies using the Basic Plasma Science Facility

Abstract: The Basic Plasma Science Facility (BaPSF) at UCLA is a collaborative research facility for studies of fundamental processes in magnetized plasmas, supported by US DOE and NSF.  The centerpiece of the facility is the Large Plasma Device (LAPD), a 20m long, magnetized linear plasma device.  The LAPD is used to study a number of fundamental processes, including: collisionless shocks; dispersion and damping of kinetic and inertial Alfv\'{e}n waves; turbulence and transport; flux ropes and 3D reconnection; and interactions of energetic ions and electrons with plasma waves. An overview of research using the facility will be given, followed by a more detailed discussion of studies of two topics: the nonlinear physics of Alfvén waves and the physics of ion cyclotron range of frequencies (ICRF) waves relevant to heating and current drive in fusion devices.  A number of recent experiments have  focused on the nonlinear properties of Alfvén waves, including three-wave interactions relevant to the MHD turbulent cascade and parametric instabilities, including the first laboratory observation of the parametric instability of shear Alfvén waves.  In this latter experiment, shear waves with sufficiently high ω/Ωc,i (> 0.6) and above a threshold wave amplitude are observed to decay into co-propagating daughter waves; one a shear Alfvén wave and the other a low-frequency quasimode, similar to the modulational decay instability. Another series of experiments using LAPD have studied wave physics relevant to ion cyclotron range of frequencies (ICRF) heating and current drive in fusion devices.  This includes high power (~ 200kW) fast wave excitation (ω ∼ 2−10Ωci) experiments that have documented the structure and scaling of RF sheaths, the formation of convective cells and associated density modification, as well as low power experiments studying parasitic coupling to the slow mode and the interaction of high-harmonic fast waves (or helicon waves) with filamentary structures to study turbulent scattering processes.

Bio: Troy Carter is a Professor of Physics at the University of California, Los Angeles. Prof. Carter is the Director of the Basic Plasma Science Facility (BaPSF), a national user facility for plasma science supported by DOE and NSF. He is also the Director of the Plasma Science and Technology Institute (PSTI), an organized research unit at UCLA. His research into waves, instabilities, turbulence and transport in magnetically confined plasmas is motivated by the desire to understand processes in space and astrophysical plasmas as well as by the need to develop carbon-free electricity generation via nuclear fusion. Prof. Carter led the DOE FESAC Long Range Planning process that resulted in the 2021 report “Powering the Future: Fusion and Plasmas.” He is a Fellow of the APS and is a recipient of the APS DPP John Dawson Excellence in Plasma Physics Research Award and of the Fusion Power Associates Leadership Award. Prof. Carter received BS degrees in Physics and Nuclear Engineering from North Carolina State University in 1995 and a PhD in Astrophysical Sciences from Princeton University in 2001.

This talk will be offered in a hybrid format. If you wish to participate remotely, please send an email to [email protected].