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Plasma Physics (Physics/ECE/NE 922) Seminar
Fusion-relevant studies using the LAPD: ICRF and mirror physics
Date: Monday, December 11th
Time: 12:00 pm - 1:15 pm
Place: 1610 Engineering Hall
Speaker: Dr. Troy Carter, Director of Basic Plasma Science Facility (BaPSF) at UCLA
Abstract: The Basic Plasma Science Facility (BaPSF) at UCLA is a US national collaborative research facility for studies of fundamental processes in magnetized plasmas supported by DOE FES and NSF. The centerpiece of the facility is the Large Plasma Device (LAPD), a 20m long, magnetized linear plasma device. LAPD has been utilized to study a number of fundamental processes, including: collisionless shocks, dispersion and damping of kinetic and inertial Alfvén waves, compressional Alfvén waves for ion-cyclotron range of frequencies heating, flux ropes and magnetic reconnection, three-wave interactions and parametric instabilities of Alfvén waves, turbulence and transport 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 fusion- and mirror-relevant studies. These include our "ICRF Campaign," focused on wave physics and parasitic effects 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 the structure and scaling of RF sheaths, the formation of convective cells and associated density modification, as well as low power experiments documenting 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. LAPD has a flexible magnetic field configuration, allowing for mirror configurations with variable mirror ratio, including periodic (many cell) mirrors. Changes to turbulence and turbulent transport have been documented as a function of mirror ratio. In a single-celled mirror, density and magnetic field fluctuation amplitudes decreased with increasing mirror ratio, while potential fluctuation amplitudes remained similar. The cross-phase between potential and density fluctuations varies with increasing mirror ratio, suggesting a shift in the underlying linear instability as the mirror ratio is increased and magnetic curvature is introduced.

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.
Host: Prof. Steffi Diem
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