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Plasma Seminar
Investigations of fundamental Alfvénic Wave Physics
Date: Thursday, February 29th
Time: 1:00 pm - 2:00 pm
Place: B343 Sterling Hall
Speaker: Seth Dorfman, Space Science Institute
Abstract: nvestigations of fundamental Alfvénic wave physics in the laboratory and in space Low frequency Alfvénic waves and fluctuations are ubiquitous in laboratory and space plasmas, and these fundamental modes of a magnetized plasma often serve as building blocks for more complicated structures and dynamics. The linear and non-linear properties of these waves may play key roles in the turbulent solar wind, heating of the solar corona, and the environment near the Earth's bow shock. In this seminar, I will present a vision for how laboratory and spacecraft studies focused on these fundamental building blocks can help us develop a more complete picture of important space physics phenomena. Our recent work on the Large Plasma Device at UCLA successfully isolated important non-linear Alfvénic phenomena that may be building blocks of the turbulent solar wind [e.g., Dorfman and Carter, PRL 2016]. Recent results include a proof-of-principle measurement of the Parametric Decay Instability (PDI) growth rate [Dorfman, et. al, in prep]; PDI has been previously shown to bound the solar wind parameter space. We also recorded the first observation of residual energy in a non-linear Alfvén wave interaction [Abler, et. al, in prep]; this is important because residual energy is observed in the inertial range of the turbulent cascade (i.e. there is more energy in the magnetic than the velocity fluctuations), but an MHD Alfvén wave has equal amounts of energy in fluctuations of each type. On the spacecraft study side, I will introduce the Earth's ion foreshock as a natural laboratory for wave studies and show a new method to detect the foreshock edge that also has wide implications for the interpretation of minimum variance techniques commonly used to determine wave properties [Dorfman, et. al, 2023]. After examining these various examples, I will discuss the prospects of a new Solar Wind Machine aimed at producing magnetized plasma turbulence in the laboratory for detailed study to complement and extend spacecraft observations [Dorfman, et. al, Heliophysics Decadal White Paper 2022]. You are invited to join us on April 18-20 for a workshop to refine physics targets and develop candidate machine designs:
Host: Jan Egedal
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