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<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue">SPACE PHYSICS SEMINAR</span><o:p></o:p></p>
<p class="MsoNormal" align="center" style="text-align:center"> <o:p></o:p></p>
<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue">DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES</span><o:p></o:p></p>
<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue">DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCES</span><o:p></o:p></p>
<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue">UNIVERSITY OF CALIFORNIA, LOS ANGELES</span><o:p></o:p></p>
<p class="MsoNormal" align="center" style="text-align:center"> <o:p></o:p></p>
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<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue">ZOOM LINK PROVIDED BELOW</span><o:p></o:p></p>
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<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue"> </span><a href="https://ucla.zoom.us/j/92101918782?pwd=Z2o5RmI4OEpBWW4zcG1DZStIUWgrZz09" target="_blank">https://ucla.zoom.us/j/92101918782?pwd=Z2o5RmI4OEpBWW4zcG1DZStIUWgrZz09</a><o:p></o:p></p>
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<b><span style="color:blue">Efficient non-thermal particle acceleration mediated by the kink instability in jets<o:p></o:p></span></b></p>
<p class="MsoNormal" align="center" style="text-align:center"><i><span style="color:blue">Professor Paulo Alves,<o:p></o:p></span></i></p>
<p class="MsoNormal" align="center" style="text-align:center"><i><span style="color:blue">Physics and Astronomy, UCLA<o:p></o:p></span></i></p>
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<p class="MsoNormal"><span style="color:blue">Astrophysical jets shine across the entire electromagnetic spectrum and are among the most powerful particle accelerators in the universe. Yet, the mechanisms underlying their particle acceleration are not well
understood. MHD simulations suggest that the development of the current-driven kink instability (KI) can play an important role in the dissipation of the jet’s internal magnetic field, but it remains clear if such process could lead to efficient non-thermal particle
acceleration, required to explain observations. In this talk, I will present 3D particle-in-cell simulations that capture the self-consistent particle acceleration associated with the development of the current-driven kink instability (KI) in magnetic field
geometries relevant to recollimation regions of relativistic jets. These simulations reveal that the development of the KI mediates the efficient dissipation of the magnetic field into high-energy particles. Non-thermal particles are accelerated by a coherent inductive
electric field that develops at the core of the current flow during the nonlinear stage of the KI. Acceleration by the large-scale inductive electric field is made efficient by the highly tangled magnetic field structure that characterizes the nonlinear phase
of the KI, which allows particles to experience rapid curvature-drift motions across the magnetic field lines and parallel to the electric field. This results in a spectral power-law tail that is robust for a large range of initial conditions and system sizes.
I will present scaling laws for this process with system size and magnetization, and discuss the implications of our results for relativistic astrophysical jets. Finally, I will discuss the possibility of exploring this physics in high-energy-density (HED)
laboratory experiments.<o:p></o:p></span></p>
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<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue">Friday, November 19, 2021<o:p></o:p></span></p>
<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue">3:30 - 5:00 PM<o:p></o:p></span></p>
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<p class="MsoNormal" align="center" style="text-align:center"><span style="color:blue">In-Charge: Marco Velli<o:p></o:p></span></p>
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