BEGIN:VCALENDAR VERSION:2.0 CALSCALE:GREGORIAN PRODID:UW-Madison-Physics-Events BEGIN:VEVENT SEQUENCE:0 UID:UW-Physics-Event-9704 DTSTART:20260527T150000Z DTEND:20260527T170000Z DTSTAMP:20260513T144904Z LAST-MODIFIED:20260512T213217Z LOCATION:B343 Sterling or https://uwmadison.zoom.us/j/99790313242?pwd= OH9YvPxo9W1R6sQOqx5LlUD655cVrM.1 SUMMARY:Measurements of Electron Pressure Anisotropy during Laboratory Magnetic Reconnection\, Thesis Defense\, Cameron Kuchta\, Physics PhD Graduate Student DESCRIPTION:The Terrestrial Reconnection EXperiment (TREX) at the Wisc onsin Plasma Physics Laboratory (WiPPL) studies magnetic reconnection\ , a process in which magnetic energy can be converted to plasma energy creating flows\, increased temperatures\, and high energy particles. The reconnection studied in TREX is most relevant to Earth's magnetosp here that brings the Sun's solar wind plasma into the magnetic fields connected to Earth's poles. This thesis consists of three diagnostic d evelopments that have enhanced our understanding of reconnection via m ore accurate measurements and access to new plasma parameters.
\n\nFor driving reconnection\, TREX applies a strong reconnection driv e which includes the sudden energization of a system of coils encircli ng the plasma. Before the formation of the reconnection current layer\ , this reconnection drive produces a strong magnetosonic wave includin g a wave-front moving radially inward towards the center of the device . The propagation speed of this front is governed by the dispersion re lation of the magnetosonic wave\, directly related to the plasma densi ty. We will discuss and show how the analysis of the wave propagation provides reliable density profiles which are consistent with measureme nts by Langmuir probes. These profiles characterize the initial plasma produced by an array of plasma guns\, which is valuable for analyzing and understanding the plasma dynamics at later times during the plasm a discharges.
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\nLangmuir probes are commonly used for measuri ng plasma temperature\, density\, and potential. We have developed a n umber of techniques that optimize the functionality of multi-tip Langm uir probes used for measuring the full current-voltage characteristic at a 10 MHz sampling rate. These upgrades gives the probe increased si gnal-to-noise ratio\, ability to measure lower plasma densities\, and more accurate resulting measurements.
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\nWe have developed a p ressure anisotropy probe that can measure plasma flows and temperature anisotropies during reconnection. TREX is in the collisionless kineti c regime in which we expect electron anisotropy effects to dominate th e physics of the ion diffusion regime near the x-point of reconnection . Embedded jets\, seen in laboratory data\, are driven into the outflo w as expected from spacecraft observation of the magnetosphere\, theor y\, and simulations. This probe has successfully measured electron pre ssure anisotropy in the laboratory\, validating the expected influence of kinetic effects during reconnection. URL:https://www.physics.wisc.edu/events/?id=9704 END:VEVENT END:VCALENDAR