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PRODID:UW-Madison-Physics-Events
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UID:UW-Physics-Event-7974
DTSTART:20221024T170000Z
DURATION:PT1H0M0S
DTSTAMP:20260412T041256Z
LAST-MODIFIED:20221019T172521Z
LOCATION:1610 Engineering Hall
SUMMARY:Exploring the new electron-positron plasma frontier: the annih
 ilation signature of cold magnetically-confined pairs and accessing th
 e relativistic and magnetized regime\, Plasma Physics (Physics/ECE/NE 
 922) Seminar\, Jens von der Linden\, IPP Garching
DESCRIPTION:Advances in positron production\, accumulation\, and trapp
 ing are enabling a new plasma physics frontier: electron-positron pair
  plasma. I will report on two parallel efforts.<br>
\n<br>
\nOne line 
 of research aims to accumulate and magnetically confine moderated posi
 trons with electrons in sufficient numbers to produce a pair plasma wi
 th a small Debye length (but with a skin depth exceeding the plasma si
 ze). The mass symmetry of pair plasma has led to many predictions with
  regard to their stability to electrostatic modes and (absence of) tur
 bulence. Yet\, it is unclear how to diagnose the behaviour of these el
 ectromagnetically transparent plasmas without terminating them. Here\,
  I show that direct annihilation in the bulk of the plasma\, positroni
 um formation and subsequent annihilation\, as well as transport to the
  wall and magnets will produce various volumetric and localized source
 s of gamma emission with rates related to the plasma parameters. Metho
 ds for diagnosing and differentiating between volumetric and localized
  gamma sources are developed.<br>
\n<br>
\nThe other effort aims to ma
 gnetize the large numbers (up to 10^12) of pairs produced through lase
 r-target interactions at intense short-pulse laser facilities. The ene
 rgy of these pair beams can be controlled by manipulating the sheath o
 n the backside of the target. The charge ratio of the pair beam can be
  made unitary with magnetic collimation. The lifetime of these pair be
 ams can be extended with magnetic mirror trapping. Together\, these ex
 perimental techniques could make the relativistic and magnetized plasm
 a regime\, prevalent around massive astrophysical objects such as magn
 etars\, accessible.<br>
\n<br>
\n
URL:https://www.physics.wisc.edu/events/?id=7974
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