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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-8684
DTSTART:20240318T170000Z
DTEND:20240318T181500Z
DTSTAMP:20260413T223409Z
LAST-MODIFIED:20240313T125906Z
LOCATION:1227 Engineering Hall
SUMMARY:"Cylindrical Implosion Experiments at Los Alamos National Labo
 ratory"\, Plasma Physics (Physics/ECE/NE 922) Seminar\, Josh Sauppe\, 
  LANL (Los Alamos National Laboratory)
DESCRIPTION:The advent of high-power laser facilities such as the Nati
 onal Ignition Facility (NIF) has ushered in a new and exciting era in 
 high-energy-density (HED) physics research\, and the flexibility of th
 e NIF allows many distinct targets to be fielded beyond the standard i
 ndirect-drive inertial confinement fusion (ICF) configuration. Los Ala
 mos scientists are using directly driven cylindrical implosion experim
 ents at the NIF to study hydrodynamic instability growth in regimes re
 levant to ICF systems\, as cylinders enable direct measurements by vie
 wing down the cylinder axis. These physical systems are often modeled 
 in more tractable two-dimensional (2D) simulations with assumed symmet
 ry\, but this simplification risks inadvertently masking crucial featu
 res. Here\, we show experimental evidence of a 3D asymmetry in directl
 y driven cylindrical implosions which was not predicted with 2D modeli
 ng\, and we accurately reproduce this feature in 3D simulations. The a
 symmetry arises from the NIF beam geometry and the dependence of laser
  absorption on beam incidence angle\, and we also find that there is a
  north/south skew to the drive asymmetry. This skew is obscured in rad
 iographs that image down the cylinder axis\, complicating inferences o
 f instability growth. This has significant implications for targets wi
 th off-normal beam pointing such as polar direct-drive ICF\, and it ma
 y also be important for a more complete understanding of indirect-driv
 e systems. In particular\, differences between experimental data and s
 ynthetic data generated from 2D simulations can be misattributed to de
 ficiencies in physics models rather than 3D effects. A similar but mor
 e subtle 3D effect is also identified for smaller-scale cylindrical im
 plosion experiments fielded at the OMEGA laser facility\, and this is 
 confirmed in recent experiments.
URL:https://www.physics.wisc.edu/events/?id=8684
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