BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Polar Direct Drive implosions on the Laser MegaJoule
DTSTART:20260526T124500Z
DTEND:20260526T134500Z
DTSTAMP:20260526T023300Z
UID:indico-event-25089@indico.gsi.de
CONTACT:p.neumayer@gsi.de\;c.deguchi@gsi.de
DESCRIPTION:Speakers: Witold Cayzac (CEA\, DAM\, DIF)\n\nWe present the fi
 rst two direct-drive implosion experiments with symmetric laser beam illum
 ination on the LMJ laser facility\, performed in the last two years. Two d
 ifferent implosion regimes have been investigated\, both using 10 laser bu
 ndles\, i.e. 20 quads and 80 beams. In both cases\, we used square laser p
 ulse shapes and the laser pointing has been optimized with the Polar Direc
 t Drive (PDD) technique as well as power balance between irradiation cones
 .\nThe 2025 experiment investigated the exploding-pusher regime using D2-f
 illed 1-mm diameter few-micrometer thick glass capsules and PDD settings o
 n the quad level. We obtained a well-characterized and robust platform tha
 t can be employed for particle generation\, though with a small convergenc
 e ratio ≈ 3 and a limited yield of up to 2x1011 neutrons. While PDD opti
 mization improves implosion symmetry\, the implosion performances appear t
 o be robust against low-mode asymmetries.\nThe 2026 experiment was aimed a
 t improving the implosion performances by exploring a more compressive (or
  ablative) implosion regime. For this purpose\, larger targets were used\,
  namely D2-filled 2-mm diameter 20-µm thick plastic capsules. To deal wit
 h the capsule size\, we tested a more advanced PDD scheme\, with moderate 
 quad defocusing as well as quad splitting in addition of PDD on the quad l
 evel. In this configuration\, convergence ratios were between 5 and 10\, a
 nd neutron yields > 5x1011 were reached. Important in-flight as well as ho
 t-spot deformations have been measured. Nevertheless\, the neutron yield r
 emained relatively robust\, indicating that the implosion regime was not y
 et fully compressive.\nThese first experiments pave the way for direct-dri
 ve experiments upcoming in the next years\, either through academic access
  or in the frame of the French TARANIS project for Inertial Fusion Energy.
 \n\nhttps://indico.gsi.de/event/25089/
LOCATION:SB3 3.170a (GSI)
URL:https://indico.gsi.de/event/25089/
END:VEVENT
END:VCALENDAR