Analysis of Laser Preheating Stage of MagLIF to Increase Laser Energy Coupling and Validate Simulations

Stephanie Miller, University of Michigan

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Magnetized Liner Inertial Fusion (MagLIF) is a type of inertial confinement fusion studied at Sandia National Laboratories. MagLIF target designs include a cylindrical tube (or “liner”) and a laser entrance hole covered by a thin (few-micron-thick) window that holds pressurized fuel inside of the target. This work includes studies of both the window and the target wall/liner. There are energy losses at the window as a preheating laser beam enters the target. Laser-window interactions reduce heating efficiency and mix window and target materials into the fuel. To reduce these losses and improve fusion yield, we implemented a system that removes this window before the laser beam passes through the window opening. This window removal method is referred to as "Laser Gate." We have demonstrated a Laser Gate proof of concept and built a test facility to allow for future studies of window opening dynamics. Additionally, this work includes studies of wall movement. In this setup, the laser enters a gas filled target and the gas heats to a plasma creating a blast wave. The blast wave bounces off the target wall and can pull target material back into the fuel. This process is important to understand because wall material mixing into the fuel could ultimately degrade fusion yield in an integrated MagLIF experiment. We are working to understand this wall mix as a function of time and radial position of the target. For this, two experimental campaigns were executed at the OMEGA and OMEGA EP facilities. Initial results show wall movement near the predicted time and in-depth analysis is ongoing. These experimental results will be compared to simulated data to further validate MagLIF simulations. We will cover the recommendations for continuing Laser Gate studies and report on the results of the recent OMEGA campaigns.

Abstract Author(s): S.M. Miller, M.R. Gomez, S.A. Slutz, M.R. Weis, N.M. Jordan, C. C. Kuranz, and R.D. McBride