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Title: Laser propagation measurements in long-scale-length underdense plasmas relevant to magnetized liner inertial fusion

Here, we report experimental results and simulations showing efficient laser energy coupling into plasmas at conditions relevant to the magnetized liner inertial fusion (MagLIF) concept. In MagLIF, to limit convergence and increase the hydrodynamic stability of the implosion, the fuel must be efficiently preheated. To determine the efficiency and physics of preheating by a laser, an Ar plasma with n e / n c r i t ~ 0.04 is irradiated by a multi-ns, multi-kJ, 0.35-μm, phase-plate-smoothed laser at spot-averaged intensities ranging from 1.0 × 10 14 to 2.5 × 10 14 W / c m 2 and pulse widths from 2 to 10 ns. Time-resolved x-ray images of the laser-heated plasma are compared to two-dimensional radiation-hydrodynamic simulations that show agreement with the propagating emission front, a comparison that constrains laser energy deposition to the plasma. The experiments show that long-pulse, modest-intensity ( I = 1.5 × 10 14 W / c m 2 ) beams can efficiently couple energy ( ~ 82 % of the incident energy) to MagLIF-relevant long-length (9.5 mm) underdense plasmas. The heating efficiency we demonstrate is significantly higher than it was thought to have been achieved in early integrated MagLIF experiments [A. B.more » Sefkow et al., Phys. Plasmas 21, 072711 (2014)].« less
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [2] ;  [4] ;  [4] ;  [1] ;  [5]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Naval Research Lab. (NRL), Washington, DC (United States)
Publication Date:
Report Number(s):
SAND2016-11073J
Journal ID: ISSN 2470-0045; PLEEE8; 648803; TRN: US1701294
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Physical Review E
Additional Journal Information:
Journal Volume: 94; Journal Issue: 5; Journal ID: ISSN 2470-0045
Publisher:
American Physical Society (APS)
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1338676
Alternate Identifier(s):
OSTI ID: 1330738