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Title: Mitigation of cross-beam energy transfer in symmetric implosions on OMEGA using wavelength detuning

The effects of frequency detuning laser beams in direct-drive symmetric implosions were investigated with a 3-D cross-beam energy transfer (CBET) model. Our model shows that interactions between beams with relative angles between 45° and 90° are most significant for CBET in OMEGA direct-drive implosions. There is no net exchange in power between beams but there is significant redistribution of power from the ingoing central portion of the beam profile to the outgoing edge as it is exiting the plasma, reducing the total absorbed power. Furthermore, redistribution of laser power because of CBET increases the root-mean-square (rms) absorption nonuniformity by an order of magnitude. CBET mitigation by shifting relative wavelengths of three groups of laser beams fed by each of the different beamlines was modeled. At an on-target wavelength shift of Δλ ~ 10 Å, the total laser absorption was maximized, and the rms absorption nonuniformity was near minimum. In order to completely decouple the three groups of beams from each other requires wavelength shifts Δλ > 30 Å.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
Publication Date:
Report Number(s):
2017-11, 1342
Journal ID: ISSN 1070-664X; 2017-11, 1342, 2296
Grant/Contract Number:
NA0001944
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 6; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Rochester, NY (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:
1366441
Alternate Identifier(s):
OSTI ID: 1372508