Multi-beam effects on backscatter and its saturation in experiments with conditions relevant to ignitiona)

To optimize the coupling to indirect drive targets in the National Ignition Campaign (NIC) at the National Ignition Facility [E. Moses et al., Phys. Plasmas 16, 041006 (2009)], a model of stimulated scattering produced by multiple laser beams is used. The model has shown that scatter of the 351 nm beams can be significantly enhanced over single beam predictions in ignition relevant targets by the interaction of the multiple crossing beams with a millimeter scale length, 2.5 keV, 0.02−0.05 × critical density, plasma. The model uses a suite of simulation capabilities and its key aspects are benchmarked with experiments at smaller laser facilities. The model has also influenced the design of the initial targets used for NIC by showing that both the stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) can be reduced by the reduction of the plasma density in the beam intersection volume that is caused by an increase in the diameter of the laser entrance hole (LEH). In this model, a linea...

[1]  N. Fisch,et al.  Amplification of an ultrashort pulse laser by stimulated Raman scattering of a 1ns pulse in a low density plasma , 2007 .

[2]  J D Lindl,et al.  Tuning the implosion symmetry of ICF targets via controlled crossed-beam energy transfer. , 2009, Physical review letters.

[3]  R. Kirkwood,et al.  Observation of ion wave decay products of Langmuir waves generated by stimulated Raman scattering in ignition scale plasmas , 2003 .

[4]  B. Albright,et al.  Different kλD regimes for nonlinear effects on Langmuir wavesa) , 2006 .

[5]  Victor Malka,et al.  High density gas jet nozzle design for laser target production , 2001 .

[6]  Milo R. Dorr,et al.  Effects of ion trapping on crossed-laser-beam stimulated Brillouin scattering , 2004 .

[7]  T. Takizuka,et al.  A binary collision model for plasma simulation with a particle code , 1977 .

[8]  K. Bowers,et al.  Ultrahigh performance three-dimensional electromagnetic relativistic kinetic plasma simulationa) , 2008 .

[9]  J. D. Moody,et al.  Scaling of saturated stimulated Raman scattering with temperature and intensity in ignition scale plasmas , 2003 .

[10]  R. Kirkwood,et al.  Observation of multiple mechanisms for stimulating ion waves in ignition scale plasmas. Revision 1 , 1997 .

[11]  L. Divol,et al.  Backscatter reduction using combined spatial, temporal, and polarization beam smoothing in a long-scale-length laser plasma. , 2001, Physical review letters.

[12]  P. Michel,et al.  Three-dimensional modeling of laser-plasma interaction: Benchmarking our predictive modeling tools versus experimentsa) , 2008 .

[13]  Edward I. Moses,et al.  The National Ignition Facility: Ushering in a new age for high energy density science , 2009 .

[14]  J. D. Moody,et al.  Symmetry tuning for ignition capsules via the symcap techniquea) , 2011 .

[15]  J. Moody,et al.  Evidence of plasma fluctuations and their effect on the growth of stimulated Brillouin and stimulated Raman scattering in laser plasmas , 1998 .

[16]  Rose,et al.  Observed Dependence of Stimulated Raman Scattering on Ion-Acoustic Damping in Hohlraum Plasmas. , 1996, Physical review letters.

[17]  Proceedings of the ACM/IEEE Conference on Supercomputing, SC 1997, November 15-21, 1997, San Jose, CA, USA , 1997, SC.

[18]  P. Michel,et al.  Stimulated Raman scatter analyses of experiments conducted at the National Ignition Facility a) , 2010 .

[19]  P. Michel,et al.  National Ignition Campaign Hohlraum energeticsa) , 2009 .

[20]  Steven W. Haan,et al.  Three-dimensional HYDRA simulations of National Ignition Facility targets , 2001 .

[21]  K. Bowers,et al.  Observation of amplification of light by Langmuir waves and its saturation on the electron kinetic timescale , 2010 .

[22]  O. Landen,et al.  The physics basis for ignition using indirect-drive targets on the National Ignition Facility , 2004 .

[23]  Stephen D. Jacobs,et al.  Direct‐drive laser‐fusion experiments with the OMEGA, 60‐beam, >40 kJ, ultraviolet laser system , 1996 .

[24]  William Daughton,et al.  Saturation of backward stimulated scattering of laser in kinetic regime: Wavefront bowing, trapped particle modulational instability, and trapped particle self-focusing of plasma waves , 2008 .

[25]  M. H. Key,et al.  The Physics of Laser Plasma Interactions , 1989 .

[26]  Scott C. Wilks,et al.  Development of a nanosecond-laser-pumped Raman amplifier for short laser pulses in plasma , 2009 .

[27]  Moody,et al.  Observation of energy transfer between frequency-mismatched laser beams in a large-scale plasma. , 1996, Physical review letters.

[28]  A. B. Langdon,et al.  Analyses of laser-plasma interactions in National Ignition Facility ignition targetsa) , 2007 .

[29]  D. F. DuBois,et al.  The effect of kinetic processes on Langmuir turbulence , 2000 .

[30]  D. S. Montgomery,et al.  Recent Trident single hot spot experiments: Evidence for kinetic effects, and observation of Langmuir decay instability cascade , 2002 .

[31]  J. Moody,et al.  Calibration of initial measurements from the full aperture backscatter system on the National Ignition Facility , 2004 .

[32]  Robert L. Kauffman,et al.  Dante soft x-ray power diagnostic for National Ignition Facility , 2004 .

[33]  Scott C. Wilks,et al.  Energy transfer between crossing laser beams , 1996 .

[34]  N. Fisch,et al.  Manipulating ultraintense laser pulses in plasmas , 2005 .

[35]  Marilyn Schneider,et al.  Analysis of the National Ignition Facility ignition hohlraum energetics experiments a) , 2011 .

[36]  D. Dubois,et al.  Transient enhancement and detuning of laser-driven parametric instabilities by particle trapping. , 2001, Physical review letters.

[37]  J. Moody,et al.  OBSERVATION OF THE NONLINEAR SATURATION OF LANGMUIR WAVES DRIVEN BY PONDEROMOTIVE FORCE IN A LARGE SCALE PLASMA , 1999 .

[38]  K. Bowers,et al.  Saturation of backward stimulated scattering of a laser beam in the kinetic regime. , 2007, Physical review letters.

[39]  F. D. Lee,et al.  Hard x-ray and hot electron environment in vacuum hohlraums at the National Ignition Facility , 2006 .

[40]  J. D. Moody,et al.  Laser–plasma interactions in ignition‐scale hohlraum plasmas , 1996 .

[41]  Williams,et al.  Effect of Ion-Wave Damping on Stimulated Raman Scattering in High-Z Laser-Produced Plasmas. , 1996, Physical review letters.