Energetics of multiple-ion species hohlraum plasmas

Journal Article · Thu May 15 00:00:00 EDT 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2890126· OSTI ID:21120384

Neumayer, P; Berger, R L; Callahan, D; Divol, L; Froula, D H; London, R A; MacGowan, B J; Meezan, N B; Michel, P A; Ross, J S; Sorce, C; Widmann, K; Suter, L J; Glenzer, S H ^[1]

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1. L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

A study of the laser-plasma interaction processes has been performed in multiple-ion species hohlraum plasmas at conditions similar to those expected in indirect drive inertial confinement fusion targets. Gas-filled hohlraums with electron densities of 5.5x10{sup 20} and 9x10{sup 20} cm{sup -3} are heated by 14.3 kJ of laser energy (wavelength 351 nm) to electron temperatures of 3 keV and backscattered laser light is measured. Landau damping of the ion acoustic waves is increased by adding hydrogen to a CO{sub 2} or CF{sub 4} gas. Stimulated Brillouin backscattering of a 351 nm probe beam is found to decrease monotonically with increasing Landau damping, accompanied by a comparable increase in the transmission. More efficient energy coupling into the hohlraum by suppression of backscatter from the heater beams results in an increased hohlraum radiation temperature, showing that multiple-ion species plasmas improve the overall hohlraum energetics. The reduction in backscatter is reproduced by linear gain calculations as well as detailed full-scale three-dimensional laser-plasma interaction simulations, demonstrating that Landau damping is the controlling damping mechanism in inertial confinement fusion relevant high-electron temperature plasmas. These findings have led to the inclusion of multiple-ion species plasmas in the hohlraum point design for upcoming ignition campaigns at the National Ignition Facility.

• OSTI ID: 21120384
• Journal Information: Physics of Plasmas, Vol. 15, Issue 5; Other Information: DOI: 10.1063/1.2890126; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAMS
BRILLOUIN EFFECT
CARBON DIOXIDE
CARBON TETRAFLUORIDE
ELECTRON DENSITY
ELECTRON TEMPERATURE
HYDROGEN
INERTIAL CONFINEMENT
ION ACOUSTIC WAVES
ION TEMPERATURE
IONS
LANDAU DAMPING
LASERS
PLASMA
PLASMA DENSITY
PLASMA HEATING
THERMONUCLEAR IGNITION
US NATIONAL IGNITION FACILITY