Observation of parametric instabilities in the quarter critical density region driven by the Nike KrF laser

Journal Article · Fri Feb 15 04:00:00 EST 2013 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4789379· OSTI ID:22113451

Weaver, J. L.; Kehne, D.; Brown, C. M.; Obenschain, S. P.; Serlin, V.; Schmitt, A. J. ^[1]; Oh, J.; Lehmberg, R. H.; Mclean, E.; Manka, C. ^[2]; Phillips, L. ^[3]; Afeyan, B. ^[4]; Seely, J.; Feldman, U. ^[5]

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1. U.S. Naval Research Laboratory, Washington DC 20375 (United States)
2. Research Support Instruments, Lanham, Maryland 20905 (United States)
3. Alogus Research Corporation, McLean, Virginia 22101 (United States)
4. Polymath Research, Inc., Pleasanton, California 94566 (United States)
5. Berkeley Research Associates, Inc., Beltsville, Maryland 20705 (United States)

The krypton-fluoride (KrF) laser is an attractive choice for inertial confinement fusion due to its combination of short wavelength ({lambda}=248 nm), large bandwidth (up to 3 THz), and superior beam smoothing by induced spatial incoherence. These qualities improve the overall hydrodynamics of directly driven pellet implosions and should allow use of increased laser intensity due to higher thresholds for laser plasma instabilities when compared to frequency tripled Nd:glass lasers ({lambda}=351 nm). Here, we report the first observations of the two-plasmon decay instability using a KrF laser. The experiments utilized the Nike laser facility to irradiate solid plastic planar targets over a range of pulse lengths (0.35 ns{<=}{tau}{<=}1.25 ns) and intensities (up to 2 Multiplication-Sign 10{sup 15} W/cm{sup 2}). Variation of the laser pulse created different combinations of electron temperature and electron density scale length. The observed onset of instability growth was consistent with the expected scaling that KrF lasers have a higher intensity threshold for instabilities in the quarter critical density region.

• OSTI ID: 22113451
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 2 Vol. 20; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DECAY INSTABILITY
DENSITY
ELECTRON DENSITY
ELECTRON TEMPERATURE
EXPLOSIONS
GLASS
HYDRODYNAMICS
INERTIAL CONFINEMENT
ION TEMPERATURE
IRRADIATION
KRYPTON FLUORIDE LASERS
KRYPTON FLUORIDES
PARAMETRIC INSTABILITIES
PLASMA DENSITY
WAVELENGTHS