LLE Review 78

Review 78


LLE Review 78 begins with two articles concerning issues relevant to 2-D SSD laser-beam smoothing on OMEGA. In the first article the design of an efficient, bulk-phase modulator operating at approximately 10.5 GHz is presented, which can produce substantial phase-modulated bandwidth with modest microwave drive power. This modulator is the cornerstone of the 1-THz UV bandwidth operation planned for OMEGA this year. In the second article a recently developed code—Waasese—that simulates the collective behavior of the optical components in the SSD driver line is described. Additional research highlights presented in this issued include:

  • Compression of shell material to areal densities of ~60 to 130 mg/cm2 was observed in a 60-beam implosion experiment of hollow-shell targets
  • this experiment also surveyed target performance based on laser-irradiation uniformity and laser pulse shape. Two charged-particle magnetic spectrometers, which LLE has developed in collaboration with MIT and LLNL, were used to perform simultaneous measurements of the fuel areal density, shell areal density, and fuel temperature of D3He-filled imploding capsules.
  • The modeling of an aperture-coupled-stripline (ACSL), electrical-waveform generator is described, which produces an optical seed pulse for OMEGA and is critically related to the on-target pulse shape. (4) A measurement technique that enables the complete characterization of electronic devices having any dynamic temporal and spectral frequency response is presented, such as the photoconductive microwave switches on OMEGA's pulse-shaping system.
  • Damage to OMEGA's stage-C-input, C-output, D-input, E-input, and F-input fused-silica, spatial-filter lenses is examined, and safe operational damage criteria are outlined.

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