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The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, is the first of its kind megajoule-class laser facility with 192 beams capable of delivering over 1.8 MJ and 500TW of 351 nm light for high accuracy laser-matter interaction experiments. It has been commissioned and operated since 2009 to support a wide range of missions including the study of inertial confinement fusion, high energy density physics, material science, and laboratory astrophysics. In the first section of this paper we discuss the current status of laser performance obtained during the 408 target experiments completed in 2017. The performance spanned a wide range of laser energies, powers and pulse durations as requested for these target experiments. A special emphasis is given on energy delivery and cone power accuracy in the UV, as these are key parameters for successful experiments. In the second section of the paper, the results obtained during the 2017 performance quad campaign are briefly described. During this campaign a series of laser-only shots were taken to perform tests at elevated energies on a single NIF quad. These tests were designed to assess laser performance limits and operational costs against predictive models. This campaign culminated with the delivery of ~54 kJ of UV on a single quad of NIF, and 14 kJ on a single beam aperture, which are both to our knowledge the largest energies achieved to date for a neodymium-glass, frequency tripled architecture.

Measurements of mass flux are obtained in a vitiated supersonic ground-test facility using a sensor based on lineof-sight diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions ( 1 1349 nm and 2 1341:5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption-related transmission fluctuations. The sensor line of sight is translated both vertically and horizontally across the test section for spatially resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the wavelength-modulation spectroscopy lineshape caused by boundary layers along the laser line of sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow nonuniformities is introduced and application of this correction brings measured velocities within 4 m=s of the predicted value in a 1630 m=s flow.

Measurements of mass flux are obtained in a vitiated supersonic ground-test facility using a sensor based on lineof-sight diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions ( 1 1349 nm and 2 1341:5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption-related transmission fluctuations. The sensor line of sight is translated both vertically and horizontally across the test section for spatially resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the wavelength-modulation spectroscopy lineshape caused by boundary layers along the laser line of sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow nonuniformities is introduced and application of this correction brings measured velocities within 4 m=s of the predicted value in a 1630 m=s flow.