10 Matching Results

Search Results

Advanced search parameters have been applied.

Detection of 1 - 100 keV x-rays from high intensity, 500 fs laser- produced plasmas using charge-coupled devices

Description: We describe a compact, vacuum compatible, large format, charge- coupled device (CCD) camera for scientific imaging and detection of 1- 100 keV x rays in experiments at LLNL JANUS-1ps laser. A standard, front-illuminated, multi-pin phase device with 250 k electron full well capacity, low dark current (10 pA/cm{sup 2} at 20 C) and low read noise (5 electron rms) is cooled to -35 C to give the camera excellent 15-bit dynamic range and signal-to-noise response. Intensity and x-ray energy linear response were determined for optical and x-ray (<65 keV) photons and are in excellent agreement. Departure from linearity was less than 0.7%. Inherent linearity and energy dispersive characteristics of CCD cameras are well suited for hard x-ray photon counting. X-rays absorbed within the depletion and field-free regions can be distinguished by studying the pulse height spectrum. Results are presented for the detection of 1-100 keV Bremsstrahlung continuum, K-shell and L-shell fluorescence spectra emitted from high intensity (10{sup 18}W cm{sup -2}), 500 fs laser- produced plasmas.
Date: January 1996
Creator: Dunn, J.; Young, B. K. F.; Conder, A. D. & Stewart, R. E.
Partner: UNT Libraries Government Documents Department

Development and characterization of a CCD camera system for use on six-inch manipulator systems

Description: The Lawrence Livermore National Laboratory has designed, constructed, and fielded a compact CCD camera system for use on the Six Inch Manipulator (SIM) at the Nova laser facility. The camera system has been designed to directly replace the 35 mm film packages on all active SIM-based diagnostics. The unit`s electronic package is constructed for small size and high thermal conductivity using proprietary printed circuit board technology, thus reducing the size of the overall camera and improving its performance when operated within the vacuum environment of the Nova laser target chamber. The camera has been calibrated and found to yield a linear response, with superior dynamic range and signal-to-noise levels as compared to T-Max 3200 optic film, while providing real-time access to the data. Limiting factors related to fielding such devices on Nova will be discussed, in addition to planned improvements of the current design.
Date: May 3, 1996
Creator: Logory, L.M.; Bell, P.M.; Conder, A.D. & Lee, F.D.
Partner: UNT Libraries Government Documents Department

Final optics damage inspection (FODI) for the National Ignition Facility

Description: The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) will routinely fire high energy shots (approaching 10 kJ per beamline) through the final optics, located on the target chamber. After a high fluence shot, exceeding 4J/cm2 at 351 nm wavelength, the final optics will be inspected for laser-induced damage. The FODI (Final Optics Damage Inspection) system has been developed for this purpose, with requirements to detect laser-induced damage initiation and to track and size it's the growth to the point at which the optic is removed and the site mitigated. The FODI system is the 'corner stone' of the NIF optic recycle strategy. We will describe the FODI system and discuss the challenges to make optics inspection a routine part of NIF operations.
Date: October 23, 2007
Creator: Conder, A; Alger, T; Azevedo, S; Chang, J; Glenn, S; Kegelmeyer, L et al.
Partner: UNT Libraries Government Documents Department

Hohlraum Target Alignment from X-ray Detector Images using Starburst Design Patterns

Description: National Ignition Facility (NIF) is a high-energy laser facility comprised of 192 laser beams focused with enough power and precision on a hydrogen-filled spherical, cryogenic target to initiate a fusion reaction. The target container, or hohlraum, must be accurately aligned to an x-ray imaging system to allow careful monitoring of the frozen fuel layer in the target. To achieve alignment, x-ray images are acquired through starburst-shaped windows cut into opposite sides of the hohlraum. When the hohlraum is in alignment, the starburst pattern pairs match nearly exactly and allow a clear view of the ice layer formation on the edge of the target capsule. During the alignment process, x-ray image analysis is applied to determine the direction and magnitude of adjustment required. X-ray detector and source are moved in concert during the alignment process. The automated pointing alignment system described here is both accurate and efficient. In this paper, we describe the control and associated image processing that enables automation of the starburst pointing alignment.
Date: December 14, 2010
Creator: Leach, R R; Conder, A; Edwards, O; Kroll, J; Kozioziemski, B; Mapoles, E et al.
Partner: UNT Libraries Government Documents Department

Study of supra-thermal electrons and K-{alpha} x-rays from high intensity 500 fs laser-produced plasmas

Description: We describe recent laser-solid interaction experiments using the 500 fs Janus Nd:glass (1053 nm) laser presently at 1.5 TW power level. The laser beam path is enclosed in vacuum from the compressor to the target and is focused using an off-axis paraboloid. Optical diagnostics monitor the near field pattern, focal spot, spectrum, temporal shape and pre-pulse level. A 12 {mu}m diameter (FWHM) focal spot is achieved (2.5 {times} diffraction limit) corresponding to a peak irradiance of 8 {times} 1017 W cm{sup {minus}2} on target. A suite of x-ray diagnostics characterize the x-ray emission from the plasma. We present results for normal incidence irradiation of high-Z (Zn, Ge, Mo, Sn) solid targets. The supra-thermal electrons produced in the short scale length plasma have temperature T{sub H} > 100 keV and can efficiently fluoresce the cold K-{alpha} lines in the 8--30 keV energy range.
Date: July 1, 1995
Creator: Dunn, J.; Young, B.K.F.; Hankla, A.K.; Conder, A.D.; White, W.E. & Stewart, R.E.
Partner: UNT Libraries Government Documents Department

Shot Planning and Analysis Tools

Description: Shot planning and analysis tools (SPLAT) integrate components necessary to help achieve a high over-all operational efficiency of the National Ignition Facility (NIF) by combining near and long-term shot planning, final optics demand and supply loops, target diagnostics planning, and target fabrication requirements. Currently, the SPLAT project is comprised of two primary tool suites for shot planning and optics demand. The shot planning component provides a web-based interface to selecting and building a sequence of proposed shots for the NIF. These shot sequences, or 'lanes' as they are referred to by shot planners, provide for planning both near-term shots in the Facility and long-term 'campaigns' in the months and years to come. The shot planning capabilities integrate with the Configuration Management Tool (CMT) for experiment details and the NIF calendar for availability. Future enhancements will additionally integrate with target diagnostics planning and target fabrication requirements tools. The optics demand component is built upon predictive modelling of maintenance requirements on the final optics as a result of the proposed shots assembled during shot planning. The predictive models integrate energetics from a Laser Performance Operations Model (LPOM), the status of the deployed optics as provided by the online Final Optics Inspection system, and physics-based mathematical 'rules' that predict optic flaw growth and new flaw initiations. These models are then run on an analytical cluster comprised of forty-eight Linux-based compute nodes. Results from the predictive models are used to produce decision-support reports in the areas of optics inspection planning, optics maintenance exchanges, and optics beam blocker placement advisories. Over time, the SPLAT project will evolve to provide a variety of decision-support and operation optimization tools.
Date: July 25, 2011
Creator: Casey, A; Beeler, R; Conder, A; Fallejo, R; Flegel, M; Hutton, M et al.
Partner: UNT Libraries Government Documents Department

3D Surface Mapping of Capsule Fill-Tube Assemblies used in Laser-Driven Fusion Targets

Description: This paper presents the development of a 3D surface mapping system used to measure the surface of a fusion target Capsule Fill-Tube Assembly (CFTA). The CFTA consists of a hollow Ge-doped plastic sphere, called a capsule, ranging in outer diameter between 2.2 mm and 2.6 mm and an attached 150 {micro}m diameter glass-core fill-tube that tapers down to a 10{micro} diameter at the capsule. The mapping system is an enabling technology to facilitate a quality assurance program and to archive 3D surface information of each capsule used in fusion ignition experiments that are currently being performed at the National Ignition Facility (NIF). The 3D Surface Mapping System is designed to locate and quantify surface features with a height of 50 nm and 300 nm in width or larger. Additionally, the system will be calibrated such that the 3D measured surface can be related to the capsule surface angular coordinate system to within 0.25 degree (1{sigma}), which corresponds to approximately 5 {micro}m linear error on the capsule surface.
Date: February 18, 2011
Creator: Buice, E S; Alger, E T; Antipa, N A; Bhandarkar, S D; Biesiada, T A; Conder, A D et al.
Partner: UNT Libraries Government Documents Department