21 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Apertures"  
Results: 1 - 21
open access

Large Diffractive Optics for GEo-Based Earth Surveillance

Description: The natural vantage point for performing Earth-centric operations from space is geosynchronous orbit (GEO); a platform there moves at the same rate as the Earth's surface, so appears to continually ''hover'' over a fixed site on the Earth. Unlike spacecraft in other orbits, which rapidly fly-over targets, a GEO-based platform remains in-position all the time. In order to insure continual access to sites using low earth orbit (LEO) platforms, one needs a large enough constellation ({approx} 50) … more
Date: September 11, 2003
Creator: Hyde, R A
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Results of Pulse-Scaling Experiments on Rapid-Growth DKDP Triplers Using the Optical Sciences Laser at 351 nm

Description: Results are reported from recently performed bulk-damage, pulse-scaling experiments on DKDP tripler samples taken from NIF-size, rapid-growth boule BD7. The tests were performed on LLNL's Optical Sciences Laser. A matrix of samples was exposed to single shots at 351 mn (3 {omega}) with average fluences from 4 to 8 J/cm{sup 2} for pulse durations of 1, 3 and 10 ns. The damage sites were scatter-mapped after testing to determine the damage evolution as a function of local beam fluence. The averag… more
Date: December 11, 2000
Creator: Runkel, M; Burnham, A K; Milam, D; Sell, W; Feit, M & Rubenchik, A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Satiated Relative Permeability of Variable-Aperture Fractures

Description: The relative permeability of a variable-aperture fracture under satiated conditions (wetting phase spans the fracture, non-wetting phase is completely entrapped) is controlled by the distribution of the entrapped phase within the fracture plane. We use simulations to investigate the combined influence of capillary forces and aperture variability on satiated relative permeability and demonstrate the effectiveness of a dimensionless perturbation curvature number (C') for predicting entrapped-phas… more
Date: December 11, 2001
Creator: Detwiler, R. L.; Glass, R. J.; Rajaram, H. & Nicholl, M. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Progress in Long Scale Length Laser-Plasma Interactions

Description: The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3{omega}) with a total intensity of 2 x 10{sup 15} W cm{sup -2}. The targets were filled with 1 atm of CO{sub 2} producing of up to 7 mm long homogeneous… more
Date: November 11, 2003
Creator: Glenzer, S. H.; Arnold, P.; Bardsley, G.; Berger, R. L.; Bonanno, G.; Borger, T. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Methods for Mitigating Growth of Laser-Initiated Surface Damage on DKDP Optics at 351nm

Description: We report an experimental investigation of mitigating surface damage growth at 351nm for machine-finished DKDP optics. The objective was to determine which methods could be applied to pre-initiated or retrieved-from-service optics, in order to stop further damage growth for large aperture DKDP optics used in high-peak-power laser applications. The test results, and the evaluation thereof, are presented for several mitigation methods applied to DKDP surface damage. The mitigation methods tested … more
Date: October 11, 2002
Creator: Hrubesh, L. W.; Brusasco, R. B.; Grundler, W.; Norton, M. A.; Donohue, E. E.; Molander, W. A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Dipole aperture and superconductor requirements

Description: The cost of an accelerator is not proportional to the aperture. A change in aperture by a certain percentage results in an overall accelerator cost change by only a fraction of that percentage; the fraction may be between 0.1 and 0.5 and is almost independent of the bending field. This estimate is obtained by analyzing the superconductor requirements as a function of aperture and by making rough estimates of the largest cost items of the accelerator such as magnets and ring tunnel.
Date: December 11, 1983
Creator: Wipf, S.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Measurement of Emittance of Beam in the Debuncher During Stacking

Description: The emittance of antiprotons in the debuncher was measured using two methods during normal stacking conditions. With 2.3 seconds of cooling the vertical emittance was found to be 3.6 {pi} mm-mr using scraper D:TJ308, and 2.9 {pi} mm-mr using the profile on SEM806. With 6.9 seconds of cooling time time the measured horizontal emittance was 2.1 {pi} mm-mr using D:RJ306 v.s. 1.9 {pi} mm-mr using SEM806; but with 2.3 seconds of cooling the measured emittance in the debuncher was larger than in the … more
Date: December 11, 1991
Creator: Halling, Mike
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Simple Apparatus for the Injection of Lithium Aerosol into the Scrape-Off Layer of Fusion Research Devices

Description: A simple device has been developed to deposit elemental lithium onto plasma facing components in the National Spherical Torus Experiment. Deposition is accomplished by dropping lithium powder into the plasma column. Once introduced, lithium particles quickly become entrained in scrape-off layer flow as an evaporating aerosol. Particles are delivered through a small central aperture in a computer-controlled resonating piezoelectric disk on which the powder is supported. The device has been used … more
Date: October 11, 2010
Creator: D. K. Mansfield, A.L Roquemore, H. Schneider, J. Timberlake, H. Kugel, M.G. Bell and the NSTX Research Team
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Summary of Radionuclide Reactive Transport Experiments in Fractured Tuff and Carbonate Rocks from Yucca Flat, Nevada Test Site

Description: In the Yucca Flat basin of the Nevada Test Site (NTS), 747 shaft and tunnel nuclear detonations were conducted primarily within the tuff confining unit (TCU) or the overlying alluvium. The TCU in the Yucca Flat basin is hypothesized to inhibit radionuclide migration to the highly transmissive and regionally extensive lower carbonate aquifer (LCA) due to its wide-spread aerial extent, low permeability, and chemical reactivity. However, fast transport pathways through the TCU by way of fractures … more
Date: October 11, 2006
Creator: Zavarin, M.; Roberts, S.; Reimus, P. & Johnson, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Comparison of Non-Redundant Array and Double Pinhole Coherence Measurements with Soft X-rays

Description: Experiments on the future Linac Coherent Light Source (LCLS) and other Free Electron Lasers will need to be performed on a single-shot basis. The double pinhole method of measuring spatial coherence requires a separate measurement, with a different pinhole separation distance, for each length scale sampled. This limits its utility for LCLS. A potential alternative uses a Non-Redundant Array (NRA) of apertures designed to probe the coherence over the range of length scales defined by their physi… more
Date: September 11, 2006
Creator: Weil, Gabriel & /SLAC, /Northwestern U.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Studies to Increase the Anti-Proton Transmission from the Targetto the Debuncher Ring

Description: The AP2 beamline at Fermilab transports anti-protons from the production target to the Debuncher ring. The measured admittance of the Debuncher ring and the theoretical aperture of the line are larger than the size of the transmitted beam. Extensive tracking studies were done using the Accelerator Toolbox (AT) to understand the sources of the difference. As simulations pointed to chromatic effects being a source of problems, measurements were done to study this. Several possible remedies were s… more
Date: May 11, 2005
Creator: Reichel, Ina; Zisman, Michael S.; Gollwitzer, Keith & Werkema, Steve
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The Storage Ring Magnets of the Australian Synchrotron

Description: A 3 GeV Synchrotron Radiation Source is being built in Melbourne, Australia. Commissioning is foreseen in 2006. The Storage ring has a circumference of 216 m and has a 14 fold DBA structure. For the storage ring the following magnets will be installed: 28 dipoles with a field of 1.3 T, and a gradient of 3.35 T/m; 56 quadrupoles with a gradient of 18 T/m and 28 with a gradient of 10 T/m; 56 sextupoles with a strength of B'' = 350 T/m and 42 with 150 T/m. The sextupoles are equipped with addition… more
Date: May 11, 2005
Creator: Barg, B.; Jackson, A.; LeBlanc, G.; Huttel, E. & Tanabe, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Searching for optimal mitigation geometries for laser resistant multilayer high reflector coatings

Description: Growing laser damage sites on multilayer high reflector coatings can limit mirror performance. One of the strategies to improve laser damage resistance is to replace the growing damage sites with pre-designed benign mitigation structures. By mitigating the weakest site on the optic, the large aperture mirror will have a laser resistance comparable to the intrinsic value of the multilayer coating. To determine the optimal mitigation geometry, the finite difference time domain method (FDTD) was u… more
Date: February 11, 2011
Creator: Qiu, S R; Wolfe, J E; Monterrosa, A M; Feit, M D; Pistor, T V & STolz, C J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Design and Fabrication of Racetrack Coil Accelerator Magnets

Description: Most accelerator magnets for applications in the field range up to 9 T utilize NbTi superconductor and a cosine theta coil design. For fields above 9 T, it is necessary to use Nb{sub 3}Sn or other strain sensitive materials, and other coil geometries that are more compatible with these materials must be considered. This paper describes their recent efforts to design a series of racetrack coil magnets that will provide experimental verification of this alternative magnet design for a dual apertu… more
Date: November 11, 1998
Creator: Chow, K.; Dietderich, D. R.; Gourlay, S. A.; Gupta, R.; Harnden, W.; Lietzke, A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

FODO-Supercell Based Compact Ring Design with Tunable Momentum Compaction and Optimized Dynamic Aperture

Description: A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and pre-damping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a superce… more
Date: May 11, 2012
Creator: Sun, Yipeng
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Measurement and simulation of the UMERbeam in the sourceregion

Description: As the beam propagates in the University of Maryland Electron Ring (UMER) complex transverse density structure including halos has been observed. A primary objective of the experiment is to understand the evolution of a space-charge-dominated beam as it propagates over a substantial distance. It is therefore important to understand which details of the beam structure result from propagation of the beam in the ring and which characteristics result from the specific details of the initial distrib… more
Date: June 11, 2004
Creator: Haber, I.; Bernal, S.; Kishek, R. A.; O'Shea, P. G.; Quinn, B.; Reiser, M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Performance results for Beamlet: A large aperture multipass Nd glass laser

Description: The Beamlet laser is a large aperture, flashlamp pumped Nd: glass laser that is a scientific prototype of an advanced Inertial Fusion laser. Beamlet has achieved third harmonic, conversion efficiency of near 80% with its nominal 35cm {times} 35cm square beam at mean 3{omega} fluences in excess of 8 J/cm{sup 2}(3-ns). Beamlet uses an adaptive optics system to correct for aberrations and achieve less than 2 {times} diffraction limited far field spot size.
Date: April 11, 1995
Creator: Campbell, J. H.; Barker, C. E.; VanWonterghem, B. M.; Speck, D. R.; Behrendt, W. C.; Murray, J. R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Initial Operation of the NSTX Fast Tangential Soft X-Ray Camera

Description: Fast, two-dimensional, soft x-ray imaging is a powerful technique for the study of MHD instabilities in tokamak plasmas. We have constructed an ultra-fast frame rate soft x-ray camera for the National Spherical Torus Experiment. It is based on a recently developed 64 x 64 pixel CCD camera capable of capturing 300 frames at up to 500,000 frames per second. A pinhole aperture images the plasma soft x-ray emission (0.2-10 keV) onto a P47 scintillator deposited on a fiber-optic faceplate; the scint… more
Date: May 11, 2004
Creator: Stratton, B. C.; Feder, R.; Von Goeler, S.; Renda, G. F.; Lowrance, J. L. & Mastrocola, V. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Frequency map analysis of nonlinear dynamics in the NLC main damping rings

Description: To avoid radiation damage, the acceptance of linear collider damping rings must be large enough that injection efficiency close to 100 percent can be achieved. Survival plots based on tracking particles in the NLC Main Damping Ring lattice suggest a dynamic aperture with some margin over the specified injected beam size and energy spread. Here, we apply Frequency Map Analysis to give a more detailed picture of the dynamical stability of particle trajectories in the presence of lattice nonlinear… more
Date: October 11, 2004
Creator: Wolski, Andrzej; Venturini, Marco; Wan, Weishi & Marks, Steve
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Comparison of Tevatron C0 and F0 Lambertson beam impedance

Description: Both the longitudinal and transverse beam impedance measurements for the Tevatron C0 and F0 lambertsons are presented. The C0 lambertsons were designed for circulating beam to travel through the 1 inch high by 6 inch wide field region. In the F0 lambertsons, circulating beam passes through the 2.5 inch high by 4 in ch wide field free region. The more recently designed F0 lambertsons have significantly less impedance than the older C0 lambertsons. Transverse impedance scales as one over the diam… more
Date: April 11, 2003
Creator: Fellenz, James L Crisp and Brian
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Retuning the APS storage ring for better chromaticity correction.

Description: When the APS storage ring was retuned to provide smaller {beta}{sub y} values in the insertion straight sections, it was necessary to increase the vertical tune by at least two units. Since the design values for the horizontal and vertical tunes are 35.22 and 16.30, respectively, this put the tunes dangerously close to the sextupole 2v{sub y}-v{sub x} coupling resonance. The large injection horizontal oscillations could couple to the vertical plane and exceed the 5-mm vertical apertures that ex… more
Date: September 11, 1999
Creator: Chae, Y.-C. & Crosbie, E.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen