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1. 8K conditioning (non-quench training) of a model SSC dipole

Description: The accepted hypothesis is that training quenches are caused by heat generation when conductors move under Lorentz force. Afterwards no conductor motion will occur until a higher field and greater Lorentz force acts. If superior heat transfer and/or greater temperature margin is provided by operating at lower bath temperature, one might expect that the heat generated by conductor motion will not cause a runaway temperature increase, or quench. To test this hypothesis, the central dipole field in SSC model magnets was ramped at 1.8 K to 7.1 tesla without the magnets' quenching. The bath was then raised to 4.4 K and the magnets quenched at their short sample limits of 6.6 tesla or higher. Comparison with similar magnets trained in He I at 4.4 K is made and the significance of the non-quench training on system operation is discussed.
Date: September 1, 1986
Creator: Gilbert, W. S. & Hassenzahl, W. V.
Partner: UNT Libraries Government Documents Department
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1-GeV Linac Upgrade Study at Fermilab

Description: A linac injector for a new proton source complex at Fermilab is assumed to have a kinetic energy of 1 GeV. This linac would be sized to accelerate 100 mA of H{sup -} beam in a 200 microsecond pulse at a 15 Hz repetition rate. This would be adequate to produce {approximately}10{sup 14} protons per pulse allowing for future improvements of the new proton source complex. An alternate proposal is to add 600 MeV of side coupled cavity linac at 805 MHz to the existing 400 MeV Linac. This addition may either be in a new location or use the present Booster tunnel. A discussion of these possibilities will be given.
Date: September 1998
Creator: Popovic, M.; Moretti, A.; Noble, R. & Schmidt, C. W.
Partner: UNT Libraries Government Documents Department
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A 2.14 ms candidate optical pulsar in SN1987A: Ten years after

Description: We have monitored Supernova 1987A in optical/near-infrared bands from a few weeks following its birth until the present time in order to search for a pulsar remnant. We have found an apparent pattern of emission near the frequency of 467.5 Hz - a 2.14 ms pulsar candidate, first detected in data taken on the remnant at the Las Campanas Observatory (LCO) 2.5-m Dupont telescope during 14-16 Feb. 1992 UT. We detected further signals near the 2.14 ms period on numerous occasions over the next four years in data taken with a variety of telescopes, data systems and detectors, at a number of ground- and space-based observatories. The sequence of detections of this signal from Feb. `92 through August `93, prior to its apparent subsequent fading, is highly improbable (< 10{sup -10} for any noise source). We also find evidence for modulation of the 2.14 ms period with a {approx}1,000 s period which, when taken with the high spindown of the source (2-3 x 10{sup -10} Hz/s), is consistent with precession and spindown via gravitational radiation of a neutron star with a non- axisymmetric oblateness of {approx}10{sup -6}, and an implied gravitational luminosity exceeding that of the Crab Nebula pulsar by an order of magnitude.
Date: September 1, 1997
Creator: Middleditch, J.; Kristian, J. A.; Kunkel, W. E.; Hill, K. M. & Watson, R. D.
Partner: UNT Libraries Government Documents Department
open access

2 MW 110 GHz ECH heating system for DIII-D

Description: A 2 MW 110 GHz ECH system using Varian 0.5 MW gyrotrons is under construction for use on the DIII-D tokamak by late 1991. Most of the components are being design and fabricated at General Atomics, including the gyrotron tanks, superconducting magnets, and transmission line. These components are intended for operation with 10 second pulses and, in the future, with 1 MW gyrotrons. 6 refs., 5 figs.
Date: September 1990
Creator: Moeller, C.; Prater, R.; Callis, R.; Remsen, D.; Doane, J.; Cary, W. et al.
Partner: UNT Libraries Government Documents Department
open access

A 2 to 4 nm high power FEL on the SLAC linac

Description: We report the results of preliminary studies of a 2 to 4 nm SASE FEL, using a photoinjector to produce the electron beam, and the SLAC linac to accelerate it to an energy up to 10 GeV. Longitudinal bunch compression is used to increases ten fold the peak current to 2.5 kA, while reducing the bunch length to the subpicosecond range. The saturated output power is in the multi-gigawatt range, producing about 10{sup 14} coherent photons within a bandwidth of about 0.2% rms, in a pulse of several millijoules. At 120Hz repetition rate the average power is about 1 W. The system is optimized for x-ray microscopy in the water window around 2 to 4 nm, and will permit imaging a biological sample in a single subpicosecond pulse.
Date: September 1, 1992
Creator: Pellegrini, C.; Rosenzweig, J.; Nuhn, H. D.; Pianetta, P.; Tatchyn, R.; Winick, H. et al.
Partner: UNT Libraries Government Documents Department
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A 3.3 MJ, Rb{sup +1} Driver Design Based on an Integrated Systems Analysis

Description: A computer model for systems analysis of heavy ion drivers has been developed and used to evaluate driver designs for inertial fusion energy (IFE). The present work examines a driver for a close-coupled target design that requires less total beam energy but also smaller beam spots sizes than previous target designs. Design parameters and a cost estimate for a 160 beam, 3.3 MJ driver using rubidium ions (A = 85) are reported, and the sensitivity of the results to variations in selected design parameters is given.
Date: September 15, 2000
Creator: Meier, W. R.; Barnard, J. J. & Bangerter, R. O.
Partner: UNT Libraries Government Documents Department
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3-D Combinatorial Geometry in the MERCURY Monte Carlo Particle Transport Code

Description: Lawrence Livermore National Laboratory is in the process of developing a new Monte Carlo Particle Transport code named MERCURY. This new code features a 3-D Combinatorial Geometry tracking algorithm. This paper details some of the characteristics of this Monte Carlo tracker
Date: September 27, 2004
Creator: Greenman, G
Partner: UNT Libraries Government Documents Department
open access

3-D electromagnetic modeling of wakefields in accelerator components

Description: We discuss the use of 3-D finite-difference time-domain (FDTD) electromagnetic codes for modeling accelerator components. Computational modeling of cylindrically symmetric structures such as induction accelerator cells has been very successful in predicting the wake potential and wake impedances of these structures, but full 3-D modeling of complex structures has been limited due to substantial computer resources required for a full 3-D model. New massively parallel 3-D time domain electromagnetic codes now under development using conforming unstructured meshes allow a substantial increase in the geometric fidelity of the structures being modeled. Development of these new codes are discussed in context of applicability to accelerator problems. Various 3-D structures are tested with an existing cubical cell FDTD code and wake impedances compared with simple analytic models for the structures; results will be used as benchmarks for testing the new time time domain codes. Structures under consideration include a stripline beam position monitor as well as circular and elliptical apertures in circular waveguides. Excellent agreement for monopole and dipole impedances with models were found for these structures below the cutoff frequency of the beam line.
Date: September 18, 1996
Creator: Poole, B.R.; Caporaso, G.J.; Ng, Wang C.; Shang, C.C. & Steich, D.
Partner: UNT Libraries Government Documents Department
open access

3-D Simulations of Plasma Wakefield Acceleration with Non-Idealized Plasmas and Beams

Description: 3-D Particle-in-cell OSIRIS simulations of the current E-162 Plasma Wakefield Accelerator Experiment are presented in which a number of non-ideal conditions are modeled simultaneously. These include tilts on the beam in both planes, asymmetric beam emittance, beam energy spread and plasma inhomogeneities both longitudinally and transverse to the beam axis. The relative importance of the non-ideal conditions is discussed and a worst case estimate of the effect of these on energy gain is obtained. The simulation output is then propagated through the downstream optics, drift spaces and apertures leading to the experimental diagnostics to provide insight into the differences between actual beam conditions and what is measured. The work represents a milestone in the level of detail of simulation comparisons to plasma experiments.
Date: September 27, 2005
Creator: Deng, S.; Katsouleas, T.; Lee, S.; Muggli, P.; Mori, W. B.; Hemker, R. et al.
Partner: UNT Libraries Government Documents Department
open access

3-D surface profile measurements of large x-ray synchrotron radiation mirrors using stitching interferometry.

Description: Stitching interferometry, using small-aperture, high-resolution, phase-measuring interferometry, has been proposed for quite some time now as a metrology technique to obtain 3-dimensional profiles of surfaces of oversized optical components and substrates. The aim of this work is to apply this method to the specific case of long grazing-incidence x-ray mirrors, such as those used in beamlines at synchrotron radiation facilities around the world. Both fabrication and characterization of these mirrors would greatly benefit from this technique because it offers the potential for providing measurements with accuracy and resolution better than those obtained using existing noncontact laser profilers, such as the long trace profiler (LTP). Measurement data can be used as feedback for computer-controlled fabrication processes to correct for possible topography errors. The data can also be used for simulating and predicting mirror performance under realistic conditions. A semiautomated stitching system was built and tested at the X-ray Optics Metrology Laboratory of the Advanced Photon Source at Argonne National Laboratory. The initial objective was to achieve a measurement sensitivity on the order of 1 {micro}rad rms. Preliminary tests on a 1 m-long x-ray mirror showed system repeatability of less than 0.6 {micro}rad rms. This value is comparable to that of a conventional LTP. The measurement accuracy was mostly affected by environmental perturbations and system calibration effects. With a fully automated and improved system (to be built in the near future), we expect to achieve measurement sensitivity on the order of 0.0 {micro}rad rms or better. In this paper, after a brief review of basic principles and general technical difficulties and challenges of the stitching technique, a detailed description of the measurement setup is given and preliminary results obtained with it are analyzed and discussed.
Date: September 12, 2002
Creator: Assoufid, L.; Bray, M.; Qian, J. & Shu, D.
Partner: UNT Libraries Government Documents Department
open access

4 MW Fast Wave Current Drive Upgrade for DIII-D

Description: The DIII-D program has just completed a major addition to its ion cyclotron range of frequency (ICRF) systems. This upgrade project added two new fast wave current drive (FWCD) systems, with each system consisting of a 2 MW, 30 to 120 MHz transmitter, ceramic insulated transmission lines and tuner elements, and water-cooled four-strap antenna. With this addition of 4 MW of FWCD power to the original 2 MW, 30 to 60 MHz capability, experiments can be performed that will explore advanced tokamak plasma configurations by using the centrally localized current drive to effect current profile modifications.
Date: September 1, 1994
Creator: Callis, R. W.; Cary, W. P. & Baity, F. W.
Partner: UNT Libraries Government Documents Department
open access

4. pi. interferometric measurements of laser fusion targets

Description: Apparatus is described for rapidly manipulating a hollow glass microsphere laser fusion target and scanning the entire wall with a double pass interference microscope.
Date: September 29, 1977
Creator: Weinstein, B.W.; Willenborg, D.L.; Weir, J.T. & Hendricks, C.D.
Partner: UNT Libraries Government Documents Department
open access

An 8-meter-long coupled cavity RFQ linac

Description: A model has been constructed of an 8-m-long high energy (7 MeV) Radio-Frequency Quadrupole (RFQ) to prove the concept of a resonantly coupled RFQ. The model consists of four 2-in-long RFQ segments resonantly coupled together. A small gap (3 mm) between the vane tips, at the segment joints, provides capacitive coupling. This model is of a RFQ designed for a proposed Los Alamos Accelerator Performance Demonstration Facility (APDF). The RFQ, as designed, will operate cw at 350 kHz and accelerate a 100-mA beam of protons to 7 MeV.
Date: September 1, 1994
Creator: Young, L. M.
Partner: UNT Libraries Government Documents Department
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A 10 Hz Grazing Incidence pumped Ni-like Mo laser at 18.9 nm with 150 mJ pump energy

Description: The first demonstration of the grazing incidence pumping (GRIP) scheme for laser-driven x-ray lasers (XRLs) is described utilizing 2-pulse pumping. A long pulse is incident normal to the target to produce a plasma with a particular density profile. Then a short pulse is incident at a grazing angle, chosen to optimally couple the short pulse laser energy into the specific density region where the inversion process will occur. The short pulse is simultaneously absorbed and refracted at a maximum electron density specified by the chosen pump angle then turns back into the gain region. The increased path length gives improved absorption allowing a reduction in the drive energy required for lasing. A Ni-like Mo XRL at 18.9 nm has been demonstrated with only 150 mJ total pump energy and a repetition rate of 10 Hz. We report high gains of 60 cm{sup -1} and the achievement of gain saturation for targets of 4 mm length.
Date: September 30, 2004
Creator: Keenan, R.; Dunn, J.; Patel, P. K.; Price, D. F.; Smith, R. F. & Shlyaptsev, V. N.
Partner: UNT Libraries Government Documents Department
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The 12 GeV Energy Upgrade at Jefferson Laboratory

Description: Two new cryomodules and an extensive upgrade of the bending magnets at Jefferson Lab has been recently completed in preparation for the full energy upgrade in about one year. Jefferson Laboratory has undertaken a major upgrade of its flagship facility, the CW re-circulating CEBAF linac, with the goal of doubling the linac energy to 12 GeV. I will discuss here the main scope and timeline of the upgrade and report on recent accomplishments and the present status. I will then discuss in more detail the core of the upgrade, the new additional C100 cryomodules, their production, tests and recent successful performance. I will then conclude by looking at the future plans of Jefferson Laboratory, from the commissioning and operations of the 12 GeV CEBAF to the design of the MEIC electron ion collider.
Date: September 2012
Creator: Pilat, Fulvia C.
Partner: UNT Libraries Government Documents Department
open access

15-foot bubble chamber characteristics

Description: Specifications, operation, characteristics, cost, and experience with the NAL 15-ft bubble chamber are described. Beam availability and some experimental proposals are discussed. (WHK)
Date: September 15, 1975
Creator: Huson, F. R.
Partner: UNT Libraries Government Documents Department
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19 mm ballistic range: a potpourri of techniques and recipes

Description: The expansion of ballistic gun range facilities at LLL has introduced state-of-the-art diagnostic techniques to glovebox-enclosed ballistic guns systems. These enclosed ballistic ranges are designed for the study of one- dimensional shock phenomena in extremely toxic material such as plutonium. The extension of state-of-the-art phtographic and interferometric diagnostic systems to glovebox-enclosed gun systems introduces new design boundaries and performance criteria on optical and mechanical components. A technique for experimentally evaluating design proposals is illustrated, and several specific examples (such as, target alignment, collateral shrapnel damage, and soft recovery) are discussed. (auth)
Date: September 23, 1975
Creator: Carpluk, G.T.
Partner: UNT Libraries Government Documents Department
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40-kV, 25-ms neutral-beam power supply for TMX

Description: Modifications are described to upgrade the neutral-beam power supply for the TMX from 40 kV, 10 ms to 40 kV, 25 ms. The redesign of the accel and suppressor power supplies to achieve separation of the high-voltage and control sections, operation of the arc pulse lines in series, operation of the arc pulse lines in a noisy environment with SCR trigger and crowbar, and modifications to the electrolytic storage banks are discussed.
Date: September 23, 1977
Creator: Leavitt, G.A.
Partner: UNT Libraries Government Documents Department
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40 mm bore Nb-Ti model dipole magnet

Description: Preliminary R and D has been started on magnets for a next-generation high-energy-physics accelerator, the 20 TeV Superconducting Supercollider (SSC). One design now being developed at LBL is described in this paper. The design is based on two layers of flattened Nb-Ti cable, a 40 mm ID winding with flared ends, and an operating field of 6.5 T. Experimental results are presented on several one-meter-long models tested at both He I and He II temperature. Measurement of field, residual magnetization, quench propagation velocity, and winding prestress are presented. (A 2-in-1 magnet based on this coil design is being jointly developed by LBL and Brookhaven National Laboratory, and 15 ft. long models are being constructed at BNL).
Date: September 10, 1984
Creator: Taylor, C.; Gilbert, W.; Hassenzahl, W.; Meuser, R.; Peters, C.; Rechen, J. et al.
Partner: UNT Libraries Government Documents Department
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A 40 mm bore quadrupole magnet for the SSC

Description: A 40 mm bore quadrupole magnet design, called QC'', has been made for the SSC with the following parameters: 208 T/m gradient at 6500A, 2-layer cos 2 {theta}'' winding arrangement with 30 strand cable and one spacer wedge per coil. Structural support is provided by self-supporting interlocking collars; two types of symmetrical laminations are pre-assembled into collar packs for ease of assembly. This paper will describe the design of a prototype quadrupole magnet for the SSC and preliminary tests results on 1 m models. 7 refs., 6 figs., 2 tabs.
Date: September 1, 1990
Creator: Taylor, C.E.; Barale, P.; Caspi, S.; Dell'Orco, D.; Fritz, D.; Gilbert, W.S. et al.
Partner: UNT Libraries Government Documents Department
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60 kilograms high explosive containment with multi-diagnostic capability

Description: In anticipation of increasingly stringent environmental regulations, Lawrence Livermore National Laboratory (LLNL) proposes to construct a 60 kilogram (kg) firing chamber to provide blast-effects containment for most of its open-air, high explosives, firing operations. Even though these operations are within current environmental limits, containment of the blast effects and hazardous debris will further drastically reduce emissions to the environment and minimize the generated hazardous waste.
Date: September 17, 1998
Creator: Simmons, L. F.
Partner: UNT Libraries Government Documents Department
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A 90-GHz Photoinjector

Description: Photocathode rf guns depend on mode locked laser systems to produce an electron beam at a given phase of the rf. In general, the laser pulse is less than {sigma}{sub z} = 10{sup o} of rf phase in length and the required stability is on the order of {Delta}{phi} = 1{sup o}. At 90 GHz (W-band), these requirements correspond to {sigma}{sub z} = 333 fsec and {Delta}{phi} = 33 fsec. Laser system with pulse lengths in the fsec regime are commercially available, the timing stability is a major concern. We propose a multi-cell W-band photoinjector that does not require a mode locked laser system. Thereby eliminating the stability requirements at W-band. The laser pulse is allowed to be many rf periods long. In principle, the photoinjector can now be considered as a thermionic rf gun. Instead of using an alpha magnet to compress the electron bunch, which would have a detrimental effect on the transverse phase space quality due to longitudinal phase space mixing, we propose to use long pulse laser system and a pair of undulators to produce a low emittance, high current, ultra-short electron bunch for beam dynamics experiments in the 90 GHz regime.
Date: September 12, 2005
Creator: Palmer, D. T.; Hogan, M. J.; Ferrario, M. & Serafini, L.
Partner: UNT Libraries Government Documents Department
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The 100,000 amp dc power supply for a staged hadron collider super ferric magnet

Description: A 1.5 volt 100,000 amp DC switcher power supply was developed for testing a superferric magnet string at FNAL. This supply was used during testing as both the ramping supply and holding supply powering a single magnet load with a total load resistance of 0.7{micro} Ohms. The supply consists of ten paralleled switcher cells, powered by a 400 volt/600 Amp DC power supply. Each cell consists of an IGBT H-bridge driving a step-down transformer at a switching frequency of 2 kHz. The transformer has an effective turns ratio of 224:1. The secondary consists of 32 parallel single-turn full wave rectifier windings. The rectification is done with 64 Shottky diodes. Each cell is rated at 1.5 volts/10,000 amps. During this test each cell was operated as a constant power source without load current or field feedback. This paper will describe the design of the switcher cell and control system used during testing. We will also describe the next level of improvements to the current feedback system to improve the ramp control.
Date: September 1, 2005
Creator: Hays, Steven L.; Claypool, Bradley & Foster, G. William
Partner: UNT Libraries Government Documents Department
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