165 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Pulse Rise Time"

open access

Optical Response of Shocked Cerium-Doped Lutetium Oxyorthosilicate

Shock experiments were performed in order to characterize the triboluminescent signature of cerium-doped lutetium oxyorthosilicate (LSO:Ce). This material shows prompt, nano-second timescale light emission when driven by explosive detonation. When properly applied to a surface, it may be used as a shock arrival sensor, and also for imaging the propagation of a shock front. Triboluminescent rise times, spectral content, and spatial resolution measurements are presented.

Date: March 2003

Creator: Stevens, G. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fast timing discriminator

The processing of pulses with very fast risetimes for timing purposes involves many problems because of the large equivalent bandwidths involved. For pulses with risetimes in the 150 ps range (and full widths at half maximum (FWHM) of 400 ps) bandwidths in excess of 1GHz are required. Furthermore, these very narrow pulses with current amplitudes as small as 1 mA carry very small charges (<10/sup -12/ coulomb), therefore, requiring very sensitive trigger circuits. The difficulty increases when t… more

Date: July 11, 1977

Creator: Lo, C. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Fluorescence Rise Time Measurements for High Temperature Fluorescence-Based Thermometry

Certain ceramic-like phosphor materials exhibit bright fluorescence with a pronounced temperature dependence over a range which spans the cryogenic to 1700 C, depending on the specific phosphor. To measure temperature, a surface, for instance a turbine blade, is coated with the material. An optical system, sometimes including optical fibers, conveys stimulating light and collects the emission for analysis. Either emission intensity or decay time may indicate temperature. Previously fielded test… more

Date: March 24, 2005

Creator: Allison, S.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

RF gas plasma source development for heavy ion fusion

Presently the Heavy Ion Fusion Virtual National Laboratory is researching ion sources and injector concepts to understand how to optimize beam brightness over a range of currents (50-2000 mA argon equivalent). One concept initially accelerates millimeter size, milliamp beamlets to 1 MeV before merging them into centimeter size, ampere beams. Computer simulations have shown the final brightness of the merged beams is dominated by the emittance growth of the merging process, as long as the beamle… more

Date: February 22, 2002

Creator: Ahle, L.E.; Hall, R.P. & Molvik, A.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Synchronization of multiple magnetically switched modules to power linear induction adder accelerators

In applications where multiple magnetic modulators are used to drive a single Linear Induction Voltage Adder (LIVA) or Linear Accelerator (LINAC), it is essential that the outputs of the modulators be synchronized. Output rise times are typically in the 10 ns to 20 ns range, often making it necessary to synchronize to within less than 1 ns. Microprocessor and electronic feedback schemes have been developed and demonstrated that achieve the required level of synchronization, however, they are so… more

Date: July 1, 1996

Creator: Reed, K.W. & Kiekel, P.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Stability Of Plasma Configurations During Compression

Magnetized Target Fusion (MTF) efforts are based on calculations showing that the addition of a closed magnetic field reduces the driver pressure and rise time requirements for inertial confinement fusion by reducing thermal conductivity. Instabilities that result in convective bulk transport at the Alphen time scale are of particular concern since they are much faster than the implosion time. Such instabilities may occur during compression due to, for example, an increase in the plasma-magneti… more

Date: October 27, 2006

Creator: Ruden, E L & Hammer, J H

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Differential current pulse preamplifier for fission counters

No Description Available.

Date: January 1, 1973

Creator: De Lorenzo, J.T.; Clay, W.T. & Guerrant, G.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Flammability tests on D0 Run II muon PDT Gas and P-10 Gas

The authors have done a series of measurements with mixtures of Argon, CF4 and CH4 to demonstrate that the mixture chosen for RunII (84% Argon, 8% CH4, 8% CF4) is not flammable. The tests were conducted in the Meson Detector Building in a test cell similar in construction to a cell of a Muon PDT. In order to establish the viability of the test set-up, they first repeated the demonstration that P-10 gas (90% Argon, 10% CH4) is in fact flammable, contrary to the classification by the US DOT. US D… more

Date: July 12, 2001

Creator: Haggerty, Herman F. & Marshall, James L. Priest and Tom

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Time resolution performance studies of contemporary high speed photomultipliers

The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single photoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed RCS 8850… more

Date: October 5, 1977

Creator: Leskovar, B. & Lo, C.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

PARTICLE DETECTORS BASED ON NOBLE LIQUIDS

In order to build a thin particle detector with 10 micron spatial resolution and automatic readout, the avalanche of ionization electrons in high electric fields in liquid argon and liquid xenon has been studied. We present a scheme using an array of points that could be used to make a reliable liquid argon filled detector. The avalanche pulses in liquid xenon have a rise time more than three orders of magnitude faster than that in liquid argon, suggesting that the positive charge carriers are … more

Date: September 1, 1970

Creator: Muller, Richard A.; Derenzo, Stephen E.; Smits, Robert G.; Zaklad, Haira & Alvarez, Luis W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Fatigue Crack Propagation from Notched Specimens of 304 SS in elevated Temperature Aqueous Environment

Fatigue crack propagation (FCP) rates for 304 stainless steel (304SS) were determined in 24 degree C and 288 degree C air and 288 degree C water using double-edged notch (DEN) specimens of 304 stainless steel (304 SS). Test performed at matched loading conditions in air and water at 288 degree C with 20-6- cc h[sub]2/kg h[sub]2O provided a direct comparison of the relative crack growth rates in air and water over a wide range of crack growth rates. The DEN crack extension ranged from short crac… more

Date: August 1, 2002

Creator: Wire, G. L. & Mills, W. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Frequency chirp and pulse shape effects in self-modulated laser wakefield accelerators

The effect of asymmetric laser pulses on plasma wave excitation in a self-modulated laser wakefield accelerator is examined. Laser pulse shape and frequency chirp asymmetries, controlled experimentally in the laser system through a grating pair compressor, are shown to strongly enhance measured electron yields for certain asymmetries. It is shown analytically that a positive (negative) frequency chirp enhances (suppresses) the growth rate of the Raman forward scattering and near-forward Raman s… more

Date: November 7, 2002

Creator: Schroeder, C. B.; Esarey, E.; Geddes, C. G. R.; Toth, Cs.; Shadwick, B. A.; van Tilborg, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

New Capabilities for Modeling Intense Beams in Heavy Ion Fusion Drivers

Significant advances have been made in modeling the intense beams of heavy-ion beam-driven Inertial Fusion Energy (Heavy Ion Fusion). In this paper, a roadmap for a validated, predictive driver simulation capability, building on improved codes and experimental diagnostics, is presented, as are examples of progress. The Mesh Refinement and Particle-in-Cell methods were integrated in the WARP code; this capability supported an injector experiment that determined the achievable current rise time, … more

Date: September 9, 2003

Creator: Friedman, A.; Barnard, J. J.; Bieniosek, F. M.; Celata, C. M.; Cohen, R. H.; Davidson, R. C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Development of a dynamic thermal model process

A dynamic electrical-thermal modeling simulation technique was developed to allow up-front design of thermal and electronic packaging with a high degree of accuracy and confidence. We are developing a hybrid multichip module output driver which controls with power MOSFET driver circuits. These MOSFET circuits will dissipate from 13 to 26 watts per driver in a physical package less than two square inches. The power dissipation plus an operating temperature range of -55{degrees} C to 100{degrees}… more

Date: April 1, 1996

Creator: Smith, F. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Low inductance gas switching.

The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the… more

Date: October 1, 2007

Creator: Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah & Elizondo, Juan E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Ground motion modeling of Hayward fault scenario earthquakes II:Simulation of long-period and broadband ground motions

We simulate long-period (T > 1.0-2.0 s) and broadband (T > 0.1 s) ground motions for 39 scenarios earthquakes (Mw 6.7-7.2) involving the Hayward, Calaveras, and Rodgers Creek faults. For rupture on the Hayward fault we consider the effects of creep on coseismic slip using two different approaches, both of which reduce the ground motions compared with neglecting the influence of creep. Nevertheless, the scenario earthquakes generate strong shaking throughout the San Francisco Bay area with… more

Date: November 4, 2009

Creator: Aagaard, B T; Graves, R W; Rodgers, A; Brocher, T M; Simpson, R W; Dreger, D et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Low-frequency RF Coupling To Unconventional (Fat Unbalanced) Dipoles

The report explains radio frequency (RF) coupling to unconventional dipole antennas. Normal dipoles have thin equal length arms that operate at maximum efficiency around resonance frequencies. In some applications like high-explosive (HE) safety analysis, structures similar to dipoles with ''fat'' unequal length arms must be evaluated for indirect-lightning effects. An example is shown where a metal drum-shaped container with HE forms one arm and the detonator cable acts as the other. Even if t… more

Date: December 7, 2010

Creator: Ong, M. M.; Brown, C. G.; Perkins, M. P.; Speer, R. D. & Javedani, J. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Suppressing Thermal Energy Drift In The LLNL Flash X-Ray Accelerator Using Linear Disk Resistor Stacks

This paper addresses thermal drift in sodium thiosulfate liquid resistors and their replacement with linear disk resistors from HVR Advanced Power Components. Sodium thiosulfate resistors in the FXR induction linear accelerator application have a temperature coefficient of {approx}1.8%/C. The FXR Marx banks send an 8kJ pulse through eight 524 cm{sup 3} liquid resistors at a repetition rate of up to 1 every 45 seconds. Every pulse increases the temperature of the solution by {approx}0.4 C which … more

Date: July 19, 2011

Creator: Kreitzer, B R; Houck, T L & Luchterhand, O C

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Plasma channel and Z-pinch dynamics for heavy ion transport

A self stabilized, free standing, z-pinch plasma channel has been proposed to deliver the high intensity heavy ion beam from the end of a driver to the fuel target in a heavy ion inertial fusion power plant. The z-pinch relaxes emittance and energy spread requirements requiring a lower cost driver. A z-pinch transport would reduce the number of beam entry port holes to the target chamber from over a hundred to four as compared to neutralized ballistic focusing thus reducing the driver hardware … more

Date: July 9, 2002

Creator: Ponce-Marquez, David

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

AN ENGINEERING SOLUTION TO THE RHIC BEAM ABORT KICKER UPGRADE.

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory is the world largest superconducting accelerator for nuclear energy research. Particle beams traveling in opposite directions in two accelerator rings, Blue and Yellow, collide at six interaction regions to create phenomena of the early universe. There are more than 1700 superconducting magnets and very sophisticate and delicate large detectors inside the RHIC tunnel. With high beam intensity and ultra high beam energy… more

Date: May 23, 2004

Creator: ZHANG,W. ROSER,T. SANDBERG,J. TAN,Y. ET AL.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Quasi-spherical direct drive fusion.

The authors present designs of quasi-spherical direction drive z-pinch loads for machines such as ZR at 28 MA load current with a 150 ns implosion time (QSDDI). A double shell system for ZR has produced a 2D simulated yield of 12 MJ, but the drive for this system on ZR has essentially no margin. A double shell system for a 56 MA driver at 150 ns implosion has produced a simulated yield of 130 MJ with considerable margin in attaining the necessary temperature and density-radius product for ignit… more

Date: January 1, 2007

Creator: VanDevender, J. Pace; Abbott, Lucas M.; Langston, William L.; McDaniel, Dillon Heirman; Nash, Thomas J.; Roderick, Norman Frederick et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Characteristics of multiwire proportional counters with delay line readout for minimum ionizing particles

The effects of gas mixture and chamber thickness on the gain and pulse shape of a multiwire proportional counter with delay line readout were studied. The primary concern was with optimizing the position accuracy for high-energy particle physics applications. The best results, both from the point of view of chamber gain and the risetime and uniformity of the delay line pulses were obtained with a 4 mm gap chamber run on a mixture of 30% carbon dioxide and 70% argon. It was found necessary to bi… more

Date: June 1, 1973

Creator: Stetz, Albert W. & Perez-Mendez, Victor

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Evaluation of the Beijing Instrument Factory GDB-44F photomultipler

Characteristics have been measured for the GDB-44F 2''-diameter photomultiplier. Some typical photomultiplier characteristics - such as gain, dark current, anode output current, transit and rise times as a function of voltage between anode and cathode, and photoelectron pulse-height spectrum, the quantum-efficiency and the single-electron transit time spread were measured. Descriptions of the measuring systems were also given.

Date: December 15, 1982

Creator: Young, E. & Lo, C.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Vacuum transmission lines for pulse sharpening and diagnostics applications

We investigated the propagation of MV electrical pulses along coaxial transmission lines (TL) in vacuum with network simulations and experiments. One goal was to establish how well a 3 m-long TL would sharpen the output pulse of a relativistic electron beam accelerator. Sharpening occurs as the cathode of the TL emits electrons and the current flow forces the TL into magnetic cut-off. The other goal was to determine how well field emission must be suppressed in a TL to avoid distortion of a pro… more

Date: June 1, 1987

Creator: Di Capua, M.S.; Goerz, D.A. & Freytag, E.K.

Item Type: Article

Partner: UNT Libraries Government Documents Department