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A grating-less, fiber-based oscillator that generates 25 nJ pulses

Description: We report a passively mode-locked fiber-based oscillator that has no internal dispersion-compensating gratings. This design, the first of its kind, produces 25 nJ pulses at 80 MHz with the pulses compressible to 150 fs. The pulses appear to be self-similar and initial data imply that their energy is further scalable.
Date: December 28, 2006
Creator: An, J; Kim, D; Dawson, J W; Messerly, M J & Barty, C J
Partner: UNT Libraries Government Documents Department

Progress toward a MEMS fabricated 100 GHz oscillator.

Description: This report summarizes an LDRD effort which looked at the feasibility of building a MEMS (Micro-Electro-Mechanical Systems) fabricated 100 GHz micro vacuum tube. PIC Simulations proved to be a very useful tool in investigating various device designs. Scaling parameters were identified. This in turn allowed predictions of oscillator growth based on beam parameters, cavity geometry, and cavity loading. The electron beam source was identified as a critical element of the design. FEA's (Field Emission Arrays) were purchased to be built into the micro device. Laboratory testing of the FEA's was also performed which pointed out care and handling issues along with maximum current capabilities. Progress was made toward MEMS fabrication of the device. Techniques were developed and successfully employed to build up several of the subassemblies of the device. However, the lower wall fabrication proved to be difficult and a successful build was not completed. Alternative approaches to building this structure have been identified. Although these alternatives look like good solutions for building the device, it was not possible to complete a redesign and build during the timeframe of this effort.
Date: February 1, 2006
Creator: Loubriel, Guillermo Manuel; Lemp, Thomas; Weyn, Mark L.; Coleman, Phillip Dale & Rowley, James E. (SAIC, Albuquerque, NM)
Partner: UNT Libraries Government Documents Department

Phase patterns of coupled oscillators with application to wireless communication

Description: Here we study the plausibility of a phase oscillators dynamical model for TDMA in wireless communication networks. We show that emerging patterns of phase locking states between oscillators can eventually oscillate in a round-robin schedule, in a similar way to models of pulse coupled oscillators designed to this end. The results open the door for new communication protocols in a continuous interacting networks of wireless communication devices.
Date: January 2, 2008
Creator: Arenas, A.
Partner: UNT Libraries Government Documents Department

On the modeling, design and validation of two dimensional quasi-static eddy current forces in a mechanical oscillator.

Description: Damping vibrations is important in the design of some types of inertial sensing devices. One method for adding damping to a device is to use magnetic forces generated by a static magnetic field interacting with eddy currents. In this report, we develop a 2-dimensional finite element model for the analysis of quasistatic eddy currents in a thin sheet of conducting material. The model was used for design and sensitivity analyses of a novel mechanical oscillator that consists of a shuttle mass (thin sheet of conducting material) and a set of folded spring elements. The oscillator is damped through the interaction of a static magnetic field and eddy currents in the shuttle mass. Using a prototype device and Laser Dopler Velocimetry (LDV), measurements were compared to the model in a validation study using simulation based uncertainty analyses. Measurements were found to follow the trends predicted by the model.
Date: October 1, 2005
Creator: Mitchell, John Anthony; Epp, David S. & Wittwer, Jonathan W.
Partner: UNT Libraries Government Documents Department

Stable local oscillator microcircuit.

Description: This report gives a description of the development of a Stable Local Oscillator (StaLO) Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. The StaLO uses a comb generator followed by surface acoustic wave (SAW) filters. The comb generator creates a set of harmonic components of the 100MHz input signal. The SAW filters are narrow bandpass filters that are used to select the desired component and reject all others. The resulting circuit has very low sideband power levels and low phase noise (both less than -40dBc) that is limited primarily by the phase noise level of the input signal.
Date: October 1, 2006
Creator: Brocato, Robert Wesley
Partner: UNT Libraries Government Documents Department

Stable local oscillator module.

Description: This report gives a description of the development of a Stable Local Oscillator (StaLO) multi-chip module (MCM). It is a follow-on report to SAND2006-6414, Stable Local Oscillator Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. This report describes the development of an MCM-based version of the complete StaLO, fabricated on an alumina thick film hybrid substrate.
Date: November 1, 2007
Creator: Brocato, Robert Wesley
Partner: UNT Libraries Government Documents Department

Using the thermal Gaussian approximation approximation for theBoltzmann Operator in Semiclassical Initial Value Time CorrelationFunctions

Description: The thermal Gaussian approximation (TGA) recently developed by Mandelshtam et al has been demonstrated to be a practical way for approximating the Boltzmann operator exp(-{beta}H) for multidimensional systems. In this paper the TGA is combined with semiclassical (SC) initial value representations (IVRs) for thermal time correlation functions. Specifically, it is used with the linearized SC-IVR (LSC-IVR, equivalent to the classical Wigner model), and the 'forward-backward semiclassical dynamics' (FBSD) approximation developed by Makri et al. Use of the TGA with both of these approximate SC-IVRs allows the oscillatory part of the IVR to be integrated out explicitly, providing an extremely simple result that is readily applicable to large molecular systems. Calculation of the force-force autocorrelation for a strongly anharmonic oscillator demonstrates its accuracy, and of the velocity autocorrelation function (and thus the diffusion coefficient) of liquid neon demonstrates its applicability.
Date: September 6, 2006
Creator: Liu, Jian & Miller, William H.
Partner: UNT Libraries Government Documents Department

Development system performance issues of the NIF master oscillator and pulse forming networking

Description: A crucial step in the development of a complex laser system is initial testing of an integrated system. Issues arise at the system level which are not easily observed in component level testing. The NIF master oscillator room (MOR) contains a network of fiber and integrated optic components which can interact, potentially reducing system performance. Here we present some of the system problems we have seen in integrated tests and our solutions. Issues include ASE in the fiber amplifiers, filtering effects in the PM fiber, and regulation of average optical power.
Date: October 29, 1998
Creator: Browning, D; Dreifuerst, G; Penko, F; Rothenberg, J & Wilcox, R
Partner: UNT Libraries Government Documents Department

An Experimental Study of an FEL Oscillator with a Linear Taper

Description: Motivated by the work of Saldin, Schneidmiller and Yurkov, we have measured the detuning curve widths, spectral characteristics, efficiency, and energy spread as a function of the taper for low and high Q resonators in the IR Demo FEL at Jefferson Lab. Both positive and negative tapers were used. Gain and frequency agreed reasonably well with the predictions of a single mode theory. The efficiency agreed reasonably well for a negative taper with a high Q resonator but disagreed for lower Q values due to the large slippage parameter and the non-ideal resonator Q. We saw better efficiency for a negative taper than for the same positive taper. The energy spread induced in the beam, normalized to the efficiency is larger for the positive taper than for the corresponding negative taper. This indicates that a negative taper is preferred over a positive taper in an energy recovery FEL.
Date: January 1, 2001
Creator: Benson, S.; Gubeli, J. & Neil, G.R.
Partner: UNT Libraries Government Documents Department

[x, p] = i{h_bar} ?

Description: Heisenberg`s commutation relation for position x and momentum p, and its validity for relativistic harmonic oscillators are examined, using the techniques of Lie algebra and dual-bosonic representation of x, p and the Hamiltonian H. A modification with [x, p] =i{h_bar}({minus_plus} 1 + H/m{sub 0}c{sup 2}) is proposed for a particle and an antiparticle in a harmonic potential. For a 2 {times} 2 matrix representation for x, p and H operators, the quantized eigenenergy E is given by (E - m{sub 0}c{sup 2})/{h_bar}{omega} = 3/2, 5/2, 7/2, ..., where 1/2 is not allowed.
Date: March 1, 1996
Creator: Tang, Jau
Partner: UNT Libraries Government Documents Department


Description: The realization of a paradigm chaotic system, namely the harmonically driven oscillator, in the quantum domain using cold trapped ions driven by lasers is theoretically investigated. The simplest characteristics of regular and chaotic dynamics are calculated. The possibilities of experimental realization are discussed.
Date: September 3, 2002
Partner: UNT Libraries Government Documents Department

System characterization in nonlinear random vibration

Description: Linear structural models are frequently used for structural system characterization and analysis. In most situations they can provide satisfactory results, but under some circumstances they are insufficient for system definition. The present investigation proposes a model for nonlinear structure characterization, and demonstrates how the functions describing the model can be identified using a random vibration experiment. Further, it is shown that the model is sufficient to completely characterize the stationary random vibration response of a structure that has a harmonic frequency generating form of nonlinearity. An analytical example is presented to demonstrate the plausibility of the model.
Date: January 1, 1986
Creator: Paez, T.L. & Gregory, D.L.
Partner: UNT Libraries Government Documents Department

Nano-electromechanical oscillators (NEMOs) for RF technologies.

Description: Nano-electromechanical oscillators (NEMOs), capacitively-coupled radio frequency (RF) MEMS switches incorporating dissipative dielectrics, new processing technologies for tetrahedral amorphous carbon (ta-C) films, and scientific understanding of dissipation mechanisms in small mechanical structures were developed in this project. NEMOs are defined as mechanical oscillators with critical dimensions of 50 nm or less and resonance frequencies approaching 1 GHz. Target applications for these devices include simple, inexpensive clocks in electrical circuits, passive RF electrical filters, or platforms for sensor arrays. Ta-C NEMO arrays were used to demonstrate a novel optomechanical structure that shows remarkable sensitivity to small displacements (better than 160 fm/Hz {sup 1/2}) and suitability as an extremely sensitive accelerometer. The RF MEMS capacitively-coupled switches used ta-C as a dissipative dielectric. The devices showed a unipolar switching response to a unipolar stimulus, indicating the absence of significant dielectric charging, which has historically been the major reliability issue with these switches. This technology is promising for the development of reliable, low-power RF switches. An excimer laser annealing process was developed that permits full in-plane stress relaxation in ta-C films in air under ambient conditions, permitting the application of stress-reduced ta-C films in areas where low thermal budget is required, e.g. MEMS integration with pre-existing CMOS electronics. Studies of mechanical dissipation in micro- and nano-scale ta-C mechanical oscillators at room temperature revealed that mechanical losses are limited by dissipation associated with mechanical relaxation in a broad spectrum of defects with activation energies for mechanical relaxation ranging from 0.35 eV to over 0.55 eV. This work has established a foundation for the creation of devices based on nanomechanical structures, and outstanding critical research areas that need to be addressed for the successful application of these technologies have been identified.
Date: December 1, 2004
Creator: Wendt, Joel Robert; Czaplewski, David A.; Gibson, John Murray (Argonne National Laboratory, Argonne, IL); Webster, James R.; Carton, Andrew James; Keeler, Bianca Elizabeth Nelson et al.
Partner: UNT Libraries Government Documents Department

Test results for 320 nm and 390 nm remote sensing sources using a 150 mJ, 100 Hz repetition rate, injection-seeded diode-pumped Nd:YAG slab-laser developed by Coherent Technologies, Inc.

Description: This report describes results of tests using a laser system designed by Coherent Technologies, Inc., in conjunction with Sandia developed nonlinear optics technology. Test results are described for three different optical parametric oscillators built at Sandia. The report concludes with recommendations for future work.
Date: July 1, 2005
Creator: Armstrong, Darrell Jewell
Partner: UNT Libraries Government Documents Department

Evidence for bifurcation and universal chaotic behavior in nonlinear semiconducting devices

Description: Bifurcations, chaos, and extensive periodic windows in the chaotic regime are observed for a driven LRC circuit, the capacitive element being a nonlinear varactor diode. Measurements include power spectral analysis; real time amplitude data; phase portraits; and a bifurcation diagram, obtained by sampling methods. The effects of added external noise are studied. These data yield experimental determinations of several of the universal numbers predicted to characterize nonlinear systems having this route to chaos.
Date: January 1, 1982
Creator: Testa, J.; Perez, J. & Jeffries, C.
Partner: UNT Libraries Government Documents Department

Supercoherent states and physical systems

Description: A method is developed for obtaining coherent states of a system admitting a supersymmetry. These states are called supercoherent states. The approach presented in this talk is based on an extension to supergroups of the usual group-theoretic approach. The example of the supersymmetric harmonic oscillator is discussed, thereby illustrating some of the attractive features of the method. Supercoherent states of an electron moving in a constant magnetic field are also described. 35 refs.
Date: January 1, 1991
Creator: Fatyga, B.W.; Kostelecky, V.A. (Indiana Univ., Bloomington, IN (USA). Dept. of Physics); Nieto, M.M. (Los Alamos National Lab., NM (USA)) & Truax, D.R. (Calgary Univ., AB (Canada). Dept. of Chemistry)
Partner: UNT Libraries Government Documents Department

The CEBAF Master Oscillator and Distribution Remodeling

Description: Jefferson Lab’s CEBAF accelerator operation requires various frequency references to be distributed along the site. Three signals: 10 MHz, 70 MHz and 499 MHz are synthesized in the Machine Control Center (MCC) while 1427 MHz and 429 MHz are derived from 499 MHz and 70 MHz signals in four separate locations. We are replacing our obsolete 10 MHz, 70 MHz and 499 MHz sources with new sources that will incorporate a GPS receiver to discipline a 10 MHz reference. In addition the MO (Master Oscillator) system will be redundant (duplicate MO) and a third signal source will be used as a system diagnostic. Moreover, the 12 GeV Energy Upgrade for CEBAF accelerator will be adding 80 new RF systems. To support them the distribution of 1427 MHz and 70 MHz signals has to be extended and be able to deliver enough LO (Local Oscillator) and IF (Intermediate Frequency) power to 320 old and 80 new 80 RF systems. This paper discusses the new MO and the drive line extension.
Date: May 1, 2009
Creator: Tomasz Plawski, J. Hovater, John Musson, Ramakrishna Bachimanchi
Partner: UNT Libraries Government Documents Department


Description: We describe a dual free-electron laser (FEL) configuration on the UV Demo FEL at Jefferson Lab that allows simultaneous lasing at FIR/THz and UV wavelengths. The FIR/THz source would be an FEL oscillator with a short wiggler providing nearly diffraction-limited pulses with pulse energy exceeding 50 microJoules. The FIR source would use the exhaust beam from a UVFEL. The coherent harmonics in the VUV from the UVFEL are out-coupled through a hole. The FIR source uses a shorter resonator with either hole or edge coupling to provide very high power FIR pulses. Simulations indicate excel-lent spectral brightness in the FIR region with over 100 W/cm-1 output.
Date: July 1, 2012
Creator: Stephen Benson, David Douglas, George Neil, Michelle D. Shinn, Gwyn Williams
Partner: UNT Libraries Government Documents Department


Description: The lifetime for the decay of a {pi} meson into {mu} meson and neutral particle was first measured by Richardson and later by Martinelli and Panofsky. The method was the same in both cases: The fraction of {pi} mesons surviving various times of flight is measured by placing photographic detectors at various path lengths from the target. In the experiment reported here we observe the time lag between the two bursts of fluorescence due to mesons decaying in a scintillation crystal. The first burst is due to the stopping of the entering {pi} meson, the second to the {mu}-meson. As is shown in Fig. 1, a particle penetrating the first and into the second crystal starts the sweep (10{sup -8} sec/mm) of an oscilloscope. The pulses in the second crystal are delayed 0.5 x 10{sup -6} sec to allow the sweep to start and brighten and are then photographed. If the responsible particle is a {pi}{sup +} meson which stops in the crystal, it undergoes {pi}-{mu} decay and two pulses appear on the trace. The {mu}{sup +} meson has a range of only 2 mm in the crystal. If its decay electron is detected some time (.5-2.5 x 10{sup -6} sec) later; a neon light flashes and is photographed together with the scope trace. Only such marked traces are measured. Of these marked traces, 650 or roughly one-half, show the two pulses of the {pi}-{mu} event. Five percent are calculated to be due to random delayed coincidences, and another 3 percent due to {pi} mesons which have decayed in flight and come to rest in the second crystal as {mu} mesons. The remaining traces are due to {pi}{mu} decays which are too fast to be resolved. The sweep speed of the oscilloscope is calibrated periodically with an oscillator of known ...
Date: May 10, 1950
Creator: Chamberlain, O.; Mozely, R.F.; Steinberger, J. & Wiegand, C.
Partner: UNT Libraries Government Documents Department