Pulsed LIDAR-Assisted Controllers for Turbine Power Capture Enhancement and Fatigue Load Mitigation Below Rated
No abstract prepared.
17 WIND ENERGY↗
SEARCH · Engineering Papers
Results for “Pulse Power”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Reliability of High Power Laser Diode Arrays Operating in Long Pulse Mode
Reliability and lifetime of quasi-CW laser diode arrays are greatly influenced by their thermal characteristics. This paper examines the thermal properties of laser diode arrays operating in long pulse duration regime.
Amzajerdian, Farzin↗
High Power, High Repetition Rate, 700-850 nm Pulsed Laser
Explore the source record for details and available documents.
43 PARTICLE ACCELERATORS↗
A Survey of Preventive and Remediating Mitigations for High-Altitude Electromagnetic Pulse Impacts on the United States Electric Power Grid.
Abstract not provided.
Garrett, Richard↗
SU-E-T-245: MR Guided Focused Ultrasound Increased PARP Related Apoptosis On Prostate Cancer in Vivo
Purpose: Our previous study demonstrated that significant tumor growth delay was observed in the mice treated with pulsed high intensity focused ultrasound (pHIFU). The purpose of this study is to understand the cell killing mechanisms of pHIFU. Methods: Prostate cancer cells (LNCaP), were grown orthotopically in 17 nude mice. Tumor-bearing mice were treated using pHIFU with an acoustic power of 25W, pulse width 100msec and 300 pulses in one sonication under MR guidance. Mutiple sonications were used to cover the whole tumor volume. Temperature (less than 40 degree centigrade in the focal spot) was monitored using MR thermometry. Animals were euthanized at pre-determined time points (n=2) after treatment: 0 hours; 6 hrs; 24 hrs; 48 hrs; 4 days and 7 days. Two tumorbearing mice were used as control. Three tumor-bearing mice were treated with radiation (RT, 2 Gy) using 6 MV photon beams. RT treated mice were euthanized at 0 hr, 6 hrs and 24 hrs. The tumors were processed for immunohistochemical (IHC) staining for PARP (a surrogate of apoptosis). A multispectral imaging analysis system was used to quantify the expression of PARP staining. Cell apoptosis was calculated based on the PARP expression level, which is the intensity of the DAB reaction. Results: Our data showed that PARP related apoptosis peaked at 48 hrs and 7 days in pHIFU treated mice, which is comparable to that for the RT group at 24 hrs. The preliminary results from this study were consistent with our previous study on tumor growth delay using pHIFU. Conclusion: Our results demonstrated that non-thermal pHIFU increased apoptotic tumor cell death through the PARP related pathway. MR guided pHIFU may have a great potential as a safe, noninvasive treatment modality for cancer therapy. This treatment modality might be able to synergize with PARP inhibitors to achieve better result.
60 APPLIED LIFE SCIENCES↗
SU-F-J-225: Histology Study of MR Guided Pulsed Focused Ultrasound On Treatment of Prostate Cancer in Vivo
Purpose: Our previous study demonstrated significant tumor growth delay in the mice treated with pulsed high intensity focused ultrasound (pHIFU). The purpose of this study is to understand the cell killing mechanisms of pHIFU. Methods: Prostate cancer cells (LNCaP), were grown orthotopically in 17 nude mice. Tumor-bearing mice were treated using pHIFU with an acoustic power of 25W, pulse width 100msec and 300 pulses in one sonication under MR guidance. Mutiple sonications were used to cover the whole tumor volume. The temperature (less than 40 degree centigrade in the focal spot) was monitored using MR thermometry. Animals were euthanized at pre-determined time points (n=2) after treatment: 0 hours; 6 hrs; 24 hrs; 48 hrs; 4 days and 7 days. Two tumorbearing mice were used as control. Three tumor-bearing mice were treated with radiation (RT, 2 Gy) using 6 MV photon beams. RT treated mice were euthanized at 0 hr, 6 hrs and 24 hrs. The tumors were processed for immunohistochemical (IHC) staining for PARP (a surrogate of apoptosis). A multispectral imaging analysis system was used to quantify the expression of PARP staining. Cell apoptosis was calculated based on the PARP expression level using the DAB analysis software. Results: Our data showed that PARP related apoptosis peaked at 48 hrs and 7 days in pHIFU treated mice, which is comparable to that for the RT group at 24 hrs. The preliminary results from this study were consistent with our previous study on tumor growth delay using pHIFU. Conclusion: Our results demonstrated that non-thermal pHIFU increased apoptotic tumor cell death through the PARP related pathway. MR guided pHIFU may have a great potential as a safe, noninvasive treatment modality for cancer therapy. This treatment modality may synergize with PARP inhibitors to achieve better therapeutic result.
60 APPLIED LIFE SCIENCES↗
Supercritical carbon dioxide tubular flow under temporally varying thermal boundary condition
During transient operation of fusion power plants the amount of thermal energy transferred from plasma to surrounding blanket modules will be varied over time, and will affect behavior of the working fluid inside the blanket and power conversion system where the coolant is in a supercritical state. Transient behavior of the power is in pulsed state in tokamak. The Optimized Supercritical Cycle Operation (OSCO) loop is constructed to investigate the thermohydraulic characteristics of the supercritical fluid under temporally varying thermal boundary condition. In this study the tube outer wall temperature data are measured for abrupt change in thermal power as a preliminary power transient test. The OSCO test conditions are selected to include the erratic behavior of the supercritical fluid under pseudo-critical condition during transient. In order to incorporate the delayed response of utilized thermocouples, a time constant is applied to adjust the obtained results. Along with the experimental study, computational fluid dynamic software is used to perform detailed analysis over the test section geometry. The preliminary test results are presented for comparison against the available correlations from the literature. (authors)
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Effect of current waveform on the performance of phosphor converted nitride light emitting diodes
We investigate the influence of the current waveform on the efficiency and the emission spectra of white, high power InGaN light emitting diodes. We consider rectangular and trapezoidal current pulses, adjusted to provide the same number of charge carriers in the space charge region. Our measurements confirm the theoretical expectation that flattening of the pulse flank increases the power efficiency. This effect is stronger according to the current amplitude. The emission blue peak at trapezoidal pulses is slightly red-shifted compared to that one at rectangular pulses. This indicates a stronger effect of the quantum confined Stark effect for trapezoidal pulse driving.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Meter-wavelength VLBI. III - Pulsars
Observations of pulsars, especially the Crab Nebula pulsar, made in very long baseline interferometry (VLBI) experiments are discussed. Based on a crude 144 MHz visibility curve which is consistent with a Gaussian brightness distribution, the measured visibilities at 196, 111, and 74 MHz were interpreted to yield apparent angular diameters (at half-power) of about 0.03 sec, 0.07 sec, and 0.18 sec, respectively. These sizes scale approximately as wavelength-squared, and the 74 MHz size agrees with recent observations using interplanetary scintillation techniques. The total flux densities lie on the extrapolation from higher frequencies of the pulsing flux densities. Variations in the total flux density up to 25 per cent were observed. A lack of fine structure other than the pulsar in the nebula is indicated by the simple visibility curves. The pulse shapes are similar to single-dish measurements at 196 MHz but reveal a steady, nonpulsing component at 111 MHz. The ratio of pulsing to total power was approximately equal to one-half but varied with time. It was found that four strong, low-dispersion pulsars were only slightly resolved.
Vandenberg, N. R.↗
RF Distribution System for High Power Test of the SNS Cryomodule
A four-way waveguide RF power distribution system for testing the Spallation Neutron Source (SNS) multi-cavity cryomodule to investigate the collective behavior has been developed. A single klystron operating at 805MHz for 1.3 msec at 60Hz powers the 4-way waveguide splitter to deliver up to 400 kW to individual cavities. Each cavity is fed through a combination of waveguide splitters and vector modulators (VM) to provide independent magnitude and phase controls. The waveguide vector modulator consists of two quadrature hybrids and two motorized waveguide phase shifters. The phase shifters and the assembled waveguide vector modulators were individually tested and characterized for low power and high RF power in the SNS RF test facility. Precise calibrations of magnitude and phase were performed to generate the look up tables (LUTs) to provide operational references during the cryomodule test. An I-Q demodulator module was developed and utilized to measure relative phases in pulsed high RF power operation. PLC units were developed for mechanical control of the phase shifters. Initial low/high power measurements were made using LabVIEW. An operation algorithm has been implemented into EPICS control for the cryomodule test stand.
43 PARTICLE ACCELERATORS↗
Demonstration of a 1 TW peak power, joule-level ultrashort Tm:YLF laser
Here we report on the demonstration of a diode-pumped, Tm:YLF-based, chirped pulse amplification laser system operating at λ ≈ 1.9 µm that produces amplified pulse energies exceeding 1.5 J using a single 8-pass power amplifier. The amplified pulses are subsequently compressed to sub-300 fs durations by a diffraction grating pair, producing record >1 TW peak power pulses. To the best of our knowledge, this is the highest peak power demonstrated for any solid-state, near-2 µm laser architecture and illustrates the potential of Tm:YLF for the next generation of high-power, diode-pumped ultrashort lasers.
47 OTHER INSTRUMENTATION↗
Characterization Testing of Lockheed Martin Micro1-2 Cryocoolers Optimized for 220 K Environment
The Mapping Imaging Spectrometer for Europa (MISE) Instrument on the Europa Clipper mission has baselined a Lockheed Martin high-power Micro1-2 pulse tube cryocooler operating at 135 Hz with a 220 K heat rejection temperature. This paper describes the testing and results of two Lockheed Martin Micro1-2 coolers optimized for these conditions. The thermal performance of the microcoolers was measured in vacuum for heat reject temperatures between 220 and 230 K. The coolers were operated with input powers ranging from 5 W to 40 W and drive frequency between 125 Hz and 145 Hz. The optimal drive frequency was strongly dependent on heat reject temperature. In addition, the exported forces and torques of the coolers were measured at 300 K heat rejection for input powers ranging from 5 W to 60 W and drive frequency between 120 Hz and 160 Hz. The exported forces were dependent on both piston amplitude and drive frequency. Moreover, the following were measured on one of the coolers: DC and AC magnetic fields at various locations, the off-state conductance of the pulse tube, and the effect of inclination angle of the pulse tube relative to gravity on the performance of the cooler. Finally, one of the coolers was subjected to random vibration testing.
Rodriguez, J.I.↗
An analytical study of non-resonant transient cross-beam power transfer relevant to recent progress in plasma photonics
Recent experimental and theoretical results have shown that crossing a probe laser in a plasma with a secondary pump can modify the amplitude, phase, and polarization of the probe in a controlled manner. Beyond fundamental physics, these results suggest that a pump-plasma based optical system could be used to amplify and control a laser pulse at high power, where the high fluence precludes using an optical system. This paper attempts to clarify the transient regime of such a pump-probe-plasma system. An analytical solution is derived to the coupled equations in the relevant regime, valid for any frequency detuning, coupling strength, and damping. Asymptotic expressions in the scantly studied off-resonance regime are derived. The time to reach the steady state is found to be roughly independent of the detuning. This time-to-steady-state defines the response time of such a plasma photonics system and can be made potentially much faster than traditional optics by controlling the damping of plasma acoustic waves. Here, we comment on the steady-state assumption typically used to interpret current experiments and design future ones.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Photon Linear Collider Gamma-Gamma Summary
High energy photon - photon collisions can be achieved by adding high average power short-pulse lasers to the Linear Collider, enabling an expanded physics program for the facility. The technology required to realize a photon linear collider continues to mature. Compton back-scattering technology is being developed around the world for low energy light source applications and high average power lasers are being developed for Inertial Confinement Fusion.
43 PARTICLE ACCELERATORS↗
Enhancing optical gains in Si nanocrystals via hydrogenation and cerium ion doping
We report optical gain enhancements in Si nanocrystals (Si-NCs) via hydrogenation and Ce{sup 3+} ion doping. Variable stripe length technique was used to obtain gains. At 0.3 W/cm{sup 2} pumping power density of pulsed laser, net gains were observed together with gain enhancements after hydrogenation and/or Ce{sup 3+} ion doping; gains after loss corrections were between 89.52 and 341.95 cm{sup −1}; and the photoluminescence (PL) lifetime was found to decrease with the increasing gain enhancement. At 0.04 W/cm{sup 2} power density, however, no net gain was found and the PL lifetime increased with the increasing PL enhancement. The results were discussed according to stimulated and spontaneous excitation and de-excitation mechanisms of Si-NCs.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
The extreme nonlinear optics of gases and femtosecond optical filamentation
Under certain conditions, powerful ultrashort laser pulses can form greatly extended, propagating filaments of concentrated high intensity in gases, leaving behind a very long trail of plasma. Such filaments can be much longer than the longitudinal scale over which a laser beam typically diverges by diffraction, with possible applications ranging from laser-guided electrical discharges to high power laser propagation in the atmosphere. Understanding in detail the microscopic processes leading to filamentation requires ultrafast measurements of the strong field nonlinear response of gas phase atoms and molecules, including absolute measurements of nonlinear laser-induced polarization and high field ionization. Such measurements enable the assessment of filamentation models and make possible the design of experiments pursuing applications. In this paper, we review filamentation in gases and some applications, and discuss results from diagnostics developed at Maryland for ultrafast measurements of laser-gas interactions.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Multiphysics Simulations of Nanofibrous High Power Targets for the Inference of Failure Modes
Fermilab s High Power Targetry Research and Development (HPT R&D) group have been developing and studying an electrospun nanofiber target concept to support the need for robust targets in future fixed target facilities. These nanofiber mats have demonstrated resistance to radiation damage, and the free motion of the individual fibers is expected to mitigate the cyclic stresses induced by a pulsed, high-power beam. To evaluate the efficacy of this concept, nanofiber mat samples have been sent by the HPT R&D group to the HiRadMat facility at CERN for prototypic thermal shock testing; the outcomes of these experiments show that the survivability of a nanofiber target depends on its construction parameters, in particular the packing density of the fibers. Samples with higher packing densities have consistently been destroyed by exposure to the HiRadMat beam, with a hole at the beam center visible, and layers of nanofibers peeled away from the center hole, whereas samples with lower densities have survived with limited damage. The exact reason for the failure of the higher density targets was unclear at the time of the original experiments, but the results of our recent multiphysics simulations which recreate the experiments support the hypothesis that the expansion and pressurization of the air inside the target after being heated by the pulsed beam is the cause; in a high density nanofiber mat, the motion of air through the pores of the mat is much more restricted, and induces a larger pressure on the fibers, blowing the mat apart. In this talk, we ll share the results of these simulations and discuss how they support this hypothesis.
Asztalos, Will↗
Low thermal budget photonic processing of highly conductive Cu interconnects based on CuO nanoinks. Potential for flexible printed electronics
The developing field of printed electronics nanoparticle based inks such as CuO show great promise as a low-cost alternative to other metal-based counterparts (e.g., silver). In particular, CuO inks significantly eliminate the issue of particle oxidation, before and during the sintering process, that is prevalent in Cu-based formulations. We report here the scalable and low-thermal budget photonic fabrication of Cu interconnects employing a roll-to-roll compatible pulse-thermal-processing (PTP) technique that enables phase reduction and subsequent sintering of inkjet-printed CuO patterns onto flexible polymer templates. Detailed investigations of curing and sintering conditions were performed to understand the impact of PTP system conditions on the electrical performance of the Cu patterns. Specifically, the impact of energy and power of photonic pulses on print conductivity was systematically studied by varying the following key processing parameters: pulse intensity, duration and sequence. Through optimization of such parameters, highly conductive prints in < 1 s with resistivity values as low as 100 n m has been achieved. We also observed that the introduction of an initial ink-drying step in ambient atmosphere, after the printing and before sintering, leads to significant improvements in mechanical integrity and electrical performance of the printed Cu patterns. Moreover, the viability of CuO reactive inks, coupled with the PTP technology and pre ink-drying protocols, has also been demonstrated for the additive integration of a low-cost Cu temperature sensor onto a flexible polymer substrate.
77 NANOSCIENCE AND NANOTECHNOLOGY↗