23 Matching Results

Search Results

Advanced search parameters have been applied.

Femtosecond laser materials processing

Description: The use femtosecond pulses for materials processing results in very precise cutting and drilling with high efficiency. Energy deposited in the electrons is not coupled into the bulk during the pulse, resulting in negligible shock or thermal loading to adjacent areas.
Date: February 1, 1997
Creator: Stuart, B.C.
Partner: UNT Libraries Government Documents Department

New applications of copper vapor lasers in micromachining

Description: We have developed a copper vapor laser based micromachinig system using advanced beam quality control and precision wavefront tilting technologies. Precision microdrilling has been demonstrated through percussion drilling and trepanning using this system. With a 30-W copper vapor from running at multi-kHz pulse repetition frequency, straight parallel holes with size varying from 500 microns to less than 25 microns and with aspect ratio up to 1:40 have been consistently drilled with good surface finish on a variety of metals. Micromilling and microdrilling on ceramics using a 250-W copper vapor laser have also been demonstrated with good result. Materialographic sections of machined parts show little (submicron scale) recast layer and heat affected zone.
Date: November 9, 1994
Creator: Chang, J.J.; Martinez, M.W.; Warner, B.E.; Dragon, E.P.; Huete, G. & Solarski, M.E.
Partner: UNT Libraries Government Documents Department

Investigation of temporal contrast effects in femtosecond pulse laser micromachining of metals.

Description: Femtosecond pulse laser drilling has evolved to become a preferred process for selective (maskless) micromachining in a variety of materials, including metals, polymers, semiconductors, ceramics, and living tissue. Manufacturers of state-of-the-art femtosecond laser systems advertise the inherent advantage of micromachining with ultra short pulses: the absence of a heat affected zone. In the ideal case, this leads to micro and nano scale features without distortion due to melt or recast. However, recent studies have shown that this is limited to the low fluence regime in many cases. High dynamic range autocorrelation studies were performed on two commercial Ti:sapphire femtosecond laser systems to investigate the possible presence of a nanosecond pedestal in the femtosecond pulse produced by chirped pulse amplification. If confirmed, nanosecond temporal phenomena may explain many of the thermal effects witnessed in high fluence micromachining. The material removal rate was measured in addition to feature morphology observations for percussion micro drilling of metal substrates in vacuum and ambient environments. Trials were repeated with proposed corrective optics installed, including a variable aperture and a nonlinear frequency doubling crystal. Results were compared. Although the investigation of nanosecond temporal phenomena is ongoing, early results have confirmed published accounts of higher removal rates in a vacuum environment.
Date: June 1, 2006
Creator: Campbell, Benjamin (Pennsylvania State University, Freeport, PA) & Palmer, Jeremy Andrew
Partner: UNT Libraries Government Documents Department

Laser Drilling - Drilling with the Power of Light

Description: Gas Technology Institute (GTI) has been the leading investigator in the field of high power laser applications research for well construction and completion applications. Since 1997, GTI (then as Gas Research Institute) has investigated several military and industrial laser systems and their ability to cut and drill into reservoir type rocks. In this report, GTI continues its investigation with a recently acquired 5.34 kW ytterbium-doped multi-clad high power fiber laser (HPFL). The HPFL represents a potentially disruptive technology that, when compared to its competitors, is more cost effective to operate, capable of remote operations, and requires considerably less maintenance and repair. To determine how this promising laser compares with other lasers used in past experimental work, GTI performed a number of experiments with results directly comparable to previous data. Experiments were designed to investigate the effect of laser input parameters on representative reservoir rock types of sandstone and limestone. The focus of the experiments was on completion and perforation applications, although the results and techniques apply to well construction and other rock cutting applications. Variables investigated include laser power, beam intensity, external purging of cut materials, sample orientation, beam duration, beam shape, and beam frequency. The investigation also studied the thermal effects on the two sample rock types and their methods of destruction: spallation for sandstone, and thermal dissociation for limestone. Optimal operating conditions were identified for each rock type and condition. As a result of this experimental work, the HPFL has demonstrated a better capability of cutting and drilling limestone and sandstone when compared with other military and industrial lasers previously tested. Consideration should be given to the HPFL as the leading candidate for near term remote high power laser applications for well construction and completion.
Date: September 28, 2004
Creator: Gahan, Brian C. & Batarseh, Samih
Partner: UNT Libraries Government Documents Department

Laser Drilling - Drilling with the Power of Light

Description: Gas Technology Institute (GTI) has been the leading investigator in the field of high power laser applications research for well construction and completion applications. Since 1997, GTI (then as Gas Research Institute) has investigated several military and industrial laser systems and their ability to cut and drill into reservoir type rocks. In this report, GTI continues its investigation with a recently acquired 5.34 kW ytterbium-doped multi-clad high power fiber laser (HPFL). The HPFL represents a potentially disruptive technology that, when compared to its competitors, is more cost effective to operate, capable of remote operations, and requires considerably less maintenance and repair. To determine how this promising laser would perform under high pressure in-situ conditions, GTI performed a number of experiments with results directly comparable to previous data. Experiments were designed to investigate the effect of laser input parameters on representative reservoir rock types of sandstone and limestone. The focus of the experiments was on completion and perforation applications, although the results and techniques apply to well construction and other rock cutting applications. All previous laser/rock interaction tests were performed on samples in the lab at atmospheric pressure. To determine the effect of downhole pressure conditions, a sophisticated tri-axial cell was designed and tested. For the first time, Berea sandstone, limestone and clad core samples were lased under various combinations of confining, axial and pore pressures. Composite core samples consisted of steel cemented to rock in an effort to represent material penetrated in a cased hole. The results of this experiment will assist in the development of a downhole laser perforation prototype tool. In the past, several combinations of laser and rock variables were investigated at standard conditions and reported in the literature. More recent experiments determined the technical feasibility of laser perforation on multiple samples of rock, cement and steel. ...
Date: September 28, 2005
Creator: Gahan, Brian C. & Batarseh, Samih
Partner: UNT Libraries Government Documents Department

LDRD 10729 Ultra Miniaturization of RF using Microwave Chip on Flex Technology, FY02 Final Report

Description: This report describes the activities on the ''Ultra Miniaturization of RF'' project conducted as part of Sandia's Laboratory Directed Research and Development (LDRD) program. The objective was to evaluate a multichip module technology known as Microwave Chip on Flex (MCOF) [1], which is a newer form of the standard high density interconnect (HDI) technology originally developed by General Electric and Lockheed Martin [2,3]. The program was a three-year effort. In the first year, the team focused on understanding the technology and developing a basic design library. In the second year, devices and interconnects used at L, X, and Ku frequency bands were evaluated via a test coupon (with no application specific circuit design). In the third year, we designed, fabricated, and evaluated a specific Ku-band circuit. The circuit design and layout was performed by Sandia, and the module fabrication was performed by Lockheed Martin Government Electronic Systems. In MCOF technology [1], bare die are placed face down on an adhesive backed flex circuit. The first level of the circuit is a pre-patterned titanium copper thin film metal system on a polyimide dielectric material. The complete module is then framed and filled with an epoxy encapsulant. The module is flipped and via holes are laser drilled through subsequent interconnect layers. Each addition layer is adhered to the top of the module and laser drilling repeated. The baseline design consisted of the original pre-patterned layer plus two additional metal layers. The base of the module is then machined so the heat spreader and frame are planar for a good thermal and electrical connection to the next assembly. This report describes the efforts conducted to evaluate the technology and its applicability to Sandia RF systems.
Date: March 1, 2003
Creator: SANDOVAL, CHARLIE E.; WOUTERS, GREGG A. & SLOAN, GEORGE R.
Partner: UNT Libraries Government Documents Department

Precision micro drilling with copper vapor lasers

Description: The authors have developed a copper vapor laser based micro machining system using advanced beam quality control and precision wavefront tilting technologies. Micro drilling has been demonstrated through percussion drilling and trepanning using this system. With a 30 W copper vapor laser running at multi-kHz pulse repetition frequency, straight parallel holes with size varying from 500 microns to less than 25 microns and with aspect ratio up to 1:40 have been consistently drilled on a variety of metals with good quality. For precision trepanned holes, the hole-to-hole size variation is typically within 1% of its diameter. Hole entrance and exit are both well defined with dimension error less than a few microns. Materialography of sectioned holes shows little (sub-micron scale) recast layer and heat affected zone with surface roughness within 1--2 microns.
Date: September 2, 1994
Creator: Chang, J.J.; Martinez, M.W.; Warner, B.E.; Dragon, E.P.; Huete, G. & Solarski, M.E.
Partner: UNT Libraries Government Documents Department

Equipment for drilling miniature holes

Description: Miniature holes are produced on 16 different types of mechanical drilling equipment. Each equipment type has significant advantages for a specific type of part. The basic capabilities vary greatly between equipment types. Some produce very precise holes and others produce very high volumes of commercial tolerance holes. At the present time machines are available for mechanicaly drilling up to 100,000 miniature holes per hour. Lasers currently are drilling as many as 15,000,000 ultra-miniature holes per hour.
Date: April 1, 1981
Creator: Gillespie, L K
Partner: UNT Libraries Government Documents Department

Laser Drilling - Drilling with the Power of Light

Description: Gas Technology Institute (GTI) has been the leading investigator in the field of high power laser applications research for well construction and completion applications. Since 1997, GTI (then as Gas Research Institute- GRI) has investigated several military and industrial laser systems and their ability to cut and drill into reservoir type rocks. In this report, GTI continues its investigation with a 5.34 kW ytterbium-doped multi-clad high power fiber laser (HPFL). When compared to its competitors; the HPFL represents a technology that is more cost effective to operate, capable of remote operations, and requires considerably less maintenance and repair. Work performed under this contract included design and implementation of laboratory experiments to investigate the effects of high power laser energy on a variety of rock types. All previous laser/rock interaction tests were performed on samples in the lab at atmospheric pressure. To determine the effect of downhole pressure conditions, a sophisticated tri-axial cell was designed and tested. For the first time, Berea sandstone, limestone and clad core samples were lased under various combinations of confining, axial and pore pressures. Composite core samples consisted of steel cemented to rock in an effort to represent material penetrated in a cased hole. The results of this experiment will assist in the development of a downhole laser perforation or side tracking prototype tool. To determine how this promising laser would perform under high pressure in-situ conditions, GTI performed a number of experiments with results directly comparable to previous data. Experiments were designed to investigate the effect of laser input parameters on representative reservoir rock types of sandstone and limestone. The focus of the experiments was on laser/rock interaction under confining pressure as would be the case for all drilling and completion operations. As such, the results would be applicable to drilling, perforation, and side tracking ...
Date: February 28, 2007
Creator: Salehi, Iraj A.; Gahan, Brian C. & Batarseh, Samih
Partner: UNT Libraries Government Documents Department

Industrial applications of high-power copper vapor lasers

Description: A growing appreciation has developed in the last several years for the copper vapor laser because of its utility in ablating difficult materials at high rates. Laser ablation at high rates shows promise for numerous industrial applications such as thin film deposition, precision hole drilling, and machining of ceramics and other refractories.
Date: August 1, 1995
Creator: Warner, B.E.; Boley, C.D.; Chang, J.J.; Dragon, E.P.; Havstad, M.A.; Martinez, M. et al.
Partner: UNT Libraries Government Documents Department

Advanced packaging technology for high frequency photonic applications

Description: An advanced packaging concept has been developed for optical devices. This concept allows multiple fibers to be coupled to photonic integrated circuits, with no fiber penetration of the package walls. The principles used to accomplish this concept involves a second-order grating to couple light in or out of the photonic circuit, and a binary optic lens which receives this light and focuses it into a single-mode optical fiber. Design, fabrication and electrical/optical measurements of this packaging concept are described.
Date: March 1, 1996
Creator: Armendariz, M.G.; Hadley, G.R. & Warren, M.E.
Partner: UNT Libraries Government Documents Department

Deflagration in stainless steel storage containers containing plutonium dioxide

Description: Detonation of hydrogen and oxygen in stainless steel storage containers produces maximum pressures of 68.5 psia and 426.7 psia. The cylinders contain 3,000 g of PuO{sub 2} with 0.05 wt% and 0.5 wt% water respectively. The hydrogen and oxygen are produced by the alpha decomposition of the water. Work was performed for the Savannah River Site.
Date: February 1, 1996
Creator: Kleinschmidt, P.D.
Partner: UNT Libraries Government Documents Department

Development of Advanced Photolytic Iodine Laser (PIL) Cutting and Joining Technologies for Manufacturing

Description: An evaluation was made of the Photolytic Iodine Laser (PIL) being developed by Advanced Optical Equipment and Services Corporation for metalworking applications. This laser operates in the infrared region of the spectrum and was anticipated to have a very small focal spot size and very low divergence. With these properties, it would be very effective at making small welds and narrow slots in metals. The program was of limited success due to low power output from the laser as well as power and positional instability. Some narrow slots were made and evaluated. The PIL may have applications in the electronics industry, even at low power, if the instability in the beam power and position can be solved.
Date: September 1, 1998
Creator: Mustaleski, T. & Richey, M.
Partner: UNT Libraries Government Documents Department

Laser processing analysis and research: tracking code 94-ERP-071. Final report

Description: This Exploratory Research Project addressed the coupling between short pulse, short wave length, high-radiance laser beams and a solid substrate. The motivation for conducting this research stems from the ever increasing application of high-radiance lasers in processing materials for science and industry. As a result of extensive research and development activities at Lawrence Livermore National Laboratory, there are now several lasers that can cut metals, ceramics, and composites rapidly with unmatched precision. Both gas and solid state lasers are now being employed in this area. The purpose of this project is to develop scientific understanding of the cutting process and to provide tools to optimize the laser system for various applications like precision hole drilling, cutting, welding, and ablative coating. There is a significant amount of scientific data and model development that supports this area of study. Kar and Mazumder reported on studies of pulsed laser coupling for the creation of nano-particles. This provided the initial motivation for our model. Here we include a more detailed discussion of light absorption and propagation, and electron plasma effects and expansion into an ambient gas rather than only in a vacuum. Our first effort began in FY1994, which yielded the basic model. In FY1995, we refined the code and later identified a more appropriate equation of state. The experimental program and the modeling effort provided the essential parametric evaluations needed to benchmark the model. This program enabled us to discover several underlying plasma effects important to the cutting or ablation process. Extensive measurements of the plume of expanding vapor and optical emissions give plasma temperatures, densities, and hydrodynamic estimates of the vapor`s neutral properties. In the first studies, both aluminum and iron are treated. Carbon studies were included in the final phases of this work. 3 refs.
Date: March 1, 1996
Creator: Chang, J.J.; Boley, C.D. & Ault, E.R.
Partner: UNT Libraries Government Documents Department

Laser Drilling: Drilling with the Power of Light Phase 1: Feasibility Study

Description: A laser drilling research team was formed from members of academia, industry and national laboratory to explore the feasibility of using modern high-powered lasers to drill and complete oil and gas wells. The one-year Phase 1 study discussed in this report had the goals of quantifying the amount of pulsed infrared laser energy needed to spall and melt rock of varying lithologies and to investigate the possibility of accomplishing the same task in water under atmospheric conditions. Previous work by some members of this team determined that continuous wave lasers of varying wavelengths have more than enough power to cut, melt and vaporize rock. Samples of sandstone, limestone, and shale were prepared for laser beam interaction with a 1.6 kW pulsed Nd:YAG laser beam to determine how the beam's size, power, repetition rate, pulse width, exposure time and energy can affect the amount of energy transferred to the rock for the purposes of spallation, melting and vaporization. The purpose of the laser rock interaction experiment was to determine the threshold parameters required to remove a maximum rock volume from the samples while minimizing energy input. Absorption of radiant energy from the laser beam gives rise to the thermal energy transfer required for the destruction and removal of the rock matrix. Results from the tests indicate that each rock type has a set of optimal laser parameters to minimize specific energy (SE) values as observed in a set of linear track and spot tests. In addition, it was observed that the rates of heat diffusion in rocks are easily and quickly overrun by absorbed energy transfer rates from the laser beam to the rock. As absorbed energy outpaces heat diffusion by the rock matrix, local temperatures can rise to the melting points of the minerals and quickly increase observed SE values. ...
Date: September 1, 2001
Creator: Gahan, Brian C.; Parker, Richard A.; Graves, Ramona; Batarseh, Samih; Reed, Claude B.; Xu, Zhiyue et al.
Partner: UNT Libraries Government Documents Department

Thin-film amorphous silicon alloy research partnership. Phase 2, Annual technical progress report, 2 February 1996--1 February 1997

Description: This is Phase II of a 3-phase, 3-year program. It is intended to expand, enhance, and accelerate knowledge and capabilities for developing high-performance, two-terminal multijunction amorphous Si alloy modules. We discuss investigations on back reflectors to improve cell performance and investigate uniformity in performance over a 1-sq.-ft. area. We present results on component cell performance, both in the initial and in the light-degraded states, deposited over a 1-sq.-ft. area. The uniformity in deposited is investigated by studying the performance of subcells deposited over the entire area. We also present results on the performance of triple- junction cells and modules. The modules use grid-lines and encapsulants compatible with our production technology. We discuss the novel laser-processing technique that has bee developed at United Solar to improve energy-conversion efficiency and reduce manufacturing costs. We discuss in detail the optimization of the processing steps, and the performance of a laser-processed, triple- junction device of 12.6 cm{sup 2} area is presented. We also present experimental results on investigations of module reliability.
Date: June 1, 1997
Creator: Guha, S.
Partner: UNT Libraries Government Documents Department

Computational modeling of ultra-short-pulse ablation of enamel

Description: A computational model for the ablation of tooth enamel by ultra-short laser pulses is presented. The role of simulations using this model in designing and understanding laser drilling systems is discussed. Pulses of duration 300 sec and intensity greater than 10{sup 12} W/cm{sup 2} are considered. Laser absorption proceeds via multi-photon initiated plasma mechanism. The hydrodynamic response is calculated with a finite difference method, using an equation of state constructed from thermodynamic functions including electronic, ion motion, and chemical binding terms. Results for the ablation efficiency are presented. An analytic model describing the ablation threshold and ablation depth is presented. Thermal coupling to the remaining tissue and long-time thermal conduction are calculated. Simulation results are compared to experimental measurements of the ablation efficiency. Desired improvements in the model are presented.
Date: February 29, 1996
Creator: London, R.A.; Bailey, D.S. & Young, D.A.
Partner: UNT Libraries Government Documents Department

Rapid prototyping of a micro pump with laser micromaching

Description: A micro electrohydrodynamic (EHD) injection pump has been developed using laser micromaching technology. Two designs have been fabricated, tested, and evaluated. The first design has two silicon pieces with KOH-etched wells which are stacked on the top of each other. The wells am etched on one side of the wafer and gold is deposited on the other side to serve as the pump electrodes. A ND:YAG laser is used to drill an array holes in the well region of both silicon die. This creates a grid distribution with a rectangular pattern. Next the well regions of the die are aligned, and the parts are bonded together using a Staystik thermoplastic. The pump unit is then mounted into a ceramic package over the hole drilled to permit fluid flow. Aluminum ribbon wire bonds are used to connect the pump electrodes to the package leads. Isolation of metallization and wires is achieved by filling the package well and coating the wires with polyimide.When a voltage is applied at the electrodes, ions are injected into the working fluid, such as an organic solvent, thus inducing flow. The second design has the die oriented ``back-to-back`` and bonded together with stayform. A ``back-to-back`` design will decrease the grid distance so that a smaller voltage is required for pumping. Preliminary results have demonstrated that this micro pump can achieved a pressure head of about 287 Pa with an applied voltage of 120 volts.
Date: August 1, 1995
Creator: Wong, C.C.; Chu, D.; Liu, S.L.; Tuck, M.R.; Mahmud, Z. & Amatucci, V.
Partner: UNT Libraries Government Documents Department

Array Automated Assembly Task, Low Cost Silicon Solar Array Project: Phase 2. Quarterly technical report No. 4 for July--September 1978

Description: An automated processing sequence is being investigated in seventeen process groups which each encompass a number of processing steps. An indepth analysis of the process steps incorporated within the individual process groups is currently being performed, and each group is discussed. These process groups are: cell test data acquisition, plasma etching of resist, laser trimming and holing operation, wafer surface preparation, laser scanning inspection, wafer printing, low pressure vapor metal deposition, silicon nitride AR coating, wafer plating, soldering coating and flux removal, cell handling for module construction, laser trimming and holing automation, cell and module test and data storage, module construction study, spray on dopants, conveyorized dopant diffusion, and module model fabrication and materials. A final SAMICS report will be submitted at the conclusion of the overall process analysis.
Date: January 1, 1978
Creator: Rhee, Sang S.; Jones, Gregory T. & Allison, Kimberly L.
Partner: UNT Libraries Government Documents Department

Computational electronics and electromagnetics

Description: The Computational Electronics and Electromagnetics thrust area at Lawrence Livermore National Laboratory serves as the focal point for engineering R&D activities for developing computer-based design, analysis, and tools for theory. Key representative applications include design of particle accelerator cells and beamline components; engineering analysis and design of high-power components, photonics, and optoelectronics circuit design; EMI susceptibility analysis; and antenna synthesis. The FY-96 technology-base effort focused code development on (1) accelerator design codes; (2) 3-D massively parallel, object-oriented time-domain EM codes; (3) material models; (4) coupling and application of engineering tools for analysis and design of high-power components; (5) 3-D spectral-domain CEM tools; and (6) enhancement of laser drilling codes. Joint efforts with the Power Conversion Technologies thrust area include development of antenna systems for compact, high-performance radar, in addition to novel, compact Marx generators. 18 refs., 25 figs., 1 tab.
Date: February 1, 1997
Creator: Shang, C. C.
Partner: UNT Libraries Government Documents Department

Design and operation of gamma scan and fission gas sampling systems for characterization of irradiated commercial nuclear fuel

Description: One of the primary objectives of the Materials Characterization Center (MCC) is to acquire and characterize spent fuels used in waste form testing related to nuclear waste disposal. The initial steps in the characterization of a fuel rod consist of gamma scanning the rod and sampling the gas contained in the fuel rod (referred to as fission gas sampling). The gamma scan and fission gas sampling systems used by the MCC are adaptable to a wide range of fuel types and have been successfully used to characterize both boiling water reactor (BWR) and pressurized water reactor (PWR) fuel rods. This report describes the design and operation of systems used to gamma scan and fission gas sample full-length PWR and BWR fuel rods. 1 ref., 10 figs., 1 tab.
Date: September 1, 1989
Creator: Knox, C.A.; Thornhill, R.E. & Mellinger, G.B.
Partner: UNT Libraries Government Documents Department