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October 2001

The Laboratory
in the News

Commentary by
Dona Crawford

Sharing the Power
of Supercomputers

Further Developments in

Simulating How
the Wind Blows

E.O. Lawrence






Nicholas J. Colella, Howard L. Davidson, John A. Kerns, Daniel M. Makowiecki
Process for Fabricating Composite Material Having High Thermal Conductivity
U.S. Patent 6,264,882 B1
July 24, 2001
A process for fabricating a composite material with high thermal conductivity for specific applications, for example, as a heat sink or heat spreader for high-density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper and basically consists of coated diamond particles dispersed in a high-conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process consists, for example, of sputter-coating diamond powder with several elements—including a carbide-forming element and a brazeable material—compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as a copper–silver alloy, thereby producing a dense diamond–copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

Ronald E. Haigh, Steve Wojtczuk, Gerard F. Jacobson, Karla G. Hagans
High Voltage Photovoltaic Power Converter
U.S. Patent 6,265,653 B1
July 24, 2001
An array of independently connected photovoltaic cells on a semi-insulating substrate contains reflective coatings between the cells to enhance efficiency. A uniform, flat-top laser beam profile is illuminated upon the array to produce electrical current of high voltage. An essentially wireless system includes a laser energy source being fed through optical fiber and cast upon the photovoltaic cell array to prevent stray electrical signals before the current from the array is used. Direct bandgap, single-crystal semiconductor materials, such as gallium arsenide, are commonly used in the array. The system is useful where high voltages are provided into confined spaces such as explosive detonation areas, accelerators, photocathodes, and medical appliances.

Barry L. Freitas, Jay A. Skidmore, John P. Wooldridge, Mark A. Emanuel, Stephen A. Payne
Monolithic Laser Diode Array with One Metallized Sidewall
U.S. Patent 6,266,353 B1
July 24, 2001
A monolithic, electrically insulating substrate that contains a series of notched grooves is fabricated. The substrate is metallized so that only the top surface and one wall adjacent to the notch are metallized. Within the grooves is a laser bar, an electrically conductive ribbon or contact bar, and an elastomer that secures or registers the laser bar and ribbon (or contact bar) firmly along the wall of the groove that is adjacent to the notch. The invention includes several embodiments for providing electrical contact to the corresponding top surface of the adjacent wall. In one embodiment, after the bar is located in the proper position, the electrically conductive ribbon is bent so that it makes electrical contact with the adjoining metallized top side of a heat sink.

James G. Berryman
Discrimination of Porosity and Fluid Saturation Using Seismic Velocity Analysis
U.S. Patent 6,269,311 B1
July 31, 2001
The method of the invention is employed for determining the state of saturation in a subterranean formation using only seismic velocity measurements (for example, shear and compressional wave velocity data). Seismic velocity data collected from a region of the formation of like solid material properties can provide relatively accurate partial saturation data derived from a well-defined triangle plotted in a (ρ/µ, λ/µ) plane. When the seismic velocity data are collected over a large region of a formation having both like and unlike materials, the method first distinguishes the like materials by initially plotting the seismic velocity data in a (ρ/λ, µ/λ) plane to determine regions of the formation having like solid material properties and porosity.

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