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Transient Temperatures in Infinite Plates, Infinite Cylinders, and Spheres During Convective Cooling from Initially Parabolic Temperature Profiles

Description: Report presenting "the evaluations of the series which represent the solutions to the Fourier equation in rectangular, cylindrical and spherical coordinates for the case in which the initial temperature field is that owing to a spatially uniform heat source" (p. 1).
Date: 1958
Creator: Epel, Lester G.
Partner: UNT Libraries Government Documents Department

Final report on LDRD project : outstanding challenges for AlGaInN MOCVD.

Description: The AlGaInN material system is used for virtually all advanced solid state lighting and short wavelength optoelectronic devices. Although metal-organic chemical vapor deposition (MOCVD) has proven to be the workhorse deposition technique, several outstanding scientific and technical challenges remain, which hinder progress and keep RD&A costs high. The three most significant MOCVD challenges are: (1) Accurate temperature measurement; (2) Reliable and reproducible p-doping (Mg); and (3) Low dislocation density GaN material. To address challenge (1) we designed and tested (on reactor mockup) a multiwafer, dual wavelength, emissivity-correcting pyrometer (ECP) for AlGaInN MOCVD. This system simultaneously measures the reflectance (at 405 and 550 nm) and emissivity-corrected temperature for each individual wafer, with the platen signal entirely rejected. To address challenge (2) we measured the MgCp{sub 2} + NH{sub 3} adduct condensation phase diagram from 65-115 C, at typical MOCVD concentrations. Results indicate that it requires temperatures of 80-100 C in order to prevent MgCp{sub 2} + NH{sub 3} adduct condensation. Modification and testing of our research reactor will not be complete until FY2005. A new commercial Veeco reactor was installed in early FY2004, and after qualification growth experiments were conducted to improve the GaN quality using a delayed recovery technique, which addresses challenge (3). Using a delayed recovery technique, the dislocation densities determined from x-ray diffraction were reduced from 2 x 10{sup 9} cm{sup -2} to 4 x 10{sup 8} cm{sup -2}. We have also developed a model to simulate reflectance waveforms for GaN growth on sapphire.
Date: March 1, 2005
Creator: Mitchell, Christine Charlotte; Follstaedt, David Martin; Russell, Michael J.; Cross, Karen Charlene; Wang, George T.; Creighton, James Randall et al.
Partner: UNT Libraries Government Documents Department

A Hybrid-Computer Program for Transient Temperature Calculations on TREAT Fast Reactor Safety Experiments

Description: Report issued by the Argonne National Laboratory discussing a computer program used for fast reactor safety experiments. As stated in the summary, "this report gives a detailed description of a hybrid-computer program for calculating temperatures in a multi-region, axisymmetric, cylindrical configuration consisting of solid materials bounded by flowing coolant. Included is an explanation of the mathematical methods, together with a discussion of special features, input-output descriptions, and several sample problems" (p. 7). This report includes tables, and illustrations.
Date: September 1967
Creator: Bryant, Lawrence T.; Dickerman, Charles E. & Stephany, William P.
Partner: UNT Libraries Government Documents Department

Transient Temperature in Infinite Plates, Infinite Cylinders, and Spheres Following a Simultaneous Step Change in Internal Heat Generation Rate, Coolant Temperature and Heat Transfer Coefficient

Description: Report regarding the problem of transient temperature in infinite plates, infinite cylinders, and spheres following during convective cooling after heat generation.
Date: 1958
Creator: Epel, Lester G.
Partner: UNT Libraries Government Documents Department

Neutron scattering effects on fusion ion temperature measurements.

Description: To support the nuclear fusion program at Sandia National Laboratories (SNL), a consistent and verifiable method to determine fusion ion temperatures needs to be developed. Since the fusion temperature directly affects the width in the spread of neutron energies produced, a measurement of the neutron energy width can yield the fusion temperature. Traditionally, the spread in neutron energies is measured by using time-of-flight to convert a spread in neutron energies at the source to a spread in time at detector. One potential obstacle to using this technique at the Z facility at SNL is the need to shield the neutron detectors from the intense bremsstrahlung produced. The shielding consists of eight inches of lead and the concern is that neutrons will scatter in the lead, artificially broaden the neutron pulse width and lead to an erroneous measurement. To address this issue, experiments were performed at the University of Rochester's Laboratory for Laser Energetics, which demonstrated that a reliable ion temperature measurement can be achieved behind eight inches of lead shielding. To further expand upon this finding, Monte Carlo N-Particle eXtended (MCNPX) was used to simulate the experimental geometric conditions and perform the neutron transport. MCNPX was able to confidently estimate results observed at the University of Rochester.
Date: June 1, 2006
Creator: Ziegler, Lee (Bechtel/Nevada, Las Vegas, NV); Starner, Jason R.; Cooper, Gary Wayne; Ruiz, Carlos L.; Franklin, James Kenneth (Ktech Corporation, Albuquerque, NM) & Casey, Daniel T.
Partner: UNT Libraries Government Documents Department