http://digital.library.wisc.edu/1793/294 Search the Channel search http://minds.wisconsin.edu/simple-search http://digital.library.wisc.edu/1793/28229 Title: Estimation of Noise Induced by Multimode Optical Fibers in Optical Sensor Systems <br/> <br/>Authors: Bartula, Renata J.; Conrad, Benjamin L.; Sanders, Scott T. <br/> <br/>Abstract: We present evidence of MMF noise and introduce an algorithm that predicts the amplitude of the noise as a function of parameters such as core diameter, fiber length, and spectral resolution. <br/> <br/>Description: Presented Thursday 16 August 2007 at the Gordon Research Conference on Laser Diagnostics for Combustion, Oxford, United Kingdom. Sun, 08 Jun 2008 22:58:59 GMT http://digital.library.wisc.edu/1793/28167 Title: Frequency Combs and Hyperspectral Sources for Absorption Spectroscopy <br/> <br/>Authors: Sanders, Scott T. <br/> <br/>Abstract: We continue to develop laser sources for high-speed gas absorption spectroscopy. A recent source cycles through 14 wavelengths in the 1325-1666nm range every 33 microseconds for combined measurements of gas temperature, H2O, and CH4. <br/> <br/>Description: Presented 5 May 2008 at the Conference on Lasers and Electro-Optics (CLEO) conference, San Jose, CA. Sun, 04 May 2008 22:58:59 GMT http://digital.library.wisc.edu/1793/24391 Title: Designs and Applications of Hyperspectral Light Sources <br/> <br/>Authors: Sanders, Scott T. <br/> <br/>Abstract: A time-division multiplexed source that cycles through 19 wavelengths every 15 s will be described. Sensing results using this and similar sources will follow, including gas thermometry at 100kHz with a precision of 4K at 2000K. <br/> <br/>Description: Presented 19 March 2008 at the Laser Applications to Chemical, Security, and Environmental Analysis (LACSEA) conference, St. Petersburg, FL. Tue, 01 Apr 2008 14:06:49 GMT http://digital.library.wisc.edu/1793/7920 Title: Numerical Modeling and Experimental Testing of a Mixed Gas Joule-Thomson Cryocooler <br/> <br/>Authors: Pettitt, J. <br/> <br/>Abstract: Mixed gas Joule-Thomson (MGJT) systems have been shown to provide order of magnitude improvements in efficiency relative to JT systems that use pure working fluids. This thesis presents theoretical and experimental work related to using a single- stage, low power (< 1 W) MGJT system for cooling the current leads required by high- temperature superconducting electronics. By thermally integrating the current leads with the recuperative heat exchanger of a MGJT cycle, it is possible to intercept the electrical dissipation and conductive heat leak of the wires at a relatively high temperature which provides a thermodynamic advantage. Also, directly cooling the leads rather than indirectly cooling the chips may provide some advantages relative to thermal integration. To design the recuperative heat exchanger for the MGJT cycle, the composition of the gas mixture was optimized using a robust genetic optimization technique. Following mixture selection, the optimization model was modified so that it included the effect of frictional pressure drop, axial conduction through the heat exchanger, and the overall conductance available from the heat exchanger on the performance of the MGJT cycle. The individual influences of these loss factors on the refrigeration power of the MGJT cycle were investigated parametrically and conceptually in order to determine the target values for a low power system and develop some insight into the relative importance of each effect. A detailed model of the specific Hampson-style heat exchanger geometry was developed and used to obtain a design for an initial demonstration device. The demonstration device was fabricated and integrated with a thermal vacuum test facility, gas handling equipment, and the appropriate instrumentation. Several tests were carried out. First, the heat exchanger alone was tested (outside of a JT cycle) using helium as the working fluid. These data provided some experimental verification of the detailed model. Next, the test facility was modified through the installation of a fixed orifice expansion valve to allow open cycle testing of the device using high pressure (9.745 MPa) pure Argon. These measurements provided further insight into the performance of the device. The test facility was subsequently integrated with a compressor in order to allow measurements of the Device's performance using gas mixtures in a closed loop configuration. These test results ultimately revealed issues relative to contamination, which were addressed through the installation of a liquid nitrogen trap, as well as liquid management. The liquid management issue is thought to be related to inadequate vapor kinetic energy which does not provide sufficient momentum transfer to the liquid to move it through the system. The liquid management issue constrains the performance of the MGJT cycle at low mass flow rates and was explored over a very limited range of conditions. Further testing is suggested which will allow the liquid management constraint to be explored more completely in order to guide future designs. <br/> <br/>Description: Under the supervision of Greg Nellis and John Pfotenhauer; 186pp. Sat, 29 Oct 2005 22:58:59 GMT