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• 101. [Article] Variability in Winter Mass Balance of Northern Hemisphere Glaciers and Relations with Atmospheric Circulation

  An analysis of variability in the winter mass balance (WMB) of 22 glaciers in the Northern Hemisphere indicates two primary modes of variability that explain 46% of the variability among all glaciers. ...

  Citation × Citation Citation Abstract Copy Title: Variability in Winter Mass Balance of Northern Hemisphere Glaciers and Relations with Atmospheric Circulation Author: McCabe, Gregory J., Fountain, Andrew G., Dyurgerov, Mark Year: 2000 An analysis of variability in the winter mass balance (WMB) of 22 glaciers in the Northern Hemisphere indicates two primary modes of variability that explain 46% of the variability among all glaciers. The first mode of variability characterizes WMB variability in Northern and Central Europe and the second mode primarily represents WMB variability in northwestern North America, but also is related to variability in WMB of one glacier in Europe and one in Central Asia. These two modes of WMB variability are explained by variations in mesoscale atmospheric circulation which are driving forces of variations in surface temperature and precipitation. The first mode is highly correlated with the Arctic Oscillation Index, whereas the second mode is highly correlated with the Southern Oscillation Index. In addition, the second mode of WMB variability is highly correlated with variability in global winter temperatures. This result suggests some connection between global temperature trends and WMB for some glaciers. Title: Variability in Winter Mass Balance of Northern Hemisphere Glaciers and Relations with Atmospheric Circulation Author: McCabe, Gregory J., Fountain, Andrew G., Dyurgerov, Mark Year: 2000 An analysis of variability in the winter mass balance (WMB) of 22 glaciers in the Northern Hemisphere indicates two primary modes of variability that explain 46% of the variability among all glaciers. The first mode of variability characterizes WMB variability in Northern and Central Europe and the second mode primarily represents WMB variability in northwestern North America, but also is related to variability in WMB of one glacier in Europe and one in Central Asia. These two modes of WMB variability are explained by variations in mesoscale atmospheric circulation which are driving forces of variations in surface temperature and precipitation. The first mode is highly correlated with the Arctic Oscillation Index, whereas the second mode is highly correlated with the Southern Oscillation Index. In addition, the second mode of WMB variability is highly correlated with variability in global winter temperatures. This result suggests some connection between global temperature trends and WMB for some glaciers. Close

• 102. [Article] The Meyer-Neldel rule for diodes in forward bias

  We analyzed the temperature dependence of the forward current of a silicon diode. Instead of representing the data in the ordinarily used current versus voltage graph, the currents are plotted for different ...

  Citation × Citation Citation Abstract Copy Title: The Meyer-Neldel rule for diodes in forward bias Author: Widenhorn, Ralf, Fitzgibbons, Michael, Bodegom, Erik Year: 2004 We analyzed the temperature dependence of the forward current of a silicon diode. Instead of representing the data in the ordinarily used current versus voltage graph, the currents are plotted for different voltages as a function of the inverse temperature. The constant voltage curves can be fitted linearly and the extrapolations of the fits seem to merge to one common focal point. Hence, we demonstrate that a real diode follows the Meyer-Neldel rule (MNR). It is shown that the MNR is due to a shift of the current from ideal-diode to high-injection-diode behavior. We will argue that the merging of the different Arrhenius plots toward one focal point, and hence a MNR, can be the result of various mechanisms. The general requirements to observe a MNR are not very restrictive. It is therefore not surprising that the MNR has been observed in a multitude of systems. The origin that gives rise to the MNR can be manifold and allows for different models to explain its occurrence. Title: The Meyer-Neldel rule for diodes in forward bias Author: Widenhorn, Ralf, Fitzgibbons, Michael, Bodegom, Erik Year: 2004 We analyzed the temperature dependence of the forward current of a silicon diode. Instead of representing the data in the ordinarily used current versus voltage graph, the currents are plotted for different voltages as a function of the inverse temperature. The constant voltage curves can be fitted linearly and the extrapolations of the fits seem to merge to one common focal point. Hence, we demonstrate that a real diode follows the Meyer-Neldel rule (MNR). It is shown that the MNR is due to a shift of the current from ideal-diode to high-injection-diode behavior. We will argue that the merging of the different Arrhenius plots toward one focal point, and hence a MNR, can be the result of various mechanisms. The general requirements to observe a MNR are not very restrictive. It is therefore not surprising that the MNR has been observed in a multitude of systems. The origin that gives rise to the MNR can be manifold and allows for different models to explain its occurrence. Close

• 103. [Article] Geophysical strain and tilt : measurement methodology and analysis of data

  Tilt and strain meters were installed on the Portland State University campus in the summer of 1982 and data was collected for 4 months. Instrument selection, operation, installation and performance are ...

  Citation × Citation Citation Abstract Copy Title: Geophysical strain and tilt : measurement methodology and analysis of data Author: MacKay, Robert Year: 1983 Tilt and strain meters were installed on the Portland State University campus in the summer of 1982 and data was collected for 4 months. Instrument selection, operation, installation and performance are discussed. Suggestions that could enhance data quality and data collection efficiency are presented. An analysis procedure is suggested and an example of this procedure for an interval of data is discussed. The influence of the temperature, pressure, rainfall and solid earth tides on the signal is investigated, as well as the correlation between similar channels of the different tilt instruments. The temperature, rainfall and solid earth tides were all determined to have an influence on the instruments. A statistical test of the influence of the barometric pressure on the signal revealed no significant influence. A very low correlation between similar components of the different tilt instruments was observed aside from their thermal dependence. It was concluded that in order to obtain high quality data for the use in quantitative calculations, the temperature influence on the raw record must be minimized. Title: Geophysical strain and tilt : measurement methodology and analysis of data Author: MacKay, Robert Year: 1983 Tilt and strain meters were installed on the Portland State University campus in the summer of 1982 and data was collected for 4 months. Instrument selection, operation, installation and performance are discussed. Suggestions that could enhance data quality and data collection efficiency are presented. An analysis procedure is suggested and an example of this procedure for an interval of data is discussed. The influence of the temperature, pressure, rainfall and solid earth tides on the signal is investigated, as well as the correlation between similar channels of the different tilt instruments. The temperature, rainfall and solid earth tides were all determined to have an influence on the instruments. A statistical test of the influence of the barometric pressure on the signal revealed no significant influence. A very low correlation between similar components of the different tilt instruments was observed aside from their thermal dependence. It was concluded that in order to obtain high quality data for the use in quantitative calculations, the temperature influence on the raw record must be minimized. Close

• 104. [Article] Approximate Thermodynamic State Relations in Partially Ionized Gas Mixtures

  Thermodynamic state relations for mixtures of partially ionized nonideal gases are often approximated by artificially partitioning the mixture into compartments or subvolumes occupied by the pure partially ...

  Citation × Citation Citation Abstract Copy Title: Approximate Thermodynamic State Relations in Partially Ionized Gas Mixtures Author: Ramshaw, John D. Year: 2004 Thermodynamic state relations for mixtures of partially ionized nonideal gases are often approximated by artificially partitioning the mixture into compartments or subvolumes occupied by the pure partially ionized constituent gases, and requiring these subvolumes to be in temperature and pressure equilibrium. This intuitively reasonable procedure is easily shown to reproduce the correct thermal and caloric state equations for a mixture of neutral nonionized ideal gases. The purpose of this paper is to point out that (a) this procedure leads to incorrect state equations for a mixture of partially ionized ideal gases, whereas (b) the alternative procedure of requiring that the subvolumes all have the same temperature and free electron density reproduces the correct thermal and caloric state equations for such a mixture. These results readily generalize to the case of partially degenerate and/or relativistic electrons, to a common approximation used to represent pressure ionization effects, and to two-temperature plasmas. This suggests that equating the subvolume electron number densities or chemical potentials instead of pressures is likely to provide a more accurate approximation in nonideal plasma mixtures. Title: Approximate Thermodynamic State Relations in Partially Ionized Gas Mixtures Author: Ramshaw, John D. Year: 2004 Thermodynamic state relations for mixtures of partially ionized nonideal gases are often approximated by artificially partitioning the mixture into compartments or subvolumes occupied by the pure partially ionized constituent gases, and requiring these subvolumes to be in temperature and pressure equilibrium. This intuitively reasonable procedure is easily shown to reproduce the correct thermal and caloric state equations for a mixture of neutral nonionized ideal gases. The purpose of this paper is to point out that (a) this procedure leads to incorrect state equations for a mixture of partially ionized ideal gases, whereas (b) the alternative procedure of requiring that the subvolumes all have the same temperature and free electron density reproduces the correct thermal and caloric state equations for such a mixture. These results readily generalize to the case of partially degenerate and/or relativistic electrons, to a common approximation used to represent pressure ionization effects, and to two-temperature plasmas. This suggests that equating the subvolume electron number densities or chemical potentials instead of pressures is likely to provide a more accurate approximation in nonideal plasma mixtures. Close

• 105. [Article] The Geography of Glaciers and Perennial Snowfields in the American West

  A comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey ...

  Citation × Citation Citation Abstract Copy Title: The Geography of Glaciers and Perennial Snowfields in the American West Author: Fountain, Andrew G., Glenn, Bryce, Basagic, Hassan J. Year: 2017 A comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey 1:24,000 topographic maps based on aerial photographs acquired during 35 years, 1955–1990, of which the first 20 years or more was a cool period with little glacier change. The mapped features were filtered for those greater than 0.01 km2. Results show that 5036 G&PS (672 km2, 14 km3) populate eight states, of which about 1276 (554 km2, 12 km3) are glaciers. Uncertainty is estimated at ±9% for area and ±20% for volume. Two populations of G&PS were identified based on air temperature and precipitation. The larger is found in a maritime climate of the Pacific Northwest, characterized by warm winter air temperatures and high winter precipitation (~2100 mm). The other population is continental in climate, characterized by cold winter air temperatures, relatively low winter precipitation (~880 mm), and located at higher elevations elsewhere. The G&PS in the Pacific Northwest, especially in the Olympic Mountains, are particularly vulnerable to warming winter air temperatures that will change the phase of winter precipitation from snow to rain, further accelerating glacier shrinkage in the future. Comparison with a recent inventory suggests that the total G&PS area in the American West may have decreased by as much as 39% since the mid-20th century. Title: The Geography of Glaciers and Perennial Snowfields in the American West Author: Fountain, Andrew G., Glenn, Bryce, Basagic, Hassan J. Year: 2017 A comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey 1:24,000 topographic maps based on aerial photographs acquired during 35 years, 1955–1990, of which the first 20 years or more was a cool period with little glacier change. The mapped features were filtered for those greater than 0.01 km2. Results show that 5036 G&PS (672 km2, 14 km3) populate eight states, of which about 1276 (554 km2, 12 km3) are glaciers. Uncertainty is estimated at ±9% for area and ±20% for volume. Two populations of G&PS were identified based on air temperature and precipitation. The larger is found in a maritime climate of the Pacific Northwest, characterized by warm winter air temperatures and high winter precipitation (~2100 mm). The other population is continental in climate, characterized by cold winter air temperatures, relatively low winter precipitation (~880 mm), and located at higher elevations elsewhere. The G&PS in the Pacific Northwest, especially in the Olympic Mountains, are particularly vulnerable to warming winter air temperatures that will change the phase of winter precipitation from snow to rain, further accelerating glacier shrinkage in the future. Comparison with a recent inventory suggests that the total G&PS area in the American West may have decreased by as much as 39% since the mid-20th century. Close

• 106. [Article] The Impact of Weather on Kingbird Foraging Behavior

  Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior ...

  Citation × Citation Citation Abstract Copy Title: The Impact of Weather on Kingbird Foraging Behavior Author: Murphy, Michael T. Year: 1987 Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior vary with weather. Foraging characteristics of five additional kingbird species were also examined to assess Fitzpatrick's (1980) generalization that kingbirds (Tyrannus spp.) are aerial hawking specialists. In Eastern Kingbirds, total foraging rate was independent of air temperature, cloud cover, wind speed, and time of day, but the rate of aerial hawking varied directly with air temperature and inversely with cloud cover (both P < 0.05). Effects of the two variables were additive. The percentage of foraging movements that were aerial hawks also increased with temperature and declined with cloud cover, and, hover-gleaning and perch-to-ground sallying were observed mainly during cloudy weather. Sally (i.e., foraging flight) distance correlated directly with perch height and air temperature, and large insects were captured almost exclusively in long upward or horizontal flights. I interpret these data to indicate that foraging behavior and the capture of large, flying insects depends on weather because of how it affects the activity of insect prey. Foraging data on kingbirds support Fitzpatrick's generalization, but the relative use of aerial hawking varies considerably among species. Resident Tropical Kingbirds( T. melancholicus) are the most specialized foragers, whereas the migrant and widely distributed Eastern Kingbird appears to be the most generalized. Certain habitats also appear to favor the use of particular foraging methods (e.g., outward striking in grasslands and perch-to-ground sallying in drier, open habitats). Title: The Impact of Weather on Kingbird Foraging Behavior Author: Murphy, Michael T. Year: 1987 Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior vary with weather. Foraging characteristics of five additional kingbird species were also examined to assess Fitzpatrick's (1980) generalization that kingbirds (Tyrannus spp.) are aerial hawking specialists. In Eastern Kingbirds, total foraging rate was independent of air temperature, cloud cover, wind speed, and time of day, but the rate of aerial hawking varied directly with air temperature and inversely with cloud cover (both P < 0.05). Effects of the two variables were additive. The percentage of foraging movements that were aerial hawks also increased with temperature and declined with cloud cover, and, hover-gleaning and perch-to-ground sallying were observed mainly during cloudy weather. Sally (i.e., foraging flight) distance correlated directly with perch height and air temperature, and large insects were captured almost exclusively in long upward or horizontal flights. I interpret these data to indicate that foraging behavior and the capture of large, flying insects depends on weather because of how it affects the activity of insect prey. Foraging data on kingbirds support Fitzpatrick's generalization, but the relative use of aerial hawking varies considerably among species. Resident Tropical Kingbirds( T. melancholicus) are the most specialized foragers, whereas the migrant and widely distributed Eastern Kingbird appears to be the most generalized. Certain habitats also appear to favor the use of particular foraging methods (e.g., outward striking in grasslands and perch-to-ground sallying in drier, open habitats). Close

• 107. [Article] A Comparison of Five Models for Estimating Clear-Sky Solar Radiation

  Many agencies in the USA are developing management approaches to address water quality concerns and threatened and endangered species habitat requirements in water bodies. Many of these water bodies are ...

  Citation × Citation Citation Abstract Copy Title: A Comparison of Five Models for Estimating Clear-Sky Solar Radiation Author: Annear, Robert Leslie, Wells, Scott A. Year: 2007 Many agencies in the USA are developing management approaches to address water quality concerns and threatened and endangered species habitat requirements in water bodies. Many of these water bodies are water quality limited for temperature. Factors influencing stream temperature include: streamside vegetation, topographic shading, inflows and outflows, stream width, stream depth, light extinction and solar radiation. One of the key driving factors in estimating a water body heat budget is calculating the amount of solar radiation incident on the water surface. Even though it is preferable to measure clear-sky solar radiation, many temperature models rely on theoretical estimates of clear-sky solar radiation. The literature on estimating short-wave solar radiation by calculating the position of the sun and attenuating the radiation through the atmosphere was reviewed. As a first step in relating water temperature to solar radiation, several empirical solar radiation models were calibrated to data at seventeen sites around the United States for clear-sky days. Sensitivity analyses were conducted and differences between the models were examined. Results indicated that the more complex models for calculating solar radiation resulted in better estimates of clear-sky solar radiation once they were calibrated to data. When no data were available, models with one or no calibration parameters did reasonably well at estimating clear-sky solar radiation. Title: A Comparison of Five Models for Estimating Clear-Sky Solar Radiation Author: Annear, Robert Leslie, Wells, Scott A. Year: 2007 Many agencies in the USA are developing management approaches to address water quality concerns and threatened and endangered species habitat requirements in water bodies. Many of these water bodies are water quality limited for temperature. Factors influencing stream temperature include: streamside vegetation, topographic shading, inflows and outflows, stream width, stream depth, light extinction and solar radiation. One of the key driving factors in estimating a water body heat budget is calculating the amount of solar radiation incident on the water surface. Even though it is preferable to measure clear-sky solar radiation, many temperature models rely on theoretical estimates of clear-sky solar radiation. The literature on estimating short-wave solar radiation by calculating the position of the sun and attenuating the radiation through the atmosphere was reviewed. As a first step in relating water temperature to solar radiation, several empirical solar radiation models were calibrated to data at seventeen sites around the United States for clear-sky days. Sensitivity analyses were conducted and differences between the models were examined. Results indicated that the more complex models for calculating solar radiation resulted in better estimates of clear-sky solar radiation once they were calibrated to data. When no data were available, models with one or no calibration parameters did reasonably well at estimating clear-sky solar radiation. Close

• 108. [Article] Mössbauer studies of stable interstitial and substitutional sites of cobalt in gold

  Precision measurements of the Debye-Waller factor of Fe57 in Au using the wide black absorber technique have been made in the temperature range from room temperature to 830 K. The major source of error ...

  Citation × Citation Citation Abstract Copy Title: Mössbauer studies of stable interstitial and substitutional sites of cobalt in gold Author: Steen, Charles Freeland Year: 1971 Precision measurements of the Debye-Waller factor of Fe57 in Au using the wide black absorber technique have been made in the temperature range from room temperature to 830 K. The major source of error arises from Au Ly x-rays which are unresolved by the radiation detection system from the 14.4 KeV gamma ray. The K absorption edge of Br has been used to correct for the presence of x-rays. These measurements have revealed the existence of two nonequivalent lattice sites which the Co57 impurity (parent of Fe57) may occupy. One of the sites has been populated by quenching the source from temperatures greater than 1150 K and has been identified as a substitutional lattice site. From an analysis of the Mössbauer spectrum it is concluded that some of the substitutional sites may be in the vicinity of dislocations. It has been determined that the impurity-host force constant for Fe57 atoms in the substitutional site is about the same as the host-host force constant; the experimental value of the anharmonicity parameter ɛ (-2) for Fe57 in the Au is nearly the same as calculated values of ɛ (-2) for pure Au. The second site forms very slowly upon annealing the source at intermediate temperatures and has been identified as being interstitial in character. The slow rate of formation of the interstitial site indicates that diffusion is a primary mechanism in its formation. The second site must therefore be more complicated than an ordinary interstitial. It is proposed that this site is a split, or dumbbell, interstitial formed by substituting two impurity atoms for one of the Au atoms. Title: Mössbauer studies of stable interstitial and substitutional sites of cobalt in gold Author: Steen, Charles Freeland Year: 1971 Precision measurements of the Debye-Waller factor of Fe57 in Au using the wide black absorber technique have been made in the temperature range from room temperature to 830 K. The major source of error arises from Au Ly x-rays which are unresolved by the radiation detection system from the 14.4 KeV gamma ray. The K absorption edge of Br has been used to correct for the presence of x-rays. These measurements have revealed the existence of two nonequivalent lattice sites which the Co57 impurity (parent of Fe57) may occupy. One of the sites has been populated by quenching the source from temperatures greater than 1150 K and has been identified as a substitutional lattice site. From an analysis of the Mössbauer spectrum it is concluded that some of the substitutional sites may be in the vicinity of dislocations. It has been determined that the impurity-host force constant for Fe57 atoms in the substitutional site is about the same as the host-host force constant; the experimental value of the anharmonicity parameter ɛ (-2) for Fe57 in the Au is nearly the same as calculated values of ɛ (-2) for pure Au. The second site forms very slowly upon annealing the source at intermediate temperatures and has been identified as being interstitial in character. The slow rate of formation of the interstitial site indicates that diffusion is a primary mechanism in its formation. The second site must therefore be more complicated than an ordinary interstitial. It is proposed that this site is a split, or dumbbell, interstitial formed by substituting two impurity atoms for one of the Au atoms. Close

• 109. [Article] A Study of Microwave curing of Underfill using Open and Closed microwave ovens

  As the demand for microprocessors is increasing with more and more consumers using integrated circuits in their daily life, the demand on the industry is increasing to ramp up production. In order to speed ...

  Citation × Citation Citation Abstract Copy Title: A Study of Microwave curing of Underfill using Open and Closed microwave ovens Author: Thakare, Aditya Year: 2015 As the demand for microprocessors is increasing with more and more consumers using integrated circuits in their daily life, the demand on the industry is increasing to ramp up production. In order to speed up the manufacturing processes, new and novel approaches are trying to change certain aspects of it. Microwaves have been tried as an alternative to conventional ovens in the curing of the polymers used as underfills and encapsulants in integrated circuits packages. Microwaves however being electromagnetic waves have non uniform energy distribution in different settings, causing burning or incomplete cure of polymers. In this study, we compare the two main types of microwaves proposed to perform the task of curing the polymers. To limit the study and obtain comparable results, both microwaves were limited to propagate in a single mode, TE10. The first is a closed microwave cavity using air as the propagation medium, and the second is an open microwave oven with a PTFE cavity that uses an evanescent field to provide energy. The open air cavity was studied with different orientations of a substrate placed inside it so as to find the best case scenario in the curing process. This scenario was then compared with the best case scenario found for a sample cured in an evanescent field. This comparison yielded results showing an advantage of the open microwave in maximum field present, thus leading to higher localized energy absorption and temperatures in the substrate, however this case also lead to a higher temperature gradient. The substrate cured in the closed microwave has a lower temperature gradient, but also a lower maximum field which leads to slower cure. In the TE10 mode therefore, a closed microwave has an overall advantage as the heating process is only slightly slower than that of an open cavity, but the temperature gradient in this case is significantly lower. Title: A Study of Microwave curing of Underfill using Open and Closed microwave ovens Author: Thakare, Aditya Year: 2015 As the demand for microprocessors is increasing with more and more consumers using integrated circuits in their daily life, the demand on the industry is increasing to ramp up production. In order to speed up the manufacturing processes, new and novel approaches are trying to change certain aspects of it. Microwaves have been tried as an alternative to conventional ovens in the curing of the polymers used as underfills and encapsulants in integrated circuits packages. Microwaves however being electromagnetic waves have non uniform energy distribution in different settings, causing burning or incomplete cure of polymers. In this study, we compare the two main types of microwaves proposed to perform the task of curing the polymers. To limit the study and obtain comparable results, both microwaves were limited to propagate in a single mode, TE10. The first is a closed microwave cavity using air as the propagation medium, and the second is an open microwave oven with a PTFE cavity that uses an evanescent field to provide energy. The open air cavity was studied with different orientations of a substrate placed inside it so as to find the best case scenario in the curing process. This scenario was then compared with the best case scenario found for a sample cured in an evanescent field. This comparison yielded results showing an advantage of the open microwave in maximum field present, thus leading to higher localized energy absorption and temperatures in the substrate, however this case also lead to a higher temperature gradient. The substrate cured in the closed microwave has a lower temperature gradient, but also a lower maximum field which leads to slower cure. In the TE10 mode therefore, a closed microwave has an overall advantage as the heating process is only slightly slower than that of an open cavity, but the temperature gradient in this case is significantly lower. Close

• 110. [Article] Studies of nucleation and heat transfer in liquid helium isotopes 3 and 4

  We report the results of a series of experiments in three interrelated areas: light induced nucleation of vapor bubbles in superheated liquid helium 4, transient heat transfer in liquid helium isotopes ...

  Citation × Citation Citation Abstract Copy Title: Studies of nucleation and heat transfer in liquid helium isotopes 3 and 4 Author: Lezak, David Year: 1985 We report the results of a series of experiments in three interrelated areas: light induced nucleation of vapor bubbles in superheated liquid helium 4, transient heat transfer in liquid helium isotopes 3 and 4, and homogeneous nucleation of vapor bubbles in superheated liquid helium 3. This work has resulted in significant contributions in each of these particular areas. Our transient heat transfer work has resulted in extremely high temperature measurements of the Kapitza thermal boundary conductance limits in helium 3 and 4, in measurements of the delay time to the onset of film boiling over a wide range of bath temperatures in helium 4, and in a determination of bubble growth rates in helium 4. These measurements have been compared with theory and have in some cases allowed the extension or elucidation of that theory. We have characterized the so called "light effect" and established photographically that small amounts of visible light will cause the formation of vapor bubbles at the interface of a solid and superheated liquid helium 4 and that this vapor can influence the quasi-steady-state heat flux vs temperature hysteresis curve. Finally, we have measured the homogeneous nucleation temperature of liquid helium 3 and found good agreement with the predictions of the Becker-Doring-Volmer-Zel'dovich Frenkel nucleation theory. This work is shown to have applications to practical cryogenic engineering, to further understanding of basic heat transfer and nucleation theory, and to practical and theoretical environmental and resource considerations. Title: Studies of nucleation and heat transfer in liquid helium isotopes 3 and 4 Author: Lezak, David Year: 1985 We report the results of a series of experiments in three interrelated areas: light induced nucleation of vapor bubbles in superheated liquid helium 4, transient heat transfer in liquid helium isotopes 3 and 4, and homogeneous nucleation of vapor bubbles in superheated liquid helium 3. This work has resulted in significant contributions in each of these particular areas. Our transient heat transfer work has resulted in extremely high temperature measurements of the Kapitza thermal boundary conductance limits in helium 3 and 4, in measurements of the delay time to the onset of film boiling over a wide range of bath temperatures in helium 4, and in a determination of bubble growth rates in helium 4. These measurements have been compared with theory and have in some cases allowed the extension or elucidation of that theory. We have characterized the so called "light effect" and established photographically that small amounts of visible light will cause the formation of vapor bubbles at the interface of a solid and superheated liquid helium 4 and that this vapor can influence the quasi-steady-state heat flux vs temperature hysteresis curve. Finally, we have measured the homogeneous nucleation temperature of liquid helium 3 and found good agreement with the predictions of the Becker-Doring-Volmer-Zel'dovich Frenkel nucleation theory. This work is shown to have applications to practical cryogenic engineering, to further understanding of basic heat transfer and nucleation theory, and to practical and theoretical environmental and resource considerations. Close