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Search Publications by: Robert F. Berg (Assoc)

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Displaying 1 - 25 of 60

Oxidation caused by water outgassed from the thermal blanket on the SDO spacecraft

June 23, 2023
Author(s)
Robert F. Berg, Charles S. Tarrio, FRANCIS EPARVIER, ANDREW JONES
The Solar Dynamics Observatory (SDO) is a sun-observing spacecraft that includes two spectrometers that use aluminum membranes to filter solar radiation. The transmission of those filters degraded by a factor of 5 during the first five years after launch

Measurements and model of UV-induced oxidation of aluminum

March 22, 2023
Author(s)
Robert F. Berg, Charles S. Tarrio, Thomas B. Lucatorto
We present measurements and a model of aluminum oxidation induced by ultraviolet (UV) radiation. Spots of oxide were grown by focusing synchrotron radiation onto a polycrystalline aluminum membrane in the presence of water vapor at pressures from 3×10-8

The hazard of UV-induced oxidation to solar-viewing spacecraft optics

March 2, 2023
Author(s)
Charles S. Tarrio, Robert F. Berg, Thomas B. Lucatorto, Dale E. Newbury, Nicholas Ritchie, Andrew Jones, Frank Eparvier
The two most prevalent outgas contaminants on satellites are organic molecules and water vapor. Adsorbed organic molecules can degrade a solar-viewing instrument when they are cracked by ultraviolet radiation (UV) and become a light-absorbing layer of

Silicone tube humidity generator

February 16, 2022
Author(s)
Robert F. Berg, Nicola Chiodo, Eric Georgin
We describe the model and construction of a two-flow (or divided-flow) humidity generator, developed at LNE-CNAM, that uses mass flow controllers to mix a stream of dry gas with a stream of humid gas saturated at 28 °C. It can generate a wide range of

Evidence Against Carbonization of the Thin-Film Filters of the Extreme Ultraviolet Variability Experiment onboard the Solar Dynamics Observatory

April 1, 2021
Author(s)
Charles Tarrio, Robert F. Berg, Thomas B. Lucatorto, Andrew Jones, Frank Eparvier, Brian Templeman, Donald Woodraska, Marie Dominique
In spite of strict limits on outgassing from organic materials, some spacecraft instruments making long-term measurements of solar extreme ultraviolet (EUV) radiation still suff er signi cant degradation. While such measures have reduced the rate of

Optics Contamination

February 5, 2018
Author(s)
Charles S. Tarrio, Shannon B. Hill, Robert F. Berg, Sasa Bajt

Time dependence in static measurements of vapor pressure

November 17, 2015
Author(s)
Robert F. Berg
The static method for measuring vapor pressure assumes that the sample is pure and that its temperature is steady and uniform. In practice, the measured pressure may be time dependent due to evaporative cooling after pumping on the sample, transpiration of

Thermally stable thin-film filters for high-power extreme-ultraviolet applications

November 12, 2015
Author(s)
Charles S. Tarrio, Robert F. Berg, Thomas B. Lucatorto, Bruce Lairson, Heidi Lopez, Travis Ayers
We investigated several types of thin-film filters for high intensity work in the extreme-ultraviolet (EUV) spectral range. In our application, with a peak EUV intensity of 2.7 W cm-2, Ni-mesh-backed Zr filters have a typical lifetime of 20 hours, at which

Viscosity-ratio measurements with capillary viscometers

May 20, 2014
Author(s)
Robert F. Berg, Eric F. May, Michael R. Moldover
Viscosity-ratio measurements made with capillary viscometers exploit the accurate values of the viscosity of helium resulting from ab initio calculations. Accurate values of the argon-to-helium viscosity ratio are now used for primary acoustic thermometry

Hydrogen traps in the outgassing model of a stainless steel vacuum chamber

March 31, 2014
Author(s)
Robert F. Berg
This article describes a model for hydrogen outgassing into a stainless steel vacuum chamber. It accounts for the geometry of the chamber components, the hydrogen dissolved in those components, and the processes of diffusion, recombination, and trapping

Viscosity-ratio measurements with capillary viscometers

November 27, 2013
Author(s)
Robert F. Berg, Eric F. May, Michael R. Moldover
Viscosity-ratio measurements made with capillary viscometers exploit the accurate values of the viscosity of helium calculated ab initio. Accurate values of the argon-to-helium viscosity ratio are now used for primary acoustic gas thermometry and for the

Recommended viscosities of 11 dilute gases at 25?degC

December 13, 2012
Author(s)
Robert F. Berg, Michael R. Moldover
Commercially manufactured meters that measure the flow of a process gas are often calibrated with a known flow of a surrogate gas. This requires an accurate model of the flow meter and accurate values of the relevant thermophysical properties for both

Recommended vapor pressure and thermophysical data for ferrocene

August 14, 2012
Author(s)
Michal Fulem, Kvetoslav Ruzicka, Marisa A. Rocha, Luis M.N.B.F. Santos, Robert F. Berg
Recommended vapor pressure data for ferrocene (CAS Registry Number: 102-54-5) in the temperature range from 242 to 447 K were developed by the simultaneous correlation of critically assessed vapor pressures, heat capacities of the crystalline phase and the

Noble gas viscosities at 25 degrees C

August 10, 2012
Author(s)
Robert F. Berg, William C. Burton
Near 25 C, ab initio calculations of the zero-density viscosity of helium gas eta_He have an uncertainty of approximately 0.001 %, which is 1/40th of the uncertainty of the best measurements. The uncertainties of the published calculations for neon [Bich

Calibration of Laminar Flow Meters for Process Gases

June 1, 2012
Author(s)
John D. Wright, Thiago Cobu, Robert F. Berg, Michael R. Moldover
We calibrated three models of commercially-manufactured, laminar flow meters (LFMs) at four pressures (100 kPa, 200 kPa, 300 kPa, and 400 kPa) with five gases (N2, Ar, He, CO2, and SF6) over a 10:1 flow range using NIST’s primary flow standards as

Thermoelectric temperature control device for vapor pressure measurements

August 31, 2011
Author(s)
Robert F. Berg
The static method of measuring equilibrium vapor pressure requires locating the sample at the coldest part of the apparatus to avoid errors due to evaporation and recondensation elsewhere. This paper describes a device that can hold the sample 1 K below

Accurate Measurements of Process Gas Flow with Laminar Flow Meters

October 15, 2010
Author(s)
Thiago Cobu, Robert F. Berg, John D. Wright, Michael R. Moldover
We calibrated three models of commercially-manufactured, laminar flow meters (LFMs) with nitrogen at four pressures (100 kPa, 200 kPa, 300 kPa, and 400 kPa) over a 10:1 flow range using NIST’s primary flow standards and a physical model. Without additional

Capillary flow meter for calibrating spinning rotor gauges

August 6, 2008
Author(s)
Robert F. Berg
This article describes a capillary flow meter whose maximum flow rate of 0.2 micromol/s (~0.2 cm3/min at ambient conditions) covers the range that is useful for calibrating spinning rotor gauges. Knowing the input pressure, output pressure, and temperature

Shear Thinning Near the Critical Point of Xenon

April 17, 2008
Author(s)
Robert F. Berg, Michael R. Moldover, M Yao, G A. Zimmerli
We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids, near the critical point of xenon. The data span the range of reduced shear rates: 0.001 < γτ < 700, where γτ is the shear rate scaled by the relaxation time τ of

Reference Viscosities of H 2 , CH 4 , Ar and Xe at Low Densities

August 1, 2007
Author(s)
E May, Robert F. Berg, Michael R. Moldover
We determined the zero-density viscosity eta of hydrogen, methane and argon in the temperature range 200 K to 400 K, with standard uncertainties of 0.084 % for hydrogen and argon and 0.096 % for methane. These uncertainties are dominated by the uncertainty

Transport Properties of Argon at Zero Density From Viscosity-Ratio Measurements

April 1, 2006
Author(s)
E May, Michael R. Moldover, Robert F. Berg, John J. Hurly
We determined the zero-density viscosity and thermal conductivity of argon with an uncertainty of only 0.039 % in the temperature range 200 K to 400 K. Our results will improve: (1) the argon-argon interatomic potential, (2) calculated boundary-layer
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