THE THICKNESS OF MOVING HELIUM II FILM

1963 ◽  
Vol 41 (7) ◽  
pp. 1047-1055 ◽  
Author(s):  
P. W. F. Gribbon ◽  
L. C. Jackson
Keyword(s):  
Stainless Steel ◽  
Liquid Helium ◽  
Polarized Light ◽  
Helium Ii ◽  
The Difference ◽  
Stainless Steel Beaker ◽  
Moving Liquid

The thickness of moving liquid helium II films has been measured using the polarized light method developed by Burge and Jackson. The moving film was that on the outside of a cylindrical stainless steel beaker emptying by creep at the rate corresponding to the temperature for the two cases 1.68° K and 1.83° K. Measured at a height of 1 cm above the outer level of the liquid the thicknesses were 5.6% and 4.5% less than those of the stationary film at 1.68° K and 1.83° K respectively. The observations are compared with the theoretical expressions for the difference in thickness of stationary and moving films derived by Kontorovich and by Franchetti.

The thickness of the helium film

1951 ◽  
Vol 205 (1081) ◽  
pp. 270-285 ◽  
Keyword(s):  
Stainless Steel ◽  
Liquid Helium ◽  
Polarized Light ◽  
Angle Of Incidence ◽  
Helium Film ◽  
Helium Ii ◽  
Reflected Light ◽  
Linearly Polarized ◽  
Barium Stearate

A description is given of an optical method for the determination of the thickness of the helium II film. Linearly polarized light is reflected from a stainless steel mirror, the upper part of which is coated with a layer of barium stearate one molecule thick and the lower part with a similar layer three molecules thick. The reflected light passes through a mica compensating plate and a nicol prism. Adjustment of the mica plate and nicol gives equality of illumination on the ‘1’ and ‘3’ areas. If now a film of helium II covers the mirror the nicol must be rotated to restore equality of illumination. The rotation is a measure of the thickness of the helium film, the relation between the two quantities being calculated in terms of the angle of incidence and the optical constants of liquid helium, barium stearate and stainless steel. The observed thickness at any given height above the liquid helium was found to be nearly independent of the temperature between 1⋅1 and 2⋅18° K but then decreased rapidly to zero at the λ -point. In the formula d = k / h 1/ z for the thickness d at height h cm. for any given temperature, the value of z varies from 3⋅5 at 1⋅1° K to 2⋅5 at 2⋅1° K. The thickness at 1 cm. and 1⋅5° K is provisionally given as 1⋅9 x 10 -6 cm.

Effects of the T-matrix center-of-mass approximation in the Brueckner–Sawada theory of liquid helium II

1985 ◽  
Vol 63 (12) ◽  
pp. 1548-1554
Author(s):  
S. K. Bose ◽  
D. F. Goble
Keyword(s):  
Liquid Helium ◽  
Center Of Mass ◽  
Interacting Particles ◽  
Excitation Spectra ◽  
Helium Ii ◽  
Mass Approximation ◽  
Interparticle Separation ◽  
T Matrix ◽  
The Difference ◽  
Bose Einstein

As a model for liquid helium II, we study the Bose–Einstein gas with a two-body interaction potential of the form ~δ(r − a), where r is the interparticle separation. Excitation spectra for various values of a are calculated using the Brueckner–Sawada approach based on the concept of the T matrix. However, unlike the work of Brueckner and Sawada and many other related works that followed, we take into account the dependence of the T matrix on the center-of-mass momentum of the interacting particles. Excitation spectra calculated with and without this dependence, using two different expressions for the two-particle propagator, indicate the validity of the Brueckner and Sawada center-of-mass approximation for physically interesting values of a. The difference between the two spectra is found to increase as a increases.

scholarly journals Scanning Accuracy of Bracket Features and Slot Base Angle in Different Bracket Materials by Four Intraoral Scanners: An In Vitro Study

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 365
Author(s):  
Seon-Hee Shin ◽  
Hyung-Seog Yu ◽  
Jung-Yul Cha ◽  
Jae-Sung Kwon ◽  
Chung-Ju Hwang
Keyword(s):  
Stainless Steel ◽  
In Vitro Study ◽  
Sem Images ◽  
Polycrystalline Alumina ◽  
Base Angle ◽  
Accurate Expression ◽  
Dental Model ◽  
Alumina Composite ◽  
The Difference

The accurate expression of bracket prescription is important for successful orthodontic treatment. The aim of this study was to evaluate the accuracy of digital scan images of brackets produced by four intraoral scanners (IOSs) when scanning the surface of the dental model attached with different bracket materials. Brackets made from stainless steel, polycrystalline alumina, composite, and composite/stainless steel slot were considered, which have been scanned from four different IOSs (Primescan, Trios, CS3600, and i500). SEM images were used as references. Each bracket axis was set in the reference scan image, and the axis was set identically by superimposing with the IOS image, and then only the brackets were divided and analyzed. One-way analysis of variance (ANOVA) was used to compare the differences. The difference between the manufacturer’s nominal torque and bracket slot base angle was 0.39 in SEM, 1.96 in Primescan, 2.04 in Trios, and 5.21 in CS3600 (p < 0.001). The parallelism, which is the difference between the upper and lower angles of the slot wall, was 0.48 in SEM, 7.00 in Primescan, 5.52 in Trios, 6.34 in CS3600, and 23.74 in i500 (p < 0.001). This study evaluated the accuracy of the bracket only, and it must be admitted that there is some error in recognizing slots through scanning in general.

Characterization of oxide particles in ODS austenitic stainless steel after heavy ion irradiation up to high doses

2011 ◽  
Vol 1298 ◽  
Author(s):  
Hiroshi Oka ◽  
Yosuke Yamazaki ◽  
Hiroshi Kinoshita ◽  
Naoyuki Hashimoto ◽  
Somei Ohnuki ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ion Irradiation ◽  
Hot Extrusion ◽  
Oxide Dispersion Strengthened ◽  
Complex Oxide ◽  
Heavy Ion ◽  
Oxide Particles ◽  
The Difference ◽  
High Doses

ABSTRACTOxide dispersion strengthened austenitic stainless steel (ODS316), which is based on advanced SUS316 steel, has been developed by mechanically alloying and hot extrusion. Hafnium and titanium were added to make a fine distribution of oxide particles. The stability of oxide particles dispersed in ODS316 under irradiation was evaluated after 250 keV Fe+ irradiation up to high doses at 500 °C. TEM observation and EDS analysis indicated that fine complex oxide particles with Y, Hf and Ti were mainly dispersed in the matrix. There are no significant changes in the distribution and the size of oxide particles after irradiation. It was also revealed that the constitution ratio of Ti in complex oxide appeared to be decreased after irradiation. This diffuse-out of Ti during irradiation could be explained by the difference in oxide formation energy among alloying elements.

scholarly journals On the Mechano-Caloric Effect in Liquid Helium II

1950 ◽  
Vol 5 (6) ◽  
pp. 1010-1013 ◽  
Author(s):  
S. Nakajima ◽  
M. Shimizu
Keyword(s):  
Liquid Helium ◽  
Helium Ii ◽  
Caloric Effect

New measurements on the fountain effect and the heat conductivity of liquid helium II

Physica ◽  
1947 ◽  
Vol 13 (4-5) ◽  
pp. 180-196 ◽  
Author(s):  
J.H. Mellink
Keyword(s):  
Liquid Helium ◽  
Heat Conductivity ◽  
Helium Ii

Measurement of the Vapour Velocity near the Surface of Liquid Helium II

1962 ◽  
Vol 80 (6) ◽  
pp. 1343-1346 ◽  
Author(s):  
Donald V Osborne
Keyword(s):  
Liquid Helium ◽  
Helium Ii

Dynamics of a rectilinear vortex in liquid helium II

1970 ◽  
Vol 3 (5) ◽  
pp. 1166-1179 ◽  
Author(s):  
H E Hall
Keyword(s):  
Liquid Helium ◽  
Helium Ii

Heat Transfer in Liquid Helium II by Internal Convection

1948 ◽  
Vol 74 (9) ◽  
pp. 1148-1156 ◽  
Author(s):  
F. London ◽  
P. R. Zilsel
Keyword(s):  
Heat Transfer ◽  
Liquid Helium ◽  
Helium Ii ◽  
Internal Convection

Thermal Excitation of Fourth Sound in Liquid Helium II

1974 ◽  
pp. 510-514
Author(s):  
H. Wiechert ◽  
R. Schmidt
Keyword(s):  
Liquid Helium ◽  
Thermal Excitation ◽  
Helium Ii ◽  
Fourth Sound
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