The Seal System in Aerostatic Journal Bearings for High Vacuum Chambers

2004 ◽  
Vol 126 (2) ◽  
pp. 310-315 ◽  
Author(s):  
S. Yoshimoto ◽  
Y. Yoshida ◽  
K. Yagi
Keyword(s):  
Pressure Distribution ◽  
Vacuum Chamber ◽  
Journal Bearing ◽  
High Vacuum ◽  
Journal Bearings ◽  
Vacuum Pump ◽  
Chamber Pressure ◽  
Design Parameters ◽  
Vacuum Chambers ◽  
High Vacuum Chamber

This paper investigates the performance of a seal system for an aerostatic journal bearing used in a high vacuum chamber. The seal system consists of axially spaced viscous seals and annular exhaust grooves that are located between the viscous seals. Each exhaust groove is coupled to a separate vacuum pump in order to achieve a vacuum chamber pressure of less than 10−3 Pa. The vacuum chamber pressure is affected by design parameters such as the number of viscous seal stages, seal length, seal gap, and exhaust tube conductance. The influence of these design parameters on the pressure distribution across seal regions and the vacuum chamber pressure are discussed theoretically. It is subsequently shown that an aerostatic journal bearing with three-stage seal system installed can obtain a reduction in the vacuum chamber pressure almost to the ultimate pressure of a vacuum pump, providing there is no leak or outgassing from materials.

Pumping Characteristics of a Herringbone-Grooved Journal Bearing Functioning as a Viscous Vacuum Pump

1999 ◽  
Vol 122 (1) ◽  
pp. 131-136 ◽  
Author(s):  
S. Yoshimoto ◽  
Y. Ito ◽  
A. Takahashi
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Slip Flow ◽  
Laser Scanner ◽  
Vacuum Pump ◽  
Chamber Pressure ◽  
Design Parameters ◽  
Theoretical Predictions ◽  
Flow Effects ◽  
Good Agreement

A laser scanner motor with low power and high speed has been developed. This scanner motor uses a herringbone-grooved journal bearing which functions as a viscous vacuum pump. The windage power loss of a polygon mirror is reduced, since the air inside the pump housing is pumped out by herringbone-grooved viscous vacuum action. In this paper, the theoretical pumping characteristic of this bearing is investigated, using the narrow-groove theory and accounting for first-order slip flow. The effects of various design parameters on the pumping characteristics are discussed. Optimum geometric design parameters were found to obtain the minimum inner chamber pressure of the housing. The theoretical predictions considering slip flow effects are in good agreement with experimental measurements. [S0742-4787(00)01801-4]

Study Of Al Surface Segregation In Icosahedral A162Cu25.5Fe12.5

1998 ◽  
Vol 553 ◽  
Author(s):  
M. GIL-GAVATZ ◽  
D. Rouxel ◽  
P. Pigeat ◽  
B. Weber ◽  
J.-M. Dubois
Keyword(s):  
Surface Segregation ◽  
Vacuum Chamber ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Electron Spectrometer ◽  
Temperature Dependent ◽  
Self Diffusion ◽  
Different Temperatures ◽  
High Vacuum Chamber

AbstractSurface segregation of aluminium was observed during oxidation experiments of icosahedral A162Cu25.5 Fel12.5, performed in-situ and at different temperatures in the ultra-high vacuum chamber of a scanning Auger electron spectrometer. Two regimes, below and above 770K, were observed in relation with severe segregation of Al atoms at the surface for T > 770K. We postulate that this temperature dependent segregation rate is representative of the aluminium transport towards the surface of the quasicrystal. By analogy with classical diffusion experiments, we can thus determine reasonable estimates of the activation energy for Al self-diffusion in this quasicrystal. The results are consistent with the existence of phason flips below 770K and thermal vacancies above this temperature.

Experimentally study of dynamic pressure distribution and oil film forces in journal bearing using ElectroMechanical Film sensor array

2019 ◽  
Vol 234 (4) ◽  
pp. 903-913
Author(s):  
Changmin Chen ◽  
Jianping Jing ◽  
Jiqing Cong ◽  
Chao Ji
Keyword(s):  
Pressure Distribution ◽  
Sensor Array ◽  
Journal Bearing ◽  
Dynamic Pressure ◽  
Vertical Direction ◽  
Journal Bearings ◽  
Film Sensor ◽  
Film Pressure ◽  
Oil Film ◽  
Oil Film Pressure

The acquisition of the oil film pressure and forces on the bearing pads through experimentation is crucial to understanding the characteristics of journal bearing. Lots of efforts had been taken in film pressure measurement, and the pressure was obtained at specified position on the bearing pads. However, due to the space and structure constraint, merely very limited number of the point pressure can be obtained with traditional sensors and acquiring the detail pressure field on whole bearing pad surface is still an open challenge. In this paper, a method based on thin-film sensors technique is proposed and employed to measure the pressure distribution and oil film forces of journal bearings. The measurement is conducted on a cylindrical journal bearing with two axial grooves, and ElectroMechanical Film sensor arrays are designed and laid on the surface of the bearing pads. The oil film pressure is acquired at up to 32 measurement points in total along the bearing pads in both circumference and axial directions. The pressure distribution in a wide rotation speed range is obtained successfully by using fitting algorithm. Furthermore, the oil film forces on horizon and vertical direction are obtained through the integration of the measured pressure filed. The test results prove that it is feasible to measure the oil pressure filed of journal bearings using ElectroMechanical Film piezo-film sensor array.

Toward Growing III-V Clusters with Metalorganic Precursors

1997 ◽  
Vol 468 ◽  
Author(s):  
A. Demchuk ◽  
J. Porter ◽  
B. Koplitz
Keyword(s):  
Excimer Laser ◽  
Vacuum Chamber ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Quadrupole Mass ◽  
Reaction Region ◽  
High Vacuum Chamber ◽  
Arf Excimer Laser ◽  
193 Nm ◽  
Pulsed Nozzle

ABSTRACTThe present work reports on the formation of GaN-containing clusters from metalorganic precursors by combining pulsed laser photolysis and pulsed nozzle methods. Ammonia (NH3) and triethylgallium (C2H5)3Ga (TEG) or trimethylgallium (CH3)3Ga (TMG) with He, Ar, or N2 as the carrier gas are introduced into a high vacuum chamber via a specialized dual pulsed nozzle source. The light from an ArF excimer laser (193 nm, 23 ns FWHM) is focused into the mixing and reaction region of the nozzle source, and the products are then mass analyzed with a quadrupole mass spectrometer. Efficient laser-assisted growth of (GaN)x-containing clusters is shown with this technique.

scholarly journals Prevention of Reversed Flow in Gas Divertor with High Vacuum Chamber

2000 ◽  
Vol 37 (6) ◽  
pp. 555-556 ◽  
Author(s):  
Akihiro MATSUBARA ◽  
Ryoichiro MURATA ◽  
Ken NAGATA ◽  
Takehisa SHIBUYA ◽  
Akira TONEGAWA ◽  
...  
Keyword(s):  
Vacuum Chamber ◽  
High Vacuum ◽  
Reversed Flow ◽  
High Vacuum Chamber

A Vacuum-Compatible Air Bearing: Design Analysis and Optimization

2007 ◽  
Vol 339 ◽  
pp. 37-44 ◽  
Author(s):  
G.H. Khim ◽  
Chun Hong Park ◽  
H.S. Lee ◽  
S.W. Kim
Keyword(s):  
Genetic Algorithm ◽  
Exhaust System ◽  
Optimization Method ◽  
Vacuum Pump ◽  
Chamber Pressure ◽  
Design Parameters ◽  
Air Bearing ◽  
Great Care ◽  
Spatial Design ◽  
Bearing Design

This paper describes the vacuum-compatible air bearing designed with a cascaded exhaust scheme to minimize the leakage of air in a vacuum environment. The design of the air bearing, including the differential exhaust system, required great care because several design parameters, such as the number of exhaust stages, diameter and length of the exhaust tube, pumping speed and ultimate pressure of the vacuum pump, and seal length and gap greatly influenced the leakage of air and thus the degree of vacuum. A leakage analysis was performed to estimate the chamber pressure and an optimization method based on the genetic algorithm was proposed under several constraint conditions. The results showed that the degree of vacuum improved dramatically compared to the initial design, and that the distribution of the spatial design parameters and technical limit of the pumping speed were well achieved.

Low Temperature Laser-Assisted Gas Phase Reactivity of TMGa with NH3 and Oxygen-Containing Compounds (H2O, CH3OH, O(CH3)2) in Constrained Pulsed Expansions

2002 ◽  
Vol 743 ◽  
Author(s):  
Alexander Demchuk ◽  
Michael Lynch ◽  
Steven Simpson ◽  
Brent Koplitz
Keyword(s):  
Gas Phase ◽  
Vacuum Chamber ◽  
Cluster Formation ◽  
High Vacuum ◽  
Oxygen Species ◽  
Quadrupole Mass ◽  
High Vacuum Chamber ◽  
Arf Excimer Laser ◽  
Gas Nozzle ◽  
193 Nm

ABSTRACTThe present work reports on the study of III-V gas phase reactivity in constrained gas pulse expansions of trimethylgallium (TMGa) and oxygen derivative compounds (H2O, CH3OH, O(CH3)2) with and without ammonia. The precursors are introduced separately into a high vacuum chamber via a multipulsed gas nozzle assembly. The gas mixtures are then exposed to a UV pulse from an ArF excimer laser (λ=193 nm) and the products are mass analyzed with a quadrupole mass spectrometer. The efficient laser-assisted growth of Ga-O-containing clusters in the form of [(CH3)2GaOR] x, where R is H or CH3, has been revealed. Different behavior can be seen in the reaction of TMG and the oxygen species depending on the presence of H atoms bonded to the oxygen. Significant influence of NH3 on cluster formation and oxygen incorporation is demonstrated.

Ultra-high-vacuum chamber

Vacuum ◽  
1965 ◽  
Vol 15 (7) ◽  
pp. 372-373
Author(s):  
CONSOLIDATEDVACUUMCORPORATION
Keyword(s):  
Vacuum Chamber ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Vacuum Chamber ◽  
Ultra High Vacuum Chamber
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