Chamber pressure

About: Chamber pressure is a research topic. Over the lifetime, 2988 publications have been published within this topic receiving 30725 citations.

A large ion beam device for laboratory solar wind studies.

Abstract: The Colorado Solar Wind Experiment is a new device constructed at the Institute for Modeling Plasma, Atmospheres, and Cosmic Dust at the University of Colorado. A large cross-sectional Kaufman ion source is used to create steady state plasma flow to model the solar wind in an experimental vacuum chamber. The plasma beam has a diameter of 12 cm at the source, ion energies of up to 1 keV, and ion flows of up to 0.1 mA/cm2. Chamber pressure can be reduced to 4 × 10-5 Torr under operating conditions to suppress ion-neutral collisions and create a monoenergetic ion beam. The beam profile has been characterized by a Langmuir probe and an ion energy analyzer mounted on a two-dimensional translation stage. The beam profile meets the requirements for planned experiments that will study solar wind interaction with lunar magnetic anomalies, the charging and dynamics of dust in the solar wind, plasma wakes and refilling, and the wakes of topographic features such as craters or boulders. This article describes the technical details of the device, initial operation and beam characterization, and the planned experiments.

Method for forming a contact opening with multilevel etching

Abstract: A multilevel contact etching method to form a contact opening is provided. The method contains using an inductively coupled plasma (ICP) etcher to produce a high plasma density condition. The plasma gas etchant is composed of C4 F8 /CH2 F2 /CO/Ar with a ratio of 3:4:12:80 so that silicon nitride can be selectively etched while the silicon and silicide are not etched. Each content ratio of the plasma gas etchant allows a variance of about 20%. Wall temperature of the ICP etcher is about 100° C.-300° C. A cooling system for a wafer pad is about -20° C.-20° C. Chamber pressure is about 5-100 mtorr. Bias power on the wafer pad is about 1000 W-3000 W. Source power of an inductance coil is about 500 W-3000 W.

Pressure effect on YBa2Cu3O7 thin film growth in off‐axis radio frequency magnetron sputtering

Abstract: YBa2Cu3O7−x (123) thin films were fabricated on (100) MgO substrates by off‐axis single target radio frequency (rf) magnetron sputtering. Our study focused on the effect of chamber pressure on the composition, microstructure, and superconductive properties on transition behavior and Tc of the grown film studied. An empirical formula was derived to explain the dependence of the deposition rate of various components on the pressure. Next, we compared the transport mechanism of the sputtered particles between the off‐axis rf and the on‐axis direct current sputtering and determined the processing conditions that result in superconducting films of better quality. According to our findings, growth at higher pressures (≳100 mTorr) produces more homogeneous and higher Tc superconducting films.

Reduction of Power Losses in Bearing Chambers Using Porous Screens Surrounding a Ball Bearing

Abstract: Trends in aircraft engine design have caused an increase in mechanical stress requirements for rolling bearings. Consequently, a high amount of heat is rejected, which results in high oil scavenge temperatures. An RB199 turbofan bearing and its associated chamber were modified to carry out a survey aiming to reduce power losses in bearing chambers. The test bearing was a 124 mm PCD ball bearing with a split inner ring employing under-race lubrication by two individual jets. The survey was carried out in two parts. In the first part, the investigations were focused on the impact on the power losses in the bearing chamber of the operating parameters, such as oil flow, oil temperature, sealing air flow, bearing chamber pressure, and shaft speed. In the second part, the investigations focused on the reduction of the dwell time of the air and oil mixture in the bearing compartment and its impact on the power losses. In this part, porous screens were introduced around the bearing. These screens would aid the oil to flow out of the compartment and reduce droplet-droplet interactions as well as droplet-bearing chamber wall interactions. The performance of the screens was evaluated by torque measurements. A high-speed camera was used to visualize the flow in the chamber. Considerable reduction in power loss was achieved. This work is part of the European Research programme GROWTH ATOS (Advanced Transmission and Oil Systems).