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Modeling and improvement of a field electric retarding potential characterization system

Anema, J.S. (2015) Modeling and improvement of a field electric retarding potential characterization system.

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Abstract:A field emission retarding potential ferp is a method to measure the work function between two materials and can for example be used to verify the purity of a material. In order to obtain such a function of several samples a high vacuum environment is desired. At the lab of CTI a certain vacuum chamber with corresponding equipment already exist, but a digital model and drawings of this configuration are lacking however. Main goal of this project is therefore to obtain a CAD model, suggest some improvements to increase the vacuum and finally to draw the system of the future. The current configuration is measured and modeled in SolidWorks and some improvements in the configuration are obtained. When one wants to increase the vacuum, sources of contamination and leakage need to be avoided as much as possible. Several equipment, like pumps and gauges need to be connected to the chamber. This connections are the main source of leakage so the sealing of this connections is essential. The best way to so is with a copper gasket (with the cf connection) but since a gasket can only be used once and parts need to be released now and then a rubber connection is often preferred regarding the costs. Since the stock and budget are limited it is hard to improve the vacuum level further. However, some kf connections, that always go with a rubber O-ring, could be removed by some rearrangements. One superfluous gauge is removed and the connection between the turbomolecular pumps is reduced, resulting in a reduction of 3 Orings in total and an improvement of the vacuum level from 5x10-6 Torr 1 up till 1.7x10-7 Torr. To obtain an ultra high vacuum level a new system is desired. A concept of the outside is modeled and presented at the end of this report. With this design a pressure level of about 1x10-11 Torr should be reasonable such that more and different experiments, like scanning tunneling microscopy (stm) are possible in the future.
Item Type:Internship Report (Master)
Center Information Tecnology Renato Archer - CTI, Brazil
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Keywords:Modelling, vacuumchamber, improvement pressure level
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