AVS 50th International Symposium
    Vacuum Technology Thursday Sessions
       Session VT-ThA

Paper VT-ThA3
Pumping Characteristics of Metal Films in a Vacuum Glass Vessel: Experimental and Theoretical Issues

Thursday, November 6, 2003, 2:40 pm, Room 323

Session: Industrial Vacuum Applications
Presenter: A. Bonucci, SAES Getters SpA, Italy
Authors: A. Bonucci, SAES Getters SpA, Italy
C. Carretti, SAES Getters SpA, Italy
G. Longoni, SAES Getters SpA, Italy
R. Giannantonio, SAES Getters SpA, Italy
M. Urbano, SAES Getters SpA, Italy
Correspondent: Click to Email
The evaluation of the pumping characteristics of metallic films deposited onto glass surfaces in a vacuum environment is a very important issue for several industrial and research applications. Many years ago, an optimized experimental setup was established to measure the pumping characteristics of barium films inside Cathode Ray Tubes (CRTs). However, some technological limitations, related both to the particular experimental configuration and to the materials used, prevented the possibility to extend this approach to a more general case, including adsorbing materials different from barium deposited onto surfaces having a geometry different from that of a CRT. The progress in vacuum technology makes today possible to use a large variety of components to assemble an experimental vacuum apparatus. Moreover, the availability of powerful computational tools allows to design the best experimental configuration for any specific purpose. In this work, a new approach to the study of the pumping characteristics of an adsorbing film in a vacuum is discussed. An improved experimental configuration is here first described and a mathematical method, based on the angular coefficients approach, able to suitably calculate the pressure distribution inside a vacuum vessel, is proposed. The agreement between the experimental and the theoretical results obtained in the simple case of a gettering surface deposited onto spherical glass bulbs having different dimensions is finally discussed.