The purpose of this article is to provide an introduction to vacuum science and technology for absolute beginners. The kinetic theory of gases is briefly described in the initial introductory part. The body of this article is divided into three parts. The first part deals with vacuum pumps. The operation principles are explained for several popular types of vacuum pumps. The second part deals with vacuum gauges. The operations of commonly used vacuum gauges are discussed. The third one deals with vacuum-tight connection with tubes and flanges. Throughout the text, basic concepts and technical terms are explained so that the text can be easily understood even by very beginners. Caution points for using vacuum systems are also given.
The vacuum components are important components to be used at the boundary of the atmosphere and vacuum, because a vacuum system is not assembled just with the vacuum vessel and the vacuum pumps. The basic technique is a vacuum sealing technique of how to prevent leakage of the atmosphere. I explain vacuum seal technology and vacuum parts as applied technology, flanges, valves, vacuum current feedthrough, and the optical window. Movable mechanisms in vacuum are described, too.
An evacuation process from atmospheric pressure to an extremely low pressure involves four stages: removal of volume gas in a vacuum chamber, outgassing of gas adsorbed on the chamber surface, release of gas diffused to the surface from the inside of the chamber wall, and release of hydrogen gas permeated through the chamber wall. These stages are explained numerically to help understand the evacuation process. Mathematical descriptions of pumping time at the first stage of evacuation are presented using a tube between a vacuum chamber and a vacuum pump and also without using a tube. The tube can be ignored in the design of a vacuum system if its conductance is large. This will help readers in designing a vacuum system according to their own conditions.
In this lecture, calculation of the transmission probability of gas molecule through the vacuum pipe by Monte-Carlo simulation is presented. The basic concepts, the computational method of the distribution of scattering angle that follows the cosine law from the homogeneous random distribution and the flow chart of program are shown. The results by Monte-Carlo simulation for the simple cylindrical pipes with various length/diameter (L/D) ratios are compared with those obtained by the approximation formulas and the analytical results. The effect of specular reflection rate in the scattering at the surface of pipe is also presented.
In order to caluculate the molecular transmission probability K of cylindrical tubes, Clausing proposed an equation as Fledholm integral equation of the second kind, so called Clausing equation in 1932. The values of K evalueted with variational method by Cole in 1970's are believed to be the most accurate to date. However, in recent report, the value of K from the direct numerical solution of Clausing equation seems to disagree with Cole's results, especially for the very long tubes. In this report, the methods for caluculating K discribed above are reviewed and some simple scripts of numerical tool to verify those results of K are supplied.
We fabricated Ni films on a flexible substrate material using magnetron sputtering with multipolar magnetic plasma confinement assisted by inductively coupled plasma. For each RF Power PRF value, argon ion emission intensity IArII near the HF coil and substrate current Is increased for applying substrate DC bias voltage VS. We observed that the effect of ion irradiation was enhanced by applying VS. For VS=−40 V and PRF=35 W, the effect of ion irradiation was maximum in deposition conditions. For increasing the effect of ion irradiation, the grain size and surface of fabricated Ni films became large and smooth. In addition, orientation of Ni(111) enhanced. For VS=−40 V and PRF=35 W a film resistivity ρ of 8.51×10−6 Ωcm was observed, which is close to the Ni bulk value of 6.84×10−6 Ωcm. From these results, we determined that the structure of the fabricated Ni films on the flexible substrate material was affected by the effect of ion irradiation.