Experimental Design of a High Vacuum System for PUPR-MC Plasma Machine

Abstract

In vacuum technology it is customary to divide a large pressure region (as of today, covering 16 orders of magnitude) into single, smaller regions. These divisions are somewhat arbitrary. Thus, the chemists frequently refer to the region between 100 and 1 mbar as an intermediate vacuum, while many technicians refers to the same region as the total pressure (below atmospheric). The pressure regions presented in this work are clearly distinguished from the point of view of the kinetic theory of gases as well as according to the kind of gas flow. Moreover, the practical technology in the different regions is distinguishable. A positive displacement pump is a mechanical vacuum pump, which transports the gas with the aid of pistons, rotors, vanes, valves and other devices, compresses it and expels it. Mechanical pumps are used when attaining a pre-vacuum region, diffusion pumps (among others) should be used in order to obtain lower levels of vacuum. A suitable gauge must be selected for each vacuum region. Each region of vacuum calls for a different kind of vacuum measurement. The vacuum system of PUPR-MC plasma machine was not working properly. This work report the design considerations and implementation of changes performed on PUPR-MC in order to attain the levels of vacuum needed for proper operation of this plasma device. After the modifications performed on the vacuum system the pressure in the plasma chamber of the device has been measured in the order of 10-5 to 10-6 range, the normal range of operation for this machine.