AVS 51st International Symposium
    Exhibitor Workshop Tuesday Sessions
       Session EW-TuL

Paper EW-TuL2
Residual Gas and Improved Pressure Control Resolution using a Cryocooled Water-Pumping Throttle Valve

Tuesday, November 16, 2004, 12:20 pm, Room Exhibit Hall B

Session: Innovations in Vacuum Techniques and Measurements
Presenter: H. Grover, MeiVac Inc.
Authors: H. Grover, MeiVac Inc.
N. GurArye, Ricor
Correspondent: Click to Email
Precise pressure and residual gas control are critical to quality, yield and profitability. Contamination control and process response/recovery advantages of Downstream versus Upstream pressure control will be discussed using multiple feedback and throttling schemes. Valve geometry and actuation methods determine maximum and minimum conductance, as well as, linearity and resolution of the throttling curve. Concepts of linear throttling control and differential pumping of residual gas will be offered including test data correlated with theoretical calculations. Throttling normally restricts flow of all gaseous components. Experimental data will be presented offering differential pumping of condensables (primarily water vapor) while throttling process gases with a high differential pumping ratio. Advantages and disadvantage of Meissner, flow through cryo water vapor pumps and appendage cryo water vapor pumps will be technically and economically compared to a combined package cryocooled water pumping throttle valve. Species range specific condensable pumping control will be presented using a unique externally controlled servo motor driven cold head instead of the conventional pneumatic driven cryo mechanism. Practical examples will be displayed using advanced cryo technology that allows self-contained cryo cooled throttle valves with no cryo compressor required.