INFICON Composer Gas Concentration Controller - Manual (Page 188)

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Composer Operating Manual
Control Gain
The steady state process gain. This is normally quantified as the ratio
of change of the controlled variable resulting from a small change of
the manipulated variable.
Control Loop
The complete electromechanical system that is involved with the
intelligent manipulation of a variable to maintain the controlled variable
at the desired value, effectively minimizing process error. A brief
description of control loop theory is given elsewhere in this manual.
The control algorithm used in this instrument system is commonly
known as a PID type.
Control Time Constant
The time required for a step change of the manipulated variable to
produce a change in the control variable equal to 63.2% of the final
change in the control variable.
Control Dead Time
The period of time between a change in the manipulated variable and a
noticeable response in the controlled variable.
Control Variable
The variable that is to be controlled, i.e., held constant. In a typical
CVD reactor this would be the concentration of precursor entering the
reactor as measured by the instrument system.
Curve Fit
A mathematical procedure (algorithm) for finding the best match
between a set of data and a curve of a particular shape.
CVD
Chemical Vapor Deposition
Delivery Line
The reactor’s tubing that extends from the source of gas or precursor to
the reactor.
Delivery System
The reactor’s complete apparatus for delivering a precise quantity of
precursor to the chamber.
Diaphragm
The tensioned membrane that separates the resonant chamber from
the drive and receive microphones.
Dilution Flow
The additional carrier gas added to the flow from the bubbler prior to
entry into the reactor’s chamber.