INFICON Composer Gas Concentration Controller - Manual (Page 191)

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Composer Operating Manual
PID
Proportional
Integral
Differential; A type of control loop algorithm.
Power Supply Module
The portion of the instrument system that converts local line power to
the 24 volt DC required to operate the controller.
PPM
Parts Per Million, a way of expressing Concentration.
Precursor
A complex chemical molecule used to carry a metal (or other) atom in
the vapor state that is easily broken apart to leave the desired atom on
the substrate to be coated.
PRT
Platinum Resistance Thermometer, the sensing element used to
determine temperature of the Resonant Chamber.
RAV
See Root Allan Variance.
RAM
Random Access Memory; An electronic component used for computer
data storage. When used in conjunction with a battery it provides
nonvolatile storage of data, sometimes called NOVRAM for nonvolatile
RAM.
Reactor
Usually refers to the growth chamber, but some times to the complete
apparatus used to deposit materials in CVD, MOCVD and MOVPE
processes.
Receiver Microphone
The acoustic energy measuring element of the transducer used for
measuring the amplitude of the resonating gas.
Reference Zero
The instrument’s reference frequency that is used as the basis for
concentration calculations. All calculations are based on this stored
value of the speed of sound through the pure reference gas. A user
may utilize the default value for the reference zero or carefully reset the
zero to obtain better results for the immediate operating conditions.
Resonant Chamber
The portion of the transducer that contains the gas for measurement
and is used indirectly for determining the length of the Standing
Acoustic Wave.