REDUCED MODEL CONTROL OF A PLASMA DEPOSITION PROCESS

This preliminary study, relating plasma stagnation pressure to the cur rent level, provided an initial step toward the development of feedbac k control of the plasma deposition process. Data consisting of an inpu t voltage and output stagnation pressure were collected about a nomina l operating point. Data Dependent Systems (DDS) methodology was utiliz ed to obtain a high-order adequate model and then to reduce it to a fi rst-order model suitable for feedback control. The power supply induct ance was credited as the source of the single root characterizing the system. A minimum mean squared control strategy was employed to develo p a control equation for the reduced system model. The simulation of t he reduced order controller compared favorably with that of an optimal controller, based on the full model.