A design study for thermal control of a CVD reactor for YBCO

Active thermal control of a reactor for YBa/sub 2/Cu/sub 3/O/sub 7-x/ chemical vapor deposition is studied using a nonlinear heat transfer model validated by preliminary component testing. LQR and LQE methods are applied to the linearized model for observer-based control. Convergence rates of the controller and observer are indicated by closed-loop eigenvalues, and the disturbance rejection is assessed with H/sub 2/ and H/sub /spl infin// norms. Design trade-offs are quantified with these measures by varying model parameters. Maximum errors in control and estimation for a nominal design case are both 21 K, and the longest time scales are 45 seconds and 10 seconds for the controller and observer, respectively.