title: Feedback control of unstable cellular solidification fronts.
abstract: We present a feedback control scheme to stabilize unstable cellular patterns during the directional solidification of a binary alloy. The scheme is based on local heating of cell tips which protrude ahead of the mean position of all tips in the array. The feasibility of this scheme is demonstrated using phase-field simulations and, experimentally, using a real-time image processing algorithm, to track cell tips, coupled with a movable laser spot array device to heat the tips locally. We demonstrate, both numerically and experimentally, that spacings well below the threshold for a period-doubling instability can be stabilized. As predicted by the numerical calculations, cellular arrays become stable with uniform spacing through the feedback control which is maintained with minimal heating.
authors.affiliation: Physics Department and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA. a.pons-rivero@neu.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Pons
authors.forename: A
authors.initials: A
authors.lastname: Karma
authors.forename: S
authors.initials: S
authors.lastname: Akamatsu
authors.forename: M
authors.initials: M
authors.lastname: Newey
authors.forename: A
authors.initials: A
authors.lastname: Pomerance
authors.forename: H
authors.initials: H
authors.lastname: Singer
authors.forename: W
authors.initials: W
authors.lastname: Losert