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Feedback control of unstable cellular solidification fronts

A. J. Pons·A. Karma·S. Akamatsu·M. Newey·A. Pomerance·H. Singer·W. Losert
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Abstract

We present a numerical and experimental study of feedback control of unstable cellular patterns in directional solidification (DS). The sample, a dilute binary alloy, solidifies in a 2D geometry under a control scheme which applies local heating close to the cell tips which protrude ahead of the other. For the experiments, we use a real-time image processing algorithm to track cell tips, coupled with a movable laser spot array device, to heat locally. We show, 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, and the spacing becomes uniform through feedback control which is maintained with minimal heating.

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A. J. Pons, A. Karma, S. Akamatsu, M. Newey, A. Pomerance, H. Singer, W. Losert. 2006-08-15. Feedback control of unstable cellular solidification fronts. https://doi.org/10.1103/physreve.75.021602

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