Instabilities in a Crystal Growth Melt Subjected to Alternating Magnetic Fields

Simple item page
dc.contributor.advisorHouchens, Brent C.en_US
dc.contributor.committeeMemberAkin, John Edward.en_US
dc.contributor.committeeMemberWarburton, Timen_US
dc.creatorDavis, Kennyen_US
dc.date.accessioned2013-09-16T15:03:09Zen_US
dc.date.accessioned2013-09-16T15:03:17Zen_US
dc.date.available2013-09-16T15:03:09Zen_US
dc.date.available2013-09-16T15:03:17Zen_US
dc.date.created2013-05en_US
dc.date.issued2013-09-16en_US
dc.date.submittedMay 2013en_US
dc.date.updated2013-09-16T15:03:18Zen_US
dc.description.abstractIn confined bulk crystal growth techniques such as the traveling heater method, base materials in an ampoule are melted and resolidified as a single crystal. During this process, flow control is desired so that the resulting alloy semiconductors are uniform in composition and have minimal defects. Such control allows for tuned lattice parameters and bandgap energy, properties necessary to produce custom materials for specific electro-optical applications. For ternary alloys, bulk crystal growth methods suffer from slow diffusion rates between elements, severely limiting growth rates and reducing uniformity. Exposing the electrically conducting melt to an external alternating magnetic field can accelerate the mixing. A rotating magnetic field (RMF) can be used to stir the melt in the azimuthal direction, which reduces temperature variations and controls the shape at the solidification front. A traveling magnetic field (TMF) imposes large body forces in the radial and axial directions, which helps reduce the settling of denser components and return them to the growth front. In either case, mixing is desired, but turbulence is not. At large magnetic Taylor numbers the flow becomes unstable to first laminar and then turbulent transitions. It is imperative that crystal growers know when these transitions will occur and how the flow physics is affected. Here, the melt driven by electromagnetic forces is analyzed through the use of 3D numerical simulations of the flow field up to and beyond the point of laminar instability. The analysis aims to emulate laboratory conditions for generating electromagnetic forces for both types of alternating magnetic fields and highlights the differences between laboratory forces and the analytical approximations that are often assumed. Comparisons are made between the resulting forces, flow fields, and points of instability as the frequency of the alternating field varies. Critical Taylor numbers and the resulting unstable flow fields are compared to the results from linear stability theory.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationDavis, Kenny. "Instabilities in a Crystal Growth Melt Subjected to Alternating Magnetic Fields." (2013) Diss., Rice University. <a href="https://hdl.handle.net/1911/71944">https://hdl.handle.net/1911/71944</a>.en_US
dc.identifier.slug123456789/ETD-2013-05-520en_US
dc.identifier.urihttps://hdl.handle.net/1911/71944en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectCrystal growthen_US
dc.subjectRotating magnetic fielden_US
dc.subjectTraveling magnetic fielden_US
dc.subjectTraveling heater methoden_US
dc.titleInstabilities in a Crystal Growth Melt Subjected to Alternating Magnetic Fieldsen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentMechanical Engineering and Materials Scienceen_US
thesis.degree.disciplineEngineeringen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
DAVIS-THESIS.pdf
Size:
8.47 MB
Format:
Adobe Portable Document Format
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.61 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Rice University Theses and Dissertations