Document Actions

Michael Bergman

Physics

Associate Professor of Physics at Simon's Rock since 1994

Education/Experience

  • Columbia University: BA summa cum laude 1986
  • MIT: PhD 1992
  • University of Glasgow: NATO Fellow 1992
  • Harvard University: Postdoctoral Fellow 1993-1994, studying fluid dynamics, magnetohydrodynamics, and the generation of planetary magnetic fields.
  • Recipient of research grants from the NSF and Research Corporation
  • Recepient of 2000 Doornbos Memorial Prize, Exeter, UK for research on the Earth's interior
  • Secretary of SEDI, an international organization of scientists interested in studies of the Earth's deep interior

Contact Information

Research interests
Geophysical Fluid Dynamics:
The Earth's magnetic field is generated by fluid motions in the molten iron outer core, but the details of this magnetohydrodynamic (MHD) dynamo are poorly understood. However, rotational and magnetic forces are certainly important. Using a rotating table and an electromagnet, we are working on a laboratory model for the solidification of the Earth's core. (View image). In particular, we are conducting studies on the effects of rotation and magnetic fields on the convection that results from solidification. Solidification of the inner core from the outer core is thought to represent a primary energy source for the fluid motions that drive the geodynamo, so that understanding the convection that results from solidification may give insight into how the Earth's magnetic field is generated. One particularly interesting style of convection that occurs during solidification is channel convection, which results from a non-linear focusing mechanism. (View image). In addition to possibly occurring at the Earth's inner-outer core boundary, channel convection occurs in solidifying sea ice sheets, where it plays an important role in the heat transfer between the atmosphere and the ocean, and in single crystal nickel-base alloys used in gas turbines, where it can be deleterious.

Mineral Physics:
When a melt solidifies, the crystallographic axes of the crystals may become aligned, resulting in what is known as a solidification texture. This texture affects a material's mechanical and electrical properties. Using a variety of materials such as sea ice and zinc-tin alloys we have been studying the effects of fluid flow during solidification on solidification textures. (View image). We have also been studying the ultrasonic properties of castings. The work is in part motivated by seismic inferences that the Earth's solid inner core exhibits a texture. We are exploring the possibility that this texture may in part be a result of fluid flow in the outer core during solidification of the inner core. We are also interested in applications of this work to solidifying sea ice sheets in the Arctic and off Antartica. (View image).

Selected publications

  • A laboratory model for solidification of Earth's core, Michael I. Bergman, Marget Macleod-Silberstein, Michael Haskel, Benjamin Chandler, and Nsikan Akpan, Phys. Earth Planet. Int. 153, 150-164 (2005).
  • Transverse solidification textures in hexagonal close-packed alloys, Michael I. Bergman, Sameer Agrawal, Michael Carter, Marget Macleod-Silberstein, J. Crystal Growth 255, 204-211 (2003).
  • Preferred crystal orientations due to melt convection during directional solidification, Michael I. Bergman, David M. Cole, & Jackson R. Jones, J. Geophys. Res. 107, ECV 6-1 - 6-8 (2002).
  • Suppression of channel convection in solidifying Pb-Sn alloys via an applied magnetic field, Michael I. Bergman, David R. Fearn, & Jeremy Bloxham, Met. Trans. A 30, 1809-1815 (1999).
  • Estimates of the Earth's inner core grain size, Michael I. Bergman, Geophys. Res. Lett. 25, 1593-1596 (1998).
  • Measurements of elastic anisotropy due to solidification texturing and the implications for the earth's inner core, Michael I. Bergman, Nature 389, 60-63 (1997).

(Complete list of publications)