Andrew Cole | Spinning Between Theory and Experiment

Andrew Cole
Assistant Professor of Applied Physics
This profile is included in the publication Excellentia, which features current research of Columbia Engineering faculty members.

—Photo by Eileen Barroso

Andrew Cole works in an area of plasma physics aimed at controlled thermonuclear fusion power. Scientists have worked for many years to harness fusion energy, making great strides in plasma performance. Stability of the plasma is a key issue for fusion power. Cole, assistant professor of applied physics, is part of a team of researchers at Columbia Engineering tackling plasma stability by improving the measurement and control of plasma behavior available to scientists.
 
Cole is one of two theorists in the Columbia Plasma Physics Laboratory and his research focuses on understanding and preventing plasma instabilities through the use of externally applied magnetic torques. Plasma must be heated to several million degrees Kelvin in order for thermonuclear reactions to occur and liberate energy from the nuclei present in the plasma. Such a high temperature precludes containment in an ordinary vessel. One solution to this problem is the tokamak, a device that uses electromagnetic fields to create a virtual container preventing the plasma from touching material surfaces during an experiment.
 
Imperfections in the confining fields are inevitable in any practical device and can drive magnetic instabilities in the plasma, degrading the fusion performance. Cole’s work focuses on understanding the effect of field errors on plasma rotation, which is a crucial component of plasma stability.
 
“What a lot of scientists want to do right now is find new ways to spin up a plasma, since rotation tends to keep it stable,” says Cole.
 
One way Cole has been addressing this stability problem is by developing models for the torque generated on the plasma moving through rippled magnetic fields. An ordinary fluid is damped by friction when it encounters ripples along its flow path. In a hot plasma, the net effect of the ripples is different—it acts to keep the plasma rotating at a value proportional to the temperature difference between the hot fusion core and the cooler plasma edge. This effect allows scientists an inexpensive means to generate plasma rotation.
 
Cole enjoys distilling intricate theory calculations into models that give a physical picture of plasma dynamics to help the experimentalists and improve the theory.
 
“Sometimes we theorists give predictions to experimentalists that enhance their understanding of what’s going on, but quite often the experimentalists come back with what’s not right with the theory,” Cole says. “The back and forth between the data and the theory—zeroing in on an answer—makes it exciting to sit at the interface between theory and experiment. I think it’s where I can learn the most.”
 
Before joining Columbia, Cole worked at the University of Wisconsin, first as a postdoctoral fellow and later an assistant research scientist. Born and raised in Portland, Oregon, Cole has been interested in nuclear fusion since high school, and studied physics and applied mathematics as an undergraduate at the University of Oregon. His first exposure to plasma physics was at Los Alamos National Laboratory, where he worked during his undergraduate summers and continues to collaborate.
 
B.A., University of Oregon, 2000; Ph.D., University of Texas, 2006
 
-Melanie A. Farmer

 

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