Efforts to harness the power of hydrogen fusion to create a small star here on earth began at many laboratories in the U.S. and around the world in 1951. One of earliest projects established to investigate controlled fusion began under the code name Project Matterhorn at Princeton University. As the name suggests, the researchers have faced an uphill climb, but the ascent has been steady and determined. Today, what began under the cloak of Cold War security has grown into the largest international scientific collaboration ever undertaken, including the construction of the International Thermonuclear Experimental Reactor (ITER) demonstration plant.
This effort aims to control the fusion reaction so that it behaves like a star--generating sustained energy--rather than exploding like a hydrogen bomb. To date, the most successful device for achieving controlled thermonuclear fusion is the tokamak (an acronym created from the Russian words, TOroidalnaya KAmera ee MAgnitnaya Katushka). This doughnut-shaped reactor is designed to confine the fuel within a complex and powerful magnetic field. Current efforts focus on the fusion of heavy hydrogen isotopes such as deuterium and tritium.
Designing the system that will contain and control a turbulent force as great as the sun's is a major challenge. Research conducted at experimental, prototype reactors such as Tokamak Fusion Test Reactor (TFTR) at Princeton University, is complemented by the Numerical Tokamak Project (NTP). NTP scientists are relying on virtual reactors simulated by computers to identify problem areas and help guide the decision-making process for engineers and materials scientists. Such numerical simulation, while never replacing experimental work at test facilities, can speed and enhance experiment.
Professor John Dawson (physics, UCLA) is the scientific leader on the NTP, a multidisciplinary program to develop the computational resources, software, hardware, and communications tools needed to simulate the complex features of the dynamics within the chamber of the tokamak reactor. NTP is a joint effort among more than a dozen academic institutions and government laboratories working with the developers of massively parallel computers and high-speed communications networks, which are critical to this effort.
NTP researchers, including Dawson's group at UCLA, are currently trying to understand the behavior of the turbulence in the plasma that causes the hot core plasma to mix with the cooler, outer layer near the wall. "It is like predicting the weather inside these machines," says Dawson. "If mixing occurs too quickly, the heat of the core falls below the critical temperature needed to sustain the reaction."
Using modern parallel computers, simulations of full scale devices are possible. Dawson's group recently simulated plasma behavior within a tokamak at the scale of the TFTR using the Cornell Theory Center's 512-processor IBM RS/6000 POWERParallel System SP. This Numerical Tokamak is the most complete and accurate model to date. The existing results are very encouraging to researchers, strengthening their belief that they will be able to predict the behavior and to improve the performance of these complex devices.
ITER hopes to run a demonstration reactor by the year 2005. "With the improved understanding gained from the NTP, the summit of the Mattterhorn project is coming into sight," says Dawson. "In experiments, we are beginning to see the first flickers of the fusion flame the first light of our manmade star."
Nuclear Fusion
Energy for the 21st Century
Virtual Reactors