April 29, 2013
Understanding Turbulence In Plasmas Leads To Potential Fusion Power Breakthrough
Lee Rannals for redOrbit.com — Your Universe Online
Researchers wrote in the journal Physics of Plasmas about experiments that helped reveal details of a cooling process that could potentially bring practical fusion closer.Fusion is the reaction that powers the sun, and a team at MIT´s Plasma Science and Fusion Center (PSFC) says they have taken steps that could potentially help develop fusion power. One reason self-sustaining fusion reactions are a difficult accomplishment is because turbulence in the plasma in the reactor causes the super hot gas to lose much of its heat, preventing it from reaching temperatures needed to overcome the electrical repulsion between atomic nuclei.
Previously, researchers found while one mathematical model known as gyrokinects works in some cases, it breaks down in others.
“Whenever a certain type of turbulence is present, the model works,” says Nathan Howard, a PSFC postdoc who is the lead author of the new report. “But when this other kind is present, it doesn´t work.”
The researchers say understanding this discrepancy could be crucial in predicting the performance of larger experimental fusion reactors that are under development. These reactors are seen as a key step toward the eventual development of commercial power-producing reactors.
Fusion power reactors would help produce energy with very little radioactive waste, using hydrogen as fuel. A reactor consists of a large donut-shaped space surrounded by heat-resistant shielding material and powerful magnetic coils. Magnetic fields help prevent the plasma inside from contacting the walls of the chambers, which would vaporize from the heat. Scientists say electrons and ions cause the loss of heat in this multimillion-degree plasma. However, researchers say they have demonstrated for the first time that this phenomenon is not universal.
“We have been able to simulate all the different types of turbulence in order to explain the experimental results," Howard said. "We need to convince ourselves that our model can correctly predict the performance of our existing reactors, so that we can then predict the performance of reactors we haven´t yet built."
Terry Rhodes, a researcher in the physics and astronomy department at the University of California at Los Angeles who was not involved in this research, said these findings were an important step in the effort to test simulations of fusion plasma turbulence and transport. Rhodes said the team's work "provides a counterexample to this discrepancy that the community has been searching for. Scientists in this area will be actively studying their results for clues as to the nature of the discrepancy.”
Last year, a team from the University of Tennessee also claimed to have made big steps in the development of fusion power technology. They said they were able to successfully develop a key technology in creating an experimental fusion reactor.