Tiny grains of lithium dramatically improve performance of fusion plasma

May 20, 2015

Scientists from General Atomics and the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have discovered a phenomenon that helps them to improve fusion plasmas, a finding that may quicken the development of fusion energy. Together with a team of researchers from across the United States, the scientists found that when they injected tiny grains of lithium into a plasma undergoing a particular kind of turbulence then, under the right conditions, the temperature and pressure rose dramatically. High heat and pressure are crucial to fusion, a process in which atomic nuclei - or ions - smash together and release energy—making even a brief rise in pressure of great importance for the development of fusion energy.

"These findings might be a step towards creating our ultimate goal of steady-state fusion, which would last not just for milliseconds, but indefinitely," said Tom Osborne, a physicist at General Atomics and lead author of the paper. This work was supported by the DOE Office of Science (Office of Fusion Energy Sciences).

The scientists used a device developed at PPPL to inject grains of measuring some 45 millionths of a meter in diameter into a plasma in the DIII-D National Fusion Facility - or tokamak - that General Atomics operates for DOE in San Diego. When the lithium was injected while the plasma was relatively calm, the plasma remained basically unaltered. Yet as reported this month in a paper in Nuclear Fusion, when the plasma was undergoing a kind of turbulence known as a "bursty chirping mode," the injection of lithium doubled the at the outer edge of the plasma. In addition, the length of time that the plasma remained at high pressure rose by more than a factor of 10.

Experiments have sustained this enhanced state for up to one-third of a second. A key scientific objective will be to extend this enhanced performance for the full duration of a plasma discharge.

Physicists have long known that adding lithium to a increases its performance. The new findings surprised researchers, however, since the small amount of lithium raised the plasma's temperature and pressure more than had been expected.

These results "could represent the birth of a new tool for influencing or perhaps controlling tokamak edge physics," said Dennis Mansfield, a physicist at PPPL and a coauthor of the paper who helped develop the injection device called a "lithium dropper." Also working on the experiments were researchers from Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, the University of Wisconsin-Madison and the University of California-San Diego.

Conditions at the edge of the plasma have a profound effect on the superhot core of the plasma where fusion reactions take place. Increasing pressure at the edge region raises the pressure of the plasma as a whole. And the greater the plasma pressure, the more suitable conditions are for fusion reactions. "Making small changes at the plasma's edge lets us increase the pressure further within the plasma," said Rajesh Maingi, manager of edge physics and -facing components at PPPL and a coauthor of the paper.

Further experiments will test whether the lithium's interaction with the bursty chirping modes - so-called because the turbulence occurs in pulses and involves sudden changes in pitch - caused the unexpectedly strong overall effect.

Explore further: Calming the plasma edge: The tail that wags the dog

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5 / 5 (3) May 20, 2015
You boys need to start work on aneutronic fusion. All these prompt neutrons are bad, m'kay?
2.1 / 5 (7) May 20, 2015
Very interesting to note that Andrea Rossi's 'Hot Cat' over unity device..uses (one of it's components)..... LITHIUM.

Go figure.

Never would'a guessed.

Who'da thunk it.

No Guff.

No Shit Sherlock.

Oligarchs be afraid. Be very afraid.
3.7 / 5 (3) May 24, 2015
The reasons they be afraid?

Well, tokamak systems are about centralized, controlled power.

Where the people are under the thumb of a energy peddler. An energy dealer, like a gang controlling a water source. A parasite.

A system of enforced oligarchy, enforced imperialism.

Rossi's hot-cat is about individualized energy independence.

Thus, the press, which is wholly owned, is all about tokamak reactors, and the maintenance of oligarchy, and nothing for the people, except that of slavery and submission.

One who posts otherwise, gets downvoted (here on physorg), and the hot-cat ridiculed, with respect to how it's intimate bits function.

This....in the very same moment that the very same function in science and research is touted as discovery....in the area of centralized energy control systems ----Like tokamak reactors.

I hope that is a bit more clear.
Mark Thomas
5 / 5 (2) Jun 29, 2015
While General Atomics (GA) and Princeton Plasma Physics Laboratory (PPPL) make continual progress on acheiving fusion, ITER has wasting billions on building construction contracts in France. New ITER leader Bernard Bigot reports he had some meetings over the last three months, but what else has he accomplished? He promised his new schedule by November 2015, so if he can't cough up something acceptable by December let's drop ITER and fund GA and PPPL to make something real happen.

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