August 25, 2015

Tri-alpha Energy targets 1 second plasma duration at 100 million degrees in the one to four years

Science Mag is reporting about Tri-alpha Energy making its plasma last for 5 milliseconds.

There are some more details about their work and their plans, however, most of this has been covered by Nextbigfuture in June 2015 The original announcement and work on 5 millisecond duration was back in 2013. They were at 2 milliseconds in 2011.

Privately funded Tri Alpha Energy has built a machine that forms a ball of superheated gas—at about 10 million degrees Celsius
—and holds it steady for 5 milliseconds without decaying away. That may seem a mere blink of an eye, but it is far longer than other efforts with the technique and shows for the first time that it is possible to hold the gas in a steady state—the researchers stopped only when their machine ran out of juice.

“They’ve succeeded finally in achieving a lifetime limited only by the power available to the system,” says particle physicist Burton Richter of Stanford University in Palo Alto, California, who sits on a board of advisers to Tri Alpha. If the company’s scientists can scale the technique up to longer times and higher temperatures, they will reach a stage at which atomic nuclei in the gas collide forcefully enough to fuse together, releasing energy.

“Until you learn to control and tame [the hot gas], it’s never going to work. In that regard, it’s a big deal. They seem to have found a way to tame it,” says Jaeyong Park, head of the rival fusion startup Energy/Matter Conversion Corporation in San Diego. “The next question is how well can you confine [heat in the gas]. I give them the benefit of the doubt. I want to watch them for the next 2 or 3 years.”

Tri Alpha’s machine also produces a doughnut of plasma, but in it the flow of particles in the plasma produces all of the magnetic field holding the plasma together. This approach, known as a field-reversed configuration (FRC), has been known since the 1960s. But despite decades of work, researchers could get the blobs of plasma to last only about 0.3 milliseconds before they broke up or melted away. In 1997, the Canadian-born physicist Norman Rostoker of the University of California, Irvine, and colleagues proposed a new approach. The following year, they set up Tri Alpha, now based in an unremarkable—and unlabeled—industrial unit here. Building up from tabletop devices, by last year the company was employing 150 people and was working with C-2, a 23-meter-long tube ringed by magnets and bristling with control devices, diagnostic instruments, and particle beam generators. The machine forms two smoke rings of plasma, one near each end, by a proprietary process and fires them toward the middle at nearly a million kilometers per hour. At the center they merge into a bigger FRC, transforming their kinetic energy into heat.

Previous attempts to create long-lasting FRCs were plagued by the twin demons that torment all fusion reactor designers. The first is turbulence in the plasma that allows hot particles to reach the edge and so lets heat escape. Second is instability: the fact that hot plasma doesn’t like being confined and so wriggles and bulges in attempts to get free, eventually breaking up altogether. Rostoker, a theorist who had worked in many branches of physics including particle physics, believed the solution lay in firing high-speed particles tangentially into the edge of the plasma. The fast-moving incomers would follow much wider orbits in the plasma’s magnetic field than native particles do; those wide orbits would act as a protective shell, stiffening the plasma against both heat-leaking turbulence and instability.

To make it work, the Tri Alpha team needed to precisely control the magnetic conditions around the edge of the cigar-shaped FRC, which is as many as 3 meters long and 40 centimeters wide. They did it by penning the plasma in with magnetic fields generated by electrodes and magnets at each end of the long tube.

In experiments carried out last year, C-2 showed that Rostoker was on the right track by producing FRCs that lasted 5 milliseconds, more than 10 times the duration previously achieved. “In 8 years they went from an empty room to an FRC lasting 5 milliseconds. That’s pretty good progress,” Hammer says. The FRCs, however, were still decaying during that time. The researchers needed to show they could replenish heat loss with the beams and create a stable FRC. So last autumn they dismantled C-2. In collaboration with Russia’s Budker Institute of Nuclear Physics in Akademgorodok, they upgraded the particle beam system, increasing its power from 2 megawatts to 10 megawatts and angling the beams to make better use of their power.

Next year they will tear up C-2U again and build an almost entirely new machine, bigger and with even more powerful beams, dubbed C-2W. The aim is to achieve longer FRCs and, more crucially, higher temperature. A 10-fold increase in temperature would bring them into the realm of sparking reactions in conventional fusion fuel, a mixture of the hydrogen isotopes deuterium and tritium, known as D-T. But that is not their goal; instead, they’re working toward the much higher bar of hydrogen-boron fusion, which will require ion temperatures above 3 billion degrees Celsius.

Tri Alpha team has revealed how fast ions, edge biasing, and other improvements have enabled them to produce FRCs (Field Reverse Configuration plasmas) lasting 5 milliseconds, a more than 10-fold improvement in lifetime, and reduced heat loss. “They’re employing all known techniques on a big, good-quality plasma,” Wurden says. “It shows what you can do with several hundred million dollars.”
To achieve fusion gain—more energy out than heating pumped in—researchers will have to make FRCs last for at least a second. Although that feat seems a long way off, Santarius says Tri Alpha has shown a way forward. “If they scale up size, energy confinement should go up,” he says. Tri Alpha researchers are already working with an upgraded device, which has differently oriented ion beams and more beam power. TAE Chief Experimental Strategist Pr. Houyang Guo revealed during a plasma physics seminar held at the University of Wisconsin–Madison College of Engineering on April 29, 2013 that C-3 will be increased in size and heating power, in order to achieve 100 milliseconds to 1 second confinement times. He also confirmed the company has a staff of 150 people

In 2015, Daniel Clery reports that Tri Alpha researchers are already working with an upgraded device, which has differently oriented ion beams and more beam power.

Nature Communications - Achieving a long-lived high-beta plasma state by energetic beam injection

Developing a stable plasma state with high-beta (ratio of plasma to magnetic pressures) is of critical importance for an economic magnetic fusion reactor. At the forefront of this endeavour is the field-reversed configuration. Here we demonstrate the kinetic stabilizing effect of fast ions on a disruptive magneto-hydrodynamic instability, known as a tilt mode, which poses a central obstacle to further field-reversed configuration development, by energetic beam injection. This technique, combined with the synergistic effect of active plasma boundary control, enables a fully stable ultra-high-beta (approaching 100%) plasma with a long lifetime.

Physics of Plasmas - A high performance field-reversed configuration

Conventional field-reversed configurations (FRCs), high-beta, prolate compact toroids embedded in poloidal magnetic fields, face notable stability and confinement concerns. These can be ameliorated by various control techniques, such as introducing a significant fast ion population. Indeed, adding neutral beam injection into the FRC over the past half-decade has contributed to striking improvements in confinement and stability. Further, the addition of electrically biased plasma guns at the ends, magnetic end plugs, and advanced surface conditioning led to dramatic reductions in turbulence-driven losses and greatly improved stability. Together, these enabled the build-up of a well-confined and dominant fast-ion population. Under such conditions, highly reproducible, macroscopically stable hot FRCs (with total plasma temperature of ∼1 keV) with record lifetimes were achieved. These accomplishments point to the prospect of advanced, beam-driven FRCs as an intriguing path toward fusion reactors. This paper reviews key results and presents context for further interpretation.

Researchers had theorized that an FRC could be made to live longer by firing high-speed ions into the plasma. Michl Binderbauer, Tri Alpha’s chief technology officer, says that once the ions are inside the FRC, its magnetic field curves them into wide orbits that both stiffen the plasma against instability and suppress the turbulence that allows heat to escape. “Adding fast ions does good things for you,” says Glen Wurden of the Plasma Physics Group at Los Alamos National Laboratory in New Mexico. Tri Alpha collaborated with Russia’s Budker Institute of Nuclear Physics in Akademgorodok, which provided beam sources to test this approach. But they soon learned that “[ion] beams alone don’t do the trick. Conditions in the FRC need to be right,” Binderbauer says, or the beams can pass straight through. So Tri Alpha developed a technique called “edge biasing”: controlling the conditions around the FRC using electrodes at the very ends of the reactor tube.

Nextbigfuture had reported on the Tri-alpha energy 5 millisecond achievement being announced in 2013. However, the published papers provide details.

Tri Alpha itself has raised over $150 million from the likes of Microsoft co-founder Paul Allen and the Russian government's venture-capital firm, Rusnano.

Tri-alpha Energy has started to let its employees publish results and present at conferences. With its current test machine, a 10-metre device called the C-2, Tri Alpha has shown that the colliding plasmoids merge as expected, and that the fireball can sustain itself for up to 4 milliseconds — impressively long by plasma-physics standards — as long as fuel beams are being injected. Last year, Tri Alpha researcher Houyang Guo announced at a plasma conference in Fort Worth, Texas, that the burn duration had increased to 5 milliseconds. The company is now looking for cash to build a larger machine.

As a science programme, it's been highly successful,” says Hoffman, who reviewed the work for Allen when the billionaire was deciding whether to invest. “But it's not p–11B.” So far, he says, Tri Alpha has run its C-2 only with deuterium, and it is a long way from achieving the extreme plasma conditions needed to burn its ultimate fuel.

Nor has Tri Alpha demonstrated direct conversion of α-particles to electricity. “I haven't seen any schemes that would actually work in practice,” says Martin Greenwald, an MIT physicist and former chair of the energy department's fusion-energy advisory committee. Indeed, Tri Alpha is planning that its first-generation power reactor would use a more conventional steam-turbine system.

This information was from Talk Polywell

Solo notes from May 1, 2013.

-150 on staff
-5ms plasma lifetime, presently limited not by instabilities but by ~1ms confinement time (energy, particles)
-very reproducible discharges despite dynamic merging procedure
-Te ~100eV, Ti ~ 400eV
-20keV beam ions orbit passes through edge, important to keep neutral density down
-plasma guns help stabilize MHD instabilities, other turbulence by biasing & driving anti-rotation
- confinement scales like (Te * r_s)^2 which is very favorable
- planning C-3 device with 100ms-1s confinement times by increased size, heating power

Форма для связи


Email *

Message *