Archive for October 2015

The bizarre reactor that might save nuclear fusion

If you’ve heard of fusion energy, you’ve probably heard of tokamaks. These doughnut-shaped devices are meant to cage ionized gases called plasmas in magnetic fields while heating them to the outlandish temperatures needed for hydrogen nuclei to fuse. Tokamaks are the workhorses of fusion—solid, symmetrical, and relatively straightforward to engineer—but progress with them has been plodding.

Now, tokamaks’ rebellious cousin is stepping out of the shadows. In a gleaming research lab in Germany’s northeastern corner, researchers are preparing to switch on a fusion device called a stellarator, the largest ever built. The €1 billion machine, known as Wendelstein 7-X (W7-X), appears now as a 16-meter-wide ring of gleaming metal bristling with devices of all shapes and sizes, innumerable cables trailing off to unknown destinations, and technicians tinkering with it here and there. It looks a bit like Han Solo’s Millennium Falcon, towed in for repairs after a run-in with the Imperial fleet. Inside are 50 6-tonne magnet coils, strangely twisted as if trampled by an angry giant.

Although stellarators are similar in principle to tokamaks, they have long been dark horses in fusion energy research because tokamaks are better at keeping gas trapped and holding on to the heat needed to keep reactions ticking along. But the Dali-esque devices have many attributes that could make them much better prospects for a commercial fusion power plant: Once started, stellarators naturally purr along in a steady state, and they don’t spawn the potentially metal-bending magnetic disruptions that plague tokamaks. Unfortunately, they are devilishly hard to build, making them perhaps even more prone to cost overruns and delays than other fusion projects. “No one imagined what it means” to build one, says Thomas Klinger, leader of the German effort.

W7-X could mark a turning point. The machine, housed at a branch of the Max Planck Institute for Plasma Physics (IPP) that Klinger directs, is awaiting regulatory approval for a startup in November. It is the first large-scale example of a new breed of supercomputer-designed stellarators that have had most of their containment problems computed out. If W7-X matches or beats the performance of a similarly sized tokamak, fusion researchers may have to reassess the future course of their field. “Tokamak people are waiting to see what happens. There’s an excitement around the world about W7-X,” says engineer David Anderson of the University of Wisconsin (UW), Madison.

Read more: The bizarre reactor that might save nuclear fusion | Science/AAAS | News

Search For Intelligent Aliens Near Bizarre Dimming Star Has Begun

The search for signs of life in a mysterious star system hypothesized to potentially harbor an “alien megastructure” is now underway.

Astronomers have begun using the Allen Telescope Array (ATA), a system of radio dishes about 300 miles (483 kilometers) northeast of San Francisco, to hunt for signals coming from the vicinity of KIC 8462852, a star that lies 1,500 light-years from Earth.

NASA’s Kepler space telescope found that KIC 8462852 dimmed oddly and dramatically several times over the past few years. The dimming events were far too substantial to be caused by a planet crossing the star’s face, researchers say, and other possible explanations, such as an enormous dust cloud, don’t add up, either.

The leading hypothesis at the moment involves a swarm of comets that may have been sent careening toward KIC 8462852, possibly after a gravitational jostle by a passing star. But it’s also possible, astronomers say, that the signal Kepler saw was caused by huge structures built by an alien civilization — say, a giant assortment of orbiting solar panels.

That latter possibility, remote though it may be, has put KIC 8462852 in the crosshairs of scientists who hunt for signals that may have been generated by intelligent aliens.

“We are looking at it with the Allen Telescope Array,” said Seth Shostak, a senior astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California.

“No problem with that; I think we ought to, for sure,” Shostak told Space.com. But, he added, people “should perhaps moderate their enthusiasm with the lessons of history.”

Shostak cited the example of pulsars, fast-spinning, superdense stellar corpses that emit beams of high-energy radiation. These beams are picked up by instruments on and around Earth as regular pulses, because they can only be detected when they’re fired straight at the planet (an event that occurs at predictable intervals because of pulsars’ rotation).

Astronomers know all this now. But in the 1960s, when the first pulsar signals were discovered, some scientists interpreted them as possible alien transmissions.

“So history suggests we’re going to find an explanation for this that doesn’t involve Klingons, if you will,” Shostak said of the KIC 8462852 mystery.

Source: Search For Intelligent Aliens Near Bizarre Dimming Star Has Begun