ვიფიქრე იქნებ ვინმეს დააინტრესოს ამ თემამ მეთქი... კი მუსიკა, თეატრი, ლიტერატურა, ხელოვნება, რელიგია და ა.შ. საინტერესოა მაგრამ მგონი არც ეს უნდა იყოს მთლად უინტერესო...
ჰოდა შევეცდები პერიოდულად დავდო ხოლმე აქ ინფორმაცია თუ რა ხდება მეცნიერებაში და რაზეც ხელი მიმიწვდება... ასევე რა თქმა უნდა თქვენც შეგიძლიათ მით უმეტეს რომ საბუნებისმეტყველო მეცნიერების იმდენი სფეროა ყველას ვერ გავწვდები და ზოგი ინფორმაციის მნიშვნელობას ვერც მივხვდები შესაბამისი ცოდნის არქონის გამო... ჰო კიდევ ბოდიშს მოგიხდით რომ სტატიები იქნება ინგლისურად მაგრამ ორიგინალები... ცოტა ძნელი იქნება ალბათ პუბლიკისათვის გაიგოს მაგრამ ვინც ცოტას გაიჭირვებს გაიგებს ... მეორე პლიუსი ამას ის ექნება რომ ინგლისურს შეეჩვევით...
ახლა კი პირველ სტატიას რაც შეეხება... მიმოხილვითი სტატია Science magazine-დან სადაც საუბარია თერმობირთვული რეაქტორების მშენებლობაზე საკმაოდ საინტერესოდ და შედარებით გასაგებ ენაზე დაწერილი... მოკლედ სულ მალე ალბათ გვექნება ენერგიის ახალი წყარო მართვადი თერმობირთვული რეაქტორი რაც როგორც მეცნიერები ვარაუდობენ პრაქტიკულად გადაწყვეტს ელექტროენერგიის პრობლემებს... ერთი ასეთი რეაქტორი the International Thermonuclear Experimental Reactor (ITER) შენდება საფრანგეთში 2016 წლისათვის მაგრამ მანამდე ჩინეთი ინდოეთი და სამხრეთ კორეა აპირებენ საკუთარი რეაქტორების გაშვებას...
ENERGY ALTERNATIVES:
Waiting for ITER, Fusion Jocks Look EAST
Dennis Normile*

China is breaking new ground with a fusion test bed that will tide researchers over until the ITER megaproject comes online
Speed matters. It has taken just over 5 years and $37 million to complete China's new tokamak, according to the Institute of Plasma Physics.
CREDIT: DONG YIDONG


HEFEI, CHINA--The official launch of the International Thermonuclear Experimental Reactor (ITER) project next week will mark a coming of age for fusion research in Asia. When the $11 billion effort was initiated in 1985, ITER's four original backers--the United States, the European Union, Japan, and the Soviet Union--accounted for nearly all worldwide research into harnessing fusion, the process that powers the sun, to produce energy. But now the three newest ITER partners, China, South Korea, and India, are showing that they didn't just buy their way into one of the biggest physics experiments since the Manhattan Project: They are contributing crucial expertise as well.
The first new Asian fusion tiger out of the gate is the Institute of Plasma Physics (IPP) of the Chinese Academy of Sciences, which in March completed testing a machine that has never been built before: a fully superconducting tokamak. This toroidal vessel isn't the largest or most powerful device for containing the superhot plasma in which hydrogen isotopes fuse and release energy. But until India and South Korea bring similar machines online (see sidebar, p. 993), it will be the only tokamak capable of confining a plasma for up to 1000 seconds, instead of the tens of seconds that machines elsewhere can muster. ITER, expected to be completed in Cadarache, France, in 2016, will have to sustain plasmas far longer to demonstrate fusion as a viable energy source. But researchers from China and around the world will be able to use IPP's Experimental Advanced Superconducting Tokamak (EAST) to get a head start on learning to tame plasmas for extended periods. "This will make a big contribution for the future of fusion reactors," declares Wan Yuanxi, a plasma physicist who heads EAST.


Fire when ready. EAST will fill a crucial gap for fusion researchers until ITER is built, says Director Wan Yuanxi.
CREDIT: D. NORMILE/SCIENCE


Fusion research over the next decade will be probing the physics of steady-state plasmas like those promised by ITER, says Ronald Stambaugh, vice president for the Magnetic Fusion Energy Program at General Atomics in San Diego, California. "EAST will play a big role in that," he says. Others credit IPP for building its advanced tokamak fast, in just over 5 years, on a shoestring $37 million budget. That's a fraction of what it would have cost in the United States, says Kenneth Gentle, a plasma physicist and director of the Fusion Research Center at the University of Texas, Austin. "That they did this in spite of the financial constraints is an enormous testimony to their will and creativity," adds Richard Hawryluk, deputy director of the Princeton Plasma Physics Laboratory.
IPP adroitly fills a generational gap. Fusion power will rely on heating hydrogen isotopes to more than 100 million degrees Celsius, until they fuse into heavier nuclei. The leading design for containing this fireball is the tokamak, a doughnut-shaped vacuum chamber in which a spiraling magnetic field confines the plasma. Ringlike metal coils spaced around the doughnut--toroidal field coils--and a current in the plasma produce this spiraling field. Additional coils in the center of the doughnut and along its circumference--poloidal field coils--induce the current in the plasma and control its shape and position.

Early tokamaks had circular cross sections and copper coils, which can only operate at peak power in brief pulses before overheating. ITER will be far more sophisticated. It will have a D-shaped cross section, designed to create a denser plasma that can generate its own current to supplement the induced current, reducing energy input. And coils will be superconducting. (No major tokamak has had superconducting poloidal field coils.) At temperatures approaching absolute zero, superconductors carry current without generating resistance, allowing more powerful magnetic fields that can be maintained longer.

Researchers want to try out a D-shaped, fully superconducting test bed before scaling up to ITER, which will be two to three times the size of current tokamaks. The Princeton Plasma Physics Laboratory had planned to build such a device. But a cost-conscious U.S. Congress killed their $750 million Tokamak Physics Experiment in 1995. EAST and the two other Asian tokamaks under construction intend to fill this gap.

"We recognized this was an opportunity for us to make a contribution for fusion research," Wan says. For support, he tapped into China's worries about its growing demand for energy. "There is no way we can rely entirely on fossil fuels," he says. China's government approved EAST in 1998.

IPP faced an enormous challenge. The institute, founded in 1978, had built a few tiny tokamaks in the 1980s and got a hand-me-down, partially superconducting tokamak from Russia's Kurchatov Institute in 1991. EAST would be a totally different beast. "We didn't have any experience in the design, fabrication, or assembly of these kinds of magnets," Wan admits. Neither did Chinese manufacturers.

Industrial partners supplied parts of the tokamak, including the vacuum vessel. But the superconducting coils and many other high-tech components would have been too expensive to import. "We had to do [these] ourselves," says the tokamak's chief engineer, Wu Songtao. So Wu's team bought precision milling machines, fabricated their own coil winders, and built a facility to test materials and components at cryogenic temperatures. "They literally built a whole manufacturing facility on site," says Hawryluk.

IPP physicists and engineers passed a major milestone earlier this year, when they tested the entire assembled device, cooling the 200 tons of coils to the operating temperature, 4.5 kelvin. They discovered only minor, fixable glitches, Wan says, and are now undertaking the necessary tweaks and installing shielding materials and diagnostic devices. In August, they plan to inject hydrogen and fire up EAST's first plasma.

With the tokamak passing its cool-down test, Wan says the team was "finally able to get a good night's sleep." They are now planning experiments to explore how to control D-shaped plasmas. Tugging a plasma into a specific shape can create instabilities, Gentle says. Control is all the more difficult because superconducting coils respond poorly to current fluctuations. IPP will probe these issues. "That's where the science is going to be extremely valuable," says Hawryluk.

EAST has limitations. The most significant is that, unlike ITER, it will not attempt a burning plasma, in which at least half the energy needed to drive the fusion reaction is generated internally. ITER will use a combination of deuterium and tritium (hydrogen isotopes with, respectively, one and two neutrons in the nucleus), which fuse at a lower temperature than other gases, to achieve a burn. Because radioactive tritium requires specialized and expensive handling systems and shielding, EAST will use only hydrogen or deuterium.

That limitation is hardly dampening enthusiasm for the hot new kids on the block. IPP researchers, says Hawryluk, "have already put themselves on the fusion community map."



--------------------------------------------------------------------------------
With reporting by Gong Yidong.

Science 19 May 2006:
Vol. 312. no. 5776, pp. 992 - 993
http://www.sciencemag.org/cgi/content/full/312/5776/992