As the new year dawned, nuclear fusion researchers in the European Union woke to an entirely new funding system aimed at sharpening their focus on generating energy. Gone are the annual block grants to national fusion laboratories; now, teams must compete to participate in "work packages" supporting the international ITER reactor in France and preparing for a prototype power reactor before the middle of the century. "It's a substantial change in the way we work," says Francesco Romanelli, acting head of EUROfusion, a consortium of all of Europe's fusion labs that will manage the new program.

The change is the handiwork of the European Union's nuclear research arm, Euratom. It funds both ITER construction, shouldering 45% of the cost—a €6.6 billion share by the time the reactor is completed in 2020—and related fusion research in labs across the continent. That is the part of the budget that the new system redirects.

In the old system, in place since the 1950s, Euratom simply gave each of the national labs a lump of money every year equal to as much as 20% of the lab's budget and gently coordinated research. Euratom also funded the only common facility, the Joint European Torus (JET) reactor in Culham, U.K., through the European Fusion Development Agreement (EFDA).

In 2011, Euratom appointed a panel to recommend how to organize fusion research in the European Union's next 7-year financial period, starting in 2014. Headed by Albrecht Wagner, former head of the DESY particle physics lab in Germany, the panel recommended a more mission-oriented approach focusing on fusion energy. "If ITER is not a success, there is no need for future research," says Alain Bécoulet, head of France's Research Institute for Magnetic Fusion.

In 2012, Euratom tasked EFDA with drawing up a road map for refocusing Europe's fusion efforts. Published at the beginning of 2013, the road map called for the European Union to concentrate on finishing and operating ITER while also preparing for its successor, a power-producing prototype, dubbed DEMO. In response, Euratom announced that the annual grants would cease at the end of the year and that the fusion community must devise a 5-year program of research based on the aims of the road map.

Since then, the heads of the fusion labs have been working furiously to comply, and they finalized the work program last month. The program, which Euratom will spend the next 3 months evaluating, includes a campaign of experiments on JET to simulate ITER operation plus experiments at smaller reactors across Europe. There's money for technology R&D for ITER and DEMO, for training future fusion scientists, and for a neutron source to test materials in the sort of neutron bombardment they will experience in a working reactor. The program also hedges its bets by supporting work on stellarators, an alternative fusion technology that could play a role if ITER fizzles.

Bécoulet worries that the program focuses too much on the future—ITER operation and DEMO—and not on the immediate needs of ITER construction. "We're very upset with the proposal," he says, adding that the program "needs to focus more on what is urgent now." Romanelli responds that the program already addresses urgent needs, with 85% of the funding directly or indirectly supporting ITER. "ITER is the first priority," he says.

Source: sciencemag.org

A surprising effect created by a 19th century device called a Helmholz coil offers clues about how to achieve controlled nuclear fusion at Sandia National Laboratories' powerful Z machine.
A Helmholz coil produces a magnetic field when electrified. In recent experiments, two Helmholz coils, installed to  provide a secondary magnetic field to Z's huge one, unexpectedly altered and slowed the growth of the magneto-Rayleigh-Taylor instabilities, an unavoidable, game-ending plasma distortion that usually spins quickly out of control and has sunk past efforts to achieve controlled fusion. "Our experiments dramatically altered the nature of the instability," said Sandia physicist Tom Awe. "We don't yet understand all the implications, but it's become a different beast, which is an exciting physics result."

The purpose of adding two Helmholz coils to fusion experiments at the Z machine, which produces a magnetic field 1,000 times stronger than the coils, was to demonstrate that the secondary field would create a magnetic barrier that, like insulation, would maintain the energy of charged particles in a Z-created plasma. Theoretically, the coils' field would do this by keeping particles away from the machine's walls. Contact would lower the fusion reaction's temperature and cause it to fail.

Researchers also feared that the Helmholz field might cause a short in Z's huge electrical pulse as it and its corresponding magnetic field sped toward the target, a small deuterium-stuffed cylinder.

Z's magnetic field is intended to crush the cylinder, called a liner, fusing the deuterium and releasing neutrons and other energies associated with nuclear fusion. Anything hindering that "pinch" or "z-pinch," would doom the experiment.

In preliminary experiments by Awe's group, the coils indeed buffered the particles and didn't interfere with the pinch.

Enter the coils

But unexpectedly, radiographs of the process showed that the coils' field had altered and slowed the growth of the magneto-Rayleigh-Taylor instabilities. Those distortions had been thought to occur unavoidably because even the most minute differences in materials turned to plasma are magnified by pressures applied over time.

The strength of instabilities seen in hundreds of previous z-pinches was reduced, possibly significantly.

The typical distortion pattern also changed shape from horizontal to helical.

The unexpected results occurred in a series of experiments to study a concept called Magnetized Liner Inertial Fusion, or MagLIF.

Experimental process like French toast

Researchers placed the Helmholz coils around a liner containing deuterium so the coils' magnetic field lines soaked both container and fuel over a period of milliseconds. The relatively slow process, like soaking bread in beaten eggs and milk to make French toast, allowed time for the magnetic field lines to fully permeate the material. Then the liner was crushed in tens of nanoseconds by the massive magnetic implosion generated by Sandia's Z machine. In previous attempts to use Z's huge field without the Helmholz coils, radiographs showed instabilities appearing on the exterior of the liner. These disturbances cause the liner's initially smooth exterior to resemble a stack of metallic washers, or small sausage links separated by horizontal rubber bands. Such instabilities increase dramatically in nanoseconds, eating through the liner wall like decay through a tooth. Eventually, they may collapse portions of the inner wall of the liner, releasing microrubble and causing uneven fuel compression that would make fusing significant amounts of deuterium impossible.

The disturbances are a warning sign that the liner might crumple before fully completing its fusion mission.

But firing with the secondary field running clearly altered and slowed formation of the instability as the liner quickly shrank to a fraction of its initial diameter. Introducing the secondary magnetic field seemed to realign the instabilities from simple circles—stacked washers, or rubber bands around sausages—into a helical pattern that more resembled the slanting patchwork of a plaid sweater.

Like a kayak crossing a river

Researchers speculate that the vertical magnetic field created by the helical coils, cutting across Z's horizontal field, may create the same effect as a river slanting a kayak downstream rather than straight across a channel. Or it may be that the kayak's original direction is pre-set by the secondary magnetic field to angle it downstream. Whatever the reason, the helical instability created does not appear to eat through the liner wall as rapidly as typical horizontal Rayleigh-Taylor instabilities.

Flashes of X-rays that were released when material from the horizontal instabilities collided in the liner's center no longer appeared, suggesting more uniform fuel compression occurred, possibly a result of the increasing resistance of the implanted vertical magnetic field to the compression generated by the Z horizontal field.

The overall approach of Awe and his colleagues uses a method described in two papers by Sandia theorist Steve Slutz. In a 2010 article in Physics of Plasmas, Slutz suggested that the magnetic field generated by Z could crush a metallic liner filled with deuterium, fusing the atoms. Slutz and co-authors then indicated, in a 2012 paper in Physical Review Letters, that a more powerful version of Z could create high-yield fusion—much more fusion energy out than the electrical energy put in.

The apparently simple method—turn on a huge magnetic field and wait a few nanoseconds—takes for granted the complicated host of engineered devices and technical services that allow Z to function. But, those aside, the process as described by Slutz needed only two additional aids: a powerful laser to preheat the fuel, making it easier for the compressed fuel to reach fusion temperatures, and Helmholz coils above and below the target to generate a separate, weaker magnetic field that would insulate charged particles from giving up their energy, thereby lowering the temperature of the reaction.

Ongoing experiments on Z will determine how well reality bears out Slutz's predictions. But for now, the reduction of distortions has been warmly received by fusion researchers, leading to an invitation to Awe to present his team's results at the 55th Annual Meeting of the APS Division of Plasma Physics, the world's largest plasma meeting.

The principle of the Z machine is simple: Z's magnetic force can crush any metal in its path. Possibly, then, it could force the fusion of ions like deuterium in a metal liner a few millimeters in diameter. The magnetic field would crush the liner's fuel to the diameter of a human hair, causing deuterium to fuse. This would release neutrons that could be used to study radiation effects, one of the key concerns of the National Nuclear Security Administration, which funds the bulk of this research. Further, in the far future, and with additional engineering problems solved, the technique when engineered to fire repetitively could be used as the basis for an electrical generating plant whose fuel is sea water, a carbon-free energy source for humankind.

"Of course the reality is not that simple," said Awe, "but the new ability to modify the instability growth on the liner surface may be a step in the right direction."

Source: phys.org

The contract for developing an important diagnostic method for the ITER international test reactor went to Max Planck Institute of Plasma Physics (IPP) at Garching: The ITER Fusion for Energy Agency will be funding a German research and industrial consortium, headed by IPP, with a total of 4.8 million euros in the next four years. The objective is advanced development of so-called bolometer cameras for recording the heat and X-radiation emitted from the ITER plasma. Award of the contract was based on a preparatory phase supported with national project funds in which the participants’ suitability for this and other ITER tasks was verified. 

The measuring method is to record the heat and light emission from the infrared to X-ray region and pinpoint their origin in the plasma. The radiation power is part of the total energy balance of the plasma. It has to be known in order to control the plasma or apply certain modes of operation.

Measuring principle of a bolometer: A metal plate the size of a postage stamp absorbs the radiation emitted from the plasma along a narrow line of sight, thus heating up. The electric resistance of a conductor located below it changes according to the temperature and is therefore a direct measure of the radiation power. Additional calculations and measured data allow the radiation to be assigned to its origin in the plasma insofar as a sufficient number of bolometers are available. This reveals exactly what site in the plasma has emitted what power.

This measuring method, developed at and patented by IPP, has been successfully applied for many years. However, the ITER large-scale device, which is to produce a burning fusion fire for the fist time, imposes new requirements: Unlike hitherto, the detectors have to withstand impinging fusion neutrons and also be capable of working reliably at temperatures of up to 450 degrees. 

For this further development IPP have since 2008 been using funds provided by the Federal Ministry of Research to pursue fruitful cooperation ventures: For example, previous IPP designs were used to develop first prototypes at the Institut für Mikrotechnik Mainz – platinum absorbers galvanically deposited on thin ceramic membranes. They have already passed neutron tests in the research reactor of the Hungarian Academy of Sciences and their spectral sensitivity has been tested in cooperation with Germany’s Physikalisch-Technische Bundesanstalt. Heat tests at IPP, however, were only partially successful. Modelling calculation with the support of the KRP Mechatec company subsequently helped to modify the design appropriately. Alternatives for the absorber material and its suspension are also being investigated.

Later about 500 lines of sight will traverse the ITER plasma and observe it from all angles in various cross-sectional planes. The absorber plates, which pick up this radiation, are located deep in the wall of the plasma vessel – at the end of long ducts covered with narrow diaphragms: the smaller the angle of sight scanned by the individual detector, the more precisely is the plasma imaged. The large ITER plasma also calls here for much higher requirements than do present-day fusion devices.

To test the accuracy attainable, a robot test rig was specially installed in conjunction with a doctoral thesis and tested in the plasma vessel of the ASDEX Upgrade fusion device at Garching. It can direct a laser beam from all directions to the entry slot of a bolometer. The measured results helped to improve the diaphragm design so as to largely suppress scattered light and reflection in the camera. Much in the way of optics, assembly, material and electronics still needs to be optimised until in four years a fully documented prototype integrable in the ITER design becomes available.

Source: ipp.mpg.de

Introducing his idea at the Lego Cuusoo website, started by Lego in 2008, graphic designer Andrew Clark has proposed a model of the ITER fusion reactor, set to become the biggest in the world, made of 498 Lego bricks including two micro figures for a sense of scale and detail.

Since the end of December 2013, people can vote for the Lego ITER model to help it get from paper to reality. If it reaches 10,000 votes until May 2014, it will be considered by the Lego team for manufacturing (lego.cuusoo.com)

It is not the first technology marvel competing at the Lego Cuusoo website. In 2012, NASA’s Martian rover Curiosity received the highest amount of votes and is already commercially available. The latest winner, selected in the autumn of 2013, is an exoskeleton suit for a tiny Lego man.

Among the current frontrunners are also several technology-inspired projects – for example a Lego Apple Store and the Apollo 11 lunar lander created in the memory of the deceased first man on the Moon Neil Armstrong. Both projects are nearing the 10,000 vote milestone, making them eligible for further consideration.

Authors of successful designs receive 1 per cent of the royalties.

Source: eandt.theiet.org

The Z machine at Sandia National Laboratories in New Mexico discharges the most intense pulses of electrical current on Earth. Millions of amperes can be sent towards a metallic cylinder the size of a pencil eraser, inducing a magnetic field that creates a force — called a Z pinch — that crushes the cylinder in a fraction of a second.

Since 2012, scientists have used the Z pinch to implode cylinders filled with hydrogen isotopes in the hope of achieving the extreme temperatures and pressures needed for energy-generating nuclear fusion. Despite their efforts, they have never succeeded in reaching ignition — the point at which the energy gained from fusion is greater than the energy put in.

But after tacking on two more components, physicists think they are at last on the right path. Researchers working on Sandia’s Magnetized Liner Inertial Fusion (MagLIF) experiment added a secondary magnetic field to thermally insulate the hydrogen fuel, and a laser to preheat it (see ‘Feeling the pinch’). In late November, they tested the system for the first time, using 16 million amperes of current, a 10-tesla magnetic field and 2 kilojoules of energy from a green laser.

“We were excited by the results,” says Mark Herrmann, director of the Z machine and the pulsed-power science center at Sandia. “We look at it as confirmation that it is working like we think it should.”

The experiment yielded about 10¹⁰ high-energy neutrons, a measure of the number of fusion reactions achieved. This is a record for MagLIF, although it still falls well short of ignition. Nevertheless, the test demonstrates the appeal of such pulsed-power approaches to fusion. “A substantial gain is more likely to be achieved at an early date with pulsed power,” says nuclear physicist David Hammer of Cornell University in Ithaca, New York, who co-wrote a 2013 US National Research Council assessment of approaches to fusion energy.

With its relatively slim US$5-million annual budget, MagLIF is a David next to two fusion Goliaths: the $3.5-billion National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in California, and the €15-billion (US$20-billion) ITER experiment under construction in France. (Sandia has about $80 million to operate the Z machine each year, but it serves other experiments in addition to MagLIF.) The NIF squashes fuel capsules using nearly 2 megajoules of laser energy, and ITER will use 10,000 tons of superconducting magnets in a doughnut-shaped ‘tokamak’ to hold a plasma in place to coax self-sustaining fusion.

Both of the big projects have run into problems. After a concerted two-year effort, NIF fell well short of achieving ignition by a 2012 deadline. Its fusion yields have since increased markedly — nearly 10¹⁶ neutrons were created in a recent shot, Herrmann says — but the more than $300-million-a-year program faces further budget cuts in 2014. Meanwhile, delays and budget overruns have become the norm at ITER. The facility is not expected to begin operations until 2027 — 11 years later than initially planned.

In addition to being cheaper, MagLIF seems to have technical advantages. The laser not only preheats the hydrogen fuel, but also makes it more conductive — and thereby more susceptible to the Z pinch. Furthermore, in a paper published late last year, MagLIF physicists showed evidence suggesting that the applied secondary magnetic field, as well as insulating the fuel, may have the happy side effect of stabilizing the cylinder as it implodes (T. J. Awe et al. Phys. Rev. Lett. 111, 235005; 2013). If so, that would cut down on hydrodynamic instabilities, which can disperse the energy and fuel before fusion can get going, says Stephen Slutz, a Sandia physicist who proposed the MagLIF system in 2009.

In the next few years, MagLIF scientists plan to turn up all three dials at their disposal. They can boost the Z machine to up to 27 million amperes; they can ramp up the magnetic field to as high as 30 tesla; and they plan to upgrade the laser to 8 kilojoules. They also aim to switch from fuel made of the hydrogen isotope deuterium to fuel containing both deuterium and another isotope, tritium — which should also lift yields. By 2015, they hope to achieve a yield of 10¹⁶ neutrons, or about 100 kilojoules — enough to show that ignition is within reach.

It could be crucial to make progress quickly. The US National Nuclear Security Administration, the division of the Department of Energy that funds the NIF, the Z machine and other laser fusion efforts, plans to deliver an assessment to Congress in 2015 about the future of these technologies. If MagLIF hits its 100-kilo­joule goal, it could bolster an argument for upgrading the Z machine to 60 million amperes or more, which simulations suggest would be sufficient to reach ignition.

“We’re all hoping that they will, in fact, find success with their early shots to justify the construction of a larger machine,” says Hammer.

Source: scientificamerican.com