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With compact lasers that use ultra-short laser pulses irradiating arrays of aligned nanowires, scientists are recreating the extreme conditions found in stars. Previously, this was only possible with large “stadium-sized” lasers, as the energy density contained in the center of a star is many billions of atmospheres…
Numerical models validated by the experiments predict that increasing irradiation intensities to the highest levels made possible by today's ultrafast lasers could generate pressures to surpass those in the center of our sun.
The results open a path to obtaining unprecedented pressures in the laboratory with compact lasers. The work could open new inquiry into high energy density physics; how highly charged atoms behave in dense plasmas…
Creating matter in the ultra-high energy density regime could inform the study of laser-driven fusion – using lasers to drive controlled nuclear fusion reactions…
[MIT’s Nuclear Science and Engineering, Director, Dennis] Whyte’s class was able to design a smaller, modular fusion reactor that made use of new high-temperature superconducting tape. After the class finished, Sorbom and other classmates fleshed out some of the less-developed ideas in the original presentation, and, with the assistance of Whyte, published a preconceptual design in the journal Fusion Engineering and Design.
The concept, now known as ARC, is in the line of high-field fusion reactor designs the PSFC [Plasma Science and Fusion Center] has long promoted, most recently with the Alcator C-Mod tokamak, which had its record-setting final run last September [and source of OP]. ARC is designed to explore all the possibilities of high temperature superconductors in a fusion device.
Sorbom soon proposed research that could help take the ARC concept one step further — or smaller. It would require testing how long the high-temperature superconductor (HTS) tapes used to control the plasma could survive the radiation created by the fusion process, and discovering how much shielding they would need.
“I started looking around at the lab spaces we have at MIT and I said, ‘Hey, we have a fission reactor, we have accelerators, we have a magnet group: We have all this infrastructure to do a lot of this testing here. So I pitched the idea to Dennis to do this HTS radiation damage testing.’”
Sorbom plans to test the new magnet technology to failure.
University of Maryland physicist Matt Landreman has made an important revision to one of the most common software tools used to design stellarators. The new method is better at balancing tradeoffs between the ideal magnetic field shape and potential coil shapes, resulting in designs with more space between the coils. This extra space allows better access for repairs and more places to install sensors. Landreman's new method is described in a paper published February 13, 2017 in the journal Nuclear Fusion.
Researchers used the previous method, called the Neumann Solver for Fields Produced by External Coils (NESCOIL) and first described in 1987, to design many of the stellarators in operation today—including the Wendelstein 7-X (W7-X). The largest stellarator in existence, W7-X began operation in [December] 2015 at the Max Planck Institute of Plasma Physics in [Gersfeld] Germany [shutdown for upgrades. Only time period given is 'first half of 2017'].
Landreman's new method, which he calls Regularized NESCOIL—or REGCOIL for short—gets around this by tackling the coil spacing issue of stellarator design in tandem with the shaping of the magnetic field itself. The result, Landreman said, is a fast, more robust process that yields better coil shapes on the first try.
Modeling tests performed by Landreman suggest that the designs produced by REGCOIL confine hot plasma in a desirable shape, while significantly increasing the minimum distances between coils.
The mind-bogglingly complex “star-chamber” called the Wendelstein 7-X creates clean, radiation-free nuclear energy by mimicking what happens in stars like our own sun.
Cold fusion [!!!] – based on safe nuclear fusion rather than the dangerous nuclear fusion of the world’s current reactors has been the dream of physicists since the 1950s.
It confines super-heated helium [!!!] – in plasma form – to spark reactions in twisted three dimensional magnetic fields.
It has now been shown conclusively to work. And the developers can now focus on creating new designs that improve the efficiency of the device.
So HTS [high temperature superconducting] magnets allow for relatively small-size and low-power devices with high performance and widespread rapid commercial deployment opportunities. They also offer energy savings over conventional superconductors, which must be cooled to 4K (-269C). We plan to cool our HTS magnets to around 20K, though they remain superconducting up to 77K.
We have already built two experimental tokamaks and are constructing a third, the ST40. This is due to launch this Spring as part three of a five-stage plan to deliver fusion energy into the grid by 2030. It is designed to ultimately produce plasma temperatures of 100 million degrees (the right temperature range for controlled fusion on earth) though the near-term aim is to reach 15 million degrees (as hot as the centre of the sun) before the end of 2017. ST40 also aims to get within a factor of ten of energy breakeven conditions. To get even closer than that, we must then fine-tune the plasma density, temperature and confinement time.
The system has two emitters with three neutral beam sources each. One emitter targets the core of the plasma while the other targets the edge to exert leverage over the plasma as a whole. A flexible magnet system allows physicists to further control the plasma rotation distribution. In general, the algorithm uses the magnetic coils and the neutral beam emitters in different combinations to change how different regions of the plasma rotate.
The algorithm also balances the effects of the magnets and the neutral beams to make sure the overall plasma doesn't lurch roughly from one speed to another. The aim is to achieve a particular amount of plasma heat, or stored energy, along with the desired plasma rotation -- an innovation that an earlier version of the algorithm lacked.
Goumiri and the team tested the new controller algorithm on a simulated tokamak created by the computer code TRANSP, a PPPL-designed program used in magnetic fusion research around the world. The test showed that the algorithm could successfully modify both the plasma's rotation profile and stored energy in ways that would increase the plasma's stability.
In the future, Goumiri hopes to test her controller algorithm on NSTX-U.
General Fusion has revealed that one of the most critical and complex areas of its research and development – plasma injector technology – has now reached the minimum performance levels required for a larger scale, integrated prototype. This marks a significant step in the company’s progress toward development of its fusion energy technology.
If you compare our approach to fusion to how a diesel engine works, we inject the fuel into a compression chamber and compress it until it gets hot enough to ignite. In our case the fuel is plasma, and the ignition is fusion.” said Chief Financial Officer and Interim CEO Bruce Colwill. “The investment we have made in our plasma injection program over the last few years has paid off.”
General Fusion’s proprietary fusion system is designed to use compression to heat a magnetized plasma of superheated hydrogen gas to temperatures above 150 million degrees Celsius. The company’s program is now advancing to the next stage – developing and integrating plasma injector, compression chamber and pistons in the design of a larger scale prototype.