Artificial Sun, Fusion etc. - The Stuff of This Century and the Next
Mar 16, 2011
The "Artificial Sun", Fusion and Cold Fusion Power By Dr. Joseph S. Maresca
The EAST project or "Artificial Sun" relies on complex theories and requires advanced technologies because exceedingly high temperatures are reached in the nuclear fusion reactions. This process is similar to reactions that take place in the sun itself . Scientists are assembling a device to withstand the extremely high temperatures of the sun together with the deuterium-tritium fusion reaction itself.
Commercialization is aimed at supplying a stable and continuous output of energy generated by a fusion reaction. The result is an "artificial sun" which produces a safe, clean, and virtually unlimited energy source. In essence, the fusion of the hydrogen isotopes deuterium and tritium results in a tiny loss of mass coupled with a huge release of energy. This is a huge undertaking in a number of fields; namely, theoretical physics, materials science/structure of matter, thermodynamics and electrical power generation.
Scientists everywhere have worked hard to build a device to meet such exacting specifications. Various experiments have shown that a Tokamak is likely to be the best solution. By the mid- 1990s , nearly 100 laboratories equipped with experimental Tokamak devices were in existence globally .
After years of theoretical study and numerous experiments, Wan Yuanxi and his colleagues believed that a non-circular Tokamak device might perform better for the deuterium-tritium fusion reaction. In 1997, Wan together with a group of scientific colleagues, conceptualized an idea to build a non-circular experimental superconducting Tokamak.
Basing his work on known scientific principles, Wan Yuanxi formulated a complete research plan to minimize the potential risks. After years of research , Wan Yuanxi and the EAST project team have made a major breakthrough in Tokamak study.
From the conceptual formulation through to the final stage of generating an electric current, the EAST project team took only a decade and 300 million yuan (US$40 million) in monetary resources. Compared to similar projects elsewhere , China's EAST project team managed to complete their research cheaply and in record time . 1)
The wiring which carries the electric current is another research challenge. Graphene is a material recently developed for use in electronics. Graphene is the name given to a flat monolayer of carbon atoms that are tightly packed into a 2D honeycomb lattice; like a molecular window screen that is one atom thick.
Graphene is the thinnest possible material and its strength is about 200 times stronger than steel . Graphene conducts electricity better than any material known in the engineering art at room temperature. Researchers at Columbia University's Fu Foundation School of Engineering explained that graphene is the strongest material ever measured . Essentially, "It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap." The next research challenge is to insulate the graphene at extremely high temperatures. 2)
Achieving fusion at room temperature was considered impossible until 1989 when Martin Fleischmann and Stanley Pons at the University of Utah (US) startled scientists with a simple experiment.
The scientists connected a battery to a pair of palladium electrodes immersed in a jar of water containing deuterium (a heavier form of hydrogen) . The electrolytic cell produced heat energy in excess of what was consumed. Both claimed that the origin of the energy was nuclear and that deuterium nuclei were being packed into the palladium’s molecular lattice in such a way that fusion could take place.
Later, it was shown by other groups and Srinivasan’s experiments at BARC in the early 1990s that the reaction produced tritium as well as helium, indicating that cold fusion was real. 3)
A fusion reactor simply can not melt down. Unlike fission, the fusion reaction requires an enormous input of energy to sustain itself . In practice, a fusion reactor consumes a large fraction of its own output in order to create the conditions necessary for the fusion reaction . Any system failure would cut the power to the reactor; thereby allowing it to cool down .
Furthermore, where fission reactors create large quantities of highly radioactive waste , a fusion reactor creates simply helium. Although the conditions for fusion are extreme, fusion is a far safer technology than fission. Even a catastrophic failure (the reactor physically disintegrates) would impact the immediate area only . There might be a charred building devoid of the radioactivity associated with fission reactions.
Fusion, the merging of two small atoms into one with an extensive release of energy, is the process that powers the sun. This is seen as a potential long-term solution to the world’s energy needs. The reason is that vast amounts of energy would be produced without the greenhouse gas emissions. The practical harnessing and commercialization of this powerhouse is thought to be decades away. The technology is well worth pursuing due to the high stakes involved.
Achieving ignition would represent an important and long-sought step toward implementation . One research problem for the researchers and engineers is that the actual reactions would be taking place inside a 2-mm diameter fuel capsule whose temperature and pressure, as it implodes to 1/40 its initial diameter, become much greater than those at the center of the sun. That’s not an easy environment for taking measurements in order to modulate the system to achieve the desired outcome . The research challenge involves developing research tools to trace the reaction inside an imploding pellet with temperatures of 200 million degrees Kelvin or higher. An operable ignition might require an ideal spherical shape at the center of a hohlraum cavity achievable through more advanced measurements in fractal geometry. Fractal geometry deals with objects in non-integer dimensions which can be achieved through complex algorithms. 4)
In a test facility at the University of Rochester, scientists were able to learn important details about the nature of the electric and magnetic fields in and around this tiny capsule.
With the system they devised, “we’re taking a snapshot of what these electric and magnetic fields look like,” Petrasso says. “This is information that is very difficult if not impossible to obtain any other way.”
National Ignition Facility (NIF) uses an approach called indirect drive inertial fusion, in which the tiny capsule of heavy hydrogen fuel is centered inside a cavity called a hohlraum. Laser beams bombard the inside walls of the hohlraum, heating it and generating x-rays that cause the capsule to implode. Ignition, the goal of the NIF, means the point at which the energy released by some fusing atoms at the center of the capsule provides the “sparkplug” that causes other surrounding super-dense atoms to fuse, and so on, in a chain reaction. 5)
To achieve ignition, diagnostic tools are needed to reveal the details of what actually happens inside the imploding pellet. Temperatures reach 200 million degrees Kelvin and the pressure can reach a trillion times atmospheric pressure. In order for the ignition to work, the capsule of deuterium and tritium (heavy forms of the element hydrogen) must be ideally spherical, strategically placed at the center of the hohlraum cavity, and set to implode with good symmetry. The room for error in this process is unknown now.
In experiments at the Laboratory for Laser Energetics in Rochester, a second capsule was placed nearby and hit by another set of laser beams. A flash of protons was produced and the first capsule was illuminated inside a hohlraum.
Nelson Hoffman, a plasma physicist at Los Alamos National Laboratory, says the MIT team has developed “several very effective ways” of measuring important aspects of what goes on inside the fusion capsules, which he says are essential to know “as an indicator of how close they are to the ignition goal.” He adds that as a result, the MIT team has already found surprising phenomena in the way the electric and magnetic fields are distributed. 6)