"Nuclear fusion" is the melting of light nuclei into heavier ones, a process that according to the laws of physics releases enormous amounts of energy. For the past 50 years many scientists have sought ways of harnessing this fusion reaction under controlled reactor conditions as a safe, clean and practically inexhaustible source of energy. Siegbert Kuhn and his team at the Institute of Theoretical Physics at Innsbruck University are making a major contribution to these efforts and positioning Austrian nuclear fusion research at the forefront of international activities in this field by carrying out particle simulation studies of divertor plasmas sponsored by the Austrian Science Fund (FWF) and in cooperation with international research groups.
In order to obtain an adequate number of nuclear fusion reactions for practical energy production, the particles involved must be made to collide with sufficient frequency and sufficient energy. In principle, this can be most readily achieved in an extremely hot hydrogen gas (approx. 100 million degrees) at appropriate density. At these temperatures the gas is fully "ionised", meaning that the gas molecules, which are electrically neutral under normal conditions, are split into positively charged nuclei ("ions") and negatively charged "electrons". "Such a gas is called a `plasma` and the plasma state is commonly referred to as the `fourth state of matter`", Kuhn goes on explaining that plasma is the stuff that stars are made of: "Only imagine it: 99.99 % of all matter in the universe is in the plasma state!". Hot plasma is confined in a ring-shaped vessel (torus) by a magnetic field of suitable structure. The most promising configuration to date is termed "tokamak". The next ambitious aim of international fusion research is the construction of the "International Thermonuclear Experimental Reactor (ITER)", which will be the first reactor to work with a plasma largely heated by the fusion reaction itself and which will come very close to the concept of a future commercial fusion reactor in terms of plasma physics.
In a tokamak a distinction is made between the hot "core plasma", in which the energy-producing nuclear fusion reactions take place, and the cooler "edge plasma" through which the high-energy plasma particles diffusing from the core plasma are passed to the baffle plates of the divertor. "Since there are strict technical limits to the amounts of energy to which divertor plates can be subjected, questions relating to the contact between the plasma and the divertor wall count among the most important scientific and technical challenges of modern fusion research", explains Kuhn. He has obtained important results for a better understanding of the divertor plasma in his project. Existing models and simulation programmes, for example, have been greatly improved and the strong influence of secondary and fast electrons on the edge layer was clearly shown and quantified. Kuhn: "We were also able to make a major contribution to understanding the forming and effects of fast particles which occur during the heating of the tokamak plasma through wave injection and which can seriously damage the divertor plates. In a next step, our results can be directly used for modelling and optimising existing and planned tokamaks."
Monika Scheifinger | alphagalileo
New NASA study improves search for habitable worlds
20.10.2017 | NASA/Goddard Space Flight Center
Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research