The secret of electron heating in low temperature plasmas has been discovered by the Bochum researchers at the Center of Excellence “Plasma Science and Technology” (CPST) at the Ruhr University – who have thereby found the answer to the question which has been puzzling scientists for decades of why particularly the electrons in such plasmas are so hot.
The non-linear behavior of the boundary sheath causes the electric current flowing in the plasma to oscillate. This results in an increase of the electrical current, and thus in the heating of the plasma. This previously unknown mechanism called “non-linear electron resonance heating” is the subject of a report by researchers in the current issue of the world's foremost physics letters journal "Physical Review Letters", which will appear in print on Friday, Aug. 29.
Basic understanding after 30 years
With their research results the Bochum Electrical Engineers Dr. Thomas Mussenbrock and Prof. Ralf Peter Brinkmann (Institute for Theoretical Electrical Engineering at the Ruhr University of Bochum) together with colleagues from the University of California at Berkeley surrounding Prof. Mike Lieberman have contributed to basic understanding of so-called low temperature plasma, which has already been in industrial use for over 30 years. “Since the nineteen seventies vigorous technical debates have been in progress regarding the function of plasma, which, however, have not led to any conclusive results. In particular, we do not fully understand the exact energy coupling mechanism“, stated Thomas Mussenbrock. “Ever since plasma has been discovered and utilized, significant differences have existed between theoretical predictions on the behavior of the plasma and actual measurements.” The mechanism now discovered at the Ruhr University provides a new approach for explaining the heating mechanisms in low temperature plasma for the first time.
Versatile types of plasma
Without plasma, no Pentium: For example electrically excited gases can be used to form the structures on microchips by removing or depositing materials in the nanometer range. Today plasma-based processes already account for nearly one-half of all processing steps in the field of microelectronics. But plasma technology is not only essential here; it is also used in lighting, environmental and medical engineering. One of the particular characteristics of the low temperature plasmas used is the number of electrons contained with temperatures of over 10,000 degrees Celsius – in contrast to ions present as well as neutral atoms and molecules, which are comparatively cold at virtually room temperature . This thermal non-equilibrium is what initiates chemical reactions and other processes, making low temperature plasmas so versatile.
Key to specific utilization
The question of why the electrons could become so hot particularly at very low gas pressures, was not clarified completely up to this time. Researchers at CPST have now been successful in proving this “non-linear electron resonance heating” theoretically and experimentally. The basis of this mechanism is the intrinsic tendency of the plasma to oscillate. Excitation of a certain oscillation – starting from non-linear behavior of the plasma boundary sheath – causes a “self-excitation” of the oscillation in the electrical current flowing in the plasma. Theoretical studies have shown that non-linear electron resonance heating can more than double the efficiency of the energy coupling. Laboratory tests at CPST by Prof. Uwe Czarnetzki (Department of Physics and Astronomy) and Prof. Peter Awakowicz (Department of Electrical Engineering and Information Technology) have confirmed this result. The RUB researchers have simultaneously provided a new approach to understanding how plasma can be excited electrically for maximum efficiency. “Electron resonance can even be controlled specifically to initiate the mechanism”, according to Thomas Mussenbrock.
Smallest transistor worldwide switches current with a single atom in solid electrolyte
17.08.2018 | Karlsruher Institut für Technologie (KIT)
Protecting the power grid: Advanced plasma switch for more efficient transmission
17.08.2018 | DOE/Princeton Plasma Physics Laboratory
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
20.08.2018 | Information Technology
20.08.2018 | Life Sciences
20.08.2018 | Information Technology