Radiative Surface Waves in Layered Plasma–Dielectric Structures and Prospects of Their Application in Plasma Microwave Electronics

Surface waves in layered systems consisting of material media with different frequency dispersions are considered: dielectric–plasma–vacuum, vacuum–plasma–plasma, and dielectric–vacuum–plasma. It is shown that in such systems, one of the surface waves can be radiative into a medium that does not form an interface for the surface wave under consideration, in view of which the wave becomes decaying. In the dielectric–vacuum–plasma system, there is only one surface wave localized at the vacuum–plasma interface, which is radiative into the dielectric in a certain region of wavenumbers with a not too small thickness of the vacuum layer. For all cases, the possibilities of exciting surface waves of a layered structure by an electron beam are analyzed. It is indicated which surface waves will be excited most efficiently. The prospects of using such waves in plasma microwave electronics in the development of sub-terahertz and possibly terahertz frequency ranges are shown.

A versatile set-up to study plasma/microwave sources for liquid fuel ignition

Motivated by the high demand for an alternative, more reliable, high energy ignition source to facilitate the re-ignition of lean-burn combustion chambers which are necessary to reduce pollutant emissions, a new set-up has been designed to study plasma/microwave sources. The use of a waveguide-based resonant cavity leads to very low power plasma ignition. An example in this paper shows that a plasma at atmospheric pressure can be maintained with less than 2 W input power. Such a performance is possible using the large variety of possible adjustments (resonance frequency, different kind of initiators, etc.) that this versatile set-up offers. To illustrate the wide range of possible studies, another example is given and discussed : minimum ignition energy for an ethanol droplet stream with aluminum and stainless steel initiators. The results show that the initiator material and its surface quality have an influence on the minimum ignition energy, especially for large gaps. Depending on the gap size we can get down to under 10 W entering the cavity to ignite the droplet stream.

RESEARCH ON DESIGNING COMPOSITE TECHNIQUES FOR OBTAINING THE 3D HYBRID COMPOSITES WITH CONDUCTIVE AND SEMICONDUCTIVE PROPERTIES FOR SENSORS AND ACTUATORS

In the paper are presented several aspects concerning the experimental preparation for sensors and actuators by using the factorial scheme based on independent and dependent variables and principal component analysis. The leading technologies envisaged are the classical ones (padding, coating, and printing) and advanced technologies such as RF plasma, microwave, and 3D printing. PCA is a statistical procedure well known by researchers and is based on orthogonal transformation of the variables possible correlated into a set of variable linearly uncorrelated (PC). The resulting vectors are a linear combination of the variables and contain x observation and represent an uncorrelated orthogonal set. Besides, in this paper are presented several technological flows for obtaining conductive or semiconductive 3D composite materials by using the standard and advanced technologies above mentioned