Plasmapienissä

Plasmapienissä is a Finnish term used in plasma physics to refer to small-scale plasmas, typically microplasmas or plasmas confined within micro- or nano-scale structures. The concept covers plasmas that exist in very small volumes, often near surfaces or inside microchannels, with properties that can differ from larger, bulk plasmas due to strong spatial confinement and rapid diffusion.

These plasmas are usually produced by applying electric fields in gases within restricted geometries. Common generation methods include dielectric barrier discharges in microchannels, capacitively coupled or radio-frequency discharges in small gaps, and atmospheric-pressure plasma jets that operate in confined regions. The small dimensions lead to high electric field strengths and rapid chemistry, enabling the formation of reactive species at relatively low gas temperatures.

In terms of properties, plasmapienissä plasmas are typically non-equilibrium: electrons are much hotter than the bulk gas, which stays close to ambient temperature. Electron densities can span a wide range, and the chemistry is dominated by short-lived radicals and ions. The confinement also influences sheath formation, diffusion, and energy transfer, often yielding unique optical emissions and surface interaction behaviors.

Applications of small-scale plasmas include materials processing, surface modification, and thin-film deposition on micro- and nano-scale devices; microfabrication and nanofabrication; spectroscopy and sensing; and biomedical research through localized sterilization or therapy studies. Diagnostics such as optical emission spectroscopy, laser-induced fluorescence, and miniature Langmuir probes are used to characterize plasmasienissä, though measurements are more challenging due to their restricted volumes and heterogeneous environments.

Note: plasmapienissä is not a universally standardized term; in many contexts, researchers refer to microplasmas or atmospheric-pressure microplasmas.