engleski

Characterisation of plasma source based on single electrode atmospheric pressure plasma jets operating in closed volume

A closed volume plasma source consisting of three independently driven single electrode atmospheric pressure plasma jets (SE-APPJ) was developed in order to study plasma treatment of small biological objects, namely plants and seeds. This design provided a controllable environment in which atmospheric plasma parameters and plasma content can be varied independently of the surrounding atmosphere. Basic SE-APPJ used in this study has been described in more details in ref [1]. The plasma treatment chamber is a cube made of 6 mm thick PVC plates forming 19x19x19 cm3 closed volume. Three jets are introduced from the top side through three tight holes. One side of the chamber has a quartz window to allow for optical spectroscopy. The opposite side of the chamber can be easily opened to allow plants or seeds to be positioned at different place relative to the SE-APPJs (between the jets or at different heights). The samples to be treated were not exposed to the jets directly, rather they were treated by the gas species created in the interaction between the jets and the chosen target material (for example water). Since the treatment chamber is not tightly closed, certain amount of air is always present and its relative content can be adjusted by changing the working gas flow (helium, argon). A stable gas mixture is obtained after a few minutes of operation. The relative content of gases has an effect on the length and width of the jets and consequently on the content of the plasma jets and the afterglow region. For measuring the discharge and plasma parameters, different probes were installed around the atmospheric plasma jets: electromagnetic parameters were measured using a high-voltage probe (Tektronix P6015A) and Pearson current monitor model 85900. Spectral emission was measured by spectrometers Ocean Optics LIBSZOOO+ with 0.1 nm spectral resolution between 200 and 970 nm and Avantes SensLine (Avaspec ULS-RS-TEC) with 0.3 nm spectral resolution from 200 nm to 750 nm. Optical and electrical characterisation of the plasma source was conducted for various input parameters (working gas, delivered power) and target materials [2].The detailed results of plasma source characterisation and the prospect for use in the frame of applications in agriculture will be discussed at the conference. This work was supported in part by Croatian Science Foundation under the project #2753. [1] R. Zaplotnik, Z. Kregar, M. Biséan, A.Vesel, U. Cvelbar, M. Mozetic, and S. Milosevic, EPL, (2014) 106 25001 [2] R. Zaplotnik, M. Biscan, Z. Kregar, U. Cvelbar, M. Mozetic, S. Milosevic, Spectrochemica Acta 8, 2015, 103, 124-130

atmospheric pressure plasma jet, optical emission spectroscopy

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