In the last two decades a rapid increase in research on nonequilibrium atmospheric-pressure discharges has occurred. Applications covers the fields of material science, plasma assisted combustion, plasma medicine. The different devices used (surface discharge, jets, microdischarge) are strongly influenced by several processes, and show a transient behaviour strongly influenced by collisions.
In the presence of such characteristics, the development and deployment of optical diagnostics is an essential tools for the understanding of microscopic processes and the development of new innovative plasma tools.
In our lab the diagnostics tools available are the following:
Optical diagnostic techniques
Time-resolved imaging, on the nanosecond and sub-nanosecond time scale, is used to visualize the breakdown mechanism in the streamer case or in the ‘plasma bullet’ propagation. In the picture The ionization wave propagation in a nanosecond volume discharge.
Time and spatially resolved optical emission spectroscopy (TROES) reaching time resolution down to tens of ps.
Laser-based techniques (laser-induced ﬂuorescence )(LIF), OODR LIF, TALIF .
The LIF techinique can be succesfully applied to monitor radicals , metastable with a time and spatial resolution limited by the laser characteristics, and high sensitivity.
The quantities accessible to spectroscopic diagnostics are gas temperature, electron density, electric ﬁeld and density of transient species, i.e. radicals and electronic metastable states.
Moreover kinetics study of transient species can be perfomed and the experimental data used as input for computer modelling of the discharge kinetics.
Our experience in the discharge design enable us to apply the above mentioned techniques in specially designed discharges, such as single streamer volume/surface dielectric barrier discharges (DBDs). Nevertheless our diagnostics tools can also be used in applicative systems.
Together with the above mentioned optical techiniques a ful set of electrical characterization tecniques is available including langmuir probes for electron density measurements,.
Part of the experimental investigation reported in this page was perfomed in collaboration of dr. Milan Simek of the Institute of PlasmaPhysics Czech Academy of Science. (Nanosecond streamer discharge) .
Energy Transfer in Plasmas @ Bari
APULIA SPACE: Esperti nell’uso di tecnologia abilitanti nel settore dello spazio, PON03PE_00067_6, (2014-2016)