Speaker
Description
WP9 - Research and Development of optical plasma diagnostics and modelling for fusion
Plasma Sources and Optical Diagnostics
Domenico Aceto, Arshad Hussain, Paolo Francesco Ambrico, Giorgio Dilecce
CNR- ISTP sezione di Bari
Within the framework of the NEFERTARI project, a high-density plasma discharge prototype based on an Inverse Brush Cathode (IBC) Reflex configuration has been designed, installed, and experimentally characterized. The system operates in pulsed DC mode, with optional RF superposition, at pressures in the 0.01–0.1 Torr range. The discharge geometry consists of eight water-cooled cathodes arranged in opposing pairs around a central spherical anode, enabling a pronounced reflex effect that enhances ionization efficiency at low pressure.
Electrical characterization was performed through current–voltage measurements under different cathode configurations, clearly demonstrating the role of the reflex mechanism in sustaining high discharge currents even in weakly collisional regimes. Time-resolved Langmuir probe diagnostics, synchronized with the discharge pulse, were employed to measure electron density, electron temperature, and plasma potential. Electron densities follow the discharge current trend, while electron temperatures remain below 1 eV, consistent with a partially ionized, low-temperature plasma well suited for spectroscopic investigations.
RF superposition produces a substantial increase in plasma luminosity and electron density. Quantitative probe diagnostics in this regime are partially affected by RF-induced perturbations, for which mitigation strategies are currently under development.
Beyond hydrogen operation, laser-induced fluorescence (LIF) diagnostics were carried out on N₂ and N₂/O₂ discharges using laser instrumentation acquired within the project [1]. A pin-to-plate geometry operating at 100 Torr in pure nitrogen and a plate-to-plate configuration fed by air at atmospheric pressure were investigated, providing spatially resolved measurements of excited-state populations and collisional processes. These results yield insight into energy transfer mechanisms and plasma chemistry relevant to both spectroscopic studies and application-oriented research [2-9], and are further supported by comparison with numerical simulations.
[1]: L. Ibba et al 2025 Plasma Sources Sci. Technol. 34 105012, DOI 10.1088/1361-6595/ae0765
[2]: M. Ambrico et al 2025 J. Mater. Chem. A 14 4996-5006, DOI 10.1039/D5TA05024C
[3]: D. Aceto et al 2025 Chem. Biol. Technol. Agric. 12 151, DOI 10.1186/s40538-025-00865-0
[4]: M. Ambrico et al 2025 J. Phys. D: Appl. Phys. 58 125302, DOI 10.1088/1361-6463/ada44d
[5]: R. D’Orsi et al 2025 J. Phys. Mater. 8 045003, DOI 10.1088/2515-7639/adf94c
[6]: P.R. Rotondo et al 2025 Sci Rep 15 5536, DOI 10.1038/s41598-025-88369-7
[7]: D. Aceto et al, Frontiers in Low Temperature Plasma Diagnostics 2024 (FLTPD XV), 28/04-02/05/2024, Castle Liblice, Prague, Czech Republic, oral presentation: “Laser Diagnostics in an Atmospheric Pressure, Plane-to-Plane Nanosecond Pulsed Diffused Dielectric Barrier Discharge”.
[8]: D. Aceto et al, Europhysics Conference on the Atomic and Molecular Physics of Ionized Gases 2024 (ESCAMPIG XXVI), 9-13/07/2024, Brno, Czech Republic, poster presentation: “Atmospheric Pressure, Low -Temperature Plasma applications for decontamination of agrifood products”.
[9]: D. Aceto et al, International Conference on Phenomena in Ionized Gases 36th Edition (ICPIG 2025), 20-25/07/2025, Aix en Provence, France, poster presentation: “Plasma-Activated Fog treatments as sustainable protective tool in post-harvest”.