Luca Vialetto

All Publications

• Plasma-induced reversible surface modification and its impact on oxygen heterogeneous recombination JOURNAL OF PHYSICS D-APPLIED PHYSICS Afonso, J., Vialetto, L., Guerra, V., Viegas, P. 2024; 57 (4)

  View details for DOI 10.1088/1361-6463/ad039b

  View details for Web of Science ID 001090052000001

• Electron-neutral collision cross sections for H2O: II. Anisotropic scattering and assessment of the validity of the two-term approximation JOURNAL OF PHYSICS D-APPLIED PHYSICS Budde, M., Dias, T., Vialetto, L., Pinhao, N., Guerra, V., Silva, T. 2023; 56 (25)

  View details for DOI 10.1088/1361-6463/accaf4

  View details for Web of Science ID 000972976300001

• A Modified Fokker-Planck Approach for a Complete Description of Vibrational Kinetics in a N-2 Plasma Chemistry Model JOURNAL OF PHYSICAL CHEMISTRY A Altin, M., Vialetto, L., Longo, S., Viegas, P., Diomede, P. 2022: 261-275

  Abstract

  The Fokker-Planck (FP) approach for the description of vibrational kinetics is extended in order to include multiquanta transitions and time dependent solutions. Due to the importance of vibrational ladder climbing for the optimization of plasma-assisted nitrogen fixation, nitrogen is used as a test case with a comprehensive set of elementary processes affecting the vibrational distribution function (VDF). The inclusion of the vibrational energy equation is shown to be the best way to model transient conditions in a plasma reactor using the FP approach. Results are benchmarked against results from the widely employed state-to-state (STS) approach for a wide parameters range. STS and FP solutions agree within ∼10% for the lowest vibrational levels, while time dependent VDFs are in agreement with the STS solution within a ∼ 5% error. Using the FP approach offers the possibility to parametrize drift and diffusion coefficients in energy space as a function of vibrational and gas temperature, providing intuitive and immediate insights into energy transport within the vibrational manifold.

  View details for DOI 10.1021/acs.jpca.2c06042

  View details for Web of Science ID 000907022300001

  View details for PubMedID 36580578

  View details for PubMedCentralID PMC9841568

• Electron-neutral collision cross sections for H2O: I. Complete and consistent set JOURNAL OF PHYSICS D-APPLIED PHYSICS Budde, M., Dias, T., Vialetto, L., Pinhao, N., Guerra, V., Silva, T. 2022; 55 (44)

  View details for DOI 10.1088/1361-6463/ac8da3

  View details for Web of Science ID 000852867700001

• Energy partitioning in N-2 microwave discharges: integrated Fokker-Planck approach to vibrational kinetics and comparison with experiments PLASMA SOURCES SCIENCE & TECHNOLOGY Altin, M., Viegas, P., Vialetto, L., van de Steeg, A. W., Longo, S., van Rooij, G. J., Diomede, P. 2022; 31 (10)

  View details for DOI 10.1088/1361-6595/ac93af

  View details for Web of Science ID 000868166100001

• Vibrational excitation cross sections for non-equilibrium nitric oxide-containing plasma PLASMA SOURCES SCIENCE & TECHNOLOGY Laporta, Vialetto, L., Guerra 2022; 31 (5)

  View details for DOI 10.1088/1361-6595/ac6a0f

  View details for Web of Science ID 000796221800001

• Charged particle kinetics and gas heating in CO2 microwave plasma contraction: comparisons of simulations and experiments PLASMA SOURCES SCIENCE & TECHNOLOGY Vialetto, L., van de Steeg, A. W., Viegas, P., Longo, S., van Rooij, G. J., van de Sanden, M. M., van Dijk, J., Diomede, P. 2022; 31 (5)

  View details for DOI 10.1088/1361-6595/ac56c5

  View details for Web of Science ID 000793493400001

• The Chemical Origins of Plasma Contraction and Thermalization in CO2 Microwave Discharges JOURNAL OF PHYSICAL CHEMISTRY LETTERS van de Steeg, A. W., Vialetto, L., da Silva, A., Viegas, P., Diomede, P., van de Sanden, M. M., van Rooij, G. J. 2022; 13 (5): 1203-1208

  Abstract

  Thermalization of electron and gas temperature in CO2 microwave plasma is unveiled with the first Thomson scattering measurements. The results contradict the prevalent picture of an increasing electron temperature that causes discharge contraction. It is known that as pressure increases, the radial extension of the plasma reduces from ∼7 mm diameter at 100 mbar to ∼2 mm at 400 mbar. We find that, simultaneously, the initial nonequilibrium between ∼2 eV electron and ∼0.5 eV gas temperature reduces until thermalization occurs at 0.6 eV. 1D fluid modeling, with excellent agreement with measurements, demonstrates that associative ionization of radicals, a mechanism previously proposed for air plasma, causes the thermalization. In effect, heavy particle and heat transport and thermal chemistry govern electron dynamics, a conclusion that provides a basis for ab initio prediction of power concentration in plasma reactors.

  View details for DOI 10.1021/acs.jpclett.1c03731

  View details for Web of Science ID 000754489600007

  View details for PubMedID 35089038

• Effect of anisotropic scattering for rotational collisions on electron transport parameters in CO PLASMA SOURCES SCIENCE & TECHNOLOGY Vialetto, L., Ben Moussa, A., van Dijk, J., Longo, S., Diomede, P., Guerra, Alves, L. L. 2021; 30 (7)

  View details for DOI 10.1088/1361-6595/ac0a4d

  View details for Web of Science ID 000668702800001

• Resolving discharge parameters from atomic oxygen emission PLASMA SOURCES SCIENCE & TECHNOLOGY Viegas, P., Vialetto, L., van de Steeg, A. W., Wolf, A. J., Bongers, W. A., van Rooij, G. J., van de Sanden, M. M., Diomede, P., Peeters, F. J. 2021; 30 (6)

  View details for DOI 10.1088/1361-6595/ac04bd

  View details for Web of Science ID 000667477200001

• Plasma Modeling and Prebiotic Chemistry: A Review of the State-of-the-Art and Perspectives MOLECULES Longo, G., Vialetto, L., Diomede, P., Longo, S., Laporta, V. 2021; 26 (12)

  Abstract

  We review the recent progress in the modeling of plasmas or ionized gases, with compositions compatible with that of primordial atmospheres. The plasma kinetics involves elementary processes by which free electrons ultimately activate weakly reactive molecules, such as carbon dioxide or methane, thereby potentially starting prebiotic reaction chains. These processes include electron-molecule reactions and energy exchanges between molecules. They are basic processes, for example, in the famous Miller-Urey experiment, and become relevant in any prebiotic scenario where the primordial atmosphere is significantly ionized by electrical activity, photoionization or meteor phenomena. The kinetics of plasma displays remarkable complexity due to the non-equilibrium features of the energy distributions involved. In particular, we argue that two concepts developed by the plasma modeling community, the electron velocity distribution function and the vibrational distribution function, may unlock much new information and provide insight into prebiotic processes initiated by electron-molecule collisions.

  View details for DOI 10.3390/molecules26123663

  View details for Web of Science ID 000666280600001

  View details for PubMedID 34208472

  View details for PubMedCentralID PMC8235047

• Revisiting spontaneous Raman scattering for direct oxygen atom quantification OPTICS LETTERS van de Steeg, A. W., Vialetto, L., Silva, A. F., Peeters, F. J., van den Bekerom, D. M., Gatti, N., Diomede, P., van de Sanden, M. M., van Rooij, G. J. 2021; 46 (9): 2172-2175

  Abstract

  In this Letter, the counterintuitive and largely unknown Raman activity of oxygen atoms is evaluated for its capacity to determine absolute densities in gases with significant O-density. The study involves ${\rm CO}_2$ microwave plasma to generate a self-calibrating mixture and establish accurate cross sections for the $^3{\!P_2}{\leftrightarrow ^3}{\!P_1}$ and $^3{\!P_2}{\leftrightarrow ^3}{\!P_0}$ transitions. The approach requires conservation of stoichiometry, confirmed within experimental uncertainty by a 1D fluid model. The measurements yield ${\sigma _{J = 2 \to 1}} = 5.27 \pm _{{\rm sys}:0.53}^{{\rm rand}:0.17} \times {10^{- 31}}\;{{\rm cm}^2}/{\rm sr}$ and ${\sigma _{J = 2 \to 0}} = 2.11 \pm _{{\rm sys}:0.21}^{{\rm rand}:0.06} \times {10^{- 31}}\;{{\rm cm}^2}/{\rm sr}$, and the detection limit is estimated to be $1 \times {10^{15}}\;{{\rm cm}^{- 3}}$ for systems without other scattering species.

  View details for DOI 10.1364/OL.424102

  View details for Web of Science ID 000645860800043

  View details for PubMedID 33929446

• Benchmarking of Monte Carlo flux simulations of electrons in CO2 PLASMA SOURCES SCIENCE & TECHNOLOGY Vialetto, L., Viegas, P., Longo, S., Diomede, P. 2020; 29 (11)

  View details for DOI 10.1088/1361-6595/abbac3

  View details for Web of Science ID 000588837500001

• Insight into contraction dynamics of microwave plasmas for CO2 conversion from plasma chemistry modelling PLASMA SOURCES SCIENCE & TECHNOLOGY Viegas, P., Vialetto, L., Wolf, A. J., Peeters, F. J., Groen, P. C., Righart, T. H., Bongers, W. A., van de Sanden, M. M., Diomede, P. 2020; 29 (10)

  View details for DOI 10.1088/1361-6595/abb41c

  View details for Web of Science ID 000582988500001

• Benchmark calculations for electron velocity distribution function obtained with Monte Carlo Flux simulations PLASMA SOURCES SCIENCE & TECHNOLOGY Vialetto, L., Longo, S., Diomede, P. 2019; 28 (11)

  View details for DOI 10.1088/1361-6595/ab4b95

  View details for Web of Science ID 000505706200003

• First hydrogen operation of NIO1: Characterization of the source plasma by means of an optical emission spectroscopy diagnostic Barbisan, M., Baltador, C., Zaniol, B., Cavenago, M., Fantz, U., Pasqualotto, R., Serianni, G., Vialetto, L., Wuenderlich, D. AMER INST PHYSICS. 2016: 02B319

  Abstract

  NIO1 (Negative Ion Optimization 1) is a compact and flexible radio frequency H(-) ion source, developed by Consorzio RFX and INFN-LNL. The aim of the experimentation on NIO1 is the optimization of both the production of negative ions and their extraction and beam optics. In the initial phase of its commissioning, NIO1 was operated with nitrogen, but now the source is regularly operated also with hydrogen. To evaluate the source performances, an optical emission spectroscopy diagnostic was installed. The system includes a low resolution spectrometer in the spectral range of 300-850 nm and a high resolution (50 pm) one, to study, respectively, the atomic and the molecular emissions in the visible range. The spectroscopic data have been interpreted also by means of a collisional-radiative model developed at IPP Garching. Besides the diagnostic hardware and the data analysis methods, the paper presents the first plasma measurements across a transition to the full H mode, in a hydrogen discharge. The characteristic signatures of this transition in the plasma parameters are described, in particular, the sudden increase of the light emitted from the plasma above a certain power threshold.

  View details for DOI 10.1063/1.4936084

  View details for Web of Science ID 000371740900140

  View details for PubMedID 26932047