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    A collisional-radiative model of iron vapour in a thermal arc plasma
    (Bristol : IOP Publ., 2017-05-15) Baeva, M.; Uhrlandt, D.; Murphy, A.B.
    A collisional-radiative model for the ground state and fifty effective excited levels of atomic iron, and one level for singly-ionized iron, is set up for technological plasmas. Attention is focused on the population of excited states of atomic iron as a result of excitation, de-excitation, ionization, recombination and spontaneous emission. Effective rate coefficients for ionization and recombination, required in non-equilibrium plasma transport models, are also obtained. The collisional-radiative model is applied to a thermal arc plasma. Input parameters for the collisional-radiative model are provided by a magnetohydrodynamic simulation of a gas-metal welding arc, in which local thermodynamic equilibrium is assumed and the treatment of the transport of metal vapour is based on combined diffusion coefficients. The results clearly identify the conditions in the arc, under which the atomic state distribution satisfies the Boltzmann distribution, with an excitation temperature equal to the plasma temperature. These conditions are met in the central part of the arc, even though a local temperature minimum occurs here. This provides assurance that diagnostic methods based on local thermodynamic equilibrium, in particular those of optical emission spectroscopy, are reliable here. In contrast, deviations from the equilibrium atomic-state distribution are obtained in the near-electrode and arc fringe regions. As a consequence, the temperatures determined from the ratio of line intensities and number densities obtained from the emission coefficient in these regions are questionable. In this situation, the collisional-radiative model can be used as a diagnostic tool to assist in the interpretation of spectroscopic measurements.
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    The 2022 Plasma Roadmap: low temperature plasma science and technology
    (Bristol : IOP Publ., 2022) Adamovich, I.; Agarwal, S.; Ahedo, E.; Alves, L.L.; Baalrud, S.; Babaeva, N.; Bogaerts, A.; Bourdon, A.; Bruggeman, P.J.; Canal, C.; Choi, E.H.; Coulombe, S.; Donkó, Z.; Graves, D.B.; Hamaguchi, S.; Hegemann, D.; Hori, M.; Kim, H.-H.; Kroesen, G.M.W.; Kushner, M.J.; Laricchiuta, A.; Li, X.; Magin, T.E.; Mededovic Thagard, S.; Miller, V.; Murphy, A.B.; Oehrlein, G.S.; Puac, N.; Sankaran, R.M.; Samukawa, S.; Shiratani, M.; Šimek, M.; Tarasenko, N.; Terashima, K.; Thomas Jr, E.; Trieschmann, J.; Tsikata, S.; Turner, M.M.; Van Der Walt, I.J.; Van De Sanden, M.C.M.; Von Woedtke, T.
    The 2022 Roadmap is the next update in the series of Plasma Roadmaps published by Journal of Physics D with the intent to identify important outstanding challenges in the field of low-temperature plasma (LTP) physics and technology. The format of the Roadmap is the same as the previous Roadmaps representing the visions of 41 leading experts representing 21 countries and five continents in the various sub-fields of LTP science and technology. In recognition of the evolution in the field, several new topics have been introduced or given more prominence. These new topics and emphasis highlight increased interests in plasma-enabled additive manufacturing, soft materials, electrification of chemical conversions, plasma propulsion, extreme plasma regimes, plasmas in hypersonics, data-driven plasma science and technology and the contribution of LTP to combat COVID-19. In the last few decades, LTP science and technology has made a tremendously positive impact on our society. It is our hope that this roadmap will help continue this excellent track record over the next 5-10 years.