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Projeto de investigação
Espectroscopia de alta precisão e modelação em plasmas de interesse astrofísico
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Higher-Order Recombination Processes in Argon Ions Observed via X-ray Emission in an EBIT
Publication . SPARC Collaboration; DF – Departamento de Física; LIBPhys-UNL; MDPI - Multidisciplinary Digital Publishing Institute
In electron–ion collisions, recombination processes play a very important role. Recently, multielectron recombination processes have been highly investigated, as they carry information about electron–electron interaction. Among them, the most basic process is dielectronic recombination (DR). The research presented here was conducted using an EBIT at Jagiellonian University. Using X-ray spectroscopy, we conducted research into K-LL, K-LM, K-LN, K-LO and K-MM resonances. The aim of this study was to investigate the contribution of the intershell higher-order recombination processes in collected spectra. A good resolution for the K-LL DR spectrum made it possible to distinguish structures for He- up to C-like Ar ions.
K- and L-shell theoretical fluorescence yields for the Fe isonuclear sequence
Publication . Pinheiro, Daniel; Fernandes, André; Godinho, César; Machado, Jorge; Baptista, Gonçalo; Grilo, Filipe; Sustelo, Luís; Sampaio, Jorge M.; Amaro, Pedro; Leitão, Roberta G.; Marques, José P.; Parente, Fernando; Indelicato, Paul; de Avillez, Miguel; Santos, José Paulo; Guerra, Mauro; DF – Departamento de Física; LIBPhys-UNL; Elsevier
In this work, we present K- and L- shell fluorescence yield values of the full isonuclear sequence of Fe ions, using a state-of-the-art multiconfiguration Dirac–Fock approach. These results may be of importance for spectral fitting and plasma modeling, both in laboratory and astrophysical studies, where Fe is an important benchmark element. The K-shell fluorescence yields were found to be very similar up to the removal of 14 electrons.
Medição de processos de colisão eletrónica em Fe XVII de interesse astrofísico
Publication . Grilo, Filipe Ventura; Amaro, Pedro Manuel Duarte Gonçalves; Shah, Chintan; Marques, José Manuel Pires; Santos, J. P.; López-Urrutia, José R. Crespo; DF – Departamento de Física; LIBPhys-UNL
A análise de espectros de raios-X de alta resolução obtidos em observatórios espaciais requer uma boa compreensão dos processos físicos, nomeadamente os atómicos, que governam a emissão e dinâmica dos plasmas. O complexo de emissão Fe-L de Fe XVII, formado por riscas 3d→2p e 3s→2p, é frequentemente utilizado na referida análise e como diagnóstico de várias propriedades físicas como temperatura, opacidade e densidade do plasma. Neste trabalho, medimos as secções eficazes dos processos de colisão que levam à formação destas riscas, tanto as não-ressoantes (excitação por colisão), como ressoantes (recombinação dieletrónica). Acresce que os dados experimentais obtidos permitem uma validação dos valores teóricos destes processos atómicos.
Measurement of differential collisional excitation cross sections for the Kα emission of He-like oxygen
Publication . Grilo, Filipe; Shah, Chintan; Marques, José; Santos, José Paulo; López-Urrutia, José R. Crespo; Amaro, Pedro; DF – Departamento de Física; LIBPhys-UNL
Hypersatellite Kα Production in Trapped Ar Ions at KK Trielectronic Recombination Energies
Publication . Biela-Nowaczyk, Weronika; Amaro, Pedro; Grilo, Filipe; La Mantia, David S.; Tanis, John; Warczak, Andrzej; DF – Departamento de Física; LIBPhys-UNL; MDPI - Multidisciplinary Digital Publishing Institute
We report measurements of hypersatellite radiation of argon ions in the electron energy region of 5200 eV to 7500 eV. Here, we observed a strong enhancement of this hypersatellite (Formula presented.) production. Trielectronic recombination (TR) is discussed as a possible channel for (Formula presented.) production leading to this enhancement where main TR resonances are expected to occur. Data analysis was mainly based on the extracted intensity ratio of hypersatellite (Formula presented.) to (Formula presented.) lines ((Formula presented.)). In addition, the collisional excitation and the collisional ionisation of the K-shell ions were modeled as main background processes of the K (Formula presented.) X-ray production. The (Formula presented.) / (Formula presented.) intensity ratio shows a significant rise around 6500 eV electron energy by a factor of about two above the background level. This observation is compared with calculations of the expected electron energies for the resonant (Formula presented.) emission due to the KK TR process. The observed rise as a function of the electron collision energy, which occurs in the vicinity of the predicted TR resonances, is significantly stronger and energetically much wider than the results of theoretical calculations for the TR process. However, the experimental evidence of this process is not definitive.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
UI/BD/151000/2021