Charge state evolution in electron beam ion trap

Recently, at the M. Smoluchowski Institute of Physics of the Jagiellonian University a commercial electron beam ion trap (EBIT) was installed for teaching and scientific purposes. The first experiments were focused on observation of radiative recombination and dielectronic recombination. An investigation of higher order resonant recombination processes was also initiated. These recombination processes depend strongly on the charge state of the ions involved in these processes. The EBIT plasma contains always a mixture of different charge states. Therefore, the charge-state distribution of the ions is crucial for the observed atomic processes. A new diagnostics tool for this distribution and a possibility of its manipulation form the main goal of the present paper which may help to better understand the processes investigated with an EBIT

Hypersatellite Kα Production in Trapped Ar Ions at KK Trielectronic Recombination Energies

Funding Information: W.B.-N. acknowledges DSC Grant MNiSzW Nr 7150/E-338/M/2018, the GET_INvolved Programme at FAIR/GSI (www.fair-center.eu/get_involved) and the JIPhD program through contract POWR.03.05.00-00-Z309/17-00. D.S.L.M. acknowledges the Kosciuszko Foundation. P.A and F.G acknowledge the FCT through project number UID/04559/2020 (LIBPhys). Publisher Copyright: © 2023 by the authors.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.publishersversionpublishe

Multielectron recombination processes in He-like oxygen at the CRYRING@ESR electron cooler

In electron-ion collisions recombination processes play a very important role.A good understanding of these processes in the laboratory enables developmentof theory, which is useful for plasma diagnostics. For example, recombinationprocesses affect the state of astrophysical objects [1, 2], as well as nuclearfusion plasma [3, 4]. In many cases electron-ion interaction involves more thanone electron. There, electron-electron interaction is a crucial aspect of theseparticular atomic reactions. This doctoral dissertation focuses on rare atomicprocesses both from theoretical and experimental perspectives.In Highly Charged Ions Laboratory in the Institute of Physics of the Jagiellonian University, an electron beam ion trap (Dresden EBIT [5, 6], DREEBITCo.) was installed in 2012. This compact room-temperature HCI-trap, equipped with an X-ray detector (XFlash 5030, Bruker Co.), opens a wide rangeof possibilities for studies of atomic processes associated with ion productionand trapping in an EBIT [6].The aim of this PhD dissertation is to collect experimental data and comparethem with theoretical calculations done with the use of Flexible Atomic Code(FAC [7]). First examined process is called radiative recombination (RR). Thecapture of a free electron into a bound state of an ion is accompanied by theemission of a photon. It is worth mentioning, that a good resolution of RRspectra for bare argon ions (Ar18+) is an evidence of EBIT great research opportunities [8, 9, 10]. Secondly, resonant recombination involving more thanone electron has been discussed. The most basic of these resonant processes isdielectronic recombination (DR) where a free electron is captured into a boundstate of an ion with the simultaneous excitation of a core electron [11, 12, 13,14, 15, 16, 17]. These resonantly populated excited states decay via characteristic K-shell X-ray emission. Very good resolution of the X-ray detectorenabled the K-LL DR resonances to be distinguished for He- up to C-like Arions [8, 18, 19]. In the observed X-ray energy region, in addition to the DR,the intrashell tricelectronic recombination (intrashell TR) has been seen [8].The last part of the presented studies is dedicated to the multishell TR, specifically to the KK TR [18]. Here, the resonant capture of a free electron toan ion-bound state transfers simultaneously two K-shell electrons to a higheratomic shell. This way, a doubly-excited K-shell state is produced and, inmost cases, it decays via emission of two photons. The first transition to the0empty K shell is responsible for emission of the Kh hypersatellite photon withan energy slightly higher than energy of the following Kssatellite transition.A maximum-like behavior of the intensity ratio between Khαand Ksα has beenreported. This behavior is a fingerprint of the investigated TR process. Finally, to the best of my knowledge, this is the first successful observation ofthis TR process [20].One has to add, that the presented research analysis was supplemented withorginal methods of determination of the charge state distribution of ions inthe UJ-EBIT plasma. These methods were based on the analysis of the X-raylines profile [21]

Higher-Order Recombination Processes in Argon Ions Observed via X-ray Emission in an EBIT

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