TY  - THES
AU  - Biela-Nowaczyk, Weronika
TI  - Multielectron recombination processes in He-like oxygen at the CRYRING@ESR electron cooler
PB  - Jagiellonian University Krakow
VL  - Dissertation
CY  - Krakow
M1  - GSI-2023-00220
SP  - 158
PY  - 2022
N1  - Dissertation, Jagiellonian University Krakow, 2022
AB  - 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].
LB  - PUB:(DE-HGF)11
UR  - https://repository.gsi.de/record/251019
ER  -