First Results of Ion Trapping in the Dresden EBIT II

Hyperfine Interactions - It is well known that many reinforced concrete structures are at risk of deterioration due to chloride ion contamination of the concrete or atmospheric carbon dioxide...     

Wavelength dispersive measurements of characteristic K X-rays of an ECR krypton plasma

X-rays from different transitions of the K series were used to analyze components of the ion charge state distribution inside a microwave heated krypton plasma. It is shown that X-ray transitions involving outer-shell electrons show spectra with clearly resolvable satellite lines arising from low charged ions. In contrast to the evaluation of K_α spectra this allows to get information about the ion charge state distribution in the low ionization region. This revised version was published online in August 2006 with corrections to the Cover Date.     

X-ray emission from highly stripped atomic ions

Relativistic Dirac-Fock (DF) and central-field Dirac-Fock-Slater (DFS) calculations of X-ray emission from highly stripped atomic lead ions have been performed. The X-ray line shifts provide a nonmonotone characteristic of outer-shell ionization. The intensities of the most intense X-ray lines are largely unaffected by the removal of outer-shell electrons.     

High resolution wavelength dispersive X-ray spectroscopy for ECR plasma diagnostics

The high resolution of a Bragg crystal diffraction spectrometer was used to investigate the ion charge distribution of krypton ions inside the plasma of an 14.5 GHz ECR ion source. Analyzing the measured spectra, we got information about the abundances and the relative densities of krypton ions of different charge states.     

Ionization of iridium ions in the Dresden EBIT studied by X-ray spectroscopy of direct excitation and radiative recombination processes

Ir^q+ ( 41≤q≤64) ions with open-shell configurations have been produced in the electron beam of the room-temperature Dresden Electron Beam Ion Trap (Dresden EBIT) at electron excitation energies from 2 keV to 13 keV. X-ray emission from direct excitation processes and radiative capture in krypton-like to aluminium-like iridium ions is measured with an energy dispersive Si(Li) detector. The detected X-ray lines are analyzed and compared with results from multiconfigurational Dirac-Fock (MCDF) atomic structure calculations. This allows to determine dominant produced ion charge states at different electron energies. The analysis shows that at the realized working gas pressure of 5×10^-9mbar for higher charged ions the maximum ion charge state is not preferently determined by the chosen electron beam energy needed for ionization of certain atomic substates, but by the balance between ionization and charge state reducing processes as charge exchange and radiative recombination. This behaviour is also discussed on the basis of model calculations for the resulting ion charge state distribution. Received 12 July 2001 and Received in final form 10 September 2001     

Energy dispersive X-ray spectroscopy for ECR plasma diagnostics

Electron-ion bremsstrahlung spectra down to 4 keV emitted from plasmas of the 7.25 GHz electron cyclotron resonance (ECR) ion source of the Forschungszentrum Rossendorf and of the 14.5 GHz ECR ion source of the Technische Universität (TU) Dresden were de-convoluted using a newly developed integration method. In the approximation of isotropy in velocity space this method yields the exact electron energy distribution function. The high energetic electrons are clearly separated into two Boltzmann distributed populations. Their densities and temperatures could be estimated. Higher frequencies of the microwave can increase the hot and warm electron densities by orders of magnitude. First results are obtained for the behaviour of this populations belonging to the mixture (argon — oxygen). Gas mixing increases the densities of these populations. The influence of the electron energy distribution function on X-ray line intensities is discussed.     

Nd,Yb, Au and UL-subshell ionization probabilities for 92 MeV Ar impact

The Nd, Yb, Au and UL-subshell X-ray emission probabilities as function of the impact parameter have been measured by X-ray—particle coincidence for 92 MeV Ar impact. The derivedL-subshell ionization probabilities show severe deviations from first order perturbation theory (SCA + corrections), although the totalL-shell ionization probabilities are still fairly well described by this approach. As is obvious from the data analysis, the discrepancy is due toL-substate coupling during the collision, which has a strong influence on the subshell ionization process, but is neglected in this theoretical approach. The observed influence of the multiple outer shell ionization on the measured data is also discussed.     

Production of highly charged argon ions from a room temperature electron beam ion trap

In this work, highly charged ions have been extracted from the advanced Electron Beam Ion Source (EBIS-A) developed in a scientific cooperation between the Dresden University of Technology and the DREEBIT GmbH Dresden. The charge state distributions of ions extracted from the EBIS-A are measured in the pulse and leaky modes under different operation conditions. Ar¹⁶⁺ ions with current of 2 pA are produced and extracted in the leaky mode. 3×10⁵ Ar¹⁸⁺ ions per pulse are extracted in the pulse mode. The ion charge state distribution is a     

Retention of the potential energy of multiply charged argon ions incident on copper

The retained fraction of the potential energy of argon ions incident on copper has been measured using stationary calorimetry at charge states up to 9+ and kinetic energies ranging from 75 to 240 eV per ionic charge. An average fraction of 30% to 40% is found with little dependence on the charge number and on the kinetic energy. The retention of the total energy ranges from 60% to 75% and can mainly be accounted for by the retained fraction of the potential energy and the collisional energy lost by reflected ions and sputtered target atoms.     

Production of highly charged argon ions from a room temperature electron beam ion trap

In this work.highly charged ions have been extracted from the advanced Electron Beam Ion Source (EBIS-A) developed in a scientific cooperation between the Dresden University of Technology and the DREEBIT GmbH Dresden.The charge state distributions of ions extracted from the EBIS-A are measured in and extracted in the leaky mode.3×105 Ar18+ ions per pulse are extracted in the pulse mode.The ion charge state distribution is a function of the ionization time.