Brian O'Rourke

Dielectronic recombination in He-like titanium ions

Dielectronic recombination (DR) has been studied in highly charged He-like Ti ions using an electron beam ion trap. X-rays emitted from radiative recombination (RR) and DR were observed as the electron beam energy was scanned through the resonances. Differential DR resonant strengths were determined by normalizing the DR x-ray intensity to the RR intensity using theoretical RR cross sections. KLn(2 ≤ n ≤ 5) resonant strengths were determined for He-like Ti ions. The differential resonant strengths were calibrated without reference to any theoretical DR calculations while the electron energy scale was derived with reference to the well-known energy for ionization of the He-like and H-like ions from the ground state. Calibration in this way facilitates a more exacting comparison between theory and experiment than has been reported previously. To facilitate this comparison, total and differential theoretical resonance strengths were calculated. These calculations were found to be in good agreement with the measured results.

Electron-impact ionization of hydrogen-like iron ions

Electron-impact ionization cross sections have been determined for hydrogen-like iron ions at selected electron energies between 1.45 and 4.3 times the threshold energy. The cross sections were obtained by measuring the equilibrium ionization balance in an electron beam ion trap. This ionization balance is obtained from x-ray measurements of radiative recombination into the K-shell of hydrogen-like and bare iron ions. The measured cross sections are compared with distorted-wave calculations and several semiempirical formulations.

Electron impact ionization of hydrogen-like molybdenum ions

The electron impact ionization cross sections of hydrogen-like molybdenum ions were measured with an electron beam ion trap at the electron energies of 49.4, 64.4 and 79.6 keV. The results are 2.82(22) × 10 −23 ,3 .13(29) × 10 −23 and 3.23(51) × 10 −23 cm 2 ,r esp ectively. These results are compared with the experimental results measured previously. The agreemen tw ith the results obtained with scaling formulae is also discussed.

A new device for the study of electron-ion interactions

Abstract The conceptual design of a new electron beam ion trap primarily intended for the study of electron–ion interactions is outlined along with some preliminary predictions regarding its capabilities.

Magnetic and electrode structure design for a new EBIT

Electron beam trajectory simulations have been performed to design a new electron beam ion trap. The design of the magnet and electrode structures was optimized based on the results of the simulations.

Design of an electron-beam ion trap to be situated at Queen’s University, Belfast

An electron-beam ion trap (EBIT) has been designed for atomic physics experiments at the Queen’s University of Belfast. A pair of permanent magnets will be used to produce an axial magnetic field to compress an electron beam, whereas pairs of superconducting magnets have been used for traditional EBITs. The design of the new EBIT is detailed and possible experiments are explained to show the feasibility of the EBIT.

Interactions Between Electrons and Highly Charged Iron Ions

This paper is a summary of recent work our group has carried out on cross section measurements of highly charged iron ions. Electron impact ionization cross sections for hydrogen-like iron [1] and dielectronic recombination resonant strengths for the KLM, KLN and KLO processes in helium-like iron were determined [2]. These experiments were performed using an electron beam ion trap.

The measurement of the electron impact ionization cross-sections of hydrogen-like ions

We have measured electron impact ionization cross-sections of hydrogen-like iron and hydrogen-like molybdenum with an electron beam ion trap. The measurements were performed in the electron energy range between 13.5 and 40 keV for hydrogen-like iron and between 50 and 80 keV for hydrogen-like molybdenum.

Dielectronic recombination in highly charged He-like ions

We have determined resonant strengths of the KLn ð2 6 n 6 5Þ resonances for helium-like Ti ions and ð3 6 n 6 5Þ resonances for helium-like Fe ions. The results were obtained using the Tokyo electron beam ion trap. Characteristic X-rays from both dielectronic recombination and radiative recombination were detected as the electron beam energy was scanned through the resonances. 2003 Elsevier Science B.V. All rights reserved.