Deceleration Beamline

MSci research, Max-Planck-Institut für Kernphysik
Supervisor: Priv.-Doz. Dr J. R. Crespo López-Urrutia
Dates: 2008 - 2009

I helped simulate, construct and commission a deceleration beamline for highly charged ions, as part of the Heidelberg Electron Beam Ion Trap (EBIT).

The solar wind is a stream of highly charged ions that flow through the solar system, originating from the sun's corona. After x-ray emission was observed from the Comet Hyakutake in 1996, it was postulated that the interaction between the solar wind and neutral atoms in the comet coma were the origin of the x-ray emission.

When highly charged ions interact with neutral atoms, charge transfer can occur from the highly charged ion to the neutral. The electron can be captured into an excited state and as it de-excites to the ground state x-ray emission occurs. In order to understand and better characterise solar x-ray spectra of these phenomena the equivalent conditions were recreated in the lab. An electron beam ion trap uses electron bombardment to generate highly charged ions, in this work the argon species Ar18+ and Ar17+. These were transported, focused and decelerated using electro-static lenses into neutral argon gas.

Identification of xenon ion species from EBIT. Image reproduced with permission © Elsevier 2010.

My work was to simulate the electrostatic properties of the deceleration lens in order to determine and optimise real-world operating parameters. With colleagues I constructed the beamline, installing and commisioning  vacuum systems, electrostatic lenses and particle detectors.

We were successfully able to identify argon K-α and higher-order transistions, as well as the decay of metastable Ar16+. Lower hardness ratios were observed in our results than by other similar experiments, as a result of lower background counts achieved using coincidence spectroscopy. We were also able to nanostructure a polymer surface using individual highly charged xenon ions (Xe48+). More about this work, along with the beamline design can be read here.

A copy of my MSci thesis detailing this work can be read here.
This research was the PhD work of Dr Rainer Ginzel which can be read here.
The research was funded by the European Commission's 6 th Framework Programme ITS-LEIF (RII3-026015).

The figures on this page are reprinted from Nuclear Instruments and Methods in Physics Research Section B, 268, Ginzel R. et al., A deceleration system at the Heidelberg EBIT providing very slow highly charged ions for surface nanostructuring, 2972–2976, copyright 2010, with permission from Elsevier.

Illustration of the deceleration beamline. Image reproduced with permission © Elsevier 2010.