22nd SPARC Topical Workshop

An Electron Beam Ion Trap (EBIT) provides highly charged ions (HCI) for spectroscopy and other experiments. To this end, a nearly monoenergetic electron beam is used. In interactions with the electrons from the beam, neutral atoms or positively charged ions can be stripped of bound electrons by means of electron impact ionisation. The electron beam originates at a so-called “electron gun”, is accelerated towards the trap centre, and dumped at a so-called “collector”. The electron beam is guided and compressed by a strong magnetic field. The positively charged ions are attracted and trapped radially by the negatively charged electron beam. Longitudinal trapping is achieved by electrostatic potentials applied to a set of cylindrical drift tubes around the beam axis. Once trapped, HCIs interact with the electron beam and emit X-rays, which can give insights into a wide range of atomic processes, of interest for plasma physics, astrophysics and fundamental research.
Facilities at GSI, such as CRYRING, ESR, and HITRAP [1] rely heavily on a steady supply of ions for a wide range of experiments. However, the dependence on the GSI accelerator limits operational flexibility, necessitating the development of independent, local ion sources. S-EBIT II emerged as a promising candidate to address this challenge, offering to be an alternative local ion source for HITRAP, supporting local experiments such as ARTEMIS [2]. It also offers stand-alone functionality for diverse experimental research into highly charged ion interactions, like dielectronic recombination (DR) pro-cesses by means of X-ray spectroscopy or using ions extracted from the trap.

Recent commissioning efforts include DR measurements with argon, alongside a new electron gun and preparing to attach S EBIT II to HITRAP. Further stand-alone experiments on isotopic shifts in the DR spectrum on few-electron krypton will be conducted in the future

References
[1] H.-J. Kluge et al., 2008, Progress in Particle and Nuclear Physics, 59, 100-115.
[2] M. Vogel et al., 2018, Annalen der Physik (Berlin), 531, 1800211.