1. REXEBIS
In the Electron Beam Ion Source (EBIS) the 1+ ions are charge bred. The positive ions are trapped in an electron beam which knocks out electrons from the ions.
EBIS working principle The positive ions are injected from the right and confined - radially in the potential well from a dense electron beam which is focused by a strong solenoidal magnetic field - longitudinally by two electrical potential barriers Inside the beam the ions perform axial, magnetron and cyclotron motions in an entangled way, as well as collide with other ions.
EBIS cross-view
Charge development During the confinement period (s to seconds), the ions are continuously bombarded with fast moving electrons from the electron beam. These knock out the electrons from the ions. When the desired charge state is reached, the ions are extracted to the right by applying an extraction voltage.
Obtained charge state:
Axial potential
Radial potential

2. REXEBIS
The REXEBIS is based on a 2 T superconducting solenoid. An immersed gun produces the electron beam and the electrons are absorbed in an iron-shielded collector. After a confinement < 20 ms a q/A > 1/4 is reached.
filling tower
racks
collector position
electron gun position
insulator
injection/extraction optics
magnet iron shield
turbo pumps
60/20 kV platform
The REXEBIS platform is switched between 60 kV (at injection) and ~20 kV (at extraction) to convert the ISOLDE energy (60 keV) to ~20 keV·q in accordance with accelerator specifications.
REX-EBIS data
B = 2 T Eelectron = 5 keV confinement < 20 ms Ie = 0.5 A je = 250 A/cm2 Ltrap < 0.8 m Warm bore q/A ~ 1/4
Uplatform (kV) t 60
10-20 ms
100s
100 s 40 20
T=10 – 20 ms
breeding
injection
extraction
5 V