The ion source extraction and low energy beam transport (LEBT) of the JYFL 14 GHz ECRIS have been upgraded from the original design in two stages in 2013 and 2015. The current electrostatic extraction system consists of an adjustable voltage puller electrode and an accelerating einzel lens presented in figure below. Originally in 2013 there were two einzel lenses but the second one was removed as it caused outgassing of the second einzel lens and sometimes a Penning discharge between the einzel lenses.The main parameters of the extraction are
- Plasma electrode aperture diameter 8 mm
- Puller electrode aperture diameter 12 mm
- Plasma electrode to puller electrode distance 35 mm
- Typical voltages: source +10 kV, puller +1 kV, einzel -10 kV
The original LEBT had a focal point before mass separation which emphasized the space charge induced problems in the beam transport at low energies. The new LEBT injects a diverging beam into the dipole magnet. The double focusing dipole magnet focuses the beam into a focal point at the collimation plane. The first solenoid SOLJ1 is used for fine tuning the beam divergence together with the electrostatic lenses.
For more information see V. Toivanen, et. al., JINST 8, P05003 (2013)