Gabor-plasma lens focusing for LEBT systems

Low energy beam transport (LEBT) of high perveance ion beams suffers from high space charge forces. Space charge compensation reduces the necessary focusing force and the filling factor of the lenses and therefrom the emittance growth due to aberrations and inner fields. The use of electrostatic lenses is restricted due to decompensation by the electric fields. On the other side magnetic lenses suffer, for high mass ions, from necessary high magnetic fields and the resulting technical problems. A different approach for a LEBT system is a lens using a static non neutral plasma confined in a magnetic and electrostatic field configuration allowing strong electrostatic focusing together with partial conservation of space charge compensation. Modelling of the plasma in a way that lens aberrations are small is very difficult and the underlying theory is not fully understood. New measurements at low residual gas pressure as well as theoretical work and the results of numerical simulations will be discussed