Plasma lens focusing of heavy ion beams utilizing a wall-stabilized discharge

At the german heavy ion accelerator facility GSI different types of plasma lenses have been developed and tested. The best results were achieved with a plasma lens utilizing a wall-stabilized discharge. This type of lens has proofen to work very efficient, stable, and reproducible. A wall-stabilized plasma lens has been extensively investigated at the GSI linear accelerator UNILAC with beam energies ranging from 5.6 to 15.4 MeV /u. Several beam tests with discharge currents of up to 25 kA have shown that the focusing is mainly limited by the beam emittance of typically 5 π mm mrad and that lens related aberrations are negligible small. The concept of this wall-stabilized plasma lens has recently been extended to discharge currents above 200 kA. A first test at the SIS heavy ion synchrotron with a beam energy of 300 MeV /u has shown the same favourable behaviour of the discharge as found in the low current regime.