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This paper describes the first results of a feasibility study undertaken at CERN to determine whether a laser-produced plasma can be used as a source of intense highly charged heavy ion beams. A variety of important measurements have been made, and the results are encouraging. Furthermore, a beam of highly charged light ions produced by the laser ion source has been accelerated successfully in a radio frequency quadrupole (RFQ) structure.

Results are presented of experiments on ion production from Ta targets using a short pulse (350-600 ps in focus) illumination with focal power densities exceeding 10 14 Wcm~2 at the wavelength of an iodine photodissociation laser (1.315 nm) and its harmonics. Strong evidence of the existence of tantalum ions with the charge state +45 near the target surface was obtained by X-ray spectroscopy methods. The particle diagnostics point to the existence of frozen high charge states (<53 + ) of Ta ions in the far expansion zone at about 2 m from the target. The measured charge state-ion energy distribution indicates the highest energy (>4 MeV) for the highest observed charge states. A tentative theoretical explanation of the observed anomalous charge state freezing phenomenon in the expanding plasma produced by a subnanosecond laser pulse is given.

Demonstration of matching a laser ion source to the GSI RFQ-Maxilac linear accelerator and the acceleration of a 1.8-mA current beam of Ta 10+ ions up to 45 keV/u energy is presented. A 10J//XS CO 2 laser has been used to produce a hot plasma plume, emitting highly charged tantulum ions. The correct geometry and potential distribution of the matching section has been designed in accordance with the results of computer simulations by using the AXCEL code. Measurements of the charge state distribution of the accelerated beam indicate that it contains about 70% Ta 10+ and 30% Ta 11+ ions.

The influence of the combined interaction of a CO2 laser (10.6 μm) and a Nd:YAG laser (1.06 μm) with a solid tantalum target has been investigated. Changing plasma parameters as temperature and density can be traced back by measurement of the charge state distribution after extraction from the expanding plasma. Analysis of the measurements for the single lasers as well as for the combined impact show an increase in plasma temperature, strongly depending on the delay between the two laser pulses. A maximum charge state rising from 11+ to 13+ can be observed.