DENSE NEGATIVE-ION CURRENTS FROM LASER-PRODUCED PLASMA

Recent studies on the Munich laser ion source were aimed at the unders tanding and optimization of the production mechanism of negative ions. The possibility of extremely high, pulsed negative ion currents is du e to the outstanding features of the laser produced plasma: a high ele ctron density in conjunction with a low electron temperature. The inte nsity of the laser beam is restricted to a relatively small range from 5 X 10(7) Up to 1 X 10(9) W/cm2. More than 20 different ions have bee n produced from pure element targets and from a number of salts. The y ields achieved are in good agreement with a model including Saha equil ibrium distributions. The comparison between pure elemental targets an d alloys or salt shows a strong influence of ions with a low ionizatio n potential on the negative ion production.