High intensity targets for ISOL, historical and practical perspectives

The concepts and technical challenges of generating radioactive ion beams from ISOL (isotope separation on line) targets irradiated with high power proton beams are discussed in an historical context. The evolution of potential target designs for high beam power dissipation over the past 20 years is reviewed with respect to effectiveness and practicality. The development of TRIUMF-ISAC high power targets and their successes and problems during on-line operation at elevated proton currents are presented.