Next generation high energy physics colliders: technical challenges and prospects

High energy particle physics is about studying the fundamental properties of matter at the highest achievable particle energies. The use of superconducting magnet technology has become central to the generation of high energy particle beams over the last 30 years. The first announcement of a practical type II superconductor, Nb/sub 3/Sn, was in 1961. Within a month high energy particle physicists began to explore the ways these new materials could be used in their research apparatus. Within a decade stable NbTi materials were being used in large, constant current magnets for particle detectors. At the end of two decades large quantities of cost effective Rutherford cable were in production, and several large particle/storage rings, using ramped dipole and quadrupole magnets, were either under construction or in the advanced stages of planning. At the end of three decades several of these were operating very successfully, and construction had begun on an accelerator/storage ring 84 kilometers in circumference. Today, almost four decades later, the SSC has succumbed to politics, not technical shortcomings, and the need for high energy particles for physics research is as urgent as ever. However, the material needs, the scale of magnet performance, and the politics are all different. It is the purpose of this paper to briefly review this development and the reasons for it, and then to describe the current needs and possible future directions.