Problems connected with the generation of continuous magnetic fields above 15 Tesla

A short review is given about the present possibilites to generate magnetic fields beyond 15 Tesla. Whereas it seems feasible to build purely superconducting magnets for fields up to 20 Tesla no conductors with the required critical data are available. at present which allow the generation of higher fields. Magnetic fields beyond 15 Tesla are generally produced by resistive, water cooled coils. If fields beyond 25 Tesla have to be generated problems are encountered because of the large amount of power which is necessary. In order to achieve the highest continuous magnetic fields hybrid magnets can be built which consist of an inner resistive part and an outer superconducting coil. The limits of this technique are discussed for various conditions.