[en] The today's situation of the experiment towards a fusion reactor seems to imply that in the near future a superconducting magnet system has to be used. A reliable and effective cooling system is one of the fundamental steps towards the reliability of the whole magnet system. This paper deals with the advantages of cooling systems based on forced circulation of liquid helium in hollow conductors. Available experimental data on forced flow of supercritical, subcooled and boiling helium are discussed. The analysis shows that, for the large superconducting magnets of a fusion reactor, forced circulation of two-phase helium seems to be very attractive. In view of the scatter of data, we are designing an experimental set up to study heat transfer, stabilization and hydrodynamic features in forced flow cooling