Abstract: The invention relates to a method for estimating a heat load imposed on a cryogenic refrigerator, to an associated computer program product, and to a method for controlling the cooling power output by said refrigerator. As the refrigerator (1, 1?) includes a phase separator (40, 40?) comprising a bath (41, 41?) of refrigerant, the method for estimating the heat load imposed on said refrigerator includes a step in which said heat load is estimated using a program executed by a computer, said program being based on a mass balance carried out on the phase separator for expressing variations in the time drift of the height of the bath of refrigerant in the phase separator.

Abstract: The invention relates to a cryogenic system for cooling a consumer having a time-variable heat load, such as a superconducting magnet, including: a cold box in thermal contact with the consumer, supplied with heat transfer gas compressed by a feed line, and connected to a delivery line for discharging said gas at a lower pressure; and an assembly for adjusting the pressures in the feed and delivery lines, comprising a plurality of controlled valves (CV1, CV2, CV3) and a controller (MC) for controlling the opening of said valves. The invention is characterized in that the controller is a multivariable controller for generating signals (SCs1, SCs2, SCs3) for controlling the opening of said valves according to measured values (PHP, PBP) and set values (P0HP, P0BP) for the pressures in the feed and delivery lines on the basis of a mathematical model of the system that factors in a coupling between the pressure values in the feed and delivery lines by means of the above-mentioned cold box.