The invention relates to a cryogenic
refrigeration installation comprising an
enclosure housing at least two thermally conductive trays (4, 5, 6, 7) forming thermal stages, the installation (1) comprising a
cryogenic temperature cooling
system for the trays (4, 5, 6, 7) and / or one or more plates (24, 25, 26) connected (30) to the trays (4, 5, 6, 7), the cooling
system comprising a refrigerator (70) with a cycle
refrigeration system for a cycle fluid and a cycle circuit (8) comprising a storage pot (17) for a reserve of liquefied cycle fluid, the cycle circuit (8) comprising a bypass line (18) diverting at least a portion of the cycle fluid flow to the first storage pot (17), the bypass line (18) comprising an expansion device (19) configured to expand the cycle gas before feeding the pot (17) storage, the cycle circuit (8) includes,upstream of the heat exchange with at least a portion of trays (4, 5, 6) and / or plates (24, 25, 26), a portion in heat exchange with the liquefied cycle fluid contained in the storage pot (17) and a bypass line (308) located in the
enclosure (2) and equipped with an expansion device (408) configured to ensure expansion of the cycle fluid that has exchanged heat in the pot (17) to produce a cooler bypass cycle fluid flow, said bypass cycle fluid being put in heat exchange with at least one additional tray or plate (27) of the installation (1). Abbreviated figure: Fig. 1,