is stored in liquid cryogen storage vessel 8 other liquid cryogens which may be used in the practice of this invention include liquid argon liquid carbon dioxide liquid air produced by liquefying ambient air and other mixtures of liquid oxygen and liquid nitrogen liquid cryogen is passed out from storage vessel 8 in line or conduit 10 through cryogenic valve 7 and then in lines 11 and 12 into distributor volume or sparger 13 which rings vaporizer 2 vaporizer or cooling device 2 has an intake and an exhaust and also has means for drawing or passing cooling fluid e g ambient air into the intake and ejecting cooling fluid out from the exhaust in the embodiment of the invention illustrated in fig1 u2013 3 this means is an electric motor 27 driving a fan 14 by operation of the electric motor and fan ambient air is drawn into intake 15 of vaporizer 2 as shown by arrows 16 passed through vaporizer 2 and ejected out of the exhaust 17 of vaporizer 2 as shown by arrows 18 preferably as illustrated in fig1 and 2 vaporizer 2 has a converging diverging configuration from the intake to the exhaust such a configuration serves to accelerate the cooling fluid as it passes through the vaporizer which in turn enhances the cooling of the cooling fluid by the heat exchange with the liquid cryogen a plurality of cryogenic spray nozzles 19 are positioned in distributor volume 13 for passing liquid cryogen into vaporizer 2 preferably as illustrated in fig1 and 2 distributor volume or sparger 13 is positioned on vaporizer 2 downstream of fan 14 by downstream it is meant between fan 14 and exhaust 17 as liquid cryogen is sprayed into vaporizer 2.