A gas liquefaction system for liquefying gas comprising: a gas intake module adapted to be connected to a gas source and configured to provide gas to the system; a thermally isolated container at least one interior tank in the container having at least one neck extending therefrom; at least one refrigeration coldhead having a coldfinger portion located inside the neck and routed toward the interior tank; a gas compressor configured to provide compressed gas to the refrigeration coldhead for the operation of the cryocooler; characterized in that: at least one gas pressure control mechanism configured to control the gas intake pressure flowing from the gas intake module and to adjust such pressure to the required elevated gas pressure inside the interior tank; and at least one control device for controlling the liquefaction performance of the system, said at least one gas pressure control mechanism and said at least one control device being configured to optimize liquefaction performance and increase liquefaction rate by controlling gas flow into the interior tank to maintain pressure inside the interior just below the critical pressure of the gas being liquefied and at least one transfer port is in fluid communication with the interior tank and is adapted to enable extraction of liquefied cryogen therefrom. a gas intake module adapted to be connected to a gas source and configured to provide gas to the system; a thermally isolated container at least one interior tank in the container having at least one neck extending therefrom; at least one refrigeration coldhead having a coldfinger portion located inside the neck and routed toward the interior tank; a gas compressor configured to provide compressed gas to the refrigeration coldhead for the operation of the cryocooler; characterized in that: at least one gas pressure control mechanism configured to control the gas intake pressure flowing from the gas intake module and to adjust such pressure to the required elevated gas pressure inside the interior tank; and at least one control device for controlling the liquefaction performance of the system, said at least one gas pressure control mechanism and said at least one control device being configured to optimize liquefaction performance and increase liquefaction rate by controlling gas flow into the interior tank to maintain pressure inside the interior just below the critical pressure of the gas being liquefied and at least one transfer port is in fluid communication with the interior tank and is adapted to enable extraction of liquefied cryogen therefrom. at least one gas pressure control mechanism configured to control the gas intake pressure flowing from the gas intake module and to adjust such pressure to the required elevated gas pressure inside the interior tank; and at least one control device for controlling the liquefaction performance of the system, said at least one gas pressure control mechanism and said at least one control device being configured to optimize liquefaction performance and increase liquefaction rate by controlling gas flow into the interior tank to maintain pressure inside the interior just below the critical pressure of the gas being liquefied and at least one transfer port is in fluid communication with the interior tank and is adapted to enable extraction of liquefied cryogen therefrom.