Molecular beam epitaxy, or MBE, is a new technique for growing high-quality thin films of crystals on crystal substrates. In ultra-high vacuum conditions, by the heating stove is equipped with all kinds of required components and generate steam, through holes formed after collimating beam atomic or molecular beam, direct injection to the appropriate temperature of the single crystal substrate, controlling molecular beam to the substrate scanning at the same time, it can make the molecules or atoms in crystal alignment layers to form a thin film on a substrate "growth".

For the normal operation of MBE equipment, high purity, low pressure and ultra-clean liquid nitrogen is required to be continuously and stably transported to the cooling chamber of the equipment. In general, a tank that provides liquid nitrogen has an output pressure between 0.3MPa and 0.8MPa.Liquid nitrogen at -196℃ is easily vaporized into nitrogen during pipeline transportation. Once the liquid nitrogen with a gas-liquid ratio of about 1:700 is gasified in the pipeline, it will occupy a large amount of liquid nitrogen flow space and reduce the normal flow at the end of the liquid nitrogen pipeline. In addition, in the liquid nitrogen storage tank, there is likely to be debris that has not been cleaned. In the liquid nitrogen pipeline, the existence of wet air will also lead to the generation of ice slag. If these impurities are discharged into the equipment, it will cause unpredictable damage to the equipment.

Therefore, the liquid nitrogen in the outdoor storage tank is transported to the MBE equipment in the dust-free workshop with high efficiency, stability and clean, and the low pressure, no nitrogen, no impurities, 24 hours uninterrupted, such transportation control system is a qualified product.