• Open-air ice-free cryogenic temperature control system
  (Cryostreamer)

The cryostreamer is designed for precise temperature control near the samples placed in open flow of cool cryogenic gas (nitrogen) without ice formation. Cryostreamer set consists of storage dewar with level gauge, liquid nigrogen/gas transfer line, gas generator, and nozzle. Cryogenic liquid is evaporated by a heater mounted at the end of the transfer line placed in the storage dewar. Then the mixture of the liquid and gas moves to the gas generator. The gas generator produces stable gas flow with a fixed temperature. In a case of the liquid nitrogen, the gas generator is placed within the dewar. In a case of the liquid helium, the gas generator is placed directly before the streamer nozzle. The nozzle forms two concentric streams, which differ in diameter about 1-2 mm. The hot outer gas beam with a circumference cross-section prevents the ice formation on the sample. The inner gas beam has a circular cross-section and containes cool gas flow directed to the sample. The temperature of the gas inside of the inner beam depends on the coordinate across the diameter. The temperature distribution has a minimum around the center of the beam within a spot with diameter 2-3 mm. Outside of this spot the temperature gradually increases up to room temperature. In the region of laminar gas flow, the inner and outer beams flow independently. The laminar flow diameter is of about the outer diameter of nozzle. The sample has to be placed within the laminar zone.

• Continuous flow cryostat for microscopy/spectroscopy

Sample in vacuum

The microCRYO102 is a compact continuous flow cryostat. A cooling agent (liquid helium or liquid nitrogen) is transferred from a storage dewar through a vacuum isolated transfer line to the heat exchanger. The sample is mounted on the cold table of the heat exchanger. The heat exchanger with the sample are placed into pumped out interior of the cryostat body. The cold table arrangement is positioned within the copper shield, cooled by outgoing cryogen flow. The sample temperature is controlled by a temperature controller unit tSTAT310xc. The electronic unit forms a continuous flow of cooling agent from the dewar, controls the power of the electrical heater at the cold table as well as the flow rate of the cryogen by differential pressure regulator and needle valve opening in the gas-flow regulator set. The design enables the use of high magnification microscope objectives and secures the high aperture for the reflectivity measurements.