Helium, refrigerated liquid

Synonyms Helium, compressed Helium, refrigerated liquid (cryogenic liquid)... 

Synonyms cas 7440-59-7 helium, compressed (dot) helium, refrigerated liquid [Pg.156]

Helium, refrigerated liquid (ciyogenic liquid) 1963 1980 21 Hexanols 1-Hexene 2282 2370 26 27... 

Most previous attempts to obtain X-ray diffraction data at very low temperatures (< 80 K) have used custom built systems with closed cycle helium refrigerators mounted on large, robust four circle diffractometers. In order to remove the inherent disadvantages of these systems - cost, single application, absorption and scattering of the windows - we have built an open flow system from mainly off-the-shelf components which uses liquid helium as the cryogen. This is not the first open flow helium system [19, 20] but is the first that is mainly off-the-shelf and is mountable on any diffractometer. It is based on an ADP Helitran ESR cryostat with modifications to the nozzle assembly and to the direction of the gas flow. The lowest temperature is estimated to be <30K. At the current price for liquid helium in... 

SYNS HEUUM, compressed (UN 1046) pOT) HELIUM, refrigerated Uquid (cryogenic liquid) (UN 1963) (DOT)... 

The magnets do require expensive helium refrigeration systems to cool the niobium-titanium coils to superconducting temperatures. Thus, a liquid nitrogen system should be less expensive, simpler to operate, and more reliable. But some scientists are dubious. Said John Hulm ... 

Fig. 1. Schematic representation of vacuum furnace closed-cycle helium refrigeration system used for metal vapor microsolution optical spectroscopy, as well as conventional metal vapor-matrix isolation experiments. (A) NaCl or Suprasil optical window, horizontal configuration (B) stainless steel vacuum shroud (C) NaCl or Suprasil optical viewing ports (D) cajon-rubber septum, liquid or solution injection port (E) gas deposition ports (F) vacuum furnace quartz crystal microbalance assembly. With the optical window in a fixed horizontal configuration, liquid or solution sample injection onto the window at any desired temperature in the range 12-300 K is performed in position 1A, metal deposition is conducted in position IB, and optical spectra are recorded in position 1C see Procedure).

Fig. 2. Low-temperature test chamber—liquid helium refrigerant. 

The cryosphere was cooled to temperatures ranging from 10° to 31 by a gaseous helium refrigerator and to 77 °K by liquid nitrogen. The temperature in the lower range was... 

The helium flow-through cryostat uses liquid helium that is pumped from a container and sprayed onto the bottom of the cold tip. In this case, temperatures of 3.5 K can be reached. The cooling process takes a long time (typically 1 h), both with the closed-cycle helium refrigerator and the flowthrough cryostat. Several samples should preferably be cooled simultaneously. 

The experiment assembly was loaded into the Low-Temperature Irradiation Facility (LTIF), a combination of a continuously operating liquid-helium refrigerator and a cryostat next to the core of the swimming-pool-type Oak Ridge Bulk Shielding Reactor. The sample chamber was then purged with dry helium gas and evacuated to about 13 Pa (0.1 torr) several times before initial cooldown. 

Helium Refrigeration (1) 41 Helium Production Process (1) 171 Hydrogen-Helium Liquefier (2) 8 Gas Chromatography as Applied to the Industrial Separation of Neon from Nitrogen and Helium (2) 197 Helium Heat Rectifiers and a Simple Magnetic Refrigerator (2) 220 A Liquid Helium Bubble Chamber (2) 330 Economic and Other Aspects of the Distribution of Navy Helium in Liquid Form (3) 114... 

Liquid helium shipped at pressures below 25.3 psig (174 kPa) in insulated containers is not subject to DOT fill densities. However, in Canada, compressed gases and refrigerated liquids are regulated regardless of pressure. 

It has over 40 hmes more refrigerating capacity per unit volume than liquid helium and more than three hmes that of liquid hydrogen. It is compact, inert, and is less expensive than helium when it meets refrigeration requirements. 

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