Armin Binneberg

Thermosiphon Cooler: A Low Microphonic Cooling System for HTC-Devices; Especially for SQUIDs

Publisher Summary Applications of HTC-devices in high-tech areas require a potentially low microphonic (or free) cooling system. Thermal fluctuations, mechanical vibrations and electromagnetic influences are to be minimized (or equalized). A hybrid cooling system is developed consisting of a small split-Stifling cryocooler as refrigeration source and a thermosiphon. The thermosiphon (condenser and evaporator, separated by capillary tubes) is filled with gaseous nitrogen and closed. The condenser is contacted to the cold head of the Stifling machine. The SQUID is mounted on the evaporator and is not affected by disturbances of machine. The analysis of the records obtained shows optimal working conditions for the thermosiphon when the diameter of the capillary tubes is about 1.2 mm. Then, the nitrogen storage tank should have a volume of 200 ml filled with nitrogen of a pressure of 0.4 MPa. The mentioned qualifications the vibrations of the cold head (without external damping of 16 μm) are reduced to 1 μm in axial direction at sensor place. The net cooling capacity is up to 0.3 W at 65 K and up to 0.6 W at 80 K without changing of temperature.

New cryosurgical probe suitable for endoscopic application in the minimal invasive therapy

Publisher Summary Object in view of the minimal invasive therapy(MIT) is to substitute the traditional open and therefore invasive surgically interventions through fewer invasive surgery. In addition to microsurgery and lasertherapy, which are mainly used in MIT, cryosurgery may also be used. Applications of endoscopic cryotips are possible in several medical disciplines e. g. in the gynecology. This chapter presents a liquid-nitrogen-cooled cryotip for use in gynecology. The cryogenic efficiency of the cryotip is proved by laboratory tests. It also presents the cryotechnical parameters, which are important for the medical therapy, such as freezing rate in dependence of the distance, isotherms, and cooling power. Cryosurgery is understood to be the applications of low temperatures down to 78 K (boiling point of liquid nitrogen) to attain therapy effects in various medical disciplines. Cryosurgery now is significant in the therapy of tumors of definite character, localizations and extend. The basic feature of cryosurgery is to devitalize the tissue by freezing in situ. By a defined regime of freezing and warming the tissue, the formation of extra- and intracellular crystallites destroys the cell membranes of cancerous tissue. In general cryosurgery includes favorable functional and cosmetic results.