National Repository of Grey Literature 43 records found  beginprevious34 - 43  jump to record: Search took 0.01 seconds. 
Helium Cryostat for Experimental Study of Natural Turbulent Convection
Urban, Pavel ; Jícha, Miroslav (referee) ; Rotter, Miloš (referee) ; Fedor,, Ján (referee) ; Musilová, Věra (advisor)
V disertační práci je popsán heliový kryostat s experimentální válcovou konvekční celou pro studium proudění při přirozené konvekci za velmi vysokých Rayleigho čísel Ra (až do řádu 10^15) a Nusseltových čísel Nu (až do řádu 10^4). Pracovní látkou je studené 4He, které umožňuje díky výhodným fyzikálním vlastnostem dosažení velmi vysokých hodnot čísel Ra. Návrh kryostatu je založen na koncepci lázňových NMR kryostatů s nízkým odparem kryokapalin. Ve středu kryostatu je umístěna konvekční cela o průměru 300 mm a výšce 300 mm. Celu tvoří horní a spodní dno a výměnná střední část. Tyto díly jsou spojeny rozebíratelnými přírubami těsněnými indiovým drátem. Výměnná část umožňuje snadnou modifikaci geometrie cely. Hlavní přednost kryostatu spočívá v minimálním vlivu konstrukce cely a použitých materiálů na studovanou konvekci. Cela kryostatu je navržena pro pracovní tlaky do 250 kPa.
Design and verification of low temperature part of UHV – STM microscope
Voňka, Jakub ; Rotter, Miloš (referee) ; Urban, Pavel (advisor)
The diploma thesis addresses the design and experimental verification of cooling system and low temperature part of UHV - STM working in temperature range of 20K - 300K. Due to the demand of variable temperature, the flow cooling system with cryogenic (~5 K) helium (He) is used. Two variants of the low temperature part of the microscope are studied. First the version with cooling only the sample holder, and second with cooling of the whole STM. Designed cooling system consists of He flow cryostat allowing to connect it to the Dewar vessel with liquid helium (LHe) using a low-loss transfer line. The cryostat consists of He inlet and outlet, heat exchangers and copper strains (i.e. braids) for the thermal connection of the sample holder/STM and radiation shield around the STM with the heat exchangers. The thesis describes the design of the flow cryostat and its initial tests in the designed vacuum chamber. Heat flow through a spot contact is also discussed to estimate thermal conductance of insulation supports based on thermal resistance of spherical contacts. The thesis was elaborated in collaboration with the Institute of Scientific Instruments of the ASCR, v.v.i.
Experimental setup for probing a von-Karman type flow of normal and superfluid helium
Schmoranzer, D. ; Rotter, M. ; Šebek, Josef ; Skrbek, L.
We describe the setup, present and discuss the available preliminary data and outline planned experiments that thanks to a possibility of simultaneous detection by three independent complementary techniques ought to bring new results in studies of quantum turbulence and its classical counterpart.
Experimental setup for probing a von-Karman type flow of normal and superfluid helium
Schmoranzer, D. ; Rotter, M. ; Šebek, Josef ; Doležal, L. ; Skrbek, L.
We describe the setup and discuss the available preliminary data that were obtained thanks to a possibility of simultaneous detection by three independent complementary techniques.
Kavitace v kapalném heliu vyvolaná vibrujícím křemenným krystalem
Blažková, Michaela ; Chagovets, Tymofiy ; Rotter, M. ; Schmoranzer, D. ; Skrbek, Ladislav
An experimental setup containing a quartz tuning fork inside a pressure cell in a glass helium cryostat enables us to experimentally observe effects in liquid He, which we ascribe to cavitation (as these are absent in gaseous He), taking place in the vicinity of the fork. Liquid helium can be prepared extremely clean and wets almost ideally any solid surface – it provides an ideal model system to study cavitation.
Křemenný krystal - frekvenční standard pro digitální hodinky jako citlivý nástroj pro studium proudění mezní vrstvy
Blažková, Michaela ; Chagovets, Tymofiy ; Pešička, J. ; Rotter, M. ; Skrbek, Ladislav
We describe basic properties of commercial quartz tuning forks – frequency standards for digital watches which can be used as a very sensitive pressuremeters, thermometers and furthermore they can generate and detect boundary layer flow of cryogenic fluids.
PIV technique for investigations of cryogenic helium flow
Blažková, Michaela ; Chagovets, Tymofiy ; Rotter, M. ; Schmoranzer, D. ; Skrbek, L.
We describe various aspects of cryogenic PIV technique and give examples of its successful application of various flows of cryogenic helium, with appropriately chosen of tracking particles such as hollow glass spheres, polymer microspheres or solid hydrogen-deuterium flakes.
Druhý zvuk - nástroj pro studium stability proudění He II
Chagovets, T. ; Rotter, M. ; Skrbek, Ladislav
Second Sound is described as a suitable probe for investigation of stability of He II flow.
Small Superconducting Magnet for Low Temperature Nuclear Orientation
Dupák, Jan ; Rotter, M. ; Srnka, Aleš
A new low temperature nuclear orientation facility was installed in the Faculty of Mathematics and Physics at Charles University in Prague. The facility is based on the small dilution refrigerator 3He-Ne of the "French" type and principally used for solid state physics research. The refrigerator allows to cool the radioactive samples down to 10 mK in the magnetic field of superconducting solenoid up to 4 T. The gammaray anisotropy is observed exclusively in the direction of the applied vertical magnetic field which is mostly suffiecient for the solid state study.

National Repository of Grey Literature : 43 records found   beginprevious34 - 43  jump to record:
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3 Rotter, Marek
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