Bruker Biospin Ag

Qonetec Ag

Philippe Stauffenegger

Daniel Marek

Oskar Schett

Cengiz Cetrefli

Marc A Schnell

Klemens Kessler

Daniel Guy Baumann

Sven Radke

Bernhard Felber

Marc Enrique Paredes

Marco Tomaselli

Marc Schnell

A method for the transmission/reception of RF signals for NMR measurements uses a heat exchanger () for cooling heat sources (), the heat exchanger having a contact element () for thermal connection between a cryogenic fluid and the heat source, is characterized in that the heat exchanger comprises a container having an interior volume Vinto which a first cryogenic fluid Fthat has a liquid component Fand a gaseous component Fflows through an inflow conduit () and from which a second cryogenic fluid Fthat has liquid component Fand a gaseous component Fflows out through an outflow conduit (). The inflow conduit has a flow cross-section Qand a circumference Ufrom which an associated parameter V=4&#xb7;Q/Uresults, wherein V&#x3e;10&#xb7;V, and the outflow conduit has a flow diameter Qwherein Q&#x2265;Q. The contact element is in close thermal contact with both the liquid volume component Vof the cryogenic fluid and with the heat source. A device for setting the inflow quantity of the first cryogenic fluid Finto the container is provided that ensures a state F/F&#x3e;F/Fduring operation. In this way, vibrations due to the cooling process can be largely reduced and the consumption of cryogenic fluid minimized.

Method for cryogenic cooling of an NMR detection system with the assistance of a container filled with a cryogenic fluid

An NMR (nuclear magnetic resonance) apparatus has a magnet system disposed in a cryostat (), the cryostat having at least one nitrogen tank () for receiving liquid nitrogen () and a room temperature bore () for receiving an NMR probehead (), wherein part(s) of the probehead or the overall probehead can be cooled to cryogenic temperatures by supplying liquid nitrogen () via a supply line (). The nitrogen tank () of the cryostat () is connected to the NMR probehead () by means of a supply line () in such a fashion that liquid nitrogen () is removed from the nitrogen tank () and guided to the NMR probehead (). The overall apparatus is therefore more compact, the operating comfort of the apparatus is increased, and the costs for acquisition, operation and maintenance are considerably reduced compared to previous comparable devices.

Cryogenic probehead cooler in a nuclear magnetic resonance apparatus

An NMR measuring system with an NMR probehead has at least one cooling device () generating a vibration spectrum of individual selective frequencies. The cooling device is mechanically connected to a vibration absorber () having an oscillating mass element (), whose resonance frequency is adjusted to the vibration frequency of the cooling device and/or to one of its harmonics. The cooling device has a cooling head which is thermally connected to an NMR resonator of the probehead via a flexible mechanical element. A vacuum housing of the probehead is designed in two parts which are mechanically connected via at least one damping element (-). The lower part and the upper part of the vacuum housing are additionally mechanically flexibly connected to each other in a vacuum-tight fashion via a corrugated bellows (). The system minimizes sidebands in NMR spectra.

Compact cryogenic NMR sensor with integrated active cooling device

A sample tube for an NMR probe head, which extends along a z axis and has an internal cavity that extends in an axial direction of the z axis, is open to the outside at the axially upper end, is closed at the axially lower end and contains a liquid NMR sample substance during operation, wherein the cross-sectional surface of this cavity extending perpendicularly to the z axis and parallel to the xy coordinate plane has an elongated shape in the direction of the x axis with maximum dimensions a in the y direction and b in the x direction, wherein a&#x3c;b, is characterized in that the cross-sectional surface of the sample tube, which extends perpendicularly to the z axis and is parallel to the xy coordinate plane has a circular outer shape. Sample tubes of this type provide a particularly large signal-to-noise ratio, can be easily inserted into a conventional cryogenic probe head and be axially and radially positioned therein by existing precision centering devices.

Reduction in eddy current losses in electrically conducting sample materials with the assistance of special NMR sample tubes

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Duebendorf, Switzerland

Philippe Stauffenegger