Bruker Biospin Ag

Bruker Switzerland Ag

Bruker Biospin Gmbh

Nicolas Freytag

Daniel Marek

Fabian Kuehler

Alia Hassan

Roger Meister

David Osen

Jevgeni Guidoulianov

Florian Helbing

Armin Purea

Arthur Schwilch

Benno Knott

Michele Zaffalon

Stephan Graf

Peter Scheuzger

Fabian Kühler

An NMR apparatus having a magnet coil system for generating a homogeneous magnetic field comprises a superconducting magnet arranged within a vacuum vessel in the cold region of a cryostat, and a shim system containing shim elements arranged outside the vacuum vessel. The superconducting magnet has a first mechanical connection point to the vacuum vessel via a magnet suspension, and the shim system has a second mechanical connection point to the vacuum vessel via a positioning element. On at least one portion of a path along the vacuum vessel from the first connection point to the second connection point and/or on at least one portion of a path along the positioning element from the second connection point to the shim system, a regulating element for regulating thermally caused changes in length is arranged on the relevant path. Magnetic field homogeneity can thus be kept largely stable.

Active reduction of temperature induced shim drift in NMR magnet systems

An NMR probehead having a transceiver coil arrangement comprises at least one transceiver coil for generating an HF B1 magnetic field, the transceiver coil having a connection region and at least one electrical conductor portion with a forward winding portion that leads in a prespecified winding direction from the connection region to an axial end. A backward winding portion leads in the same winding direction, from the axial end to the connection region, with windings having a pitch P with the opposite sign to windings of the forward winding portion. The forward and backward windings, with the exception of crossover regions in which the forward and backward windings cross over each other, are arranged on the same cylindrical surface about a longitudinal axis Z'. With the invention, electric fields visible for the sample are reduced, together with other types of performance losses.

NMR probehead

An NMR probe head has a transceiver coil arrangement with a first transceiver coil for generating a first RF magnetic field B, wherein the first transceiver coil comprises an electrical conductor having multiple windings about a longitudinal axis Z', and wherein the electrical conductor of the first transceiver coil is designed as a strip-shaped conductor with a conductor width W that decreases at least twice and increases at least twice within each winding. The NMR probe head thereby has a transceiver coil that has maximum quality factor with simultaneous transparency to other RF magnetic fields that may be radiated.

A temperature-control system for an NMR magnet system. A permanent magnet arrangement () with a central air gap () generates a homogeneous static magnetic field inside the air gap. A probehead () transmits RF pulses and receives RF signals from a test sample (). An H0 coil changes the amplitude of the static magnetic field. A shim system () in the air gap further homogenizes the magnetic field. A first insulation chamber () surrounds and thermally shields the permanent magnet arrangement and includes an arrangement () controlling a temperature T1 of the first insulation chamber. The shim system, the H0 coil and the NMR probehead are arranged outside the first insulation chamber in the air gap. A heat-conducting body () is arranged between the shim system and the H0 coil on one side and the permanent magnet arrangement on the other, thereby enhancing field stability and suppressing drift.

Temperature-control system for MR apparatuses with a permanent magnet arrangement

A first radial bearing includes nozzles in the stator at a radius rand a bearing surface on a circular section of the rotor at a radius R. A second radial bearing includes nozzles in the stator at a radius rand a bearing surface on the rotor at a radius R. An axial bearing includes a nozzle in the stator and a bearing surface on an axial end of the rotor, which runs orthogonally to the rotation axis and has an outer radius R. The second radial bearing is formed on an end section of the rotor, which has a smaller radius than or a radius that decreases away from the circular section, so that R&#x3c;Rand r&#x3c;r. The third bearing surface is formed on an end of the end section facing away from the circular section, so that R&#x2264;R

MAS-NMR rotor system with improved space utilization

An MAS NMR probe head arrangement has a stator () aligned along an axis of rotation (RA) to support a rotor (), a stator mount (), and a RF coil arrangement () to emit/receive RF pulses into/from the measurement substance () in the rotor. The stator mount has a stator bearing () into which the stator can be axially inserted and extracted. The stator, when inserted, passes through the RF coil arrangement (), and can be fed through the RF coil arrangement (). A mechanism fixes the stator axially in the stator bearing () when inserted. This arrangement enhances both ease of assembly and maintenance of the arrangement.

MAS NMR probe head arrangement with replaceable stator

A method for operating an NMR probehead () with an MAS stator () receiving a circular-cylindrical hollow MAS rotor () with an outer jacket. The MAS rotor is mounted on pressurized gas in a measuring position within the MAS stator via a gas supply device with a bearing nozzle (') and rotates about the cylinder axis of the MAS rotor at a rotation frequency f&#x2265;30 kHz. During a measurement, a temperature control gas is blown by a temperature control nozzle () onto the outer jacket of the rotor at an angle &#x3b1;&#x3c;90&#xb0; with respect to the longitudinal axis of the cylinder-symmetrical rotor. The flow speed of the temperature control gas corresponds in the nozzle cross section to at least half the circumferential speed of the outer jacket of the rotating rotor and to at most the speed of sound in the temperature control gas.

Temperature control of an NMR-MAS rotor

An HF coil assembly for generating independent alternating magnetic fields in an examination volume of a magnetic resonance apparatus is presented, the HF coil assembly comprising a first coil pair of saddle coils and a second coil pair of saddle coils, each saddle coil having longitudinal conductor elements and curved conductor elements arranged along a common lateral surface of a circular cylinder having a cylinder axis. Each coil pair comprises curved conductor elements and longitudinal conductor elements which are interconnected at a high frequency. The saddle coils also have diagonal conductor elements and/or bridge elements that connect the longitudinal and curved conductor elements. The coil pairs are opposite to each other relative to the cylinder axis.

HF coil assembly

A nuclear magnetic resonance coil configuration having at least one flat or cylindrical coil (), through which current flows in operation, which coil generates a high-frequency magnetic Bfield at the location of a sample () which is oriented parallel to an x-axis, and which for the purpose of connection to a tuning network is connected to at least two electrical feed lines (), through which in-phase currents flow in operation, and which generate a high-frequency magnetic Bfield in the sample (), the orientation of which encloses an angle &#x3b1; with the direction of the Bfield, is characterized in that the following applies for the angle &#x3b1;: &#x3b1;=180&#xb0;&#xb1;&#x394;&#x3b1;, where &#x394;&#x3b1;&#x3c;90&#xb0;. In this way, a Bfield profile, which is as rectangular as possible and is particularly steep on both sides, can be generated.

NMR transmitting/receiving coil configuration

An HF resonator assembly generates at least two independent alternating magnetic fields in a test volume of a magnetic resonance apparatus. The HF resonator assembly includes a first pair of flat coils that form a first HF resonator and comprise electrical conductor portions that surround a planar surface portion. The flat coils are arranged on opposing sides of the test volume, on coil support plates that are mutually parallel and in parallel with the longitudinal axis. A second pair of flat coils forms a second HF resonator on second coil support plates. The projections of the planar surface portions of the flat coils in each of the first pair of flat coils and the second pair of flat coils overlap in part, but not completely, when viewed in a direction perpendicular to the respective planar surface portions.

HF resonator assembly

A probehead of an NMR-MAS apparatus includes a sample which has a rotation axis tilted by an angle &#x3b8;&#x3e;0 with respect to the z-axis. The angle &#x3b8; can be adjusted about a target angle &#x3b8;by tilting around a tilt axis. The rotation axis has a fixed angle with respect to the probehead, and the NMR-MAS apparatus tilts at least part of the probehead to adjust the angle &#x3b8;. The probehead has an outer contour K between an upper end and a lower end. For all z between the upper end and the lower end, a cross-section S(z) of the contour K exists parallel to the xy-plane with a width Q(z) in the x-direction. The width Q(z) is smaller at points away from z=0, such that Q(z)&#x3c;Q() and Q(z)&#x3c;Q() for z&#x3c;0 and z

Probehead with adjustable angle for NMR-MAS apparatus

A probehead of an NMR-MAS apparatus with a rotation axis (RA), which lies in an xz-plane, titled by an angle &#x3b8;&#x3e;0 relative to a z-axis. The angle &#x3b8; is adjusted by tilting around a tilt axis (DA) parallel to the y-axis relative to a target angle &#x3b8;. An angle measurement apparatus () has a first sensor element (), which, together with a second sensor element () generates sensor signals dependent on the amplitude B0 of the static magnetic field and the vectorial orientation between the magnetic field B0 and a sensitivity vector. Two sensitivity vectors have an angle 5&#xb0;&#x3c;&#x3b1;i&#x3c;175&#xb0; to the z-axis and an angle &#x3b2;&#x3e;10&#xb0; to each other. The angle between the rotation axis and the z-axis can be measured precisely and reliably over a large range, providing a feedback signal for regulated adjustment or tracking of the angle &#x3b8;.

Probehead of an NMR-MAS apparatus with a device for determining the angle between the MAS rotor and the static magnetic field

A gradient coil system has a cylindrical section in a central region, which contains no conductor elements and has a maximum outer radius that is larger than a minimum inner radius of conductor elements of a main gradient coil. An outer radius of this cylindrical section is only insubstantially smaller or equal in size to a minimum inner radius of a shielding coil in this axial range. The free space in the center of the gradient coil system is used to insert a passive RF shield, whose radius in a central region becomes larger over a certain length than its radius in outer regions. The RF shield is constructed from at least three partial sections, which are electrically interconnected. The actively shielded gradient coil system maximizes the volume of the RF region without loss of gradient coil system performance.

Actively shielded, cylindrical gradient coil system with passive RF shielding for NMR devices

An RF resonator has a birdcage resonator with two electrically conducting ring elements () and N electrically conducting bars (). At least one pair of electrically conducting ring segments () forms an additional electrical connection between precisely two bars (). The pair of ring segments () define a current path () with these two bars () which is capacitively interrupted at at least one point. The ring segments () and the bars () electrically connected to the ring segments () are disposed symmetrically with respect to the yz-plane. The field homogeneity and efficiency are thereby optimized even with frequencies that are far apart.

Doubly tuned RF resonator

A method for regulating radio frequency (RF) signals in a nuclear magnetic resonance (NMR) system, comprising a spectrometer, a control loop, and an NMR probe head with RF components (B, L, B), wherein the spectrometer comprises a transmitter that transmits RF signals at measuring frequencies with a transmission power (P), the NMR probe head contains an RF oscillating circuit, and the RF oscillating circuit comprises an RF coil (L), is characterized in that the control loop controls the duration and/or the phase and/or the power of the transmitted RF signals. Measurement of a parameter is performed by means of the NMR probe head, via which parameter the current in or the voltage across one of the RF components (B, L, B) can be determined, and the transmission powers (P) and/or the phases and/or the duration of the RF signals are regulated in dependence on the measured parameter. Any occurring losses can thereby be compensated for without reducing the pulse duration.

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Binz, Switzerland

Nicolas Freytag