Abstract: A DNP apparatus includes a cryostat (7) having an opening (8) and a loading path for a sample (1), the loading path extending from the opening to a sample receptacle (29), with a cryomagnet and a microwave source (2) as well as a configuration for supplying microwave radiation from the microwave source to the sample, which comprises a microwave path extending directly to the sample. The microwave path extends spatially separately from the loading path and the configuration for supplying microwave radiation has at least one microwave feed-through passing through one or more walls of the cryostat. The microwave path is incident on the sample from a direction opposite to the loading path or from a sideward direction at right angles to or at an inclination with respect to the axis of the loading path. This leads to simple and efficient polarization of the electron spins in the sample.

Abstract: An NMR probe head (3) has a coil system (9) and a radial centering mechanism for a sample vial (4) having two centering devices spaced axially from each other to center the sample vial in the radial direction only. The first centering device (5) is disposed above the receiver coil system and at least one further centering device (6) is disposed axially above the coil system with an axial spacing (d) above the first centering device. The first and second centering devices restrict the radial scope for movement of the sample vial to such an extent that the sample vial cannot touch an endangered space (7) during the entire duration of transport of the sample vial to its measuring position, thereby precluding damage to the probe head components in the endangered space by the sample vial.

Abstract: A method for charging a magnet arrangement having a superconducting tape conductor with a first transition temperature in a cryostat device. The magnet arrangement is temperature-controlled to a first pre-operating temperature between the first transition temperature and the operating temperature, a first pre-operating current is excited, the magnet arrangement is cooled to operating temperature and a first operating current is excited. The magnet arrangement has a second magnet winding composed of a second superconductor material with a second transition temperature above the operating temperature and at least 15 K below the first transition temperature, wherein a second operating current in the second magnet winding is excited at the latest after cooling of the magnet arrangement to the operating temperature, and with the second operating current the second magnet winding generates a second operating magnetic field in the volume of the first magnet winding.

Abstract: An NMR apparatus includes a superconducting magnet coil system configured to generate a homogeneous magnetic field, and a helium (He) tank having an inner tube mechanically rigidly connected to the He tank and in which the magnet coil system is positioned. The He tank is configured to contain liquid helium to cool the magnet coils. A radiation shield has a radiation shield inner tube encompassing the He tank and spaced from the He inner tube to create a space between the He inner tube and the radiation shield inner tube to reduce an evaporation rate of the liquid helium. The NMR apparatus additionally includes a field shaping device with a magnetic material arranged in the space, in order to shim the homogeneous magnetic field. The field shaping device is fixed in the space so as to be in rigid mechanical contact with the He tank but without contacting the radiation shield.

Abstract: In a coil arrangement for nuclear magnetic resonance comprising a main coil (13), a shielding coil (14), and at least one correction coil (41), the function of which consists in forming a magnetic field gradient with eddy current properties which are as good as possible, the main coil (13) and the shielding coil (14) are electrically connected in series with the correction coil (41). The deviations of the residual field from the desired design generated by production tolerances are thereby modified by the correction coil in such a fashion that the long-lasting eddy currents are suppressed. This either reduces the waiting time that must lapse after a gradient pulse before a predetermined field homogeneity is achieved or e.g. the deviations from the desired field are minimized in imaging applications.

Abstract: An electronic interface (10) between a pure NMR receiver resonator (RO) and a preamplifier is characterized in that one or more control diodes (Dmatch1, Dtune1) are provided by means of which the current designed to flow through the switching diodes can be fed into these switching diodes, and the control diodes are connected to the switching diodes directly or via one or more additional series impedances. In this fashion, the impedance of the resonator is transformed to the required preamplifier or line impedance during the receiving process with little loss. In particular, during the receiving process, matching can be adjusted during the transmitting process, the current in the inductance of the resonator generated by the B1 field of the transmitting resonator is minimized and all components are protected against damage.

Abstract: An ICR cell (01) operates with a duplexer (08), which is an integral part of a transmission and receiving device (09) of an FT-ICR mass spectrometry device. The device transmits a transmitter (03) voltage to at least one electrode (11) of the ICR cell during an ion excitation phase and protects a preamplifier (04) from overvoltage. An ion received signal passes through a reception path (12) to the preamplifier during an ion detection phase. The duplexer has at least one active serial switch (07) with two switchable states, each with different series impedances, which is inserted in the reception path (12). As a result, a duplexer for an ICR cell of an FT-ICR mass spectrometry device is provided in which at least one electrode can be used for both ion excitation and for subsequent ion detection.

Abstract: An electrical circuit with one or more semiconductor components (10) is characterized in that at least one semiconductor junction of at least one of the semiconductor components of the electrical circuit is disposed such that the average direction of motion of the charge carriers in the semiconductor junction is essentially parallel to the lines of force of the magnetic field B0, wherein the corresponding semiconductor component is disposed directly on a substrate (12), which is made of a material with good thermal conduction properties. In this way, undistorted characteristics of the semiconductor component used can be ensured despite the very strong magnetic field and the low operating temperatures.

Abstract: An NMR probe head has a capacitor with a dielectric (5), which surrounds a cavity (15) in which a capacitor piston (7) is disposed. A sliding bush (9) has a through hole (16) in which a piston operating rod (8) extends. The piston operating rod (8) is connected to a piezo-electric actuator and to the capacitor piston (7) in such a way that it displaces the capacitor piston linearly when a sawtooth voltage is applied to the piezo-electric actuator. The sliding bush thereby applies braking friction to the piston operating rod during linear displacement of the capacitor piston and only allows the piston operating rod to slide through during the steep edges of the sawtooth voltage. This avoids the disadvantages of prior art, wherein the NMR probe head remains compact and the material cost and manufacturing complexity are reduced.

Abstract: A method for converting a cryostat configuration (1) having a first container (2) with a liquid helium bath (3) and a second container (6) which is filled with liquid nitrogen (7) is characterized in that a cooling medium (12) which is in a gaseous state at a temperature of 60K and a pressure of 1 bar, is introduced into the second container and is cooled by a refrigerator (16) by means of a cooling circuit (11), the coolant lines of which are guided into the second container, to an operating temperature of ?60K. With this retrofit for existing cryostat configurations that utilize both liquid helium and also liquid nitrogen for cooling a superconducting coil, use of liquid nitrogen can be completely avoided and the evaporation rate of the liquid helium can also be considerably reduced without having to re-liquefy the cryogens used.

Abstract: An NMR measuring configuration has a temperature control device for a sample vial (1). The temperature control device has a temperature sensor with supply wires which are both surrounded by a sensor tube (15). The sensor tube (15) is connected to a measurement space via a sensor flow inlet (26) in such a way that a partial flow of a temperature-control fluid flows as a temperature-control flow (16) into a free space (17) between the temperature sensor and the inner wall of the sensor tube along the supply wires and flows out of the sensor tube via a sensor flow outlet (18) at the opposite end of the sensor tube. This minimizes both the temperature penetration factor and the difference between the sensor and sample temperatures (?Tp).

Abstract: A method for producing hyperpolarized sample material for use in magnetic resonance investigations involves preparing a target material containing high ? nuclei with a short T1, a polarizing agent with a broad EPR line, and low ? nuclei with a long T1. The polarizing agent in the target material is irradiated with microwave radiation, wherein the target material is at a cryogenic temperature and exposed to a static magnetic field B0?4.0 T, thus polarizing the high ? nuclei by DNP, and the polarization is transferred from the high ? nuclei to the low ? nuclei by Cross Polarization. A dissolved sample material is prepared containing the hyperpolarized low ? nuclei from the target material. Nuclei with a long longitudinal relaxation time T1 can thereby be quickly hyperpolarized to a high polarization level.

Abstract: A method for producing a hyperpolarized sample for use in a magnetic resonance investigation has the following steps: a) providing a solid sample (50), containing long T1 nuclei and short T1 nuclei in the same molecules (51); b) hyperpolarizing the short T1 nuclei in the solid sample (50); c) transforming the solid sample (50) into a liquid sample (52); and d) transferring the polarization of the short T1 nuclei to the long T1 nuclei within the molecules in the liquid sample (52) by Cross Polarization. The method can provide samples with hyperpolarized long T1 nuclei, in particular 13C or 15N, in a simple and efficient way.

Abstract: A method for high resolution NMR (=nuclear magnetic resonance) measurements using the application of excitation pulses and the acquisition of data points, whereby a dwell time ?t separates the acquisition of two consecutive data points, which is characterized in that one or more tickling rf (=radio frequency) pulses of duration ?p are applied within each dwell time ?t, and that the average rf field amplitude of each of the tickling rf pulses approximately fulfills the condition ?1=?1?p/?t=?J wherein J is the scalar J-coupling constant and ?1=?B1 with ? being the gyromagnetic ratio and B1 being the strength of the magnetic component of each tickling rf pulse. This method is effective in decoupling homonuclear couplings.

Abstract: An RF resonator has a birdcage resonator with two electrically conducting ring elements (12, 33, 47) and N electrically conducting bars (11). At least one pair of electrically conducting ring segments (32a, 32b, 40, 43) forms an additional electrical connection between precisely two bars (11). The pair of ring segments (32a, 32b, 40, 43) define a current path (41, 42) with these two bars (11) which is capacitively interrupted at at least one point. The ring segments (32a, 32b, 40, 43) and the bars (11) electrically connected to the ring segments (32a, 32b, 40, 43) are disposed symmetrically with respect to the yz-plane. The field homogeneity and efficiency are thereby optimized even with frequencies that are far apart.

Abstract: A device for the high pressure densification of superconducting wire from compacted superconductor material or superconductor precursor powder particles, has four hard metal anvils (5, 6, 7, 8) with a total length (L2) parallel to the superconducting wire, the hard metal anvils borne in external independent pressure blocks (9, 10, 11), which are in turn either fixed or connected to high pressure devices, preferably hydraulic presses. At least one of the hard metal anvils is a free moving anvil (6) having clearances of at least 0.01 mm up to 0.2 mm towards the neighboring hard metal anvils (5, 8), so that no wall friction occurs between the free moving anvil and the neighboring anvils. This allows for high critical current densities Jc at reduced pressure applied to the hard metal anvils.

Abstract: An NMR (nuclear magnetic resonance) apparatus has a magnet system disposed in a cryostat (1), the cryostat having at least one nitrogen tank (3b) for receiving liquid nitrogen (5b) and a room temperature bore (7) for receiving an NMR probehead (8), wherein part(s) of the probehead or the overall probehead can be cooled to cryogenic temperatures by supplying liquid nitrogen (5b) via a supply line (14). The nitrogen tank (3b) of the cryostat (1) is connected to the NMR probehead (8) by means of a supply line (14) in such a fashion that liquid nitrogen (5b) is removed from the nitrogen tank (3b) and guided to the NMR probehead (8). 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.

Abstract: A method for performing magnetic resonance spectroscopy on solid samples containing nuclei of interest with spin quantum number I subjects the sample to a static magnetic field. The sample is spun at the magic angle and broad-band excitation of transverse magnetization of the nuclei of interest is effected by applying a first train of rotor-synchronized rf-pulses, having a carrier frequency, to the nuclei of interest with a pulse duration 0.1 ?s<?p<2 ?s, the first train of rf-pulses comprising k·n pulses extending over k rotor periods ?rot with n pulses per rotor period ?rot, wherein n is an integer n>1. Uniform excitation of a great number of spinning sidebands or families of sidebands that arise from large first-order quadrupole or hyperfine interactions is enabled and signal intensity is thereby improved.

Abstract: A sample container (2) for NMR measurements defines a volume (V) of sample substance. The sample container (2) has a first interface (G1) towards an environment (1) and a second interface (G2) towards the sample substance (3). A susceptibility jump at the second interface G2 is sufficiently large that the maximum value of |B?G2/B0| within the volume (V) is at least 0.5 ppm. The geometry of the sample container (2) is selected in such a fashion that, when a homogeneous magnetic field B0 has been applied, a location-dependent relative field change F is present in the volume (V), which is larger than 20 ppb at least at one point in a center partial volume (V1) and a first residual field (R1) in the center partial volume (V1) is smaller than 1.6 ppb. A second residual field (R2a) in the lower partial volume (V2a) is smaller than 30 ppb.

Abstract: An NMR measuring system with an NMR probehead has at least one cooling device (5a, b) generating a vibration spectrum of individual selective frequencies. The cooling device is mechanically connected to a vibration absorber (9a, 9b) having an oscillating mass element (27), 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 (30a-d). 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 (8a, 8b). The system minimizes sidebands in NMR spectra.