摘要:
An X-ray analysis device makes use of a variable aperture for controlling the position and cross section of the X-ray beam. The variable aperture is configured to allow changes in the cross section and/or position of the beam by movement of one aperture component in one direction. In one embodiment, the aperture medium is a perforated disk that is rotated to expose different aperture holes to the beam. In another embodiment, the aperture medium is a perforated tape that is moved in a linear direction to expose different aperture holes to the beam. The tape may be wound about two axes to control its movement, or may be a continuous loop. A cassette may also be used to house the tape.
摘要:
The system describes a means and a method for stabilizing the magnetic field generated in the measuring volume of a high-resolution magnetic resonance spectrometer having an actively shielded magnet coil (4) which is located in a cryostat (2) and which is superconductingly short-circuited. The system comprises a compensation coil (12) which is decoupled from the magnet coil (4), and is disposed on the shielding coil (4b) of the magnet coil (4).
摘要:
A description is given of a method for determining the content of a first component of a sample, which first component provides a first NMR signal and has a first self-diffusion coefficient D1, the sample additionally containing at least one further component which provides a further NMR signal and has a larger self-diffusion coefficient D2, in particular for determining the fat content of a hydrous sample, with the aid of a low-resolution nuclear magnetic resonance (NMR) pulse spectrometer, the sample being excited by a radio-frequency (RF) excitation pulse and being exposed to a magnetic gradient field and to a sequence of further refocusing RF pulses for generating spin echo signals, the spin echo signals being detected and their amplitude values being determined, from which a value for the content of the first component of the sample is determined. The magnetic gradient field is not switched off during the sequence of further refocusing RF pulses.
摘要:
The invention concerns a means and a method for stabilizing a magnetic field generated by a superconductingly short-circuited main coil located in a cryostat in the measuring volume of a high-resolution magnetic resonance spectrometer, which comprises compensation coils which are dimensioned and positioned such that they, in their entirety, are suited to largely compensate for field drifts of the superconductingly short-circuited main coil in the measuring volume. The drift compensation coils consist of HTS material and are disposed radially outside of the main coil at a higher temperature level.
摘要:
A device for the safe discharge of a superconducting magnet coil (4) which is located inside a cryostat (2) and superconductively short-circuited by a superconducting switch (7) providing at or in the cryostat (2) a transmitter (10) of electromagnetic energy being located at a temperature level considerably above the cryogenic temperature of the superconducting magnet coil (4), which transmitter can be switched on quickly from outside, and by arranging in the region of the superconducting switch (7) at the cryogenic temperature level of the superconducting magnet coil (4) a receiver (20) for the emitted electromagnetic energy, which transmits the received energy directly or indirectly to a heating device (15) of the superconducting switch (7) or which activates an auxiliary energy source (41) in the region of the superconducting switch (7) , which on its turn effects a heating of the superconducting switch (7), so that it becomes normal-conducting and causes a discharge process of the superconducting magnet coil (4) via resistors (18) and/or diodes (19), being located at the cryogenic temperature level, there being no electrically conducting connection between transmitter (10; 10') and receiver (20). In this way, the magnet can be discharged without contact.
摘要:
A device for the safe discharge of a superconducting magnet coil (4) which is located inside a cryostat (2) and superconductively short-circuited by a superconducting switch (7) providing at or in the cryostat (2) a transmitter (10) of electromagnetic energy being located at a temperature level considerably above the cryogenic temperature of the superconducting magnet coil (4), which transmitter can be switched on quickly from outside, and by arranging in the region of the superconducting switch (7) at the cryogenic temperature level of the superconducting magnet coil (4) a receiver (20) for the emitted electromagnetic energy, which transmits the received energy directly or indirectly to a heating device (15) of the superconducting switch (7) or which activates an auxiliary energy source (41) in the region of the superconducting switch (7), which on its turn effects a heating of the superconducting switch (7), so that it becomes normal-conducting and causes a discharge process of the superconducting magnet coil (4) via resistors (18) and/or diodes (19), being located at the cryogenic temperature level, there being no electrically conducting connection between transmitter (10; 10') and receiver (20). In this way, the magnet can be discharged without contact.
摘要:
In a magnet system with two coil systems of different mean diameter arranged coaxially with respect to the longitudinal axis of the system defined by the direction of the field in the homogeneity region, which are rotationally symmetrical and are arranged symmetrically about the transverse median plane of the system perpendicular to the longitudinal axis and can carry exciting currents which result in overlapping magnetic fields that compensate, at least approximately, for the dipole fields of the two coil systems, an operating mode selector switch device (22) configured as a superconducting network is provided, by means of which the magnet system (10) can also be switched, as an alternative to the operating mode which provides considerable dipole-field compensation in the outer space of the magnet system (10), to that operating mode in which the magnetic fields generated by the two coil systems (11 and 12) at the center thereof are aligned in the same direction. In a special configuration, the ratio B.sub.0i :B.sub.0a between the values of the field strengths B.sub.0 1 and B.sub.a generated by the inner field coil (11) and the outer field coil (12) is equal to 3.
摘要:
The present invention relates to a method and a device for compensating undesirable side bands in nuclear magnetic resonance spectrometers. The frequency (.omega..sub.m) and the phase of rotation of the sample (10) are detected by means of a light sensor (12) and supplied to a compensation generator (18). The latter generates modulation signals (44 and 43) for modulating the amplitude and the phase of the detected nuclear magnetic signal of the sample, using an amplitude modulator (13) and a phase modulator (14), the modulation frequency being equal to an integral multiple, including the simple value, of the frequency of rotation (.omega..sub.m) of the sample. The additional frequency components heterodyne with the side bands provoked by the rotation of the sample (10) in the static magnetic field (B.sub.O), whereby the said side bands are eliminated.
摘要:
An X-ray or neutron-optical analysis device comprising means for directing radiation from a source (1) onto a sample (2), and a detector (7) with n substantially identical detector elements (Di) which are disposed parallel, next to each other in a first direction x and which extend in strips in a second direction y, wherein i=1, . . . n, for one-dimensional spatially-resolved detection of radiation reflected, scattered or diffracted by the sample (2) onto the detector (7), and with a detection electronics for processing the detector signals of the n detector elements (Di), wherein the detection electronics can reliably process a maximum radiation intensity per detector element (Di) without overloading, is characterized in that an optical element is disposed in front of the detector (7) which covers or weakens radiation incident on the surfaces of the respective n detector elements (Di) in correspondence with a predetermined, non-constant transmission function f(x) and/or the optical element comprises a collimator (6) which can be displaced along the strip direction y. The inventive analysis device permits artificial enlargement of the dynamic range of the detector (7).
摘要:
The invention concerns an NMR (nuclear magnetic resonance) high field magnet coil system comprising superconducting conductor structures for generating a homogeneous magnetic field B0 in a measuring volume (23) with several radially nested solenoidal coil sections (12, 13, 31), which is characterized in that the radially innermost coil section (31) is wound with a band-shaped superconductor with an aspect ratio (width to thickness) >3 on a coil support which axially projects, at least at one axial end, past the winding packet of the radially neighboring coil section (12) and the band-shaped superconductor is guided on this side tangentially towards the outside to a region of reduced magnetic field strength and terminates in at least one electrical connecting point (16). This permits use of a brittle band-shaped superconductor for the innermost coil system (31) which cannot be strongly bent at the upper edge.