62results about How to "Improve field uniformity" patented technology

A superconducting magnet configuration (4; 14) for generating a homogeneous magnetic field B0 in an examination volume (4b), has an interior radial superconducting main field coil (1) which is disposed rotationally symmetrically about an axis (z-axis) and an oppositely driven coaxial radially exterior superconducting shielding coil (2) is characterized in that the magnet configuration (4; 14) consists of the main field coil (1), the shielding coil (2), and a ferromagnetic field formation device (3; 18), wherein the ferromagnetic field formation device (3; 18) is located at the radially inside of the main field coil (1), the main field coil (1) consisting of an unstructured solenoid coil or of several radially nested unstructured solenoid coils (15, 16) which are driven in the same direction, the axial extent Labs of the shielding coil (2) being smaller than the axial extent Lhaupt of the main field coil (1), wherein the axial magnetic field profile (5) generated by the main field coil (1) and the shielding coil (2) during operation has a minimum of the field strength along the axis (z-axis) in the center (4a) and a maximum of the field strength on each side of the center (4a), and wherein the axial magnetic field profile (6) generated by the ferromagnetic field formation device (3; 18) during operation has a maximum of the field strength along the axis (z-axis) in the center (4a) and a minimum of the field strength on each side of the center (4a). The magnet configuration in accordance with the invention has a very simple structure.

A method and apparatus for drying book and similar paper-based materials in wet or frozen state, in which the material dried is exposed to microwave irradiation with frequency from 500 MHz to 10 GHz and in which the book or similar paper-based materials is lined with ceramic slabs before the drying. In this arrangement the materials are subsequently exposed to microwaves under atmospheric or reduced pressure. An apparatus for carrying out the method includes microwave drying oven modified for a batch or continuous operation, which includes adjustable ceramic slabs capable to absorb both moisture and microwaves.

An RF coil includes two coil portions that are spaced apart to define a slab therebetween. Each coil portion is a microstrip transmission line formed as a loop wherein the microstrip includes a conductive strip disposed on one side of a dielectric material and a ground plane disposed on the other side of the dielectric material. When energized, a uniform RF field is produced in the slab. An array of such RF coils arranged back to back can be formed to allow for the selective excitation of a desired slab.

An apparatus for DNP-NMR measurement on a sample, with a magnet configuration for producing a magnetic field in a first working volume and in, a second working volume with a magnetic field gradient in the direction of an axis (z) which extends through the second working volume, with a device for measuring MR signals, with a DNP excitation device, and with a positioning mechanism for transferring the sample, is characterized in that, near the second working volume, a compensation configuration made of magnetic material is mounted that, in the operating condition of the magnet configuration, produces a magnetic field gradient in the direction of the axis (z) in the second working volume that is between −90% and −110% of the magnetic field gradient of the same order of the stray field of the magnet configuration.

In an even numbered polygonal microwave resonator wherein a high mode microwave mode is formed and in the resonator volume a homogeneous field distribution is established for the thermal processing of workpieces, a microwave in-coupling structure pair is provided along a joining edge of two wall segments alternately at opposite sides and the in-coupling structure pairs or in communication, via a rectangular microwave guide channel, with a microwave sources supplying microwaves to the in-coupling structure pairs so that the microwaves entering the resonator from each in-coupling structure are directed toward an opposite corner area of the resonator and are reflected from the opposite corner area back into the center area of the resonator in the form of separate beams.

A sample slide stage includes at least four fixed members that are arranged at, or about at, a focal plane of the slide stage, and are configured to receive a slide; and a plurality of compression members that apply a controlled force to compress a slide towards the fixed members at the focal plane, whereby a surface of a non-planar slide in the sample stage is deformed towards the focal plane. Methods of deforming non-planar slides towards a focal plane include inserting a non-planar slide into a sample slide stage that has at least four fixed members arranged at or about at a focal plane; and applying a controlled force to compress the non-planar slide to the fixed members at the focal plane, whereby a surface of the non-planar slide is deformed towards the focal plane.

A low pass RF ladder coil, which is named as a millipede surface coil, comprises a first and a second conductor end strips running parallel to each other. A set of rung elements are placed between them, alternate rung elements are connected to the first and second strip respectively. The number and spacing of the rung elements are sufficient for resonating the coil at the desired imaging frequency. This millipede surface coil may have 100 or more rung elements. Fixed and variable capacitors are provided for separately tuning and matching the first and second mode resonant frequencies, and for coupling and impedance matching the two modes to external circuits. An active detuning is provided that detunes the ladder coil when a separate RF coil is transmitting.