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

An antenna and shield apparatus for detecting phenomenal signals using nuclear and electronic resonance detection technology, comprising: a transmit and receive antenna, an electric field shield 60 and an outer shield 52. The antenna is a multiple parallel loop transmit-receive antenna forming a main coil assembly 11 having a plurality of loop segments 20 optionally interconnected by connectors in the form of conducting bars 10, relays 16, or nothing. The electric field shield 60 comprises an inner sleeve of conducting material 60, 68 disposed on the inside of the coil assembly 11 for shielding the electric field emanating from the coil assembly 11 from the target volume circumscribed by the assembly. The outer shield 52 comprises a central screen portion 55, waveguides 57 at either end thereof and a sloping channel portion for interconnecting the two. The coil assembly 11 and the electric field shield 60 are housed within the outer shield 52.

The present invention concerns an apparatus (1′) for NMR spectroscopy and/or NMR imaging of a sample. The apparatus comprises a static probe comprising an outer coil for excitation of nuclei of the sample by generating an incident radio frequency field at the Larmor frequency of the nuclei, and for reception of a return radio frequency field emitted by the sample, and a sensitive inner coil (6a′) which is mounted closely around or in contact with the sample container and which is wirelessly coupled to the outer coil by an electromagnetic radio frequency field. The sensitive inner coil is embedded in an inner spinning rotor (2) which is rotatively mounted inside the static probe and which is integral with the sample container, so that the filling factor and the radio frequency field amplitude in the sensitive coil are maximized.

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.

Disclosed are a source stirring electromagnetic reverberation chamber and a stirring method thereof. The reverberation chamber includes an electromagnetic shielding chamber, a source stirring device installed on the side wall of the electromagnetic shielding chamber, and the source stirring method used for describing installation, motion and control method of an transmitting antenna. Simultaneous change of the position and polarization direction of the transmitting antenna is realized through control of a rotating shaft to rotate. A drive device of the rotating shaft is installed at the outer side of the reverberation chamber and the rotating shaft which is installed on the inner wall of the reverberation chamber is driven to rotate through a changeover mechanism. The reverberation chamber realizes field uniformity in the reverberation chamber through rotation of a single antenna so that space utilization rate in the reverberation chamber is effectively improved and a source stirring reverberation chamber of the same volume can realize a larger test area; relative to an EUT of the same size, a source stirring reverberation chamber which is smaller in volume can be designed so that generation of high field intensity is better facilitated; and the reverberation chamber is also applicable to a condition in which a plurality of transmitting antennae are configured in a reverberation chamber to carry out source stirring.

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 L_abs of the shielding coil (2) being smaller than the axial extent L_haupt 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.

An apparatus for DNP-NMR measurement on a sample (P), with a magnet configuration (M) for producing a magnetic field in a first working volume (V1), wherein the magnet configuration (M) produces a stray field in a second working volume (V2) in the direction of an axis (z) with a magnetic field gradient (H1M, H2M, HnM) in the direction of the axis (z), wherein the axis (z) extends through the second working volume (V2), with a device (N) for measuring MR signals, with a DNP excitation device (D), and with a positioning mechanism (T) for transferring the sample (P), is characterized in that, near the second working volume (V2), a compensation configuration (m) made of magnetic material is mounted that, in the operating condition of the magnet configuration (M), produces a magnetic field gradient (H1m, H2m, Hnm) in the direction of the axis (z) in the second working volume (V2) that is between −90% and −110% of the magnetic field gradient of the same order (H1M, H2M, . . . ; HnM) of the stray field of the magnet configuration (M) in the direction of the axis (z) in the second working volume (V2). Thus, homogenization of the magnetic field in the second working volume can be achieved by technically simple means.

A magnetic field source is provided comprising a support structure upon which is positioned a conducting surface path of superconductor material. The support structure has an at least partially radially overlapping layer of material arranged in a spiral. A corresponding conducting surface path of superconductor material is arranged on the surface of the support structure such that the conducting path has a first point for the introduction of current and a second point for the extraction of current.

The invention provides a mixing stirring device of mechanical stirring and source stirring of an electromagnetic reverberation chamber. The mixing stirring device comprises the electromagnetic reverberation chamber and further comprises a mechanical stirring assembly and a source stirring assembly, wherein the mechanical stirring assembly and the source stirring assembly are arranged on the side wall of the electromagnetic reverberation chamber. The mechanical stirring assembly comprises a first motor and a mechanical stirrer connected with the first motor; the source stirring assembly comprises a second motor, a rotary shaft connected with the second motor and a transmitting antenna disposed on the rotary shaft. By means of combination of a mechanical stirring device, a source stirring device and a method, change of electromagnetic field distribution in the reverberation chamber depends on more variable changes which include changes of the length, the width and the height of an equivalent reverberation chamber and changes of the position of an excitation current source or/and orthogonal coordinate components of current density, and therefore more choices are provided for further improving field uniformity of a testing area in the reverberation chamber so that performance of the reverberation chamber is more likely to be improved.

An aperture design for a linear ion trap is provided in which the aperture is optimized to minimize possible axial field inhomogeneities whilst preserving the structural integrity of the quadrupole rods. In general, the invention provides a linear ion trap for trapping and subsequently ejecting ions. The linear ion trap comprises a plurality of rods which define an interior trapping volume which has an axis extending longitudinally. One or more of the rods includes an aperture which extends both radially through the rod and longitudinally along the rod. The aperture being configured such that the ions can pass from the interior trapping volume through the aperture to a region outside the interior trapping volume. At least one recess is disposed adjacent the aperture, extending longitudinally along the rod and facing the interior trapping volume, the recess not extending radially through the rod.

A magnet for magnetic resonance imaging has an interior working space within the magnet frame sufficient to accommodate a physician and a patient. Because the physician is positioned inside the magnet frame, the physician has unimpeded access to the patient. Elements of the magnet frame desirably encompass a room, and the magnet frame may be concealed from view of a patient within the room. Preferred embodiments facilitate MRI imaged guided surgery and other procedures performed while the patient is being imaged, and minimize claustrophobia experienced by the patient. Also provided is a magnet having field coils disposed about the of pole portions of the magnet. A diagnostic facility for high volume MRI use is also disclosed.

The present invention proposes an AC cable termination joint using a nonlinear prefabricated rubber stress cone, which belongs to the design field of high-voltage AC cable accessories. The AC cable termination joint includes a cable termination joint body composed of a silicone rubber insulating base and a silicone rubber insulating umbrella skirt, a cable conductor link fitting, a sealing cap and a nonlinear prefabricated rubber stress cone, wherein the conductive or semiconductive part of the stress cone is compounded of silicon rubber and carbon black; and the insulating part of the stress cone is compounded of zinc oxide ceramic powder particles and silicon rubber using a nonlinear conductive composite material. The cable termination joint of the present invention enables the scope of application of the voltage class of the prefabricated rubber stress cone to be further enlarged, which is not only applicable to low-voltage-class cable termination joints, but also plays a good role of homogenizing field intensities for high-voltage-class cable termination joints; and meanwhile, not only solves the problem that the field intensity is concentrated at the notch of a cable shielding layer but also solves the problem that the field intensity is concentrated at the cone surface of the stress cone, thereby improving the reliability of the long-time running of a power cable system.

A conductor assembly and method for making an assembly of the type which, when conducting current, generates a magnetic field or which, in the presence of a changing magnetic field, induces a voltage. In one series of embodiments the assembly comprises a spiral configuration, positioned along paths in a series of concentric cylindrical planes, with a continuous series of connected turns, each turn including a first arc, a second arc and first and second straight segments connected to one another by the first arc. Each of the first and second straight segments in a turn is spaced apart from an adjacent straight segment in an adjoining turn.

An RF LDMOS device is disclosed, including: a substrate having a first conductivity type; a channel doped region having the first conductivity type and a drift region having a second conductivity type, each in an upper portion of the substrate, the channel doped region having a first end in lateral contact with a first end of the drift region; a first well having the first conductivity type in the substrate, the first well having a top portion in contact with both of a bottom of the first end of the channel doped region and a bottom of the first end of the drift region; and a second well having the first conductivity type in the substrate, the second well having a top portion in contact with a bottom of a second end of the drift region. A method of forming such an RF LDMOS device is also disclosed.

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.

An electroporation device and method having a plurality of electrotherapeutic devices for insertion into and surrounding a sensitive target tissue e.g. the brain of a patient where the electroporation device and the electrotherapeutic devices are adapted for applying a precisely controlled electrical field, and to avoid or limit damages to the healthy tissue surrounding the target tissue to be treated.

Methods for fabricating field emission display devices. A first substrate is provided. A cathode structure is formed on the first substrate. A surface treatment procedure is performed on the first substrate with cathode structure thereon. A second substrate opposing the first substrate is provided and assembled in vacuum with a wall rib therebetween. The surface treatment procedure includes free radical oxidization and a supercritical CO₂ fluid cleaning.

A wavy micro gas chromatography column includes a silicon substrate and a bonded glass cover. A micro channel having a rectangular cross section is etched on the silicon substrate and coated with a stationary phase film. A projection figure of the micro channel on the silicon substrate includes multiple regular wavy curves. Each wavy curve is formed through alternately connecting first upper arcs with first lower arcs. Because the groove has a curving structure, the carrier gas velocity is decreased as the increase of the arc angle, resulting in an improvement of the flow uniformity at the zones between two adjacent bends but also an enlarging nonsymmetric distribution at the bends. Thus, an optimal curving structure can make the overall flow more even, and in turn achieve a better separation performance compared to the straight channel columns. Meanwhile, a wavy channel realizes a longer column length on a given area.

A system for one-sided measuring a presence of magnetic particles in a probe volume comprises a one-sided coil assembly and a current controller, wherein the one-sided coil assembly is arranged around a central coil assembly axis for generating a rotating magnetic field distribution and comprises at least 3, preferably at least 4, circumferentially distributed coil assembly sectors, wherein the current controller is configured to generate a time varying current in each of said coil assembly sectors, said time varying current comprising a periodic modulation with a rotation frequency and phase shifted between adjacent coil assembly sectors to generate a magnetic field rotating in a plane perpendicular to the coil assembly axis, said magnetic field rotating with a rotation frequency associated with a frequency of said periodic modulation, and wherein the system is configured for measuring said presence of magnetic particles in said probe volume with said one-sided coil assembly.

Insulators (3) support an inner conductor (2) in a tubular outer conductor (4) and fasten on the inner conductor on one side and on the outer conductor on the other side by means of first (5) and second (6) external electrodes. The insulator acts as a disk and links to a cast mushroom-shaped control electrode (7) towards the inner conductor.