Varian, Inc.

Marco A Romo

Wai Ha Wong

Thomas De Swiet

James Finnigan

Sean T Burns

Nancy Winward

Superconducting birdcage coil with low-pass and high-pass coil configurations are formed by using strips each with an elongated sapphire substrate with a layer of a high temperature superconductor (HTS) material grown in a wavy pattern over its entire length on one of its main surfaces. A low-pass coil is formed with a pair of ring elements made of an electrically conductive metal and a plurality of such strips arranged parallel to one another and interconnecting these ring elements at junctions which are spaced peripherally along each of the rings. At each of the junctions, the ring element and the HTS layer form a capacitance. A high-pass coil is formed by a plurality of such strips each with electrodes of the HTS material also grown at two end positions separated from each other on the other main surface of its sapphire substrates. These strips are arranged parallel to each other and sequentially around a central axis, each lying in a plane which includes the center axis. The electrodes and the HTS layers on mutually adjacent pairs of strips are closely in face-to-face relationship so as to serve as the ring part of a birdcage configuration containing capacitors.

Method of producing a birdcage superconducting coil

A birdcage resonator has a pair of conductor rings separated from each other along a central axis and a plural number of axially disposed conductor rungs, which extend between the rings and are evenly spaced around the central axis. Each of the rungs has a sectional shape with thickness or a radial extension comparable to or greater than its width or its azimuthal extension. Measures of the width and thickness of the rungs may be determined by using them as parameters to calculate the values of Q factor from an analytical procedure to locate parameter value ranges corresponding to maximal Q. Geometric calculations for filling factor yield ranges of parameters providing for compromise parameter values. Saddle coils have been found to exhibit similar enhancement of Q with radially oriented conductor cross section.

NMR resonators optimized for high Q factor

A radio-frequency (RF) coil for a nuclear magnetic resonance (NMR) probe includes rounded longitudinal conductors connecting end rings formed by sheets. The rounded conductors can be formed by curled sheets or wires. The rounded conductors allow reduced RF losses at the coil window edges, and thus allow increased coil sensitivities. The rounded conductors also allow increased coil sensitivities for an orthogonal coil, by allowing increased transparency to the magnetic field generated by the orthogonal coil. A curled-sheet RF coil can be generated from a single etched sheet by curling longitudinal sections of the sheet into tubular longitudinal conductors. To make such a coil, each longitudinal section is inserted into a longitudinal slot of a sheet-curling member, and the member is rotated about its longitudinal axis. As the curling member is rotated, the longitudinal sheet section wraps around the curling member and becomes curled. The curling member can be provided as part of a sheet-curling tool including two transverse plates for securing the coil into place between the plates, and a set of guides allowing the longitudinal motion of one plate relative to the other.

Rounded-conductor NMR RF resonators

Superconducting birdcage coil with low-pass and high-pass coil configurations are formed by using strips each with an elongated sapphire substrate with a layer of a high temperature superconductor (HTS) material grown in a wavy pattern over its entire length on one of its main surfaces. A low-pass coil is formed with a pair of ring elements made of an electrically conductive metal and a plurality of such strips arranged parallel to one another and interconnecting these ring elements at junctions which are spaced peripherally along each of the rings. At each of the junctions, the ring element and the HTS layer form a capacitance. A highpass coil is formed by a plurality of such strips each with electrodes of the HTS material also grown at two end positions separated from each other on the other main surface of its sapphire substrates. These strips are arranged parallel to each other and sequentially around a central axis, each lying in a plane which includes the center axis. The electrodes and the HTS layers on mutually adjacent pairs of strips are closely in face-to-face relationship so as to serve as the ring part of a birdcage configuration containing capacitors.

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Castro Valley, CA, United States of America

Marco A Romo