Abstract: A magnetic structure enclosing a prismatic cavity of regular polygonal cross-section is presented. The structure contains the field within the volume of the magnet without the need of an external ferromagnetic yoke, which makes it suitable for generating fields of several Tesla. The structures presented are designed to generate uniform fields for NMR studies, especially high intensity fields.

Abstract: An open magnetic structure comprising a conical permanent magnetic structure that generates an MRI imaging field around the body part of a patient in a cavity of the structure. The permanent magnetic sections include a recess over the cavity, with the surface of the structure bounding the recess following a cone angle of the conical permanent magnetic structure. The structure can be configured sufficiently large to accommodate a full patient body.

Abstract: An open magnetic structure comprising a conical magnetic structure that generates an NMR imaging field around the head of a patient, and a transition magnetic structure including a cylindrical magnet connected to the conical magnetic structures that extends the uniform field generated in the head magnet cavity to or near the shoulders of the patient. The overall geometry is designed to integrate the magnetic structure in a surgical suite with a minimum interference with surgical procedures, which typically involve surgery on the brain of the patient. A method for improving field uniformity by shimming is also included. Advantages include improved field uniformity, and reduced weight and size.

Abstract: An open magnetic structure comprising a conical magnetic structure including a hollow conical magnet surrounding and contacting an inner pole piece that generates an NMR imaging field around the head of a patient. The annular surface of contact between the conical magnetic structure and the inner pole piece is configured such that that annular surface of contact is maintained as an equipotential surface to maintain a uniform imaging field. An advantage is to integrate as one-piece the various permanent magnetic sections to greatly simplify fabrication. A method for determining the profile of the annular surface of contact is also included.

Abstract: An open magnetic structure comprising a conical magnetic structure including a hollow conical magnet surrounding and contacting an inner pole piece that generates an NMR imaging field around the head of a patient. The annular surface of contact between the conical magnetic structure and the inner pole piece is configured such that that annular surface of contact is maintained as an equipotential surface to maintain a uniform imaging field. An advantage is to integrate as one-piece the various permanent magnetic sections to greatly simplify fabrication. A method for determining the profile of the annular surface of contact is also included.

Abstract: An open magnetic structure comprising a conical magnetic structure that generates an NMR imaging field around the head of a patient, and a transition magnetic structure including a cylindrical magnet connected to the conical magnetic structures that extends the uniform field generated in the head magnet cavity to or near the shoulders of the patient. The overall geometry is designed to integrate the magnetic structure in a surgical suite with a minimum interference with surgical procedures, which typically involve surgery on the brain of the patient. A method for improving field uniformity by shimming is also included. Advantages include improved field uniformity, and reduced weight and size.

Abstract: An open magnetic structure comprising a conical magnetic structure that generates an NMR imaging field around the head of a patient, and a transition magnetic structure including a cylindrical magnet connected to the conical magnetic structures that extends the uniform field generated in the head magnet cavity to the shoulders of the patient. The overall geometry is designed to integrate the magnetic structure in a surgical suite with a minimum interference with surgical procedures, which typically involve surgery on the brain of the patient.