A magnetic field device, with a first magnet, a first ferromagnetic element positioned adjacent to the first magnet, a second magnet, a second ferromagnetic element positioned adjacent to the second magnet and relative to the first ferromagnetic element to create a gap between the first ferromagnetic element and the second ferromagnetic element, and a third magnet positioned between the first ferromagnetic element and the second ferromagnetic element and within the gap.

Some variations provide a permanent-magnet structure comprising: a region having a plurality of magnetic domains and a region-average magnetic axis, wherein each of the magnetic domains has a domain magnetic axis that is substantially aligned with the region-average magnetic axis, and wherein the plurality of magnetic domains is characterized by an average magnetic domain size. Within the region, there is a plurality of metal-containing grains characterized by an average grain size, and each of the magnetic domains has a domain easy axis that is dictated by a crystallographic texture of the metal-containing grains. The region has a region-average easy axis based on the average value of the domain easy axis within that region. The region-average magnetic axis and the region-average easy axis form a region-average alignment angle that has a standard deviation less than 30 within the plurality of magnetic domains. Many permanent-magnet structures are disclosed herein.

Provided is an electromagnetic device for magnetic particle imaging, including: a return yoke having a gap, which extends in a Y direction and forms a magnetic field space; a gradient magnetic field generating unit, which is provided to the return yoke, and is configured to generate, in the magnetic field space, a gradient magnetic field in an X direction, and to form, in the magnetic field space, a zero-field region extending in the Y direction; an alternating magnetic field generating unit, which is provided to the return yoke, and is configured to generate an alternating magnetic field in the magnetic field space; and a rotation mechanism configured to rotate the gradient magnetic field and the alternating magnetic field relative to a subject with a Z direction being a rotation axis.

A magnet array includes multiple magnet rings and a frame. The multiple magnet rings are positioned along a longitudinal axis and coaxially with the longitudinal axis, wherein at least two of the magnet rings include mixed-phase magnet rings that are phase-dissimilar. The multiple magnet rings are configured to jointly generate a magnetic field along a direction parallel to the longitudinal axis of at least a given level of uniformity inside a predefined inner volume. The frame is configured to fixedly hold the multiple magnet rings in place.

Generally, a system for generating a magnetic field having a desired magnetic field strength and/or a desired magnetic field direction is provided. The system can include a plurality of magnetic segments and/or a plurality of ferromagnetic segments. Each magnetic segment can be positioned adjacent to at least one of the plurality of magnetic segments. Each ferromagnetic segment can be positioned adjacent to at least one of the plurality of magnetic segments. In various embodiments, a size, shape, positioning and/or number of magnetic segments and/or ferromagnetic segments in the system, as well as a magnetization direction of the magnetic segments can be predetermined based on, for example, predetermined parameters of the system (e.g., a desired magnetic field strength, direction and/or uniformity of the magnetic field, a desired elimination of a magnetic fringe field and/or total weight of the system) and/or based on a desired application of the system (e.g., performing a magnetic resonance imaging of at least a portion of a patient and/or performing a magnetic resonance spectroscopy of a sample).

A magnetic field device, with a first magnet, a first ferromagnetic element positioned adjacent to the first magnet, a second magnet, a second ferromagnetic element positioned adjacent to the second magnet and relative to the first ferromagnetic element to create a gap between the first ferromagnetic element and the second ferromagnetic element, and a third magnet positioned between the first ferromagnetic element and the second ferromagnetic element and within the gap.

Apparatus or system for homogenizing or modifying the magnetic fields of magnets, particularly the magnetic fields employed in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) applications. The apparatus features passive structures for making magnetic field homogenizations or modifications, and specifically permits the production of desirable correction fields in which the correction field strength has a continuously adjustable value of field strength. Passive shim structures are provided and manipulated so to create correction fields that can have a continuously adjusted value of field strength, such that errors in the original field can be corrected with high fidelity. The passive structures may be physically modified or adjusted by rotation so that truly continuous adjustment of strength and orientation of the corrective fields may be achieved. Also, the passive structures may be manipulated or rotated in a time-dependent fashion so to produce time-dependent modifications to a magnetic field.

In an embodiment, the present disclosure pertains to a method of making a composite. In some embodiments, the method includes applying an external magnetic field to a mixture composed of a plurality of magnetic materials in a container, in which the external magnetic field produces a homogenous and uniform magnetic flux in the container. In some embodiments, the method further includes solidifying the mixture to result in the growth of solvent crystals in the mixture, and subliming a solvent phase of the mixture in the container to thereby form a composite having uniformly aligned magnetic materials. In an additional embodiment, the present disclosure pertains to a composite having uniformly aligned magnetic materials. In some embodiments, a majority of the magnetic materials in the composite are aligned in the same direction.

A method of producing a permanent magnet shim configured to improve a profile of a B.sub.0 magnetic field produced by a B.sub.0 magnet is provided. The method comprises determining deviation of the B.sub.0 magnetic field from a desired B.sub.0 magnetic field, determining a magnetic pattern that, when applied to magnetic material, produces a corrective magnetic field that corrects for at least some of the determined deviation, and applying the magnetic pattern to the magnetic material to produce the permanent magnet shim. According to some aspects, a permanent magnet shim for improving a profile of a B.sub.0 magnetic field produced by a B.sub.0 magnet is provided. The permanent magnet shim comprises magnetic material having a predetermined magnetic pattern applied thereto that produces a corrective magnetic field to improve the profile of the B.sub.0 magnetic field.

A system of electron irradiation includes an electron accelerator and an electron beam focusing device. The electron accelerator emits and accelerates a beam of electrons. The electron beam focusing device is located at a rear end of the electron irradiation and includes a beam restraining rail and 2n+1 sets of magnetic poles. The beam restraining rail forms a beam restraining channel through which the beam of electrons are to pass. The 2n+1 sets of magnetic poles are installed on the beam restraining rail and distributed at different locations of the beam restraining channel. An nth set of magnetic poles thereof are arranged for performing, on the beam of electrons, focusing in a first direction. An (n+1)th set of magnetic poles thereof are arranged for performing, on the beam of electrons, focusing in a second direction. The second direction is perpendicular to the first direction. The n is a positive integer.