Provided, in one aspect, is a downhole magnetic debris removal apparatus. The downhole magnetic debris removal apparatus, in one aspect, includes a housing having a longitudinal axis, and a plurality of magnets arranged as one or more Halbach arrays of magnets coupled to the housing, the one or more Halbach arrays of magnets having a strong side and a weak side.

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).

An apparatus for providing a magnetic field includes a magnet having a surface, and a structure disposed above the magnet surface. The structure includes a material of high magnetic permeability. The apparatus provides an interface between the material of high magnetic permeability and a material of low magnetic permeability. The apparatus may have two poles in magnetic communication with the magnet, the poles extending above the surface of the magnet, and the structure is disposed between the poles. The structure may have alternating regions of high magnetic permeability and low magnetic permeability. The apparatus alters the magnetic field of the magnet to reduce or remove a disorder in the magnetic field, and/or decrease the magnitude of the magnetic field, and/or induce a distortion in the magnetic field, and/or align or re-align the magnetic field, and/or orientate or re-orientate the magnetic field, and/or alter distribution or shape of the magnetic field.

A magnet arrangement having a hollow-cylindrical magnet element that has an axial length L.sub.z,M and an inner radius R.sub.in, is constructed from magnet segments arranged concentrically around the z-axis, and has a Halbach magnetization. At least one ring-shaped magnet element has a notched, hollow-cylindrical cutout extending circumferentially around the z-axis symmetrically with respect to the plane z=0, the axial extent L.sub.z,A of the cutout being less than the axial length L.sub.z,M of the magnet element. The cutout has a radial depth T.sub.A and an axial length L.sub.z,A<L.sub.z,M between the z-positions z=−z.sub.A to z=+z.sub.A. The radial depth T.sub.A and the axial length L.sub.z,A of the cutout are to ensure that the remaining inhomogeneity of the homogenous magnetic field B.sub.0 in a predefined measurement volume having an axial plateau length L.sub.P in the center of the magnet arrangement does not exceed 10 ppm.

A magnet system for use in a nuclear magnetic resonance (NMR) apparatus includes a first magnet and a second magnet located on a backplane to form a gap therebetween, wherein the first magnet and the second magnet are each shaped to form trapezoidal prisms with dimensions selected to optimize a magnetic field at a target region in space external to the magnet system.

Apparatuses, systems, and methods for producing an electromagnetic pulse (EMP). Charged-particle intercalated graphite is disposed at least partially around an explosive and both are positioned within a non-geomagnetic magnetic field. The non-geomagnetic magnetic field accelerates charged particles released by the detonation of the explosive. The non-geomagnetic magnetic field may be generated by permanent magnets. The explosive may be formed in a layer with the non-geomagnetic field being oriented perpendicular to the layer. The layer may be form in the shape of a disc. The explosive and the charged-particle intercalated graphite may be positioned within a resonant cavity that is configured to amplify one or more specific frequencies of electromagnetic energy.

A microprojection device and a magnetic suspension base are provided. The microprojection device comprises a microprojector and a main suspension magnet. The microprojector is fixed to the main suspension magnet. The magnetic field direction at a magnetic field center of the main suspension magnet is in the vertical direction so the microprojector can be driven to be suspended in a magnetic field environment. The magnetic suspension base comprises: a housing and at least three base magnets disposed therein. The magnetic field direction at the center of a combined magnetic field formed by the at least three base magnets is in the vertical direction; the magnetic intensity at the center of the combined magnetic field is less than the magnetic intensity near the base magnets; and the microprojector can be driven to be suspended under the magnetic field environment by being fixed on the magnet.

A device is dynamically programmable to generate at least a first magnetic field during a first time interval, and at least a second magnetic field during a second time interval thereby causing the particles exposed to the change in the magnetic field to aggregate to a target region. The device is further dynamically programmable to switch between the first and second magnetic fields for any number of cycles. Optionally, the device includes a multitude of conductors that receive a first current during the first time interval to generate the magnetic field, and a second multitude of conductors that receive a second current during the second time interval to generate the second magnetic field. The second multitude of conductors may be substantially parallel to the first multitude of conductors. A controller disposed within the device is adapted to vary the frequency of switching between the first and second magnetic fields.

A programmable permanent magnet actuator, a magnetic field generation apparatus and a method of controlling thereof. The actuator has a first body that is a ferromagnetic material, a second body that is a single magnetized ferromagnet and a magnetic field generation device associable to the second body to generate a magnetic field in proximity with the second body. The actuator also has a controller adapted to control the magnetic field generation device to generate a controlled magnetic field. The controlled magnetic field is adapted to modify a magnetization of the second body such as to produce with the second body a required magnetic field to move one of the first or the second body with respect to one another according to a desired position or a desired torque. The desired position or the desired torque is maintained even after the application of the controlled magnetic field. The apparatus has a permanent magnet that has an intrinsic coercivity (Hci) value that is greater than 200 kA/m and a remanence (Br) value that is greater than 0.4 Tesla. The apparatus also has a magnetic field generation device associated to the permanent magnet and a controller connected to the magnetic field generation device. The controller is adapted to control the magnetic field generation device to produce a controlled magnetic field to variably modify a magnetization of the permanent magnet in order to produce a desired variable magnetic field and influence the electrically charged or magnetized material when placed in the desired variable magnetic field.

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.