The United States of America As Represented by the United States

Field Effects

Klaus Halbach

Paul Remillard

Techniques for operating a power amplifier in driving a highly inductive load are provided. More particularly, the voltage across a coil load is integrated to obtain a signal representative of the flux and this signal is fed back as an error signal to the power amplifier to conform the instantaneous flux to the input voltage of the power amplifier. Since the power amplifier is operated in a voltage output mode and the flux is forced to conform to the input voltage, the effects of eddy currents are automatically compensated for while the power amplifier displays maximum bandwidth for pulse and sinusoidal input sequences.

Methods and apparatus for controlling power amplifiers driving highly

This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles.

Strong permanent magnet-assisted electromagnetic undulator

An improved method and structure is disclosed for adjusting the magnetic field generated by a group of electromagnet poles spaced along the path of a charged particle beam to compensate for energy losses in the charged particles which comprises providing more than one winding on at least some of the electromagnet poles; connecting one respective winding on each of several consecutive adjacent electromagnet poles to a first power supply, and the other respective winding on the electromagnet pole to a different power supply in staggered order; and independently adjusting one power supply to independently vary the current in one winding on each electromagnet pole in a group whereby the magnetic field strength of each of a group of electromagnet poles may be changed in smaller increments.

Magnetic field adjustment structure and method for a tapered wiggler

Disclosed is a new type of electromagnet which can be used as a gradient coil in NMR imaging systems. The cylindrical electromagnet produces a transverse magnetic field perpendicular to the magnet axis which varies as the displacement along the magnet axis. An NMR imaging system using this new magnet is also disclosed.

Cylindrical electromagnet for an NMR imaging system

Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling therebetween. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.

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Berkeley, CA, United States of America

Klaus Halbach