Circular induction accelerator for borehole logging
First Claim
1. In a magnetic induction accelerator including a magnetic induction accelerator including a magnetic circuit having a field magnet, a pair of opposed generally circular pole pieces, a core magnet, an excitation circuit including a field coil surrounding said field magnet and said core magnet and a core coil surrounding said core magnet, an annular acceleration chamber interposed between said pole pieces, means for applying time-varying acceleration voltage pulses across said circuit for accelerating charged particles in said acceleration chamber, means for injecting charged particles into the acceleration chamber, means for compressing the particle orbits to trap particles within generally circular orbits in said acceleration chamber, and means for expanding the particle orbits to eject particles from said generally circular orbits, the improvement comprising:
- said field magnet and said pole pieces being composed of a class of ferrite having the general formula M2+ Fe23+ O4, where M represents two or more divalent metal ions from the group consisting of Mn, Zn and Ni; and
said core magnet comprises at least one closed loop section, with one leg of each loop passing axially through the center of the circular pole pieces and through said core coil.
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Accused Products
Abstract
A compact circular magnetic induction accelerator (betatron) for use as a borehole gamma ray source includes a field magnet and generally circular pole pieces composed of a class of ferrite having the general formula M2+ Fe23+ O4, where M represents two or more divalent metal ions from the group consisting of Mn, Zn and Ni. The core magnet is in the form of two symmetrical closed loops, with one leg of each loop passing axially through the circular pole pieces. The field coil and the core coil may be arranged in series or in parallel, and switching circuits are provided for effecting electron beam capture and ejection. In an illustrative borehole application, the betatron is used as a gamma ray source in a bulk density logging tool.
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Citations
33 Claims
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1. In a magnetic induction accelerator including a magnetic induction accelerator including a magnetic circuit having a field magnet, a pair of opposed generally circular pole pieces, a core magnet, an excitation circuit including a field coil surrounding said field magnet and said core magnet and a core coil surrounding said core magnet, an annular acceleration chamber interposed between said pole pieces, means for applying time-varying acceleration voltage pulses across said circuit for accelerating charged particles in said acceleration chamber, means for injecting charged particles into the acceleration chamber, means for compressing the particle orbits to trap particles within generally circular orbits in said acceleration chamber, and means for expanding the particle orbits to eject particles from said generally circular orbits, the improvement comprising:
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said field magnet and said pole pieces being composed of a class of ferrite having the general formula M2+ Fe23+ O4, where M represents two or more divalent metal ions from the group consisting of Mn, Zn and Ni; and said core magnet comprises at least one closed loop section, with one leg of each loop passing axially through the center of the circular pole pieces and through said core coil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. In a downhole logging sonde adapted to be moved through a borehole, a source of gamma rays in said sonde for irradiating earth formations traversed by the borehole, one or more gamma ray detectors for detecting gamma rays scattered back to the sonde from the irradiated earth formations, and means for transmitting signals representative of the detected gamma rays to the earth'"'"'s surface for processing, the improvement wherein said gamma ray source comprises a magnetic induction particle accelerator, including:
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a magnetic circuit having a field magnet, generally circular opposed pole pieces, and a core magnet comprising at least one closed loop section, with one leg of each loop passing axially through the center of the circular pole pieces, said field magnet and said pole pieces being composed of a class of ferrite having the general formula M2+ F23+ O4, where M represents two or more divalent metal ions from the group consisting of Mn, Zn and Ni; an excitation circuit including a field coil surrounding said field magnet and said core magnet and a core coil surrounding said central axially leg of said core magnet; an annular acceleration chamber interposed between said pole pieces; means for applying time-varying acceleration voltage pulses across said primary excitation circuit; means for injecting charged particles into orbit within said acceleration chamber; means for compressing the particle orbits to trap particles within generally circular orbits within said acceleration chamber; means for generating a particle accelerating magnetic flux in said magnetic circuit;
anmeans for ejecting charged particles from said generally circular orbits and into contact with a target to produce gamma ray photons. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification