INTERLACED MULTI-ENERGY BETATRON WITH ADJUSTABLE PULSE REPETITION FREQUENCY
First Claim
1. A method of operating a betatron device having swing coils for accelerating electrons and having bias coils to provide electron pulses at different energies, the method comprising:
- operating the swing coils to generate a swing component of a total magnetic field at the electron orbit over a plurality of cycles, the electron orbit being a circular path in which accelerated electrons travel;
operating the bias coils to generate a bias component of the total magnetic field at the electron orbit;
operating the bias coils such that the bias magnetic component has a constant first magnitude during a first acceleration portion of a first cycle of the plurality of cycles;
accelerating, with the swing coils, a first packet of electrons with a first swing in flux subject to the total magnetic field during the first acceleration portion of the first cycle to have a first energy;
expanding an electron orbit of the first packet of electrons at an end of the first acceleration portion;
operating the bias coils such that the bias magnetic component has a constant second magnitude during a second acceleration portion of a second cycle of the plurality of cycles, the second magnitude being different than the first magnitude; and
accelerating, with the swing coils, a second packet of electrons with a second swing in flux subject to the total magnetic field during the second acceleration portion of the second cycle to have a second energy, the second energy being different than the first energy.
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Accused Products
Abstract
Variable pulse frequency during an output session of a betatron device and adjustable energy from pulse to pulse are provided. A different bias magnetic field may be used for different cycles of an output session, thereby providing different pulse energies. In one example, the bias field can be switched from a positive value to zero, with energy stored in a storage device when the bias field is zero. The bias field can also be used to expand electrons from a stable orbit when the bias field is decreased. For variable pulse frequency, when a current in the swing coils decreases to zero, the swing coils can be disengaged from a storage device for an adjustable time before re-engaging for a next cycle, thereby adjusting the frequency. In addition, radiation dose output can be adjusted by varying a length of time for the injection of electrons into a betatron.
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Citations
35 Claims
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1. A method of operating a betatron device having swing coils for accelerating electrons and having bias coils to provide electron pulses at different energies, the method comprising:
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operating the swing coils to generate a swing component of a total magnetic field at the electron orbit over a plurality of cycles, the electron orbit being a circular path in which accelerated electrons travel; operating the bias coils to generate a bias component of the total magnetic field at the electron orbit; operating the bias coils such that the bias magnetic component has a constant first magnitude during a first acceleration portion of a first cycle of the plurality of cycles; accelerating, with the swing coils, a first packet of electrons with a first swing in flux subject to the total magnetic field during the first acceleration portion of the first cycle to have a first energy; expanding an electron orbit of the first packet of electrons at an end of the first acceleration portion; operating the bias coils such that the bias magnetic component has a constant second magnitude during a second acceleration portion of a second cycle of the plurality of cycles, the second magnitude being different than the first magnitude; and accelerating, with the swing coils, a second packet of electrons with a second swing in flux subject to the total magnetic field during the second acceleration portion of the second cycle to have a second energy, the second energy being different than the first energy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A betatron device for providing electron pulses at different energies, the betatron device comprising:
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a vacuum enclosure for electrons to orbit during acceleration portions of respective cycles; magnetic cores that conduct and contain magnetic flux and that shape magnetic fields at the electron orbit; swing coils configured to generate a swing in magnetic flux within the electron orbit and a swing component of a total magnetic field at the electron orbit over a plurality of cycles of a single output session; bias coils configured to generate a bias component of the total magnetic field at the electron orbit during the acceleration portions of the respective cycles; a bias storage device selectively coupled to the bias coils via at least a bias storage switch; and a bias power supply selectively coupled to the bias coils and the bias storage device via at least a bias power switch; - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method of operating a betatron device having a swing coil for accelerating electrons to provide electron pulses at adjustable cycle rates, the method comprising:
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operating the swing coils to generate a swing component of a total magnetic field at the electron orbit over a plurality of cycles, the electron orbit being a circular path in which accelerated electrons travel; accelerating, with the swing coils, a first packet of electrons with a first swing in flux subject to the total magnetic field during a first acceleration portion of a first cycle of the plurality of cycles; expanding an electron orbit of the first packet of electrons at an end of the first acceleration portion; after the first acceleration portion of the first cycle, storing energy of the swing component in a swing storage device as the swing component decreases; when a current in the swing coils decreases to zero, disengaging the swing coils from the swing storage device for a first adjustable delay time; and after the first adjustable delay time, engaging the swing coils with the swing storage device for a next cycle. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A betatron device for providing electron pulses at adjustable cycle rates, the betatron device comprising:
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a vacuum enclosure for electrons to orbit during acceleration portions of respective cycles; magnetic cores that conduct and contain magnetic flux and that shape magnetic fields at the electron orbit; swing coils configured to generate a swing in magnetic flux within the electron orbit and a swing component of a total magnetic field at the electron orbit over a plurality of cycles of a single output session; a swing storage device selectively coupled to the swing coils via at least a swing storage switch; a swing power switch configured to selectively couple a swing power supply to the swing coils and the swing storage device, wherein the swing storage switch is configured to engage the swing coils with the swing storage device during a cycle and to disengage the swing coils from the swing storage device for an adjustable delay time between cycles, and wherein the first power switch is configured to disconnect the swing power supply from the swing coils and the swing storage device during a cycle. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34)
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35. A method of controlling an amount of x-ray radiation dose emitted by a betatron device, the method comprising:
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adjusting a length of time of an injection pulse of electrons into a betatron device; accelerating a respective packet of electrons during an acceleration portion of each of a plurality of cycles while the electrons are in an electron orbit; expanding the electron orbit for the respective packets of electrons at an end of the acceleration portion of each cycle; and hitting a metal target with the expanded electrons to produce x-ray radiation, wherein the length of time of the injection pulse is adjusted based on a desired amount of dose output for the radiation beam.
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Specification