Claims
- 1. A magnetically-focused linear beam microwave tube having a central axis, said tube comprising:
- electron gun means adjacent one end of said tube for originating a strongly converging electron beam, said gun including a cathode having a concave emitting surface, and an envelope means, said envelope means including electrically insulating material, said gun operable at a high voltage;
- collector means at the opposite end of said tube for collecting the electrons of said beam;
- means disposed between said gun and collector alongside said beam for supporting energy-exchanging electron beam-microwave interaction;
- said electron gun means, said means for supporting energy-exchanging interaction, and said collector means being in a vacuum-tight relationship;
- an anode having a passage therethrough for accepting said beam from said gun, said anode operable at a voltage which is positive with respect to said cathode;
- magnetic circuit means for focusing said beam to a substantially uniform and narrow diameter within said interaction means, said circuit means including a polepiece extending about said gun;
- means for externally adjusting primarily the magnetic field acting on said cathode, said means for adjusting the magnetic field being substantially at ground potential during tube operation, said means for adjusting the magnetic field including magnetic material disposed within said polepiece outside and adjacent said envelope means, and being moveable axially about said cathode during tube operation, said magnetic material including at least one permanent magnet portion, whereby the diameter of said electron beam may be optimized, while maintaining variations in said beam diameter with beam travel at a negligible level; and
- means for fixing the position of said means for adjusting the magnetic field after beam diameter optimization.
- 2. A magnetically-focused linear beam microwave tube having a central axis, said tube comprising:
- electron gun means adjacent one end of said tube for originating a strongly converging electron beam, said gun including a cathode having a concave emitting surface, and an envelope means;
- collector means at the opposite end of said tube for collecting the electrons of said beam;
- means disposed between said gun and collector alongside said beam for supporting energy-exchanging electron beam-microwave interaction;
- an anode having a passage therethrough for accepting said beam from said gun, said anode operable at a voltage which is positive with respect to said cathode;
- said electron gun means, said means for supporting energy-exchanging interaction, said anode and said collector means being in a vacuum-tight relationship;
- magnetic circuit means for focusing said beam to a substantially uniform and narrow diameter within said interaction means, said circuit means including a polepiece extending about said gun, said polepiece defining an axial cavity therewithin, said envelope means being positioned within said cavity, said cavity being of a transverse diameter larger than the transverse dimensions of said envelope means;
- means for externally adjusting substantially only the magnetic field within the gun region, said means including a hollow cylinder of magnetic material disposed within and engaging said cavity, and outside and adjacent said envelope means in spaced coaxial relationship thereto to insure isolation at gun operating voltages, said means being moveable axially in the vicinity of said gun during tube operation, whereby the diameter of said electron beam may be reduced or optimized during operation, while maintaining variations in said beam diameter with beam travel at a negligible level; and
- means for fixing the position of said means for adjusting the magnetic field after beam diameter optimization.
- 3. A magnetically-focused linear beam microwave tube having a central axis, said tube comprising:
- electron gun means adjacent one end of said tube for originating a strongly converging electron beam, said gun including a cathode having a concave emitting surface, and an envelope means;
- collector means at the opposite end of said tube for collecting the electrons of said beam;
- means disposed between said gun and collector alongside said beam for supporting energy-exchanging electron beam-microwave interaction;
- an anode having a passage therethrough for accepting said beam from said gun, said anode operable at a voltage which is positive with respect to said cathode;
- said electron gun means, said means for supporting energy-exchanging interaction, said anode and said collector means being in a vacuum-tight relationship;
- magnetic circuit means for focusing said beam to a substantially uniform and narrow diameter within said interaction means, said circuit means including a polepiece extending about said gun; said polepiece defining an axial cavity therewithin, said envelope means being positioned within said cavity, said polepiece extending inwardly to define a central aperture of diameter smaller relative to that of said axial cavity, said cavity terminating in said aperture, said envelope means being of larger diameter than said aperture, but smaller than said axial cavity, said envelope means extending into said cavity to a position closely adjacent said aperture;
- means for externally adjusting substantially only the magnetic field within the gun region, said means including magnetic material disposed within said polepiece outside and adjacent said envelope means, and being moveable axially between positions in the vicinity of said gun during tube operation, said means extending inwardly into said axial cavity and generally symmetrically about said gun in even spaced relationship to said gun, whereby the diameter of said electron beam may be reduced or optimized during operation, while maintaining variations in said beam diameter with beam travel at a negligible level; and
- means for fixing the position of said means for adjusting the magnetic field after beam diameter optimization.
- 4. The tube of claims 2 or 3 in which said envelope means includes electrically insulating material, said gun operates at a high voltage, and said means for adjusting the magnetic field is substantially at ground potential during tube operation.
- 5. In a magnetically-focused linear electron beam microwave tube having a central axis:
- a moderately-to-highly converging, confined-field-flow-magnetically-focused electron gun means at one end of said tube for developing and projecting an electron beam along said axis, said gun including a cathode having a concave emitting surface operable at a high negative voltage, and an insulating envelope;
- collector means at the opposite end of said tube for collecting the electrons of said beam;
- electron beam-microwave interaction means extending along said axis in vacuum-tight relationship with said cathode, said interaction means defining a tunnel for said beam;
- said electron gun means and said means for supporting energy-exchanging interaction being in a vacuum-tight relationship;
- a polepiece positioned about said gun and having a restricted outlet opening into said interaction means; said electron beam passing into said interaction means via said outlet;
- an anode axially disposed adjacent said restricted outlet and having a passage therethrough for accepting said beam from said gun, said anode operable at a voltage which is positive with respect to said cathode; and
- an externally adjustable first magnetic material means interposed between said gun envelope and said polepiece, said means including at least one permanent magnet portion, said means being at ground potential and moveable with respect to said gun and polepiece toward or away from said cathode between axial positions in the vicinity of said cathode for enabling substantial adjustment of said electron beam diameter for optimal performance, while holding variations in beam diameter along said axis to a minimum; and
- means for fixing the position of said means for adjusting the beam diameter after beam diameter optimization.
- 6. In a magnetically-focused linear electron beam microwave tube having a central axis:
- a converging, confined-field-flow-magnetically-focused electron gun means at one end of said tube for developing and projecting an electron beam along said axis, said gun including a cathode having a concave emitting surface operable at a high negative voltage, and an insulating envelope of generally cylindrical shape;
- collector means at the opposite end of said tube for collecting the electrons of said beam;
- electron beam-microwave interaction means extending along said axis in vacuum-tight relationship with said cathode;
- an anode having a passage therethrough for accepting said beam from said gun, said anode operable at a voltage which is positive with respect to said cathode;
- a polepiece positioned about said gun and having a restricted outlet opening into said interaction means; said electron beam passing into said interaction means via said outlet, said polepiece defining an axial cavity of substantially uniform circular cross section and diameter throughout most of its axial length, said gun envelope positioned within said cavity, the diameter of said envelope being less than the diameter of said cavity;
- and an externally adjustable first magnetic material means interposed between said gun envelope and said polepiece, said means being at ground potential and being axially moveable with respect to said gun and polepiece toward or away from said gun between axial positions in the vicinity of said gun, for enabling substantial adjustment of said electron beam diameter for optimal performance, while holding variations in beam diameter along said axis to a minimum; and
- means for fixing the position of said means for adjusting the beam diameter after beam diameter optimization.
- 7. The tube of claims 5 or 6 in which said magnetic material means is rotatable relative to said gun.
- 8. The tube of claims 5 or 6 in which a second magnetic material means is affixed within said first means.
- 9. The tube of claim 8 in which said second means is of a different thickness than that of said first magnetic material means.
- 10. In a magnetically-focused linear electron beam microwave tube having a central axis:
- a converging, confined-field-flow-magnetically-focused electron gun means at tone end of said tube for developing and projecting an electron beam along said axis, said gun including a cathode having a concave emitting surface operating at a high negative voltage, and an insulating envelope;
- collector means at the opposite end of said tube for collecting the electrons of said beam;
- electron beam-microwave interaction means extending along said axis in vacuum-tight relationship with said cathode;
- an anode having a passage therethrough for accepting said beam from said gun, said anode operable at a voltage which is positive with respect to said cathode;
- a polepiece positioned about said gun and having a restricted outlet opening into said interaction means; said electron beam passing into said interaction means via said outlet;
- and an externally adjustable magnetic material means interposed between said gun envelope and said polepiece, said means being at ground potential and including first and second sections, both said sections being generally cylinders and complementarily threaded, said first cylinder being fixed to said polepiece, said second cylinder being rotatable so as to be threadable into and from the vicinity of said gun between axial positions in the vicinity of said gun, for enabling substantial adjustment of said electron beam diameter for optimal performance, while holding variations in beam diameter along said axis to a minimum; and
- means for fixing the position of said means for adjusting the beam diameter after beam diameter optimization.
- 11. In a magnetically-focused linear electron beam microwave tube having a central axis:
- a converging, confined-field-flow-magnetically-focused electron gun means at one end of said tube for developing and projecting an electron beam along said axis, said gun including a cathode having a concave emitting surface operating at a high negative voltage, and an insulating envelope;
- collector means at the opposite end of said tube for collecting the electrons of said beam;
- electron beam-microwave interaction means extending along said axis in vacuum-tight relationship with said cathode;
- an anode having a passage therethrough for accepting said beam from said gun, said anode operable at a voltage which is positive with respect to said cathode;
- a polepiece positioned about said gun and having a restricted outlet opening into said interaction means; said electron beam passing into said interaction means via said outlet;
- and an externally adjustable magnetic material means interposed between said gun envelope and said polepiece, said means being at ground potential and being slideably engaged within said polepiece so as to be moveable with respect to said gun and polepiece toward or away from said gun between axial positions in the vicinity of said gun, said means including a portion extending outside said polepiece and engaging a threaded screw member axially bearing upon an end portion of said polepiece, for enabling substantial optimization of sad electron beam diameter for optimal performance by rotating said screw member while holding variations in beam diameter along said axis to a minimum; and
- means for fixing the position of said means for adjusting the beam diameter after beam diameter optimization.
- 12. The tube of claim 11 in which said magnetic material means includes a layer of high magnetic permeability material extending symmetrically about said gun in contact with said permanent magnet portions, and positioned between said permanent magnet portions and said gun.
- 13. The tube of claims 5 or 6 in which said interaction means defines a tunnel for said beam having a diameter of less than 100 mils.
- 14. The tube of claim 13 in which said beam is of a diameter in the range of 5 to 30 mils.
- 15. The tube as in claim 13 in which said beam has a power density ranging upwardly from the vicinity of 50 megawatts per square centimeter.
- 16. The tube as in claim 13 in which said magnetic material means adjusts said beam to said diameter, and wherein said beam diameter is a substantial fraction of said tunnel diameter.
- 17. The tube as in claim 6 in which said interaction means defines a tunnel for said beam and in which said adjusting means adjusts the diameter of said beam to be a large fraction of that of said tunnel.
- 18. The tube of claims 1, 2 or 3, in which said magnetic circuit means includes a permanent magnet.
- 19. The tube of claims 5 or 6, which further includes a permanent magnet cooperating with said polepiece.
- 20. In a magnetically-focused linear electron beam tube having a central axis for use with magnetic means for focusing the beam over a linear path:
- magnetically-focused electron gun means for generating and projecting said electron beam along said path, said gun means including a cathode having a concave emitting surface and an insulating envelope thereabout, said means moderately-to-strongly converging said beam;
- electron-beam microwave interaction means extending along said axis in vacuum-tight relationship with said cathode;
- collector means at the opposite end of said tube for collecting the electrons of said beam;
- a polepiece positioned about said gun, said polepiece having an opening to allow said beam therethrough;
- an anode having a passage therethrough for accepting said beam from said gun, said anode operating at a voltage which is positive with respect to said cathode;
- means positioned within said polepiece, and about and outside said envelope, said means including a ring of magnetic material disposed about said envelope, said means being moveable axially in the vicinity of said cathode for adjusting a magnetic field acting on said cathode while affecting the field downstream of said cathode comparatively minimally whereby the diameter of said electron beam may be optimized; and
- means for fixing the position of said means for adjusting the magnetic field after beam diameter optimization.
- 21. The tube of claims 1, 2, 3, 5, 6, 10 or 11 in which said means for adjusting the magnetic field includes a ring of magnetic material disposed about said envelope and axially moveable relative thereto.
- 22. The tube of claims 1, 2, 3, 5, 6, 10, 11 or 20 in which said magnetic material comprises iron.
- 23. The tube of claims 2, 3, 6, 10, 11 or 20 in which said magnetic material includes at least one permanent magnet portion.
- 24. The tube of claims 1, 2, 3 or 20 in which said means for adjusting the magnetic field includes axially extending portions portions to permit manual adjustment during tube operation.
Parent Case Info
This application is a continuation of application Ser. No. 309,366, filed Oct. 7, 1981, now abandoned.
US Referenced Citations (14)
Continuations (1)
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Number |
Date |
Country |
Parent |
309366 |
Oct 1981 |
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