With Increased Emissivity Patents (Class 378/129)
  • Patent number: 11887803
    Abstract: The disclosure relates to an X-ray tube, comprising a cathode and an anode, the cathode and anode being accommodated in a housing which provides a vacuum environment.
    Type: Grant
    Filed: May 16, 2022
    Date of Patent: January 30, 2024
    Assignee: Siemens Healthcare GmbH
    Inventors: Xiao Dong, Zhen Neng Zhang, Da Peng Hao, Qi Zhou
  • Patent number: 11798772
    Abstract: Provided are an on-chip miniature X-ray source and a method for manufacturing the same. The on-chip miniature X-ray source includes: an on-chip miniature electron source; a first insulating spacer provided on an electron-emitting side of the on-chip miniature electron source, where the first insulating spacer has a cavity structure; and an anode provided on the first insulating spacer, where a closed vacuum cavity is formed between the on-chip miniature electron source and the anode. The on-chip miniature X-ray source has the advantages of stable X-ray dose, low working requirements for vacuum, fast switch response, capability of integration and batch fabrication, and can be used in various types of small and portable X-ray detection, analysis and treatment devices.
    Type: Grant
    Filed: November 7, 2019
    Date of Patent: October 24, 2023
    Assignee: PEKING UNIVERSITY
    Inventor: Xianlong Wei
  • Patent number: 10692685
    Abstract: The present disclosure relates to the production and use of a multi-layer X-ray source target. In certain implementations, layers of X-ray generating material may be interleaved with thermally conductive layers. To prevent delamination of the layers, various mechanical, chemical, and structural approaches are related, including approaches for reducing the internal stress associated with the deposited layers and for increasing binding strength between layers.
    Type: Grant
    Filed: April 13, 2017
    Date of Patent: June 23, 2020
    Assignee: GENERAL ELECTRIC COMPANY
    Inventors: Vance Scott Robinson, Yong Liang, Thomas Robert Raber, George Theodore Dalakos, Christoph Wild
  • Patent number: 10229808
    Abstract: A transmission-type target includes a target layer and a transmissive substrate. The target layer is configured to generate X-rays in response to irradiation of electrons. The transmissive substrate supports the target layer and is configured to allow the X-rays generated in the target layer to pass therethrough. The transmissive substrate includes polycrystalline diamond in which grain boundaries extend in a substrate thickness direction and a substrate plane direction. The grain boundaries define an electrical potential of the target layer.
    Type: Grant
    Filed: July 9, 2015
    Date of Patent: March 12, 2019
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yoichi Ikarashi, Shuji Yamada, Tadayuki Yoshitake, Takao Ogura, Takeo Tsukamoto
  • Patent number: 9177754
    Abstract: An x-ray tube includes an evacuated envelope, and a cathode assembly and an anode assembly both disposed in the evacuated envelope. The cathode assembly includes a cathode shield, a supporting body disposed inside the cathode shield, and an electron source attached to the supporting body and partially enclosed by the cathode shield. The anode assembly includes a target configured to produce x-rays upon impingement by electrons produced by the electron source. The cathode shield comprises a shield base material and a layer over at least a portion of the base material. The layer comprises an emissivity enhancer having an emissivity greater than the emissivity of the shield base material. The layer may comprise an emissive coating applied on the portion of the base material. Alternatively, the layer may comprise a greened surface formed by a greening process.
    Type: Grant
    Filed: February 9, 2013
    Date of Patent: November 3, 2015
    Assignee: Varian Medical Systems, Inc.
    Inventors: Wayne Hansen, Kasey Greenland, Todd Parker
  • Publication number: 20150103978
    Abstract: An anode 30 for an X-ray tube 10 comprising at least a stem 29 for rotary supporting the anode 30 and a disc 34, being coaxially attached to the stem 29 and having a peripheral target area 32 as target for an electron beam 27 on its frontal side, can be efficiently cooled if the anode 30 has at least one cavity extending into the disc 34 and in particular, if the cavity has a coating 50 of at least one inorganic salt.
    Type: Application
    Filed: November 24, 2014
    Publication date: April 16, 2015
    Inventor: Ki CHAN
  • Patent number: 8923485
    Abstract: An anode disk element for the generation of X-rays that provides improved dissipation of heat from a focal track includes an anisotropic thermal conductivity. The anode disk element includes a focal track and at least one heat dissipating element. The anode disk element is rotatable about a rotational axis with the focal track being rotationally symmetrical to the rotational axis. The at least one heat dissipating element is configured for heat dissipation from the focal track in the direction of reduced thermal conductivity of the anode disk element.
    Type: Grant
    Filed: June 24, 2010
    Date of Patent: December 30, 2014
    Assignee: Koninklijke Philips N.V.
    Inventors: Kevin Kraft, Gerald J. Carlson, Paul Xu
  • Publication number: 20140105366
    Abstract: Finned anode. In one example embodiment, an anode suitable for use in an x-ray tube includes a hub, a front side, and a target surface disposed on the front side. The hub is configured to attach to a bearing assembly and the front side substantially faces the bearing assembly. The anode further includes a rear side substantially opposite the front side, as well as two or more annular anode fins extending from the rear side. The annular anode fins are positioned radially outward from the hub to an outer periphery of the rear side.
    Type: Application
    Filed: October 12, 2012
    Publication date: April 17, 2014
    Applicant: VARIAN MEDICAL SYSTEMS, INC.
    Inventors: Jeffrey Steven Wassom, Dennis H. Runnoe, Robert Clark Treseder
  • Publication number: 20120189104
    Abstract: An x-ray tube having a coated x-ray tube frame inner surface and a coated anode assembly is provided. The x-ray tube includes an x-ray tube frame in which an anode assembly is disposed therein. A cathode assembly is also disposed within the x-ray tube frame that emits an electron beam to strike a target surface of the anode assembly and form x-rays. A plasma-sprayed tungsten oxide coating is formed on an inner surface of the x-ray tube frame and on the anode assembly to dissipate heat created by the electron beam.
    Type: Application
    Filed: April 2, 2012
    Publication date: July 26, 2012
    Inventor: Madhusudhana T. Subraya
  • Patent number: 8175222
    Abstract: One example embodiment includes an electron emitter. The electron emitter comprises a conductive member that defines a plurality of filament segments that are integral with each other. Each filament segment includes an intermediate portion and an interconnecting portion attached to an adjacent filament segment. The intermediate portions are substantially coplanar with each other and each intermediate portion includes a substantially planar electron emission surface.
    Type: Grant
    Filed: August 27, 2009
    Date of Patent: May 8, 2012
    Assignee: Varian Medical Systems, Inc.
    Inventors: Paul D. Moore, Stephen G. Bandy, Clifford K. Nishimoto, David H. Humber, Gary F. Virshup
  • Patent number: 7903786
    Abstract: A target assembly for generating x-rays includes a target substrate, and an emissive coating attached to the target substrate, the emissive coating including a textured material including a plurality of granular protrusions arranged to increase gray body emissive characteristics of the target assembly above that of the target substrate.
    Type: Grant
    Filed: August 25, 2008
    Date of Patent: March 8, 2011
    Assignee: General Electric Company
    Inventors: Dalong Zhong, Dennis M. Gray, Michael Hebert, Thomas Raber, Gregory Alan Steinlage, Thomas C. Tiearney
  • Patent number: 7720200
    Abstract: A composite target for generating x-rays includes a target substrate and at least one material applied to the target substrate with a laser beam.
    Type: Grant
    Filed: October 2, 2007
    Date of Patent: May 18, 2010
    Assignee: General Electric Company
    Inventors: Gregory Alan Steinlage, Michael Hebert, Michael Lathrop, Kirk A. Rogers, Thomas C. Tiearney, Jr.
  • Patent number: 7672433
    Abstract: A target assembly for generating x-rays includes a target substrate, and an emissive coating applied to a portion of the target substrate, the emissive coating comprising one or more of a carbide and a carbonitride.
    Type: Grant
    Filed: May 16, 2008
    Date of Patent: March 2, 2010
    Assignee: General Electric Company
    Inventors: Dalong Zhong, Dennis M. Gray, Michael Hebert, Don Mark Lipkin, Thomas Raber, Gregory Alan Steinlage, Thomas C. Tiearney
  • Patent number: 7658987
    Abstract: A metal x-ray device component is provided that includes a high emissivity inorganically bonded ceramic coating that can be applied with minimal surface preparation and that provides good resistance to corrosion and oxidation of substrates in high temperature, vacuum environments. The coating has good dielectric properties, is stable in the high temperature, vacuum environment characteristic of x-ray devices, and provides effective and reliable performance over a wide range of operating temperatures.
    Type: Grant
    Filed: September 23, 2003
    Date of Patent: February 9, 2010
    Assignee: Varian Medical Systems, Inc.
    Inventor: Don Warburton
  • Patent number: 7643614
    Abstract: A target for generating x-rays includes a target substrate, a target shaft attached to the target substrate, and a radiation emissive coating applied to at least one of the target substrate and the target shaft, wherein a center-of-gravity of the target is positioned between a front bearing assembly and a rear bearing assembly of an x-ray tube.
    Type: Grant
    Filed: September 25, 2007
    Date of Patent: January 5, 2010
    Assignee: General Electric Company
    Inventors: Michael Hebert, Gregory Alan Steinlage, Thomas C. Tiearney, Jr.
  • Publication number: 20090080615
    Abstract: A target for generating x-rays includes a target substrate, a target shaft attached to the target substrate, and a radiation emissive coating applied to at least one of the target substrate and the target shaft, wherein a center-of-gravity of the target is positioned between a front bearing assembly and a rear bearing assembly of an x-ray tube.
    Type: Application
    Filed: September 25, 2007
    Publication date: March 26, 2009
    Inventors: Michael Hebert, Gregory Alan Steinlage, Thomas C. Tiearney, JR.
  • Patent number: 7356122
    Abstract: A focal track region of an x-ray anode in an example is electrochemically etched. In a further example, an x-ray anode comprises a thermally-compliant focal track region for impingement of electrons from an x-ray cathode to create an x-ray source. The thermally-compliant focal track region comprises a pattern of discrete relative expanses and gaps.
    Type: Grant
    Filed: May 18, 2006
    Date of Patent: April 8, 2008
    Assignee: General Electric Company
    Inventors: Thomas Raber, Bernard Bewlay, Andrew Trimmer, Bin Wei, Colin R. Wilson, Mark Benz, Ernest Balch
  • Patent number: 7095821
    Abstract: An rotor assembly (30) for an imaging X-ray tube (32) is provided. The imaging X-ray tube rotor assembly (30) includes at least partially a magnetic non-corrosive material. A method of producing the imaging tube X-ray rotor assembly (30) is also provided including forming a rotor core (52) at least partially from a magnetic non-corrosive material.
    Type: Grant
    Filed: July 25, 2003
    Date of Patent: August 22, 2006
    Assignee: General Electric Company
    Inventors: Gregory A. Steinlage, Alexander M. Blok, Mohamed Osama
  • Patent number: 6487272
    Abstract: The object of this invention is to provide a highly reliable penetrating type X-ray tube and a manufacturing method thereof, preventing interfacial exfoliation between a transmission window and a target film before it happens. This invention is characterized in that at least one intermediate film 39 of at least one metal element or an alloy thereof selected from a group of copper, chromium, iron, nickel, etc. between x-ray penetrating window plate 37 of beryllium stuck vacuum-tightly to a portion of evacuated envelope 33, and target film 40 of tungsten which is provided on the evacuated side of the window plate and emanates X rays is formed by a physical method such as spattering.
    Type: Grant
    Filed: February 4, 2000
    Date of Patent: November 26, 2002
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Hiroki Kutsuzawa
  • Patent number: 6477222
    Abstract: An optical switch includes a core and a fluid reservoir. The core includes a base, a matrix controller substrate, and a planar lightwave circuit. The planar lightwave circuit has a plurality of waveguides and a plurality of trenches. Each trench is located at an intersection of two waveguides. The fluid reservoir supplies a fluid to the plurality of trenches of the core. The optical switch further includes a getter for removing atmospheric gases from the fluid. The getter may be a porous silica getter, a non-evaporable getter, or an evaporable getter. By removing atmospheric gases from the fluid, the getter improves the capacity and operation of the optical switch. The optical switch may further include a membrane to separate the getter in a getter chamber from the fluid in a fluid chamber.
    Type: Grant
    Filed: April 30, 2001
    Date of Patent: November 5, 2002
    Assignee: Agilent Technologies, Inc.
    Inventors: Michael J. Nystrom, C. Girvin Harkins
  • Patent number: 6456692
    Abstract: An x-ray tube having one or more components, such as the rotor, that include a coating of relatively high emissivity. The coating, a metal oxide composition for example, is selectively applied to desired portions of the component by plasma spray or similar process. The relatively high emissivity of the coating enhances the ability of the coated surface to radiate heat, and thereby aids in implementation of a cooling effect with respect to the x-ray tube.
    Type: Grant
    Filed: September 28, 2000
    Date of Patent: September 24, 2002
    Assignee: Varian Medical Systems, Inc.
    Inventor: Ricky B. Smith
  • Patent number: 6390875
    Abstract: A method is provided for enhancing heat transfer within an X-ray vacuum tube, from a hot component such as the rotating anode assembly to a cooler component such as the metal tube housing, by increasing surface emissivity of respective components. The method comprises the steps of fabricating each component from an alloy containing a specified minimum amount of chromium, and then implementing a first heating operation, wherein a fabricated component is heated in a dry hydrogen atmosphere for a first specified time period. Thereafter, a second heating operation is implemented, wherein the fabricated component is heated in a wet hydrogen atmosphere for a second specified time period. This procedure forms a refractory chromium oxide coating on the component that exhibits high absorption in the NIR region of the electromagnetic spectrum.
    Type: Grant
    Filed: March 24, 2000
    Date of Patent: May 21, 2002
    Assignee: General Electric Company
    Inventors: John M. Warren, Michael Price, Martin W. Plutowski
  • Patent number: 6144720
    Abstract: A high energy x-ray tube includes an evacuated chamber (12) containing a rotor (34) which rotates an anode (10) in the path of a stream of electrons (A) to generate an x-ray beam (B) and heat. The rotor includes an armature (36) which rotates around a stationary rotor support (40). An emissive coating is formed on the rotor by depositing an iron Fe.sub.3 O.sub.4 oxide plasma onto the surface of the armature. Heat generated in the anode during the production of x-rays is conducted through the anode and the rotor to the emissive coating which irradiates the heat across vacuum, thereby increasing the lifetime of the tube. A stator (32) generates an oscillating magnetic field which induces opposing fields in the Fe.sub.3 O.sub.4 coating to create the rotational forces to rotate the anode.
    Type: Grant
    Filed: August 28, 1998
    Date of Patent: November 7, 2000
    Assignee: Picker International, Inc.
    Inventors: Frank D. DeCou, Paul M. Xu, Robert J. Zielinski
  • Patent number: 5553114
    Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved coating for the x-ray tube rotor. The surface of the x-ray tube rotor is coated with a ductile, metal coating, preferably iron, having a thickness of about 0.2 to about 5.0 mils thick. The rotor coating has ductile properties with a strain to fail greater than 0.05% and thermal expansion properties which when placed on an x-ray tube rotor, provides at least about 40,000 x-ray scan-seconds prior to tube failure due to rotor spalling.
    Type: Grant
    Filed: April 4, 1994
    Date of Patent: September 3, 1996
    Assignee: General Electric Company
    Inventors: Paul A. Siemers, Richard W. Lindberg, Stephen F. Rutkowski
  • Patent number: 5461659
    Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved coating for the x-ray tube rotor. The surface of the x-ray tube rotor is coated with a ductile coating wherein at least about 40,000 x-ray scan-seconds are accomplished prior to tube failure due to spalling. The coating may be a ductile alloy such as Rene' 80 having a thickness of about 0.2 to about 5.0 mils thick and may be even thicker. The rotor coating has ductile properties with a strain to fail greater than 0.05% and thermal expansion properties which when placed on an x-ray tube rotor, provides at least about 40,000 x-ray scan-seconds prior to tube failure due to rotor spalling.
    Type: Grant
    Filed: March 18, 1994
    Date of Patent: October 24, 1995
    Assignee: General Electric Company
    Inventors: Paul A. Siemers, Mark G. Benz, Stephen F. Rutkowski, Mehran Mohsenian
  • Patent number: 5264801
    Abstract: A target track (20) of an anode (14) of an x-ray tube becomes heated adjacent a focal spot (18) to temperatures on the order of 1100.degree.-1400.degree. C. To protect the anode, a body portion (34) is coated (46) with a thermal energy emissive oxide layer (48). In order to prevent carbon from the body portion from migrating out to the oxide layer and forming carbon monoxide gas, a carbide forming barrier layer (36) is formed (38,40) between the body and the oxide coating. The barrier layer is a dense, substantially pore-free coating of a metal that has a free energy of carbide formation of at least 100 KJ/mole at 1200.degree. C. Preferably, the barrier layer material is zirconium, although hafnium, titanium, vanadium, uranium, tantalum, niobium, chromium, and their alloys also provide acceptable barriers to carbon atom migration.
    Type: Grant
    Filed: May 5, 1992
    Date of Patent: November 23, 1993
    Assignee: Picker International, Inc.
    Inventors: Donald Frank DeCou, Jr., James G. Hull
  • Patent number: 5159619
    Abstract: A high performance x-ray tube rotating target having a reactive barier layer between the substrate and the emissive coating and, if desired, a protective layer of molybdenum between the reactive barrier and the emissive coating is disclosed.
    Type: Grant
    Filed: September 16, 1991
    Date of Patent: October 27, 1992
    Assignee: General Electric Company
    Inventors: Mark G. Benz, Melvin R. Jackson, Robert J. Zabala, Karen A. Lou, Thomas C. Tiearney, Jr.
  • Patent number: 5157705
    Abstract: The invention relates to enhancing the thermal emissivity of metal X-ray tube anodes by means of applying an oxide coating to the anode. The oxide coating layer is formed of a mixture of zirconium oxide, titanium oxide, aluminum oxide and/or calcium oxide, with silicon oxide added from about 1-20% by weight of said oxide coating layer. Preferably, the coating includes from about 4-7% by weight of silicon oxide. The oxide coating layer is then applied to the anode pursuant to a standard method such as plasma spraying. The oxide coating, as formulated, displays improved layering characteristics over prior formulations while retaining good thermal emissivity and adhesive properties. Moreover, the formulation according to the invention enables an improved application to the anode of such oxides or oxide compounds over previous formulations, without negatively affecting the layer adhesion or thermal emission coefficient properties of the coating.
    Type: Grant
    Filed: October 2, 1990
    Date of Patent: October 20, 1992
    Assignee: Schwarzkopf Technologies Corporation
    Inventor: Wolfgang Hohenauer
  • Patent number: 5157706
    Abstract: An X-ray anode, in particular a rotary anode, having a parent body made of a carbon-containing refractory material. To improve the thermal radiation characteristics of the anode, the anode is provided with an oxidic top layer outside the focal spot or the focal track regions which contains a homogeneously fused phase. A two-ply interlayer arrangement, containing a first-ply of molybdenum and/or tungsten, and a second oxidic ply of Al.sub.2 O.sub.3, containing 1-30% by weight of TiO.sub.2, is arranged between the parent body and the oxidic top layer. As a result of this interlayer structure, the fusion of the oxidic top layer so as to form a homogeneous phase becomes possible without problems. In addition, the ageing resistance of the thermal emission coefficient (".epsilon.") is substantially improved.
    Type: Grant
    Filed: November 21, 1991
    Date of Patent: October 20, 1992
    Assignee: Schwarzkopf Technologies Corporation
    Inventor: Wolfgang Hohenauer
  • Patent number: 5150397
    Abstract: A high thermal emittance coating for an x-ray tube anode target which permits broad application parameters and a stable and smooth coating. The coating is composed of ZrO.sub.2 present in an amount of 8% to 20% by weight and Al.sub.2 O.sub.3 and TiO.sub.2 present in an amount of 92% to 80% by weight with the Al.sub.2 O.sub.3 and TiO.sub.2 being present in a ratio in the range of 4 to 1. A preferable coating is composed of about 10% by weight of ZrO.sub.2 and 90% by weight of Al.sub.2 O.sub.3 and TiO.sub.2.
    Type: Grant
    Filed: September 9, 1991
    Date of Patent: September 22, 1992
    Assignee: General Electric Company
    Inventor: Michael J. Randzaao
  • Patent number: 5056127
    Abstract: Means for enhancing heat transfer from liquid cooled rotating anode x-ray tubes that provide for extended surfaces on the liquid cooled concave curved heat exchange surfaces opposing the electron beam focal track. The extended surfaces take the form of fins lying in the direction of coolant flow, said fins preferably being generally triangular in cross section.
    Type: Grant
    Filed: March 2, 1990
    Date of Patent: October 8, 1991
    Inventors: Arthur H. Iversen, Stephen Whitaker
  • Patent number: 4975621
    Abstract: A coated article suitable for use in a vacuum consisting essentially of a refractory metal substrate and a first coating of TiB.sub.2 and Mo. An overcoat of TiB.sub.2 may be applied to the first coating as a second layer upon which additional layers may be applied if desired.
    Type: Grant
    Filed: June 26, 1989
    Date of Patent: December 4, 1990
    Assignee: Union Carbide Corporation
    Inventors: Harold H. Fukubayashi, Jiinjen A. Sue, Robert C. Tucer, Jr., Ronnie J. Doan
  • Patent number: 4953190
    Abstract: A high thermal emittance coating for an x-ray tube anode target which permits broader application parameters and a stable coating. The coating is composed of Al.sub.2 O.sub.3 present in an amount of 50% to 80% by weight and ZrO.sub.2 or La.sub.2 O.sub.3 and TiO.sub.2 present in an amount of 50% to 20% by weight with the TiO.sub.2 and ZrO.sub.2 or La.sub.2 O.sub.3 being present in a ratio in the range of 1:1 to 10:1. A preferable coating is composed of about 80% by weight of Al.sub.2 O.sub.3 and 20% by weight of TiO.sub.2 and ZrO.sub.2.
    Type: Grant
    Filed: June 29, 1989
    Date of Patent: August 28, 1990
    Assignee: General Electric Company
    Inventors: Dennis G. Kukoleck, Peter C. Eloff
  • Patent number: 4901338
    Abstract: Rotary graphite anode for use in X-ray tubes comprising a basic body consisting of graphite and a high melting alloy and having a tungsten alloy focal track. The basic body is secured to a graphite substrate. The graphite substrate is coated by a layer of carbon formed by decomposition of hydrocarbon gases in an activated d.c. voltage discharge.
    Type: Grant
    Filed: June 12, 1989
    Date of Patent: February 13, 1990
    Assignee: Schwarzkopf Development Corporation
    Inventors: Peter Rodhammer, Karlheinz Kailer
  • Patent number: 4870672
    Abstract: A fused metal oxide ceramic coating is disclosed for application in a particular region of the target employed in an x-ray tube. The disclosed ceramic coating enhances the thermal emittance of a refractory metal target and comprises the fused product of a metal oxide physical mixture comprising Al.sub.2 O.sub.3, ZrO.sub.2, and TiO.sub.2 which exhibits a minimum melting point of approximately 1580.degree. C. A preferred ceramic coating comprises from about 40 weight percent up to about 70 weight percent TiO.sub.2, from about 20 weight percent up to about 40 weight percent ZrO.sub.2, and from about 10 weight percent up to about 20 weight percent Al.sub.2 O.sub.3. A process for the in situ preparation of said ceramic coating is also disclosed along with a particular rotating type x-ray tube and radiographic imaging system employing said improved target.
    Type: Grant
    Filed: August 26, 1987
    Date of Patent: September 26, 1989
    Assignee: General Electric Company
    Inventor: Richard W. Lindberg
  • Patent number: 4731805
    Abstract: A rotary anode for an X-ray tube is in the form of a disc (1) the surface of which has, at least partially, a blackening coating (2). The latter is in the form of a sintered porous composition of titanium grains, mainly of the dendritic structure, of a size from 0.5 to 150 .mu.m, and at least one high-melting metal having a melting point above 2500.degree. C., the quantity the high-melting metal in the composition being from 5 to 60% by mass.
    Type: Grant
    Filed: January 28, 1986
    Date of Patent: March 15, 1988
    Inventors: Maiya F. Boyarina, Vladimir G. Vildgrube, Jury S. Sergeev, Oleg V. Filatov, Lev G. Andruschenko, Jury N. Zelenov, Valery N. Kupriyanov, Elena I. Taubkina
  • Patent number: 4520496
    Abstract: The invention relates to an anode disc for a rotary-anode X-ray tube which consists of a rotationally-symmetrical body of molybdenum and a corresponding body of graphite. The connection zone between the two bodies is smaller than the inner diameter of the focal path. Thanks to this construction the connection zone between the two bodies will not be thermally overloaded.
    Type: Grant
    Filed: July 6, 1983
    Date of Patent: May 28, 1985
    Assignee: U.S. Philips Corporation
    Inventors: Peter Schreiber, Klaus Huth