Abstract: Various systems and methods are provided for a biased cathode assembly of an X-ray tube with improved thermal management and a method of manufacturing same. In one example, a cathode assembly of an X-ray tube comprises an emitter assembly including an emitter coupled to an emitter support structure, and an electrode assembly including an electrode stack and a plurality of bias electrodes. The emitter assembly including a plurality of independent components that are coupled together. The electrode assembly including a plurality of independent components that are coupled together, and the emitter assembly being coupled to the electrode assembly.

Abstract: At least one example embodiment provides an electron emitter apparatus having a first ring of field-effect emitter needles, the field-effect emitter needles of the first ring forming a first emitter surface on an inner side of the first ring; and a second ring of field-effect emitter needles, the field-effect emitter needles of the second ring forming a second emitter surface on an inner side of the second ring, wherein the first ring and the second ring are arranged in such that the first emitter surface and the second emitter surface form a substantially contiguous three-dimensional overall emitter surface, the substantially contiguous three-dimensional overall emitter surface defining a hollow channel along a longitudinal axis of the electron emitter apparatus.

Abstract: X-ray transparent insulation can be sandwiched between an x-ray window and a ground plate. The x-ray transparent insulation can include aluminum nitride, boron nitride, or polyetherimide. The x-ray transparent insulation can include a curved side. The x-ray transparent insulation can be transparent to x-rays and resistant to x-ray damage, and can have high thermal conductivity. An x-ray window can have high thermal conductivity, high electrical conductivity, high melting point, low cost, and matched coefficient of thermal conductivity with the anode. The x-ray window can be made of tungsten. For consistent x-ray spot size and location, a focusing plate and a filament can be attached to a cathode with an open channel of the focusing plate aligned with a longitudinal dimension of the filament. Tabs of the focusing plate bordering the open channel can be bent to align with a location of the filament.

Abstract: Various systems and methods are provided for a biased cathode assembly of an X-ray tube with improved thermal management and a method of manufacturing same. In one example, a cathode assembly of an X-ray tube comprises an emitter assembly including an emitter coupled to an emitter support structure, and an electrode assembly including an electrode stack and a plurality of bias electrodes. The emitter assembly including a plurality of independent components that are coupled together. The electrode assembly including a plurality of independent components that are coupled together, and the emitter assembly being coupled to the electrode assembly.

Abstract: An apparatus for generating electron radiation comprises a wire-shaped hot cathode that is much more extensive in a longitudinal direction than in a transverse direction. Electron radiation emerges from the hot cathode that, due to the elongated shape of the hot cathode, exhibits an elongated, line-shaped cross section perpendicular to its direction of propagation, where the extension in longitudinal direction of the line is significantly greater than in transverse direction of the line. The apparatus further comprises a cathode electrode and an anode. A voltage for accelerating the electrons emitted from the hot cathode is applied between the cathode electrode and the anode. The hot cathode is arranged to be spaced apart from the cathode electrode such that electrons that are accelerated to the anode are emitted from the hot cathode in each of the transverse directions.

Abstract: According to one embodiment, an X-ray tube includes an anode target, a cathode including a first filament and a converging electrode, and a vacuum envelope. The converging electrode includes a flat front surface, a flat first surface, a first groove portion, and a pair of first protruding portions. The pair of first protruding portions is formed to protrude from the first surface toward the front surface and sandwich the first groove portion in a first length direction. An upper surface is formed of a plurality of flat inclined surfaces.

Abstract: A cooling device for x-ray tubes in x-ray generators, comprising a housing with a central receiving device for receiving an x-ray tube with an inlet opening for supplying a gaseous coolant, an outlet opening for discharging the gaseous coolant, and a gas-conducting channel which extends between the inlet opening and the outlet opening. The gas-conducting channel is designed to conduct the gaseous coolant directly by the high-voltage x-ray tube housing during operation. The gas-conducting channel additionally extends in a helical manner about the x-ray tubes such that the electric potential applied to the x-ray tubes drops to zero potential along the gas-conducting channel.

Abstract: The current disclosure is related to a downhole tool that comprises an electronic photon generator and at least one detector. The electronic photon generator comprises a cathode configured to emit electrons, a first target configured to generate photons when struck by the electrons, a second target configured to generate photons when struck by the electrons, and a beam steering device that directs the electrons to a first or second target. The at least one detector is configured to detect at least some of the photons emitted by the first target and at least some of the photons emitted by the second target.

Abstract: An emitter for a closed x-ray tube includes an emitter body formed of a low work function emitter material, the emitter body having a major surface and a secondary surface. The major surface is adapted for emission of electrons from the low work function material. The emitter assembly is adapted to reduce an emission current density emitted from the secondary surface of the emitter body, as compared to the major surface.

Abstract: The present invention relates to an apparatus for generating X-rays. It is described to produce (210) with a power supply (40) at least two voltages between at least one cathode (20) and an anode (30), wherein the at least two voltages comprises a first voltage and a second voltage. The at least one cathode is positioned relative to the anode. Electrons are emitted (220) from the at least one cathode. Electrons emitted from the at least one cathode are interacted (230) with the anode with energies corresponding to the at least two voltages. X-rays are generated (230) from the anode, wherein the electrons interact with the anode to generate the X-rays. First X-rays are generated when the power supply produces the first voltage and second X-rays are generated when the power supply produces the second voltage. The power supply is controlled (250), such that a ratio between the first X-rays and the second X-rays is controllable.

Abstract: The present disclosure relates to a method and system for adjusting a focal point position of an X-ray tube. The method may include: obtaining a first thermal capacity and a first position of a focal point of an X-ray tube; obtaining a second thermal capacity of the X-ray tube; determining a second position of the focal point the X-ray tube based on the second thermal capacity; determining a target grid voltage difference of a focusing cup of the X-ray tube based on the first position and the second position of the focal point; and adjusting the X-ray tube based on the target grid voltage difference.

Abstract: A radiation emitting target, a radiation generating device, and a radiography system are provided in which adhesion between a target layer and a diamond substrate is improved and stable radiation emitting properties are exhibited. A transmission type target includes a target layer, a carbon-containing region including sp2 bonds, and a diamond substrate that supports the target layer. The carbon-containing region is positioned between the target layer and the diamond substrate.

Abstract: A flat emitter for uses within an x-ray tube is formed of an electron emissive material that includes one or more stress compensation features capable of reducing the total stress in the flat emitter due to thermal expansion and/or centrifugal acceleration force. The one or more stress compensation features of the flat emitter for reducing the total stress in the flat emitter are formed directly on the flat emitter, are formed on the support structure for the flat emitter and connected to the flat emitter, or a combination thereof.

Abstract: A target assembly for an x-ray emission apparatus, the apparatus assembly including: a vacuum chamber having at least one conductive wall; an insulating element projecting through the conductive wall; a conductive high voltage element extending along the insulating element from outside the chamber to an end portion of the insulating element furthest from the conductive wall; an x-ray-generating target arranged at the end portion of the insulating element and electrically connected to the high voltage element; and a suppressive electrode arranged at the end portion of the insulating element and configured to suppress acceleration toward the outer surface of the insulating element of electrons which are emitted from a junction between the outer surface of the insulating element and an inner surface of the conductive wall.

Abstract: An X-ray tube can include: a cathode including an electron emitter that emits an electron beam; an anode configured to receive the electron beam; a first magnetic quadrupole between the cathode and the anode and having a first yoke with four first pole projections extending from the first yoke and oriented toward a central axis of the first yoke and each of the four first pole projections having a first quadrupole electromagnetic coil; a second magnetic quadrupole between the first magnetic quadrupole and the anode and having a second yoke with four second pole projections extending from the second yoke and oriented toward a central axis of the second yoke and each of the four second pole projections having a second quadrupole electromagnetic coil; and at least one steering coil collocated with a quadrupole on a pole projection.

Abstract: In the present invention, a computed tomography system, an X-ray tube used therein and a cathode assembly disposed in the X-ray tube, as well as an associated method of use, is provided that includes a gantry and the X-ray tube coupled to the gantry. The X-ray tube includes the cathode assembly having a pair of emission surfaces for generating an electron beam, where the pair of emission surfaces are disposed in the cathode assembly at angles with respect to one another. The X-ray tube further includes a focusing electrode for focusing the electron beam, an extraction electrode which electrostatically controls the intensity of the electron beam by adjustment of a positive or negative biasing voltage applied to the extraction electrode, a target for generating X-rays when impinged upon by the electron beam and a magnetic focusing assembly located between the cathode assembly and the target for focusing the electron beam towards the target.

Abstract: An anode for an X-ray tube can include a ceramic body, e.g., material that includes yttrium-oxide derivatives. Upon collision with an anode, the kinetic energy of an electron beam in an X-ray tube is converted to high frequency electromagnetic waves, i.e., X-rays. An anode with a ceramic body can reduce costs and/or weight, extend the life of the anode or associated components (e.g., bearings) and simultaneously provide a high heat storage capacity.

Abstract: In the present invention, an X-ray tube is provided including a cathode assembly with a cathode cup, and an emitter disposed within the cup configured to emit an electron beam therefrom. The emitter is formed with a central portion including legs with varying lengths and/or spaces formed therein. The legs including spaces of varying lengths provides additional emissive material at the center of the emitter to better withstand strikes from ions formed within the X-ray tube. The legs of varying overall lengths provides a void in the emitter through which the ions can pass without striking the emitter.

Abstract: An electrostatic-dissipation device comprising an x-ray tube and an electrically-conductive shell that is electrically coupled to an anode of the x-ray tube can be used for electrostatic dissipation, especially at a bottom side of a flat-panel-display (FPD).

Abstract: A cathode head can include: a first electron emitter filament having a first size; a first grid pair defining walls of a first filament slot having the first filament therein, each grid member of the first grid pair being electronically coupled to different voltage sources; a second electron emitter filament; and a second grid pair defining walls of a second filament slot having the first electron emitter therein, each grid member of the second grid pair being electronically coupled to different voltage sources. The first grid pair can have a first and second grid members; and the second grid pair can have the second grid member and a third grid member. The first grid member and third grid member are electronically coupled to the same voltage source and the second grid member being electronically coupled to a different voltage source.

Abstract: An X-ray includes: electron emission devices that are arranged in one dimension or in two dimensions and are configured to emit electrons; and an anode electrode configured to emit an X-ray by using the electrons emitted by the electron emission devices and comprising regions having irregular thicknesses.

Abstract: An example embodiment includes a cathode assembly. The cathode assembly includes a cathode head, a filament, a focusing structure, and a non-rectilinear focusing aperture. The cathode head defines a filament slot. The filament is positioned in the filament slot that is capable of emitting electrons by thermionic emission. The focusing structure is positioned at least partially between the filament and an anode. The non-rectilinear focusing aperture is defined in the focusing structure. The non-rectilinear focusing aperture is configured to shape an emission profile of electrons emitted by the filament.

Abstract: An X-ray source with optical indication of radiation, which can be used in various measuring devices for parameters control and visualization of structure of industrial and biological objects, is proposed. The source comprises a vacuum housing, an anode irradiated by electrons and generating the divergent flux of radiation, an exit window for X-ray radiation, means for optical indication of X-ray radiation beam including a source of optical radiation and an optical mirror. The anode is made composite in the form of a thin film and a radiolucent substrate luminescent in the optical range. The anode structure is an exit window of the source, and behind it the coaxially arranged means of collimation and focusing of X-ray and optical radiation and means of optical visualization of X-ray focus are mounted. The proposed device significantly increases the accuracy and informativity of optical indication of X-ray radiation parameters.

Abstract: Provided is an X-ray tube including an anode, a target on the anode, a cathode disposed separate from the target and the anode and comprising an emitter providing an electron beam to the target, and a side wall disposed between the cathode and the anode, and surrounding the target and the emitter. The side wall reflects a light generated by collision of the electron beam with the target to the cathode, and electrically insulates the cathode from the anode.

Abstract: An X-ray tube for generating two focal spots displaced with respect to each other and a medical device using such X-ray tube are proposed. The X-ray tube (1) comprises a cathode (7) and an anode (9) wherein the cathode (7) comprises a first electron emitter (15) adapted for emitting a first electron beam (17) for generating a first focal spot (25) on the anode (9) and a second electron emitter (19) for emitting a second electron beam (21) for generating a second focal spot (27) on the anode (9). Therein, each electron emitter (15, 19) comprises an associated switchable grid (37, 39) for blocking the respective emitted electron beam (17, 21). In order to realize a desired displacement of the first and second focal spots (25, 27) in a y-direction, the first and second electron emitters (15, 19) may be displaced in the z-direction. Due to the focal spots (25, 27) being displaced in y-direction, an overall resolution of for example a high quality CT scanner may be significantly enhanced.

Abstract: An electron source for an X-ray scanner includes an emitter support block, an electron-emitting region formed on the support block and arranged to emit electrons, an electrical connector arranged to connect a source of electric current to the electron-emitting region, and heating structure arranged to heat the support block.

Abstract: The present invention relates to a cathode for an X-ray tube, an X-ray tube, a system for X-ray imaging, and a method for an assembly of a cathode for an X-ray tube. In order to provide a cathode with an improved and facilitated assembly, a cathode (10) for an X-ray tube is provided, comprising a filament (12), a support structure (14), a body structure (16), and a filament frame structure (18). The filament is provided to emit electrons towards an anode in an electron emitting direction (24), and the filament at least partially comprises a helical structure (26). Further, the filament is held by the support structure, which is fixedly connected to the body structure. The filament frame structure is provided for electron-optical focussing of the emitted electrons, and the filament frame structure is provided adjacent to the outer boundaries of the filament.

Abstract: The present subject matter relates to inspection systems, devices and methods for x-ray inspection of objects. A conveyor can move an object to be inspected through an inspection zone along a direction of travel, one or more multibeam x-ray source arrays can provide multiple collimated x-ray beams through the inspection zone along a direction substantially perpendicular to the direction of travel, and one or more x-ray detector arrays can detect x-ray beams passing through the inspection zone from the x-ray source array. X-ray signals detected by the x-ray detector array can be recorded to form multiple x-ray projection images of the object, and the multiple x-ray projection images can be processed into three-dimensional tomographic images of the object.

Abstract: An x-ray generator includes a voltage source and a voltage divider network coupled thereto, a housing, and an insulator carried within the housing. An emitter cathode is carried within the housing and emits electrons and undesirable conductive particles. In addition, there is a shielding electrode carried within the housing downstream of the emitter cathode and coupled to the voltage divider network. A target is carried within the housing downstream of the at least one shielding electrode. The voltage divider is configured so that the emitter cathode and the shielding electrode have a voltage difference therebetween such that an electric field generated in the housing accelerates electrons emitted by the emitter cathode to toward the target. The shielding electrode is shaped to capture the undesirable conductive particles emitted by the emitter cathode that would otherwise strike the insulator.

Abstract: The present disclosure relates to a field emission X-ray tube apparatus for facilitating cathode replacement, and more particularly, to a field emission X-ray tube apparatus for facilitating cathode replacement in which gates and cathodes are easily arranged through a joining member and a rotation preventing guide when gates and insulating spacers are rotated and joined with the cathodes while the cathodes and respective gates maintain electrical insulation, thereby easily replacing the cathodes.

Abstract: A mesh electrode adhesion structure includes: a substrate, and an opening defined in the substrate; a mesh electrode on the substrate, and a first combination groove defined in the mesh electrode; and an adhesion layer between the substrate and the mesh electrode. The mesh electrode includes: a mesh region corresponding to the opening defined in the substrate, and an adhesion region in which the first combination groove exposes the adhesion layer.

Abstract: An elongated x-ray tube that can emit a linear curtain of x-rays along its length. Methods of using an elongated curtain of x-rays.

Abstract: A dual energy X-ray source for use in Homeland Security, Medical, Non-destructive Testing, and other markets includes a power supply, and a single x-ray tube. The X-ray tube includes two cathodes, and a single anode. The electrons from the cathodes travel predominantly along the axis of the x-ray tube, and impact the anode. The grid and/or focus coil direct the electrons so that electrons can pass by the cathode. The cathodes are kept at different potential, such that the tube can rapidly switch energies, and can rapidly switch output flux from each cathode.

Abstract: Disclosed is an X-ray generator (1) comprised of an electron emission element (10) which receives energy to emit electrons; a metal piece (20) which receives the electrons emitted from the electron emission element (10) to emit an X-ray; and energy supply portions (3, 5) which supply energy to the electron emission element (10), wherein the energy supply portions (3, 5) irradiate a pyroelectric element functioning as an electron emission element with, for example, ultraviolet pulsed light, and a high-energy local portion is formed in the pyroelectric element. Thus, the X-ray generator wherein the size thereof can be reduced, and an on/off control for the generation of X-ray can be easily performed, can be provided.

Abstract: Provided is an X-ray generating tube with improved withstand voltage property by a simple structure, the X-ray generating tube including a cathode connected to one opening of an insulating tube and an anode connected to the other opening, in which a resistive film having a lower sheet resistance value than that of the insulating tube is disposed on an outer periphery of the insulating tube, and the cathode and the anode are electrically connected to each other via the resistive film.

Abstract: Provided is an X-ray generator comprising a cathode for generating electrons; a rotating anode having a cylindrical electron impingement surface, an X-ray focal point being formed by a region in which the electrons impinge upon the electron impingement surface; and a Wehnelt electrode for imparting an electric field to the electrons emitted from the cathode. The Wehnelt electrode has a field formation surface for forming the electric field, and an electron passage aperture formed by the field formation surface. The field formation surface of the Wehnelt electrode is inclined with respect to a plane tangent to an outer circumferential surface of the rotating anode at the center of the X-ray focal point. The center of the cathode is in a plane orthogonal to the field formation surface and aligned with the center of the electron passage aperture.

Abstract: Provided is an X-ray generator for generating X-rays from an X-ray focal point that is a region in which electrons emitted from a filament impinge upon a rotating anode. The X-ray generator has a Wehnelt electrode for surrounding the filament, an attachment part formed integrally with the Wehnelt electrode, a pedestal to which the attachment part is attached, and a casing for housing the pedestal and the anticathode. The width of the space in which the anticathode is housed by the casing is less than the width of the space in which the pedestal is housed by the casing. The Wehnelt electrode extends into the space in which the anticathode is housed by the casing, in a state in which the attachment part is attached to the pedestal.

Abstract: An industrial X-ray tube formed by accommodating a cathode and anode in a container having an evacuated interior, in which electrons emitted from the cathode are caused to strike the anode and X-rays are emitted from the anode. The cathode is formed from graphite. The graphite is a layered crystal obtained by layering a plurality of carbon hexagonal planes. The graphite is cut based on crystal axes of the carbon hexagonal planes. The resulting cut surface is caused to function as an electron-emitting surface. For example, directions of an a- and b-crystal axis may be set so as to be arbitrary between each of the layers of the carbon hexagonal planes, the graphite may be cut along a surface parallel to the c-axis, and the resulting cut surface may be caused to function as an electron-emitting surface. The graphite may also be cut along a surface orthogonal to the c-axis.

Abstract: An asymmetric x-ray tube. In one example embodiment, an x-ray tube includes an evacuated enclosure, a cathode assembly at least partially positioned within the evacuated enclosure and defining a first axis, and an anode assembly at least partially positioned within the evacuated enclosure and defining a second axis. The anode assembly includes a rotating anode having a focal spot. The focal spot and the second axis define a plane. The first axis is positioned beneath the plane.

Abstract: An x-ray generator includes a housing, a cathode block that is arranged in the housing and emits electrons via a field emission scheme, an anode block that is arranged in the housing and generates x-rays in response to the electrons emitted from the cathode block and collide with the anode block, and a heat sink block that contacts the cathode block and dissipates heat generated therein to an outside of the housing.

Abstract: Systems and methods are described for a compact x-ray system that uses optical energy for triggering x-ray generation rather than a traditional filament. A photocathode is illuminated and the ensuing electrons are directed to an anode resulting in x-ray generation, resulting in increased x-ray source durability. Pulsing, beam forming, scanning, varying x-ray characteristics, longevity of source and other desirable attributes not currently available in the state of the art are achievable, through the use of shaped, multi-materialed photocathodes, shaped, multi-materialed anodes, arrays of optical lines, and so forth, as some examples. Inexpensive, highly controllable sources such as solid-state lasers can be used, permitting a wide variety of applications and power levels.

Abstract: Cathode assembly for a long throw length x-ray tube. In one example embodiment, a cathode assembly for an x-ray tube includes an electron emitter, an acceleration region, and a drift region. The electron emitter includes a curved emitting surface configured to emit an electron beam having a y-dimension that is greater than an x-dimension at the electron emitter. The acceleration region is defined adjacent to the electron emitter. The acceleration region is configured such that when the electron beam propagates within the acceleration region, the electron beam accelerates in a z-direction substantially normal to a midpoint of the curved emitting surface. The drift region is defined between the acceleration region and an anode. The drift region is configured such that the combined lengths of the drift region and the acceleration region are sufficient for the y-dimension to be less than the x-dimension at the anode.

Abstract: An x-ray imaging system includes a detector positioned to receive x-rays, an x-ray tube configured to generate x-rays toward the detector from a focal spot surface, the x-ray tube includes a target having the focal spot surface, a cathode support arm, and a cathode attached to the cathode support arm. The cathode includes a split cathode cup having a first portion and a second portion that is separate from the first portion, the first and second portions having respective first and second emitter attachment surfaces, and a flat emitter that is attached to the first and second emitter attachment surfaces such that, when an electrical current is provided to the first portion of the cathode cup, the current passes through the flat emitter and returns through the second portion of the cathode cup such that electrons emit from the flat emitter and toward the focal spot surface.

Abstract: A reduced power consumption x-ray source comprising: In one embodiment, an x-ray tube including an infrared heat reflector disposed inside an x-ray tube cylinder between the cathode and the anode and oriented to reflect a substantial portion of infrared heat radiating from a filament back to the filament, thus reducing heat loss from the filament. In another embodiment, an alternating current source for an x-ray tube filament including a switch for allowing power to flow to the filament for a longer or shorter time depending on the desired output x-ray flux. In another embodiment, a neutral grounded, direct current (DC) high voltage, power supply with parallel high voltage multipliers, each supplied by separate alternating current sources, but both the output of one alternating current source connected to ground and the input of another alternating current source connected to ground. The output of both high voltage multipliers are connected.

Abstract: Provided is a field emission X-ray tube. The field emission X-ray tube includes a cathode electrode provided to one end of a vacuum vessel and including a field emission emitter, an anode electrode provided to the other end of the vacuum vessel in an extending direction of the vacuum vessel, and a gate electrode provided on an outer surface of the vacuum vessel adjacent to the cathode electrode.

Abstract: An x-ray tube comprising an anode and a cathode disposed at opposing ends of an electrically insulative cylinder. The x-ray tube includes an operating range of 15 kilovolts to 40 kilovolts between the cathode and the anode. The x-ray tube has an overall diameter, defined as a largest diameter of the x-ray tube anode, cathode, and insulative cylinder, of less than 0.6 inches. A direct line of sight exists between all points on an electron emitter at the cathode to a target at the anode.

Abstract: An X-ray tube includes an emitter, and an electrode assembly. The emitter is configured to emit an electron beam toward a target. The electrode assembly includes at least one electrode having a bias voltage with respect to the emitter. At least one electrode of the electrode assembly is a segmented electrode including a plurality of segments. The plurality of segments includes a first member and a second member. The first member is configured to have a first bias voltage and the second member is configured to have a second bias voltage that is different from the first bias voltage.

Abstract: An apparatus for producing x-rays for use in imaging applications having a piezoelectric or pyroelectric crystal with an upper surface and a conducting film coating the upper surface. The crystal includes a plurality of field emitters formed as micrometer-scale exposed regions in the crystal having a one or more sharp peaks or ridges, or parallel trenches forming a wedge shaped emitter. The crystal is alternately heated and cooled over a period of time so that spontaneous charge polarization occurs in the crystal. The spontaneous charge polarization causes a perpendicular electric field to arise on the crystal's top and bottom faces, that is enhanced by the sharp peaks or ridges, thereby causing field emission of surface electrons from that location. X-rays are produced when the emitted electrons strike a target material located adjacent to the emitting face, and the X-rays may be filtered or collimated.

Abstract: A flat filament includes a first electron emission surface, a first current supply leg, a second current supply leg, a second electron emission surface disposed laterally of the first electron emission surface and connected to a first end region of the first electron emission surface, a third current supply leg, a third electron emission surface disposed laterally of the first electron emission surface, opposite from the second electron emission surface, and connected to a second end region of the first electron emission surface, and a fourth current supply leg.

Abstract: Embodiments of the disclosure relate to electron emitters for use in conjunction with X-ray devices. In one embodiment, the emitter features a round emission area capable of emitting electrons when heated, wherein the round emission area comprises at least one of a gap, a channel, or a combination thereof that separates a first portion of the round emission area from a second portion of the round emission area and permits thermal expansion of the first portion and the second portion within the at least one gap or channel without permitting the first portion and the second portion to touch one another. The two electrically conductive legs coupled to the surface at respective locations outside the round emission area and that are capable of supplying current to the round emission area.