摘要:
The present invention generally relates to systems and methods for generating controllable beam of electrons using a hollow-cathode triode electron gun that substantially mitigate impact of back-streaming electrons.
摘要:
The present invention generally relates to systems and methods for generating controllable beam of electrons using a hollow-cathode triode electron gun that substantially mitigate impact of back-streaming electrons.
摘要:
A variable spot size x-ray tube comprises a cathode having an electron emitting surface providing an electron beam that travels essentially along the tube axis of symmetry to an anode. The anode, spaced from the cathode, includes a target, the front surface of which is disposed at an oblique angle with respect to the axis of symmetry. The potential of the anode is generally positive with respect to that of the cathode. The cathode is heated to a temperature at which electrons are emitted by the thermionic emission process. Current from the cathode can be controlled by varying the cathode temperature if the cathode is operated in the temperature limited region. The incident electron beam forms a spot on the target surface whereupon x-rays are produced in response to impingement of the electron beam on the target. The x-rays propagate outwardly from the target spot through a vacuum window to form a beam of x-radiation outside the x-ray tube. An aperture grid is disposed between the cathode and the anode, and has a central aperture permitting the electron beam to pass therethrough. The aperture grid further has a variable voltage applied to it which may be positive, negative, or equal to the potential of the cathode. The voltage on the control grid is used to control the diameter of the electron beam which impinges upon the target. Specifically, the electron beam diameter varies in correspondence with the variable aperture grid voltage, and selective variation of the electron beam diameter results in a corresponding variation in size of the x-ray imaging spot.
摘要:
A method for bonding thermally-mismatched elements of a traveling wave tube employs a metallic plate of undulating character. The plate is located at the region of the interface between tube elements formed of materials of materially-differing thermal character such as the ceramic termination piece and an adjacent sever pole piece of copper. Through either a brazing or a sintering process, pluralities of bonds are formed at points of tangency between the plate and the two elements of differing thermal expansion coefficients. As a result, a good heat flow path, accompanied by a more stable r.f. interface, is formed between the materials that is not subject to fracture as are prior art diffusion bonds.
摘要:
A method for bonding thermally-mismatched elements of a traveling wave tube employs a metallic plate of undulating character. The plate is located at the region of the interface between tube elements formed of materials of materially-differing thermal character such as the ceramic termination piece and an adjacent sever pole piece of copper. Through either a brazing or a sintering process, pluralities of bonds are formed at points of tangency between the plate and the two elements of differing thermal expansion coefficients. As a result, a good heat flow path, accompanied by a more stable r.f. interface, is formed between the materials that is not subject to fracture as are prior art diffusion bonds.
摘要:
An electron gun for use in remediation of hazardous volatile organic compounds is provided. The electron gun comprises a cathode having a concave emitting surface and a dome-shaped focusing electrode concentrically surrounding the emitting surface. The focusing electrode has an inwardly protruding lip portion that extends at least partially into a beam focusing region defined in front of the emitting surface. A target grid is spaced from the cathode and a negative voltage is applied between the emitting surface and the target. The target grid has a surface area that is substantially larger than an associated surface area of the emitting surface. An electron beam is provided by the emitting surface in response to the negative voltage, and is focused into a broad diverging beam by the focusing electrode. The electron gun may be configured for temperature limited emission or space charge limited emission.
摘要:
An improved electron window is provided for use with a diverging electron beam for use in remediation of hazardous volatile organic compounds. The electron window comprises a support grid having a plurality of circular holes disposed in a diverging bolt circle pattern. Individual electrons of the diverging electron beam pass through respective ones of the plurality of holes. A barrier is provided on a downstream side of the support grid so that the individual electrons pass through the barrier. The circular holes are each of substantially uniform diameter. The diverging bolt circle pattern further comprises a single one of the holes substantially centered on the support grid, and a plurality of groups of the holes concentrically disposed around the single one of the holes. Each of the groups of the holes is disposed in a circular pattern. A number of the holes defined within successive ones of the plurality of groups of holes increases arithmetically as an associated diameter of the circular patterns increases. Also, an associated angle of the holes defined within successive ones of the plurality of groups of holes increases as an associated diameter of the circular patterns increases. The diverging electrons are transmitted through the support grid at a maximum rate of efficiency without undesired interception with the surfaces of the grid holes.
摘要:
A loss button for a traveling wave tube. The front and rear planar surfaces of the ceramic pill-shaped button body are of coated metallic composition. The periphery is uncoated to permit r.f. energy to enter the button through thee cavity of the planar, metallic spacer into which the button is inserted. By coating the body surfaces, the button itself acts as a resonant cavity for attenuation of a predetermined bandwidth so that the dimensional changes that occur during heating to the surrounding and adjacent metallic elements, including the cavity in the spacer for receiving the button and the adjacent braze washers, will not affect the attenuation band of the tube.