摘要:
An electrodeless lamp arrangement powered by RF energy. The lamp arrangement having an envelope that is rotated and most importantly the envelope forms the center of a coaxial arrangment used to transfer the RF energy into the envelope.
摘要:
A plasma asher which obviates microwave leakage and attendant problems by providing a microwave trap proximate the opening through which the plasma tube exits the microwave cavity.
摘要:
A microwave powered lamp wherein microwave energy is coupled to a cavity in which an electrodeless bulb is disposed, such that a rotating field of constant ellipticity is established in the cavity.
摘要:
A power supply for providing a stable operating current to a magnetron-excited lamp. The power supply includes a DC to DC inverter for driving a primary winding of a high voltage transformer. The DC to DC inverter has a circuit including two pairs of switching elements for connecting a DC voltage supply to the primary winding. During each half of the switching cycle, one of the switching elements is pulse width modulated while the other remains on for a substantially fixed period of time. During the second half of the cycle, the remaining pair operates so that one switching device is on for a pulse width modulated period of time, and the other is on a substantially constant amount of time. The on time for the pulse width modulated switching elements is defined by an input voltage setting representing a desired brightness level for the lamp, the output magnetron current, and a representative of the integral of the current flowing through the primary of the inverter transformer.
摘要:
A circularly polarized microwave oven. Microwave energy is coupled from a waveguide above the ceiling to the cavity by a rotatable vertical probe. A strip transmission line closely spaced to the ceiling to limit radiation therefrom conducts the microwave current from the probe to a helical strip antenna radially offset from the axis of the probe. The helical strip antenna has a cylindrical segment which has a downward slope from its feed end to gradually increase the spacing between the cylindrical segment and the ceiling which functions as a ground plane. The increase in radiative efficiency around the cylindrical segment caused by increasing the spacing to the ceiling offsets the magnitude of the current traveling wave diminishing as a result of radiation losses. Accordingly, the magnitude of the X and Y electric vectors are substantially equal over a relatively wide angle thus defining circular polarization. Connected to the opposite end of the cylindrical segment is a flat or horizontal segment of the helical antenna. Rotation of the probe about its axis moves the helical antenna in a horizontal circular path thus further enhancing the heating uniformity.
摘要:
An imaging tube assembly (11) for a computed tomography (CT) system (10) includes an insert (60) that has a vacuum chamber (72). An anode (58) resides within the vacuum chamber (72) and rotates on a shaft (66) via one or more bearing (70). In one embodiment, a seal (52) resides between the insert (60) and the shaft (66). The seal (52) prevents the passage of a gas (80) into the vacuum chamber (72). In another embodiment, a pressure transition chamber (104) is coupled to an insert (60″) and a shaft (66″). The pressure transition chamber (104) has an associated middle fluid pressure that is between an internal fluid pressure of the vacuum chamber (104) and an external fluid pressure of said insert (60″).
摘要:
An electrodeless lamp waveguide structure includes tuned absorbers for spurious RF signals. A lamp waveguide with an integral frequency selective attenuation includes resonant absorbers positioned within the waveguide to absorb spurious out-of-band RF energy. The absorbers have a negligible effect on energy at the selected frequency used to excite plasma in the lamp. In a first embodiment, one or more thin slabs of lossy magnetic material are affixed to the sidewalls of the waveguide at approximately one quarter wavelength of the spurious signal from an end wall of the waveguide. The positioning of the lossy material optimizes absorption of power from the spurious signal. In a second embodiment, one or more thin slabs of lossy magnetic material are used in conjunction with band rejection waveguide filter elements. In a third embodiment, one or more microstrip filter elements are tuned to the frequency of the spurious signal and positioned within the waveguide to couple and absorb the spurious signal's energy. All three embodiments absorb negligible energy at the selected frequency and so do not significantly diminish the energy efficiency of the lamp.
摘要:
Apparatus for coupling electromagnetic energy to electrodeless lamps. A waveguide having one end connected to a source of electromagnetic radiation was closed at the second opposite end. A coupling device at the second end couples microwave energy from the waveguide to an electrodeless lamp. The coupling device includes a coaxial transmission line having a center conductor extending through one of the walls of the waveguide adjacent the second end. An alcove partition within the waveguide contacts the extending conductor and forms an alcove in the waveguide. The alcove portion provides for an impedance matching structure between the transmission line and waveguide. The electrodeless lamp which is positioned above the free end of the coaxial transmission line is excited with the coupled microwave energy.
摘要:
A microwave powered discharge device which utilizes a TM.sub.NMO cavity. A conductive body is positioned at a null in a discharge device which utilizes a TM.sub.210 cavity to reduce direct coupling from the microwave coupling means, e.g., slot of the cavity. A plurality of TM.sub.110 cavities are ganged together, and a single discharge tube extends through all of the cavities.
摘要:
A microwave oven having a directional rotating antenna axially supported on an axis of one wall of a microwave oven cavity of the microwave oven which provides circularly symmetric uniform energy distribution of microwave energy within the microwave oven cavity and consistent heating of a product in the microwave oven cavity. The directional rotating antenna includes a two-by-two array of antenna elements where each element is an end driven half-wavelength resonating antenna element supported by a length of conductor perpendicular to the wall of the microwave oven cavity. A parallel plate transmission line connects to each of the supports, four of which join at a junction which connects to a cylindrical probe antenna. The probe antenna is excited by microwave frequency currents of a waveguide adjacent to the wall of the microwave oven cavity. The directional antenna is rotated by a moving stream of air circulated through the microwave oven cavity. A dome having a flattened conical shape extending outwardly in the wall of the microwave oven cavity provides a nearly circular recess partially surrounding the directional rotating antenna and provides uniform energy distribution in the product being heated. The dome returns microwave energy reflected from the product towards a circular area in the middle area of the microwave oven cavity. A transition section extends between the top of the dome and the one wall of the microwave oven cavity. The waveguide including three sides affixed to the outside wall of the dome, the transition section, and an extension of the wall extending beyond the microwave oven cavity which supports the microwave power source, all of which comprise the fourth wall of the waveguide. The microwave oven provides a consistent cooking pattern, especially for sensitive foods by utilizing high power of the microwave power source.