Abstract: An electrodeless gas discharge lamp includes a vitreous envelope containing a discharge medium. An excitation coil is positioned in relation to the vitreous envelope so as to excite the discharge medium therein. The excitation coil is adapted to be driven by an RF oscillator. The excitation coil has first and second ends and is effective for exciting the discharge medium to emit light with electromagnetic fields that are generated by the excitation coil. The excitation coil includes a first wire wound generally helically from the first end to the second end in a first helical direction to form first winding turns, and further includes a second wire wound generally helically from the first end to the second end in second helical direction opposite to that of the first helical direction to form second winding turns. Preferably, a generally cylindrical former is provided for holding the first and second wires between the first and second ends of the coil.

Abstract: A novel plasma gun having a gas distribution plug which enhances the circumferential velocity component of the plasma gas. The gas distribution plug has a bore with a greater circumferential component proximate the gas egress end then at the gas ingress end.

Abstract: Method and apparatus for the disposal of waste including a rotary kiln comprising at least one, and preferably a plurality of plasma guns positioned within a chamber defined by the rotary kiln, and at least one target electrode which is rotatable. One preferred embodiment of the present invention comprises a portable waste disposal unit wherein a rotary kiln, at least one plasma gun and a movable target electrode are advantageously positioned on a truck for ready transportation to a waste site.

Abstract: An electrostatic shield is provided between the induction coil and the arc tube of an electrodeless HID lamp. In one embodiment, the shield is a transparent glass cylinder coated with a thin, transparent, conductive layer of tin oxide. In another embodiment, the electrostatic shield is a conductive, transparent tin oxide coating applied to either the inner or outer surface of an outer light-transmissive jacket surrounding the arc tube. The tin oxide layer is discontinuous so as to minimize currents induced in the conductive tin oxide layer by the induction coil. The thickness of the tin oxide layer is sufficient to make it conductive and form an approximately equipotential surface, thereby shielding the arc tube and plasma discharge from intense electric fields, reducing arc tube wall damage and increasing lamp life. In addition, tin oxide functions as an infrared reflector which returns infrared radiation to the arc tube, resulting in higher efficacy.

Abstract: An excitation coil for an electrodeless fluorescent lamp of the type having a core of insulating material, is made of a metal having a low thermal expansion coefficient which is plated with a high-conductivity metal. An insulating coating is applied over the metal plating. An exemplary coil includes a molybdenum wire, plated with silver, and finally coated with alumina. The result is a thermally stable excitation coil that maintains its shape, even at high operating temperatures, and hence maintains its impedance characteristic over the operating range of the lamp.

Abstract: A starting circuit for an electrodeless HID lamp includes a visible light radiator for illuminating a gas probe starter during lamp starting. In one embodiment, a light emitting diode (LED) illuminates the gas probe starter via a quartz tube. Excitation is provided to the LED by the same source used to excite the gas probe starter.

Abstract: A series resonant starting circuit for providing a starting voltage to a starting probe for initiating an arc discharge in an electrodeless HID lamp includes an electrically variable inductance. The HID lamp is of a type having an excitation coil situated around an arc tube containing an ionizable fill in which the arc discharge is ignited. The electrically variable inductance includes a magnetic core having a main winding wound thereon that is coupled in series with a resonant capacitance. A bias winding is also wound on the magnetic core. Either the bias winding is coupled in series with a bias inductor, or, alternatively, the main and bias windings are configured on the magnetic core as a cross-field inductor. A bias circuit supply provides dc or relatively low-frequency ac current to the bias winding in order to vary the permeability of the magnetic core, and hence the inductance of the main winding, thereby tuning the starting circuit.

Abstract: The fill of a self-extinguishing gas probe starter for an electrodeless high intensity discharge lamp includes a starter fill component which has a relatively low vapor pressure and is substantially inert in the starter fill at ambient temperatures, but which component vaporizes and becomes electronegative as the temperature of the lamp increases, so that the starter fill component attaches electrons of the starting discharge in the gas probe starter and thereby extinguishes the starting discharge after initiation of the arc discharge in the arc tube. As a result, the flow of currents between the gas probe starter and the arc tube, which would otherwise have a detrimental effect on the arc tube wall, is avoided.

Abstract: A passive starting circuit foran electrodeless HID lamp includes a series resonant LC circuit including an inductor of variable impedance coupled in series with the parasitic capacitance between a starting probe and the excitation coil of the lamp, and further including a coupling capacitance for directly coupling the starting circuit to the excitation coil. The coupling capacitance is connected between the high terminal of the excitation coil, or a point in the circuit at approximately the same potential thereof, and a conductive support for holding the lamp and starting probe in a lamp fixture. In this way, the starting voltage is maximized for more efficient and rapid starting. Preferably, the series resonant capacitance of the starting circuit is optimized so that the ballast requires little, if any, retuning after the lamp has started.

Abstract: A starting circuit for an electrodeless HID lamp, comprising a series resonant LC circuit of variable impedance, provides a starting voltage to a fixed or movable starting probe substantially simultaneously with the application of power to the excitation coil from the main power source. In a preferred embodiment, the starting circuit provides a starting signal to a gas probe starter of the type including a fixed starting electrode coupled to a starting chamber which contains a relatively low-pressure gas and is attached to the outer wall of the arc tube. Resonant operation of the starting circuit results in the application of a sufficiently high voltage to ignite a glow discharge in the low-pressure starting chamber. In turn, the starting voltage is capacitively coupled to the arc tube, ionizing the fill and initiating an arc discharge therein.

Abstract: A starting circuit for an electrodeless HID lamp provides a two-stage resonant starting signal to a gas probe starter of the type comprising a starting chamber which contains a relatively low-pressure gas and is attached to the outer wall of the arc tube. The starting circuit comprises a resonant LC circuit of variable impedance including the series combination of a variable inductance and the parasitic capacitance between the gas probe starter and the excitation coil. In operation, the resonant circuit is tuned to a predetermined value so that, upon application of an RF signal to the excitation coil, resonant operation of the starting circuit results in the application of a sufficiently high starting voltage to the starting chamber to ignite a low-current glow discharge therein. Once the glow discharge is ignited, the starting circuit is retuned to ensure that a sufficiently high starting voltage is capacitively coupled to the arc tube to ionize the arc tube fill and initiate an arc discharge therein.

Abstract: A high-frequency capacitor includes first and second conductive members, each having a plurality of U-shaped metal plates disposed parallel to each other and a terminal plate coupled between the ends thereof. The metal plates of the first and second conductive members are interleaved, and a dielectric material is disposed between the adjacent metal plates. The result is a low-inductance capacitor suitable for use in a high-frequency electronic circuit, such as an electrodeless high intensity discharge (HID) lamp ballast. Furthermore, such acapacitor may be suitably integrated with a heat sink in an electrodeless HID lamp ballast.

Abstract: An excitation coil for a high intensity discharge lamp has an optimized configuration for maximizing efficiency and minimizing output light blockage. The coil comprises a conductive surface having a shape which corresponds to rotating a bilaterally symmetrical trapezoid about a coil center line in the same plane as the trapezoid without intersecting the center line. The conductive surface is disposed on a conductive core for efficient heat removal from the coil, resulting in reduced coil losses. In one embodiment, the coil cross section is increased by adding a rectangular portion to the trapezoidal portion, thereby extending the coil outwardly from the coil center line so as to remove heat from the coil more quickly without affecting light output from the lamp. The coil is constructed by separately casting the coil turns and brazing a connecting member therebetween, and then cutting a slit in each turn so as to electrically connect them in series.

Abstract: An excitation coil for a high intensity discharge lamp has an optimized configuration for maximizing efficiency and minimizing output light blockage. The coil includes a conductive surface having a shape which corresponds to rotating a bilaterally symmetrical trapezoid about a coil center line in the same plane as the trapezoid without intersecting the center line. The conductive surface is disposed on a conductive core for efficient heat removal from the coil, resulting in reduced coil losses. In one embodiment, the coil cross section is increased by adding a rectangular portion to the trapezoidal portion, thereby extending the coil outwardly from the coil center line so as to remove heat from the coil more quickly without affecting light output from the lamp.

Abstract: An X-ray imaging system includes an X-ray tube, which is biased by a high voltage power supply connected to the tube by one or two shielded cables which have a characteristic impedance. The cables are coupled to the X-ray tube by a resistance which is substantially equal to the characteristic impedance when a single cable is used or to twice the characteristic impedance when two cables are used. During a breakdown of the X-ray tube, the resistance depresses electrical current flow between the anode and the cathode of the tube. This current is in part due to the energy stored in the cable, which is not depressed by conventional current limiting circuits in the high voltage power supply.

Abstract: A method and system, which minimize contact bounce during closure of a piezoelectric bender switch, control the switch closure to occur when the movable contact is traveling at a low velocity, when the phase of oscillation of the movable contact tends to press the contacts together after closure, and when the magnitude of the closing force developed in the first piezoelectric layer is only a fraction of its maximum value.

Abstract: A power switch which comprises a plurality of contact pairs connected in series provides substantial operational advantages. Included in these advantages are fast operating speed and direct imposition of circuit opening. The individual contact pairs are preferably controlled by piezoelectric benders to provide a compact, lightweight switch.

Abstract: This application describes a number of novel advanced piezoelectric ceramic power switching devices which are mounted within protective gastight enclosures that are either evacuated to a high degree of vacuum or filled with an inert gas protective atmosphere. The devices thus constructed are capable of operating over a range of load voltages extending from about 100 volts to 5000 volts or more with corresponding currents of from a few amperes to hundreds of amperes and wherein it is possible to provide a number of such structures in a single common protective gastight enclosure. For certain circuit applications the devices thus constructed have unpoled portions on which are mounted either passive circuit components such as resistors, capacitors and the like or active semiconductor devices all interconnected in circuit relationship with each other and the switching devices by using printed circuit or integrated circuit fabrication techniques.

Abstract: This application described a number of novel advanced piezoelectric ceramic power switching devices which are mounted within protective gastight enclosures that are either evacuated to a high degree of vacuum or filled with an inert gas protective atmosphere. The devices thus constructed are capable of operating over a range of load voltages extending from about 100 volts to 5000 volts or more with corresponding currents of from a few amperes to hundreds of amperes and wherein it is possible to provide a number of such structures in a single common protective gastight enclosure. For certain circuit applications the devices thus constructed have unpoled portions on which are mounted either passive circuit components such as resistors, capacitors and the like or active semiconductor devices all interconnected in circuit relationship with each other and the switching devices by using printed circuit or integrated circuit fabrication techniques.

Abstract: This application describes a number of novel advanced piezoelectric ceramic power switching devices which are mounted within protective gastight enclosures that are either evacuated to a high degree of vacuum or filled with an inert gas protective atmosphere. The devices thus constructed are capable of operating over a range of load voltages extending from about 100 volts to 5000 volts or more with corresponding currents of from a few amperes to hundreds of amperes and wherein it is possible to provide a number of such structures in a single common protective gastight enclosure. For certain circuit applications the devices thus constructed have unpoled portions on which are mounted either passive circuit components such as resistors, capacitors and the like or active semiconductor devices all interconnected in circuit relationship with each other and the switching devices by using printed circuit or integrated circuit fabrication techniques.