Abstract: The invention is directed to a radiation source for generating extreme ultraviolet (EUV) radiation based on a hot, dense plasma generated by gas discharge.

Abstract: A remote plasma generator receives an A.C. source supplied from an A.C. power, ionizes process gas supplied from a gas source, generates plasma gas, and remotely supplies the generated gas to a process chamber. The remote plasma generator includes a main body with a gas inlet that is connected to the gas source and a gas outlet that is connected to the process chamber. A core cylinder is installed within the main body and cylindrical-shaped with an opening penetrating its center. A ring-shaped core is installed on the core cylinder. A connection pipe is included for connecting the outer surface of the main body to the inner surface of the core cylinder. An inductor coil is wound on the ring-shaped core and exposed to the outside of the main body via the connection pipe so as to be electrically connected to the A.C. power.

Abstract: An electrode assembly for use in a plasma processing system including a base electrode adapted to be coupled to a source of RF energy, a removable electrode removably coupled to the base electrode, and a material interposed between a surface of the base electrode and a surface of the removable electrode.

Abstract: A dielectric window performs three functions, namely, (1) extraction of a microwave, (2) generation and transmission of a surface wave, and (3) keeping the vacuum. An O-ring, which keeps the vacuum between the dielectric window and a chamber, is arranged so as to surround the vicinity of a bottom plate 1a of a microwave waveguide. Dielectric plates area arranged in parallel with each other in the dielectric window and performs only the transmission of a surface wave. The dielectric plates may be different from the dielectric window in at least one of a shape, a thickness, and a dielectric constant.

Abstract: The preferred embodiments described herein provide a magnetic mirror plasma source. While the traditional magnetic/electrostatic confinement method is ideal for many applications, some processes are not best served with this arrangement. The preferred embodiments described herein present a new technique to confine electrons (3) to produce a low pressure, dense plasma directly on a substrate surface (75). With these preferred embodiments, a combination of electrostatic and mirror magnetic confinement is implemented. The result is a novel plasma source that has unique and important advantages enabling advancements in PECVD, etching, and plasma treatment processes.

Abstract: Apparatus for producing and sustaining a glow discharge plasma in a plasma discharge space comprising at least two oppositely spaced electrodes, means for supplying a gas or a gas mixture under atmospheric pressure conditions in the discharge space, AC power supply means for energizing the electrodes, and electric stabilisation means for stabilizing current variations in the plasma. The stabilisation means connect between the electrodes and the power supply means, and are arranged for providing a negative feedback opposed to a positive feedback of the plasma to instabilities in the plasma.

Abstract: A method of plasma generation is provided in which the application of a static magnetic field perpendicular to the direction of the RF electric field allows for the propagation of an electromagnetic wave from a coil outside the chamber, through a dielectric window and into the plasma. The RF electric field and the DC magnetic field are both in the plane of the dielectric window in what may be called a planar helicon configuration. Due to magnetic field effects, the electromagnetic wave excites an electron cyclotron wave that heats the electrons by mode conversion of the whistler wave a few centimeters from the dielectric window where a mode conversion relationship among characteristic antenna wavelength, generator frequency, magnetic field strength and plasma electron density is satisfied. The curvature of the magnetic field lines generates plasma flows that expel the plasma towards the processing space.

Abstract: An apparatus and method which maintains plasma discharges (for instance 25) in containers (for instance 20) which have an internal section of 1 cm or less in width are described. The very small cross-section plasma discharges are useful in MEMS devices, in spectrometers and in spectroscopy.

Abstract: A plasma apparatus of fabricating a semiconductor device includes: a chamber including a reaction region; a chuck in the reaction region; and a plasma-measuring device on a top surface of the chuck, comprising: a probing plate including a plurality of probes on a top surface thereof; and a detecting plate under the probing plate, the detecting plate including a plurality of detecting portions corresponding to the plurality of probes, the plurality of detecting portions being electrically connected to the plurality of probes.

Abstract: A plasma processing apparatus processing a surface of a substrate by spraying a process gas in a plasma state from a gas spray opening of a spray nozzle onto the substrate includes: an exhaust opening for exhausting residual gas generated at the time of processing the surface of the substrate, the exhaust opening being provided at a position close to the periphery of the gas spray opening; and an air jet opening generating airflow, the air jet opening being provided surrounding the exhaust opening so as to prevent the residual gas from flowing out.

Abstract: The invention in one embodiment is realized in a plasma reactor for processing a semiconductor workpiece. The reactor includes a vacuum chamber having a side wall and a ceiling, a workpiece support pedestal within the chamber and generally facing the ceiling, a gas inlet capable of supplying a process gas into the chamber and a solenoidal interleaved parallel conductor coil antenna overlying the ceiling and including a first plurality conductors wound about an axis of symmetry generally perpendicular to the ceiling in respective concentric helical solenoids of at least nearly uniform lateral displacements from the axis of symmetry, each helical solenoid being offset from the other helical solenoids in a direction parallel to the axis of symmetry. An RF plasma source power supply is connected across each of the plural conductors.

Abstract: A plasma vacuum pump including an array of permanent magnets, one or more plasma conduits or ducts, components for accelerating plasma ions through these conduits, and supporting structures that together comprise at least one applied plasma duct system (APDS) cell. The APDS cell permits large volumes of particles and plasma to flow rapidly in a preferred direction while constricting the flow of neutral particles in the reverse direction. A plasma pump utilizing APDS technology is intended to permit a large throughput of ionized gas at the intermediate pressures of interest in the plasma-enhanced processing industry, compressing this gas to a pressure at which blower-type pumps can be used efficiently to exhaust the spent processing gas at atmospheric pressure.

Abstract: A remote plasma generator receives an A.C. source supplied from an A.C. power, ionizes process gas supplied from a gas source, generates plasma gas, and remotely supplies the generated gas to a process chamber. The remote plasma generator includes a main body with a gas inlet that is connected to the gas source and a gas outlet that is connected to the process chamber. A core cylinder is installed within the main body and cylindrical-shaped with an opening penetrating its center. A ring-shaped core is installed on the core cylinder. A connection pipe is included for connecting the outer surface of the main body to the inner surface of the core cylinder. An inductor coil is wound on the ring-shaped core and exposed to the outside of the main body via the connection pipe so as to be electrically connected to the A.C. power.

Abstract: Here is disclosed a plasma generator using microwave wherein a plasma generating chamber is provided with a plurality of wave guide tubes extending in parallel one to another at regular intervals, each of the wave guide tubes being formed with a plurality of coupling ports arranged intermittently in an axial direction of the wave guide tube and dimensioned so that coupling coefficient thereof become gradually higher toward a distal end of the wave guide tube, and a plurality of dielectric windows provided through the plasma generating chamber in association with the respective coupling ports so that microwave electric power radiated through the coupling ports into the plasma generating chamber may be uniformized and thereby plasma of a large area may be generated with high and uniform density.

Abstract: A microcavity plasma discharge device comprising a micro-cavity device structure which includes N dielectric material structures wherein N is a whole number greater than or equal to one, each N dielectric material structure including a dielectric spacer region with a first opening wherein the dielectric spacer region is sandwiched therebetween a first dielectric material region with a second opening and a second dielectric material region with a third opening wherein the second opening and the third opening are positioned adjacent to the first opening to form a trench with a width and wherein a first conductive material layer is sandwiched between the dielectric spacer region and the first dielectric material region and a second conductive material layer is sandwiched between the dielectric spacer region and the second dielectric material region.

Abstract: Hollow cathode microdischarges in a tube geometry provides the formation of stable, high-pressure discharges in a variety of flowing gases including argon, helium, nitrogen, and hydrogen. Direct current discharges are ignited in stainless steel capillary tubes (dhole=178 &mgr;m) which are operated as the cathode and using a metal grid or plate as the anode. Argon discharges can be sustained at atmospheric pressure with voltages as low as 260 V for cathode-anode gaps of 0.5 mm. In one embodiment using a molybdenum substrate as the anode, microjets are struck in H2/CH4 mixtures at 200 Torr to deposit diamond films with well-faceted crystals. Optical emission spectroscopy of discharges used for growth confirms the presence of atomic hydrogen and CH radicals. Ballasting of individual tubes allows parallel operation of the microjets for larger area materials processing.

Abstract: A method and system for controlling electron densities in a plasma processing system. By applying a dither voltage and a correction voltage to a voltage-controlled oscillator, electron (plasma) density of a plasma processing system (acting as an open resonator) may be measured and controlled as part of a plasma-based process.

Abstract: A vacuum plasma processor includes a voltage-current detector connected between a matching network and a reactive impedance for exciting gas in a chamber to a plasma for processing a workpiece. A constant non-zero AC parameter is maintained in a connection between an electrode in the chamber and ground. The electrode and connection to ground are such that no AC or DC source is DC coupled with the electrode.

Abstract: A plasma processing apparatus including a processing chamber having an upper surface, a first inlet, and a second inlet. The apparatus includes a wall extending from the upper surface into the processing chamber. The wall encircles the first inlet, and the wall has a base end and a terminal end, where the terminal end includes the second inlet. The apparatus includes a first inductive coil provided within the wall and encircling the first inlet, and a second inductive coil provided within the wall and encircling the second inlet. Additionally, the apparatus includes a first magnet array provided within the base end of the wall adjacent the first inlet, and a second magnet array provided within the terminal end of the wall adjacent the second inlet. A method of controlling plasma chemistry within a plasma processing apparatus is provided that includes the steps of providing a first magnetic field about a first injection region and providing a second magnetic field about a second injection region.

Abstract: A plasma in a vacuum chamber where a workpiece is processed is bounded by a plasma confinement volume including a region between a first electrode simultaneously responsive to power at first and second RF frequencies and a DC grounded second electrode. A DC grounded extension is substantially aligned with the first electrode. A substantial percentage of power at the first frequency is coupled to a path including the first and second electrodes but not the extension while a substantial percentage of power at the second frequency is coupled to a path including the first electrodes and extension, but not the second electrode. Changing the relative powers at the first and second frequencies, as applied to the first electrode, controls DC bias voltage of the first electrode.

Abstract: Various aspects of the invention provide improved approaches and methods for efficiently:

Abstract: A plasma generating method generates plasma in a treating chamber by controlling a high-frequency generating unit to generate a high-frequency signal and by feeding the high-frequency signal to the treating chamber through an impedance matching device. The plasma generating method includes controlling the impedance matching device, when the plasma is generated in the treating chamber, so as to satisfy a preset matching condition, and then controlling the high-frequency generating unit to generate and feed the high-frequency signal of the power generating the plasma, to the treating chamber.

Abstract: A microcavity plasma discharge device comprising a micro-cavity device structure which includes N dielectric material structures wherein N is a whole number greater than or equal to one, each N dielectric material structure including a dielectric spacer region with a first opening wherein said dielectric spacer region is sandwiched therebetween a first dielectric material region with a second opening and a second dielectric material region with a third opening wherein the second opening and the third opening are positioned adjacent to the first opening to form a trench with a width and wherein a first conductive material layer is sandwiched between the dielectric spacer region and the first dielectric material region and a second conductive material layer is sandwiched between the dielectric spacer region and the second dielectric material region.

Abstract: A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Abstract: An apparatus for producing a stable, high pressure plasma column with long length, and high axial uniformity. Rotating a gas-filled tube about an horizontal axis creates a vortex with minimal, or no shear flow. Such a vortex provides a stable equilibrium for a central column of high temperature gas and plasma when, for a given rotation speed, the centrifugal force dominates over the gravitational force inside the smallest radial dimension of the containment envelope. For gas pressures sufficiently high that the particle mean free path is short compared with the thickness of the gas layer between the central plasma column and the wall, thermal transport across this sheath layer is small and its temperature is low. High pressure discharges inside a rotating envelope may be sustained by a variety of means, including electrical, electromagnetic and chemical; they may find application in plasma torches, light sources, etc.

Abstract: An indirectly heated cathode ion source includes an arc chamber housing that defines an arc chamber, an indirectly heated cathode and a filament for heating the cathode. The cathode may include an emitting portion having a front surface, a rear surface and a periphery, a support rod attached to the rear surface of the emitting portion, and a skirt extending from the periphery of the emitting portion. A cathode assembly may include the cathode, a filament and a clamp assembly for mounting the cathode and the filament in a fixed spatial relationship and for conducting electrical energy to the cathode and the filament. The filament is positioned in a cavity defined by the emitting portion and the skirt of the cathode. The ion source may include a shield for inhibiting escape of electrons and plasma from a region outside the arc chamber in proximity to the filament and the cathode.

Abstract: An ion implanting system including an ion implanting chamber for implanting an ion into a semiconductor wafer, a load lock chamber for loading the semiconductor wafer into the ion implanting chamber, a turbo pump for creating a high vacuum atmosphere in the load lock chamber, a low vacuum pump for creating a low vacuum atmosphere in the turbo pump, a cryo pump controller for generating a control signal to control a pumping operation of the turbo pump, a control voltage generator for generating a control voltage in response to the control signal generated from the cryo pump control, an interface for generating a starting signal in response to the control voltage, and a turbo pump controller for applying a voltage to operate the turbo pump and the low vacuum pump in response to the starting signal output from the interface.

Abstract: A discharge tube (11) made of a dielectric material extends through a hole (3) of a rectangular waveguide (1) and through a coaxial microwave cavity (4) so as to be coaxial with the central axis of the cavity (4). This discharge tube (11) has a double-tube structure including an outer tube (12) and an inner tube (13). The sectional area of an annular gap formed between the outer tube (12) and the inner tube (13) is held constant over the entire length of the inner tube (13). This allows the generation of a stable thermal plasma when a reaction gas containing an organic halide and water vapor is supplied into the outer tube through the annular gap with a microwave transmitted from the rectangular waveguide (1) into the cavity (4).

Abstract: A method and system for controlling electron densities in a plasma processing system. By applying a dither voltage and a correction voltage to a voltage-controlled oscillator, electron (plasma) density of a plasma processing system (acting as an open resonator) may be measured and controlled as part of a plasma-based process.

Abstract: A method of treating a first chemical species in a gas using a plasma, the method including the steps of providing an array of micro-scale cavity discharge devices capable of sustaining the plasma where the first chemical species is capable of flowing proximate to the array of micro-scale cavity discharge devices, wherein the first chemical species is converted to a second chemical species within the plasma.

Abstract: There is provided a plasmar processing apparatus capable of positively controlling the temperature distribution of a semiconductor wafer during etching processing in a clear state, wherein an electrode block is provided with independent slits as coolant flow paths on the inner and outer peripheries and, at the same time, between these slits is formed a slit for suppressing heat transfer between the inner and outer peripheries, and owing to this slit for suppressing heat transfer, a uniform temperature in the electrode block is suppressed and thus it is possible to obtain an arbitrary independent temperature in the plane of the electrode block and positive and clear control of temperature distribution patterns can be performed.

Abstract: An apparatus and method to contain plasma at optimal fill capacity of a metallic container is disclosed. The invention includes the utilization of anodized layers forming the internal surfaces of the container volume. Bias resistors are calibrated to provide constant current at variable voltage conditions. By choosing the appropriate values of the bias resistors, the voltages of the metallic container relative to the voltage of an anode are adjusted to achieve optimal plasma fill while minimizing the chance of reaching the breakdown voltage of the anodized layer.

Abstract: A confinement assembly for confining a discharge within an interaction space of a plasma processing apparatus comprising a stack of rings and at least one electrically conductive member. The rings are spaced apart from each other to form slots therebetween and are positioned to surround the interaction space. At least one electrically conductive member electrically couples each ring. The electrically conductive member contacts each ring at least at a point inside of the outer circumference of each ring.

Abstract: A plasma processing system that includes a plasma chamber, an open resonator movably mounted within the plasma chamber, and a detector. The open resonator produces a microwave signal, and the detector detects the microwave signal and measures a mean electron plasma density along a path of the signal within a plasma field. Alternatively, the plasma processing system includes a plasma chamber, a plurality of open resonators provided within the plasma chamber, a plurality of detectors, and a processor. The processor is configured to receive a plurality of mean electron plasma density measurements from the detectors that correspond to locations of the plurality of open resonators.

Abstract: A plasma processing apparatus has a plasma processing chamber that accommodates an electrode pair of a plasma excitation electrode for exciting plasma and a susceptor electrode facing the plasma excitation electrode, a workpiece to be treated being placed therebetween. The apparatus also has a chassis that accommodates an impedance matching circuit, provided in the middle of a supply path for feeding RF power from an RF generator to the plasma excitation electrode, for matching the impedance between the RF generator and the plasma processing chamber. In the chassis, impedances are axisymmetrically equal at a predetermined frequency with respect to the direction of a high-frequency current returning to the RF generator. The matching circuit has at least two inductance coils connected in parallel.

Abstract: An electrode assembly (50) and an associated plasma reactor system (10) and related methods for a variety of plasma processing applications. The electrode assembly provides control of a plasma density profile (202) within an interior region (30) of a plasma reactor chamber (20). The electrode assembly includes an upper electrode (54) having a lower surface (54L), an upper surface (54U) and an outer edge (54E). The lower surface of the upper electrode faces interior region of the plasma chamber housing the plasma (200), and thus interfaces with the plasma. The electrode assembly further includes a segmented electrode (60) arranged proximate to and preferably substantially parallel with the upper surface of the upper electrode. The segmented electrode comprises two or more separated electrode segments (62a, 62b, . . . 62n), each having an upper and lower surface. Each electrode segment is spaced apart from the upper electrode upper surface by a corresponding controlled gap (Ga, Gb, . . . Gn).

Abstract: The invention is embodied in a plasma reactor for processing a semiconductor wafer, the reactor having a gas distribution plate including a front plate in the chamber and a back plate on an external side of the front plate, the gas distribution plate comprising a gas manifold adjacent the back plate, the back and front plates bonded together and forming an assembly. The assembly includes an array of holes through the front plate and communicating with the chamber, at least one gas flow-controlling orifice through the back plate and communicating between the manifold and at least one of the holes, the orifice having a diameter that determines gas flow rate to the at least one hole. In addition, an array of pucks is at least generally congruent with the array of holes and disposed within respective ones of the holes to define annular gas passages for gas flow through the front plate into the chamber, each of the annular gas passages being non-aligned with the orifice.

Abstract: A plasma pump and method for pumping ions from a first to second region, the pump including a partition member having a through opening defining a plurality of conduits (30); a group of magnets (24) to provide magnetic forces that extend to the conduits; and a plurality of electric potential sources (14) for creating electrostatic fields which accelerate ions from the conduits to the second region.

Abstract: An improved double chamber ion source comprising a plasma generating chamber, a charge exchange chamber and a divider structure therebetween. The charge exchange chamber includes magnetic shielding material to reduce exposure of interior components to magnetic field lines externally generated. The double compartment ion source further comprises inclusion of a heat shield and/or a cooling system to overcome deleterious effects caused by increased temperature in the plasma generating chamber. The divider structure has a plurality of apertures having a configuration to reduce surface area on the divider structure in the charge exchange chamber.

Abstract: For a plasma accelerator arrangement having a focused electron beam introduced into a plasma chamber, an annular structure of the chamber and a hollow cylindrical form of the electron beam are presented. A beam-guiding magnet system and, if appropriate, an electrode system is preferably formed in a plurality of stages in an adapted toroidal form.

Abstract: A plasma processing apparatus processing a surface of a substrate by spraying a process gas in a plasma state from a gas spray opening of a spray nozzle onto the substrate includes: an exhaust opening for exhausting residual gas generated at the time of processing the surface of the substrate, the exhaust opening being provided at a position close to the periphery of the gas spray opening; and an air jet opening generating airflow, the air jet opening being provided surrounding the exhaust opening so as to prevent the residual gas from flowing out.

Abstract: A plasma processing apparatus has a plasma processing chamber, a radiofrequency generator, and an matching circuit. The plasma processing chamber includes a plasma excitation electrode and a susceptor electrode for exciting a plasma. The radiofrequency generator is connected to plasma excitation electrode. The matching circuit matches the impedance between the plasma processing chamber and the radiofrequency generator. A capacitance which is 26 times a plasma electrode capacitance Ce between the plasma excitation electrode and the susceptor electrode is greater than a loss capacitance CX between the plasma excitation electrode and ground potential positions which are DC-grounded.

Abstract: A plasma valve includes a confinement channel and primary anode and cathode disposed therein. An ignition cathode is disposed adjacent the primary cathode. Power supplies are joined to the cathodes and anode for rapidly igniting and maintaining a plasma in the channel for preventing leakage of atmospheric pressure through the channel.

Abstract: The present invention is directed to a plasma processor, and more specifically, to an apparatus to reduce or eliminate plasma lighting inside a gas line in a strong RF field in the plasma processor. More particularly, the present invention uses shielding and gas flow restricting to reduce or eliminate plasma lighting in a gas line used to deliver gas to cool the work piece in the plasma processor.

Abstract: A plasma processing apparatus including a processing chamber having an upper surface, a first inlet, and a second inlet. The apparatus includes a wall extending from the upper surface into the processing chamber. The wall encircles the first inlet, and the wall has a base end and a terminal end, where the terminal end includes the second inlet. The apparatus includes a first inductive coil provided within the wall and encircling the first inlet, and a second inductive coil provided within the wall and encircling the second inlet. Additionally, the apparatus includes a first magnet array provided within the base end of the wall adjacent the first inlet, and a second magnet array provided within the terminal end of the wall adjacent the second inlet. A method of controlling plasma chemistry within a plasma processing apparatus is provided that includes the steps of providing a first magnetic field about a first injection region and providing a second magnetic field about a second injection region.

Abstract: The RF-powered plasma accelerator/homogenizer produces a quiescent plasma having a generally homogenous preselected plasma potential VPA and a space-charge neutralized plasma beam. The plasma accelerator/homogenizer includes an RF-conductive accelerator/homogenizer structure (17) having a plurality of dielectric-coated accelerator/homogenizer surfaces (619) with total surface area ARF and a containment assembly that includes an RF-grounded structure (112) with a total ground surface area AG, where ARF>AG. The accelerator/homogenizer structure is reactively coupled to an RF source using various approaches for direct or stray capacitive coupling (16).

Abstract: A spiral-like multi-turn coil excites a plasma for treating a workpiece in a vacuum plasma processor. In one embodiment two of the turns have a discontinuity. Each discontinuity has a capacitor connected across it. An RF source drives the coil via a matching network, an inductor connected to one coil excitation terminal and a capacitor connected to another coil excitation terminal. The impedances of the inductors and the capacitors at the RF source frequency and the discontinuity locations are such as to cause a standing wave voltage of the coil to have (1) equal and opposite values at the coil terminals, (2) sudden amplitude and slope changes, slope reversals and polarity reversals at each of the discontinuities, and (3) three gradual standing wave voltage polarity reversals, spaced from each other by 120°. Two of the gradual polarity reversals are azimuthally aligned with the discontinuities. In a second embodiment, one turn has a discontinuity having a series capacitor connected across it.

Abstract: A plasma is produced in a treatment space by diffusing a plasma gas at atmospheric pressure and subjecting it to an electric field created by two metallic electrodes separated by a dielectric material, a vapor precursor is mixed with the plasma, and a substrate material is coated by vapor deposition of the vaporized substance at atmospheric pressure in the plasma field. The use of vaporized silicon-based materials, fluorine-based materials, chlorine-based materials, and organo-metallic complex materials enables the manufacture of coated substrates with improved properties with regard to moisture-barrier, oxygen-barrier, hardness, scratch- and abrasion-resistance, chemical-resistance, low-friction, hydrophobic and/or oleophobic, hydrophilic, biocide and/or antibacterial, and electrostatic-dissipative/conductive characteristics.

Abstract: A plasma processing chamber is provided which provides improved wafer area pressure control. The plasma processing chamber is a vacuum chamber with a device connected for generating and sustaining a plasma. Part of this device would be an etchant gas source and an exhaust port. A confinement ring defines an area above a wafer. The wafer area pressure is dependent on the pressure drop across the confinement ring. The confinement ring is part of a wafer area pressure control device that provides wafer area pressure control range greater than 100%. Such a wafer area pressure control device may be three adjustable confinement rings and a confinement block on a holder that may be used to provide the desired wafer area pressure control.

Abstract: A compound plasma configuration can be formed from a device having pins, and an annular electrode surrounding the pins. A cylindrical conductor is electrically connected to, and coaxial with, the annular electrode, and a helical conductor coaxial with the cylindrical conductor. The helical conductor is composed of wires, each wire electrically connected to each pin. The annular electrode and the pins are disposed in the same direction away from the interior of the conducting cylinder.