Abstract: A plasma antenna with an acoustic modulator is provided. An ionizer produ a plasma in a horizontal tube to form a bounded plasma column extending along a longitudinal axis. An amplitude-, phase- or frequency-modulated signal is applied to an acoustic transducer that directs an acoustic wave along the longitudinal axis into the plasma. The acoustic wave acts as an ion acoustic wave to oscillate ions parallel to the axis. This movement radiates an amplitude-, phase- or frequency-modulated electromagnetic field from the plasma column.

Abstract: A gas in a vacuum plasma processing chamber is ignited to a plasma by subjecting the gas to an r.f. field derived from an r.f. source having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma. The r.f. field is supplied to the gas by a reactive impedance element connected via a matching network to the r.f. source. The matching network includes first and second variable reactances that control loading of the source and tuning a load, including the reactive impedance element and the plasma, to the source. The value of only one of the reactances is varied until a local maximum of a function of power coupled between the source and the load is reached. The value of only the other reactance is varied until a local maximum of the function is reached. The two varying steps are then repeated as necessary.

Abstract: A radio frequency (RF) generating system for forming pulse plasma utilizes a plasma reaction device comprises a function generator, an amplifier, and an input port. The function generator generates a signal of time-modulated RF power according to a modulation function having a waveform, wherein the waveform gradually ascends at a rising edge and gradually descends at a falling edge. The input port receives the signal from the function generator and transmits the signal to the amplifier. The amplifier amplifies the signal to a predetermined level and then transmits the amplified signal to the plasma reaction device.

Abstract: A microwave launcher includes a hollow microwave cavity in the shape of a plus sign, four coplanar exit ports in the arms of the microwave cavity, and a non-coplanar entry port at a central hub of the microwave cavity. A single magnetron is in communication with the entry port. There is a controllable, electrically activated microwave barrier at each of the exit ports. Each microwave barrier includes an electrical signal input whose operation controls the activation of the microwave barrier. A switching circuit has a voltage source for the electrical signal input of each of the microwave barriers. Microwave power output from the single microwave source is launched from the selected exit port by using the switching circuit to selectively block microwave passage through each of the nonselected exit ports, but to leave the selected exit port unblocked.

Abstract: A method and portable apparatus for self-powered, sensitive analysis of solid, liquid or gas samples for the presence of elements is provided. The apparatus includes a compact sensor system which utilizes a microwave power source and a shorted waveguide to induce a plasma. The microwave power source may be a magnetron or the like. The device includes a portable power supply and preferably includes a portable battery charger. The portable power supply includes a compact generator- internal combustion engine unit. The device can be operated by directly using power from the portable power supply or in a more compact embodiment by using power from batteries that are recharged by a separate portable power supply module. Pulsed microwave operation can be used to reduce average power requirements and facilitate the use of very compact units using batteries. The device is capable of being transported to and from remote sites for analysis by an individual without the need for heavy transportation equipment.

Abstract: An impedance matching network for an RF coupled plasma reactor having RF excitation apparatus receiving RF power through the impedance matching network from an RF generator for producing a plasma in the reactor has at least one capacitor connected to the output of the RF generator and having a capacitance value providing an impedance match to the plasma impedance during a steady state of the plasma, at least a first rapidly tunable capacitor connected in parallel with the one capacitor, the rapidly tunable capacitor being rapidly switchable between a high capacitance value providing a match to the plasma impedance during the onset of plasma ignition and a lesser minimum capacitance value, and a controller for rapidly switching the rapidly tunable capacitor from the high to the lesser capacitance value upon reaching the plasma steady state.

Abstract: Microwave-induced plasma for continuous, real time trace element monitoring under harsh and variable conditions. The sensor includes a source of high power microwave energy and a shorted waveguide made of a microwave conductive, high temperature capability refractory material communicating with the source of the microwave energy to generate a plasma. The high power waveguide is constructed to be robust in a hot, hostile environment. It includes an aperture for the passage of gases to be analyzed and a spectrometer is connected to receive light from the plasma. Provision is made for real time in situ calibration. The spectrometer disperses the light, which is then analyzed by a computer. The sensor is capable of making continuous, real time quantitative measurements of desired elements, such as the heavy metals lead and mercury. The invention may be incorporated into a high temperature process device and implemented in situ for example, such as with a DC graphite electrode plasma arc furnace.

Abstract: A microwave switch selectively directs a microwave signal along first and second signal paths. The switch includes a microwave transmission member, a microwave chamber formed by the transmission member for containing an ionizable gas, input and output ports formed by the transmission member to communicate with the microwave chamber and a triggered plasma generator which is configured to generate, in response to a voltage trigger signal, a trigger electron density N.sub.t in the gas. The microwave signal increases the trigger electron density N.sub.t to a reflective electron density N.sub.r. Consequently, the microwave signal is reflected along a first path from the input port when the trigger electron density N.sub.t is present and is directed along a second path to the output port when the trigger electron density N.sub.t is absent. A plurality of these microwave switches is arranged to form a tunable microwave short.

Abstract: A detector circuit for controlling an RF match circuit that receives an RF power signal from an RF source and delivers the RF power signal to a load. The RF match circuit includes a first variable reactance element which is controlled by a first control signal and a second variable reactance element is controlled by a second control signal. The detector circuit includes a dual directional coupler which generates a forward signal that is proportional to RF power delivered to the match circuit and a reflected signal that is proportional to RF power reflected back from the RF match circuit. The detector also includes a first branch circuit receiving the reflected signal and producing a first and second output signal therefrom and a second branch circuit receiving the forward signal and producing a first and second output signal therefrom.

Abstract: A fluid-cooled plasma applicator for microwave absorbing fluids is described. The applicator includes a discharge tube substantially transparent to microwave energy and a cooling member surrounding the tube defining a channel and a medium. The channel is formed along an inner surface of the member and it encircles an outer surface of the tube for transporting a microwave absorbing cooling fluid over the outer surface of the tube. The medium adjacent to the channel allows an electric field to enter the tube and sustain a plasma in the tube while the fluid is flowing through the channel.

Abstract: A corrugated waveguide is disclosed comprising a cylindrical body with outer and inner surfaces. The inner surface is provided with plurality of ridges uniformly spaced around the inner surface. Presence of 2n ridges secures the formation of microwaves with stable TE.sub.n1 modes where n is an integer and n>1. Disclosed also is an electron cyclotron resonance system for plasma processing of which system the corrugated waveguide described in the above is a part.

Abstract: A plasma processing system including a plasma processing chamber; an antenna circuit including a source antenna positioned relative to the processing chamber so as to couple energy into a plasma within the chamber during processing, the antenna circuit having a first terminal and a second terminal with the source antenna electrically coupled between the first and second terminals; and a local impedance transforming network connected to the antenna circuit, the local impedance transforming network including a first capacitor connected between the first terminal and a grounded node, and a second capacitor connected between the second terminal and the grounded node.

Abstract: A fluid-cooled dielectric window for a microwave plasma system which uses microwave absorbing fluids is described. The window includes a dielectric window and a cooling member in contact with an outer surface of the window which defines a channel and a medium adjacent to the channel. The channel transports a microwave absorbing cooling fluid over the outer surface of the window. The medium allows an electric field to enter through the window and sustain a plasma in a chamber while the fluid is flowing through the channel.

Abstract: A low-pressure high-density plasma is excited in a plasma chamber surrounded by a cylindrical inner wall of a ring-shaped waveguide resonator to which the microwave energy is fed by a coupling from a microwave generator. The output coupling of the microwave energy from the standing wave maintained in the waveguide resonator to the plasma chamber is effected through a multiplicity of equispaced slits whose spacing is one half or one waveguide wavelength and which extend parallel to the generatrices of the cylindrical inner wall of the ring-shaped waveguide resonator.

Abstract: A microwave introducing device has an endless circular waveguide provided with a plurality of slots. The circular waveguide is provided with a microwave introducing portion connected to a microwave power source, and the plurality of slots are spaced through an inner side of the circular waveguide such that the slots are arranged at the inner side of the circular waveguide at a given interval. A plasma treating apparatus can be provided with the microwave introducing device.

Abstract: Microwave-induced plasma for continuous, real time trace element monitoring under harsh and variable conditions. The sensor includes a source of high power microwave energy and a shorted waveguide made of a microwave conductive, refractory material communicating with the source of the microwave energy to generate a plasma. The high power waveguide is constructed to be robust in a hot, hostile environment. It includes an aperture for the passage of gases to be analyzed and a spectrometer is connected to receive light from the plasma. Provision is made for real time in situ calibration. The spectrometer disperses the light, which is then analyzed by a computer. The sensor is capable of making continuous, real time quantitative measurements of desired elements, such as the heavy metals lead and mercury.

Abstract: A block of dielectric material having a long axis and a short axis and having low losses at a selected microwave frequency and a dielectric constant selected to produce a desired degree of phase modulation is mounted on a rotatable shaft in an orientation perpendicular to the long and short axes and arranged inside a waveguide feeding a CVD reactor containing a plasma species. The block is spun by a rotational force applied to the shaft at an angular acceleration such that the two axes of the block successively intersect the axis of the waveguide within the decay period of the plasma species. The frequency of phase modulation can be varied by changing the angular acceleration of the shaft, and the amplitude of the phase modulation can be varied by changing the ratio of block length to thickness and/or by selecting a material with higher dielectric constant. The incident microwave power may be modulated as a function of angular position of the spin shaft.

Abstract: A plasma processing apparatus has a waveguide along which microwaves are propagated from a microwave generator to a plasma-forming region in a low-pressure processing chamber. The waveguide has a large cross-sectional area, to enable a large region of plasma to be achieved. Uniformity and stability of the plasma are improved by a mode restrictor which inhibits mixing of propagation modes which is otherwise liable to occur in a wide waveguide. The mode restrictor consists of electrically-conductive dividers which divide the waveguide cross-section into an array of sub-guides before the plasma-forming region.

Abstract: An improved microwave plasma CVD apparatus for forming a functional deposited film which is provided with a microwave transmissive window composed of a sintered alpha-alumina ceramics body containing alpha-alumina as a matrix comprised of fine particles with a mean particle size d satisfying the equation 0.5 .mu.m.ltoreq.d.ltoreq.50 .mu.m and with a ratio of .rho..sub.2 /.rho..sub.1 between the theoretical density .rho..sub.1 and the bulk density .rho..sub.2 satisfying the equation 0.800.ltoreq..rho..sub.2 /.rho..sub.1 .ltoreq.0.995.

Abstract: In a plasma processing apparatus including a plasma chamber having a strip-shaped rectangular window having a longitudinal length formed in a side wall of the plasma chamber, an object to be processed is provided within the plasma chamber so as to be close to the window. The plasma processing apparatus includes a coupling rectangular waveguide having a strip-shaped rectangular slit formed in an E-plane thereof so as to extend in a direction of an axis thereof, wherein the coupling rectangular waveguide is provided so that the direction of the axis of the coupling rectangular waveguide is parallel to the longitudinal direction of the window of the plasma chamber. A coupling member made of a material for propagating a microwave is mounted between the slit of the coupling rectangular waveguide and the window of the plasma chamber, and electromagnetically couples the slit with the window in an airtight state.

Abstract: An isolator is disposed between a plasma reactor and its electrical energy source in order to isolate the reactor from the electrical energy source. The isolator operates as a filter to attenuate the transmission of harmonics of a fundamental frequency of the electrical energy source generated by the reactor from interacting with the energy source. By preventing harmonic interaction with the energy source, plasma conditions can be readily reproduced independent of the electrical characteristics of the electrical energy source and/or its associated coupling network.

Abstract: An arrangement for coupling microwave energy with a reaction chamber, including electrically stable tuning and being, within limits, tolerant against changes in critical dimensions and power fluctuations. A coaxial line between a hollow waveguide and the reaction chamber is of such a structure that it forms, at least together with the reaction chamber, a loss resonator for the microwave frequency employed. The coaxial line can comprise an absorber or, alternatively, can be made of a poorly conductive material. There is also the possibility of downgrading the quality of the resonator by leaving an annular gap between a metal plate and an outer conductor section.

Abstract: Apparatus for the production of glow discharge, preferably for a large-area plasma CVD process, including a vacuum coating chamber (K) and a microwave waveguide resonator with one or more coupling points, wherein the resonator is made in the form of a microwave waveguide ring resonator (13, 13'), reaction zones (R) are formed at the coupling points between the microwave waveguide ring resonator (13, 13') and the vacuum chamber (K), and in each case a series of magnets (5, 5', . . . ; 6, 6', . . . ) of different polarity are provided, so that in front of the reaction zone (R) individual tunnels of magnetic field lines (16, 16') running parallel thereto are formed and each magnetic field (16, 16') encloses a spatially uniform plasma tube (17) in the reaction zone (R).

Abstract: In a microwave plasma generating method and apparatus according to the present invention, a slow wave structure is disposed in the propagation region of microwaves, and the microwaves are introduced at a delayed phase velocity into a discharge chamber so that treating gases are transformed into plasma. Thus, the phase velocity of the microwaves is adjusted to a relatively low velocity, at which charged particles are distributed most densely in the plasma, so that the energy may be efficiently transformed to many more charged particles in the plasma. Thus, the plasma of high density is generated to improve a plasma treating rate.

Abstract: A microwave plasma generating apparatus radiates a microwave to a source gas to produce a plasma. A plurality of spaced fins are disposed in a path of travel of the microwave, from the microwave guide to an area of origin of the plasma within the plasma generating chamber to lie in a direction perpendicular to the direction of an electric field of the microwave, for the purpose of locking the position at which the plasma has been produced.

Abstract: A block of dielectric material having a long axis and a short axis and having low losses at a selected microwave frequency and a dielectric constant selected to produce a desired degree of phase modulation is mounted on a rotatable shaft in an orientation perpendicular to the long and short axes and arranged inside a waveguide feeding a CVD reactor containing a plasma species The block is spun by a rotational force applied to the shaft at an angular acceleration such that the two axes of the block successively intersect the axis of the waveguide within the decay period of the plasma species. The frequency of phase modulation can be varied by changing the angular acceleration of the shaft, and the amplitude of the phase modulation can be varied by changing the ratio of block length to thickness and/or by selecting a material with higher dielectric constant. The incident microwave power may be modulated as a function of angular position of the spin shaft.

Abstract: A microwave window assembly for transmitting high power microwave energy from microwave propagating means into the interior of a chamber and including first and second windows formed of a dielectric material substantially transparent to microwave energy with the first window sealed in a wall of the chamber and the second window spaced rearwardly from the first window to define a space therebetween. A cooling fluid is circulated in the space between the windows to cool the window positioned in the wall of the vacuum chamber and a waveguide tube extends from the microwave propagating means to the rear surface of the second window to define a waveguide surface extending from the microwave source to the rear surface of the second window.

Abstract: A harmonic and subharmonic filter is coupled between a high power RF energy source and a non-linear RF load via a matching network, such as a plasma chamber. The filter passes high power RF energy in a band centered on a predetermined radio frequency, i.e., 13.56 MHz, but blocks and attenuates out-of-band energy at frequencies which are multiples of or fractions of the predetermined frequency. The harmonic and subharmonic filter comprises an input terminal, an output terminal, a series LC resonance path connected between the input and output terminals, and tuned to the predetermined radio frequency, a series resistive path formed of first and second resistors, and a parallel LC resonance path between the junction of the two resistors and ground.

Abstract: The present invention is directed to a plasma generator which can generate a localized plasma. To localize the plasma, a low pressure plasma generator, containing a vacuum chamber and at least one microwave radiation source, which does not by itself produce a field strength sufficient to form plasma in the vacuum chamber, is equipped with at least one aerial for the radiation of microwaves. This at least one aerial acts as a secondary radiator in the vacuum chamber and can generate a localized plasma at its free tips.

Abstract: A microwave plasma processing apparatus includes a microwave waveguide connected to a microwave power source, a mode converting wave guide and a plasma chamber.

Abstract: A laser-induced switch and a multiple cavity configuration are disclosed for producing high power microwave pulses. The microwave pulses are well controlled in wavelength and timing, with a quick rise time and a variable shape and power of the pulse. In addition, a method of reducing pre-pulse leakage to a low level is disclosed.Microwave energy is directed coherently to one or more cavities that stores the energy in a single mode, represented as a standing wave pattern. In order to switch the stored microwave energy out of the main cavity and into the branch waveguide, a laser-actuated switch is provided for the cavity. The switch includes a laser, associated optics for delivering the beam into the main cavity, and a switching gas positioned at an antinode in the main cavity. When actuated, the switching gas ionizes, creating a plasma, which becomes reflective to the microwave energy, changing the resonance of the cavity, and as a result the stored microwave energy is abruptly switched out of the cavity.

Abstract: A window assembly for transmitting relatively high power microwave energy from a waveguide, held at substantially atmospheric pressure levels, into a microwave reaction chamber at sub-atmospheric pressure levels. The window assembly provides for the transmission of microwave energy to generate a glow discharge plasma without suffering from catastrophic failure as a result of excessive temperature and pressure conditions.

Abstract: A window assembly for transmitting relatively high power microwave energy from a waveguide, held at substantially atmospheric pressure levels, into a microwave reaction chamber at sub-atmospheric pressure levels. The window assembly provides for the transmission of microwave energy to generate a glow discharge plasma without suffering from catastrophic failure as a result of excessive temperature and pressure conditions.

Abstract: A waveguide having walls defining an opening. An optically transmissive aperture in one wall allows light from an optical illumination source such as a laser diode array to illuminate the opening in which is located a semiconductor slab positioned to be illuminated. When the array illuminates the slab, the propagation characteristics (phase velocity and attenuation constant) of the waveguide changes. A continuous wave signal passing through the waveguide is thus attenuated and phase shifted. The laser array may be pulsed on and off while still maintaining the altered propagation constant.

Abstract: A microwave plasma source apparatus having a combination of a plane waveguide with a cylindrical coaxial waveguide. Microwave power is efficiently supplied to a body of discharge plasma produced inside a discharge tube located along the central axis of an inner conductor of the cylindrical coaxial waveguide. The plane waveguide has an open end through which to introduce microwave power and an end plate installed opposite to the open end. The cylindrical coaxial waveguide has its central axis located one quarter of the wavelength of the microwave power in use away from the end plate of the plane waveguide toward its open end. The inner and outer conductors of the cylindrical coaxial waveguide are coupled respectively with the bottom and upper walls of the plane waveguide. This arrangement allows the cylindrical coaxial waveguide to function as an efficient mode transformer addressing the microwave electromagnetic field formed in the plane waveguide.

Abstract: A device for propagating microwave energy to a plasma discharge tube from an antenna coupled to a microwave generator includes a hollow rectangular conduit and a strip-line resonator or strip-line conductor disposed therein. The discharge tube is mounted perpendicular to and through a central opening in the strip-line resonator and is disposed at a distance, from one end of the strip-line where the antenna is located, of one-half the wavelength of the microwave energy and one-quarter wavelength from the opposite end. The strip-line is attached to one end of the rectangular conduit and is supported by a dielectric member at a point one-quarter wavelength from the antenna. Microwave energy is propagated from the antenna by the strip-line dimensioned to the resonant frequency of the microwave the energy. A gas, such as argon or helium, is introduced into the discharge tube and is ionized by microwave energy to form a plasma.

Abstract: An improved apparatus for the formation of a functional deposited film using a microwave plasma chemical vapor deposition process characterized in that a microwave transmissible dielectric material is used for the microwave introducing window, and the window has a structure wherein the dielectric material is divided into blocks of the same or different dielectric materials having a specific inductive capacity of more than 1.0. In this way it is possible to adjust not only the resonant frequency characteristics but also the electromagnetic resonant mode of the window to resonate with the microwave oscillation frequency so as to enhance microwave transmission.

Abstract: A method of accelerating neutral plasma, consisting of electrons and positively charged ions, from low energy to high energy, by reflection of electromagnetic waves directed into the plasma, the frequency .omega. of the electromagnetic wave being smaller than the plasma frequency of the neutral plasma.

Abstract: A high-power, high-frequency discharge apparatus is disclosed. An electrical wave is guided toward the discharge region by a hollow waveguide that is coupled to a discharge electrode via a waveguide transition element. The waveguide transition element can be formed of various shapes. Obstacles placed in the waveguide provide impedance matching and minimize power reflected back toward the source. The obstacles may be movable to optimize impedance matching.

Abstract: A microwave resonant cavity for a spectroscopic light source includes a housing having therein a chamber formed by side walls and a cylindrical outer wall. The side walls having aligned openings therethrough which are on the longitudinal axis of the outer wall. A refractory tube which is adapted to contain a gaseous plasma extends through the aligned openings and across the chamber in the housing. The portion of the side walls of the chamber adjacent the openings are closer together than the remaining portions of the side walls so that the chamber has a first portion around the refractory tube which is narrower than a second portion of the chamber around the first portion. A coupling loop is electrically coupled to a side wall of the chamber within the second portion of the chamber and is connector to a coaxial connector which extends through the outer wall of the housing to deliver microwave power to the chamber.

Abstract: A microwave plasma production apparatus of the present invention comprises: a circular coaxial wave guide having a cylindrical outer conductor to inject a microwave power from one end and an inner conductor; a metal end plate in which at the other end of the circular coaxial wave guide, the cylindrical outer conductor is set to be longer than the inner conductor, and which is arranged in the edge portion of the cylindrical outer conductor and has a window of an inner diameter which is almost equal to an inner diameter of a cylinder provided for the inner conductor; a gap portion formed between the edge of the inner conductor and the metal end plate; and a discharge tube arranged from the inside of the cylinder of the inner conductor through the window to form a plasma of a material to be transformed to a plasma by the microwave electric field generated in the gap portion.

Abstract: A window assembly for transmitting relatively high power microwave energy from a waveguide, held at substantially atmospheric pressure levels, into a microwave reaction chamber at sub-atmospheric pressure levels. The window assembly provides for the transmission of microwave energy to generate a glow discharge plasma without suffering from catastrophic failure as a result of excessive temperature and pressure conditions.

Abstract: An improved apparatus for the formation of a functional deposited film using microwave plasma chemical vapor deposition process is characterized in that the relative setting angle between waveguides confronting each other is set to be 60.degree. or 240.degree. in the counterclockwise direction, which makes it possible to stably introduce the microwave energy into the vacuum chamber simultaneously from the plural microwave power sources without any interference among them.

Abstract: The invention concerns a method and apparatus to produce a noble-gas plasma for excitation in optical emission spectrometry. The apparatus includes an hf generator feeding an oscillation circuit consisting of at least one inductor and one capacitor. The capcitor includes at least two capacitor plates which are so shaped and mutually arranged that they enclose a cavity in which the plasma may form.

Abstract: The present invention relates to a device for generating plasma (ionizing gas) by a propagating surface wave. The device comprises a wave launching structure mounted on a plasma vessel and connected to an impedance matching network. The latter comprises a coupler and a tuner which is either formed by a section of a transmission line or is of the lumped circuitry type. The launching structure may either generate an azimuthally symmetric or a non symmetric propagating wave. This invention also relates to a method and a device for shaping plasma which comprises a plasma vessel receiving a surface wave generator and having a serviceable portion of a size and/or shape substantially different from the shape and/or size of the portion of the plasma vessel receiving the wave generator.

Abstract: A system for instantaneously ionizing and continuously delivering energy in the form of surface waves to a low pressure gas or mixture of low pressure gases, comprising a source of rf energy, a discharge container, (such as a fluorescent lamp discharge tube), an rf shield, and a coupling device responsive to rf energy from the source to couple rf energy directly and efficiently to the gas or mixture of gases to ionize at least a portion of the gas or gases and to provide energy to the gas or gases in the form of surface waves. The majority of the rf power is transferred to the gas or gases near the inner surface of the discharge container to efficiently transfer rf energy as excitation energy for at least one of the gases. The most important use of the invention is to provide more efficient fluorescent and/or ultraviolet lamps.

Abstract: In a high-frequency discharge apparatus utilizing a discharge tube positioned between an electrode and a ground plane, the electrode is shaped so as to increase the uniformity of the electric field across the discharge tube. Furthermore, a transmission line is formed between a conductor connected to the electrode and the ground plane, and impedance matching in the transmission line is provided by metal and/or dielectric tuning slugs inserted between the conductor and the ground plane.

Abstract: A plasma-filled waveguide acts as a dispersive element for pulse compression or power multiplication of a frequency chirped microwave signal. In one embodiment, the frequency of the source is chirped near a plasma resonance while the plasma waveguide is held contant in time. In a second embodiment, the source frequency is held fixed while the plasma filled waveguide parameters are varied in time in the vicinity of a plasma resonance.

Abstract: A resonant double loop radio frequency (rf) antenna for radiating high-power rf energy into a magnetically confined plasma. An inductive element in the form of a large current strap, forming the radiating element, is connected between two variable capacitors to form a resonant circuit. A real input impedance results from tapping into the resonant circuit along the inductive element, generally near the midpoint thereof. The impedance can be matched to the source impedance by adjusting the separate capacitors for a given tap arrangement or by keeping the two capacitances fixed and adjustng the tap position. This results in a substantial reduction in the voltage and current in the transmission system to the antenna compared to unmatched antennas. Because the complete circuit loop consisting of the two capacitors and the inductive element is resonant, current flows in the same direction along the entire length of the radiating element and is approximately equal in each branch of the circuit.

Abstract: A resonant cavity waveguide coupler for ICRH of a magnetically confined plasma. The coupler consists of a series of inter-leaved metallic vanes disposed withn an enclosure analogous to a very wide, simple rectangular waveguide that has been "folded" several times. At the mouth of the coupler, a polarizing plate is provided which has coupling apertures aligned with selected folds of the waveguide through which rf waves are launched with magnetic fields of the waves aligned in parallel with the magnetic fields confining the plasma being heated to provide coupling to the fast magnetosonic wave within the plasma in the frequency usage of from about 50-200 mHz. A shorting plate terminates the back of the cavity at a distance approximately equal to one-half the guide wavelength from the mouth of the coupler to ensure that the electric field of the waves launched through the polarizing plate apertures are small while the magnetic field is near a maximum.