A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.

An apparatus for igniting a combustible mixture. In one example, the apparatus can include a coaxial cavity resonator assembly in a combustion environment. The apparatus can also include an operational feedback system and a controller. The operational feedback system can measure at least one of a voltage value and a current value of the coaxial cavity resonator assembly in the combustion environment. The controller can be configured to determine a condition of the coaxial cavity resonator assembly and modulate operation of the coaxial cavity resonator assembly based at least in part on the determined condition.

A method of providing spark ignition for an engine or other equipment having a combustion chamber. A radio frequency wave or a microwave (RF/microwave) generator delivers radio frequency waves or microwaves to a transmit antenna inside the combustion chamber. At least one RF/microwave receive antenna is attached to an internal surface of the combustion chamber and comprises two or more RF/microwave focusing features with a spark gap between them. The transmit antenna wirelessly energizes the receive antenna, which generates a spark between the two focusing features.

A method of providing spark ignition for an engine or other equipment having a combustion chamber. A radio frequency wave or a microwave (RF/microwave) generator delivers radio frequency waves or microwaves to a transmit antenna inside the combustion chamber. At least one RF/microwave receive antenna is attached to an internal surface of the combustion chamber and comprises two or more RF/microwave focusing features with a spark gap between them. The transmit antenna wirelessly energizes the receive antenna, which generates a spark between the two focusing features.

A plasma assisted spark ignition system includes an ignitor and a power supply. The first ignitor includes: a casing having a first end, a second end that forms a first electrode, and a longitudinally extending passage, a second electrode which protrudes longitudinally outward from an opening at the second end of the casing and laterally spaced inwardly to form a spark gap, and an electrical insulator (dielectric) surrounding a portion of the second electrode, and which has a terminus that is at least closely spaced to an interior surface of the end of the casing. The power supply supplies a plurality of voltage pulses to the ignitor per ignition event to generate a flash over on the dielectric. Subsequent pulses in an ignition event may be at lower amplitude than an initial pulse in the ignition event. Pulses may, for example, have a duration on the order of a nanosecond.

A plasma generator comprises a radio frequency power source, a coaxial cavity resonator assembly, and a direct current power source. The radio frequency power source provides a voltage supply of radio frequency power having a first ratio of power over voltage. The resonator assembly includes a center conductor coupled to the radio frequency power source, and also includes a virtual short circuit. The direct current power source is connected to the center conductor at the virtual short circuit, and provides a voltage supply of direct current power having a second ratio of power over voltage that is less than the first ratio.

An ignition device for an internal combustion engine includes optical focusing lenses, including a center optical focusing lens and satellite optical focusing lens. The center optical focusing lens focuses laser light from a laser generator to a center ignition point in a combustion chamber of a cylinder of the internal combustion engine. The satellite optical focusing lenses focus laser light from the laser generator to satellite ignition points in the combustion chamber of the cylinder of the internal combustion engine. The satellite optical focusing lenses are directionally angled away from the center optical focusing lens. A firing depth of the center ignition point is greater than a firing depth of the at least one satellite ignition point.

An ignition device includes a center electrode, a center dielectric covering the center electrode, a ground electrode disposed so as to form a discharge space with the center dielectric, and a high energy source for applying an AC voltage between the center electrode and the ground electrode to generate a streamer discharge. A distal end portion of the center electrode projects beyond a distal end of the ground electrode to an inside of the combustion chamber of an internal combustion engine to make a dielectric discharge portion. The ground electrode is formed with an airflow inlet and en airflow outlet at a lateral portion thereof for enabling an in-cylinder airflow to be introduced into the discharge space. A distal end portion of the ground electrode projects radially inward to make a ground electrode projecting portion so that a discharge space narrow portion is formed with the dielectric discharge portion.

An ignition unit improves an air-fuel-ratio, i.e., good mileage and lean burn without changing a gasoline engine structure significantly. The ignition unit comprises a discharge device including a booster and a discharger provided at an output side of the booster, the booster having a resonance structure configured to boost the electromagnetic wave inputted from the electromagnetic wave oscillator so as to cause a discharge from the discharger, and an electromagnetic wave emitter electrically connected to the electromagnetic wave oscillator and configured to emit the electromagnetic wave inputted from the electromagnetic wave oscillator. Moreover, the ignition unit further includes a housing part including a first hole into which the discharge device is inserted and a second hole into which the electromagnetic wave emitter is inserted such that the housing part houses therein both the discharge device and the electromagnetic wave emitter, and the housing part can be inserted into a single hole of a cylinder head of an internal combustion engine.

A compression-ignition type internal combustion engine that burns a gaseous fuel, improves an ignition performance not only at a center part of the combustion chamber but also at an outer edge part. The compression-ignition engine comprises an electromagnetic wave generator configured to generate an electromagnetic wave, a controller configured to control the electromagnetic wave generator, and a plasma generator comprising a boosting circuit that constitutes a resonator configured to boost the electromagnetic wave, a first electrode configured to receive an output from the boosting circuit, and a second electrode provided to a vicinity of the first electrode, and the plasma generator is configured such that the first electrode is extruded and exposed toward a combustion chamber of the internal combustion engine, and a plurality of plasma generators are provided.