In some general aspects, a surface of a structure within a chamber of an extreme ultraviolet (EUV) light source is cleaned using a method. The method includes generating a plasma state of a material that is present at a location adjacent to a non-electrically conductive body that is within the chamber. The generation of the plasma state of the material includes electromagnetically inducing an electric current at the location adjacent the non-electrically conductive body to thereby transform the material that is adjacent the non-electrically conductive body from a first state into the plasma state. The plasma state of the material includes plasma particles, at least some of which are free radicals of the material. The method also includes enabling the plasma particles to pass over the structure surface to remove debris from the structure surface without removing the structure from the chamber of the EUV light source.

A system for plasma ignition and maintenance of an atmospheric pressure plasma. The system has a variable frequency alternating current (AC) power source, a transformer, a cable connected to a secondary winding of the transformer, a programmed microprocessor for control of power to the atmospheric pressure plasma. The microprocessor is configured to a) at pre-ignition, power the AC power source at an operational frequency f.sub.op higher than the resonant frequency f.sub.r, b) decrease the operational frequency f.sub.op of the AC power source until there is plasma ignition, and c) after the plasma ignition, further decrease the operational frequency f.sub.op of the AC power source to a frequency lower than the resonant frequency f.sub.r.

A sterilization system having a controllable non-ionizing microwave radiation source for providing microwave energy for combining with a gas to produce atmospheric low temperature plasma for sterilizing biological tissue surfaces or the like. A plasma generating region may be contained in a hand held plasma applicator. The system may include an impedance adjustor e.g. integrated in the plasma applicator arranged to set a plasma strike condition and plasma sustain condition. The gas and microwave energy may be transported to a plasma generating region along an integrated cable assembly. The Integrated cable assembly may provide a two way gas flow arrangement to permit residual gas to be removed from the surface. Invasive surface plasma treatment is therefore possible. The plasma applicator may have multiple plasma emitters to produce a line or blanket of plasma.

An array antenna radiates an electromagnetic wave into a chamber of a plasma processing apparatus. The array antenna includes antennas and coupling prevention elements arranged at intervals between the antennas. Each of the coupling prevention elements includes a first member connected to a ceiling wall which is a ground surface in the chamber and a second member connected to a tip end of the first member or a vicinity of the tip end of the first member.

A compound double coaxial line atmospheric pressure low-temperature microwave plasma jet source includes an outer coaxial line, and an inner coaxial line arranged inside the outer coaxial line. The outer coaxial line includes a tube body. A metal tube is arranged in the tube body. A short-circuit plunger is arranged at the bottom of the metal tube. The inner coaxial line includes a needle electrode, and the needle electrode is arranged in the metal tube. A first gas inlet is arranged on the tube body, and the first gas inlet is connected between the tube body and the metal tube. A second gas inlet is arranged at the bottom of the metal tube, and the second gas inlet is connected between the metal tube and the needle electrode. The tube body is further provided with a microwave input port, and the microwave input port is connected to the metal tube.

A membrane plate assembly is disclosed for use with a cold atmospheric plasma applicator to expose a medium to plasma beams from the plasma applicator. The membrane plate assembly includes a membrane plate stack configured to receive the plasma beams from the plasma applicator. The membrane plate stack includes a plurality of membrane-covered structures facing each other in a generally parallel arrangement and being spaced apart to define a channel therebetween through which the plasma beams are directed. Each membrane-covered structure includes a structure and a membrane covering outer surfaces of the structure with a gap therebetween through which the medium is flowed.

A high temperature plasma generating system has a ceramic magnetron insulator joined to a frustoconical waveguide reflector. A cavity magnetron tube is joined to the frustoconical waveguide reflector. An antenna is set in the cavity magnetron tube and extending through the ceramic magnetron insulator. Applying an electrical current to the magnetron creates multipactor in the frustoconical waveguide reflector generating plasma focused at the tip of the magnetron antenna.

In some general aspects, a surface of a structure within a chamber of an extreme ultraviolet (EUV) light source is cleaned using a method. The method includes generating a plasma state of a material that is present at a location adjacent to a non-electrically conductive body that is within the chamber. The generation of the plasma state of the material includes electromagnetically inducing an electric current at the location adjacent the non-electrically conductive body to thereby transform the material that is adjacent the non-electrically conductive body from a first state into the plasma state. The plasma state of the material includes plasma particles, at least some of which are free radicals of the material. The method also includes enabling the plasma particles to pass over the structure surface to remove debris from the structure surface without removing the structure from the chamber of the EUV light source.

A system for plasma ignition and maintenance of an atmospheric pressure plasma. The system has a variable frequency alternating current (AC) power source, a transformer, a cable connected to a secondary winding of the transformer, a programmed microprocessor for control of power to the atmospheric pressure plasma. The microprocessor is configured to a) at pre-ignition, power the AC power source at an operational frequency f.sub.op higher than the resonant frequency f.sub.r, b) decrease the operational frequency f.sub.op of the AC power source until there is plasma ignition, and c) after the plasma ignition, further decrease the operational frequency f.sub.op of the AC power source to a frequency lower than the resonant frequency f.sub.r.

The impedance of an antenna is reduced and gaps generated between electrodes constituting a capacitance element and a dielectric body are eliminated. An antenna (3) for generating inductively coupled plasma P includes at least two conductor elements (31), an insulation element (32) that is arranged between the mutually adjacent conductor elements (31) and insulates the conductor elements (31), and a capacitance element (33) that is connected electrically to and in series with the mutually adjacent conductor elements (31). The capacitance element (33) is configured from a first electrode (33A) electrically connected to one of the mutually adjacent conductor elements (21), a second electrode (33B) electrically connected to the other of the mutually adjacent conductor elements (21), and a liquid dielectric body filling the space between the first electrode (33A) and the second electrode (33B).