Systems and methods for adjusting power and frequency based on three or more states are described. One of the methods includes receiving a pulsed signal having multiple states. The pulsed signal is received by multiple radio frequency (RF) generators. When the pulsed signal having a first state is received, an RF signal having a pre-set power level is generated by a first RF generator and an RF signal having a pre-set power level is generated by a second RF generator. Moreover, when the pulsed signal having a second state is received, RF signals having pre-set power levels are generated by the first and second RF generators. Furthermore, when the pulsed signal having a third state is received, RF signals having pre-set power levels are generated by the first and second RF generators.

A plasma generating device utilizes a cold plasma to contain and direct a stream of electrons with a hand held nozzle to enhance healing of wounds and skin surface abnormalities, and to kill pathogens on skin surfaces in humans and animals wounds, abnormalities and pathogens.

A matching network for a system having a non-linear load and powered by a first RF power supply operating at a first frequency and a second RF power supply operating at a second frequency. The matching network includes a first matching network section for providing an impedance match between the first power supply and the load. The matching network also includes a second matching network section for providing an impedance match between the second power supply and the load. A the first matching network section includes a first variable reactance, and the variable reactance is controlled in accordance with IMD sensed in the signal applied to the load by the first RF power supply. The variable reactance is adjusted in accordance with the IMD to reduce the detected IMD.

In a plasma processing apparatus of an exemplary embodiment, a radio frequency power source generates radio frequency power for plasma generation. A bias power source periodically applies a pulsed negative direct-current voltage to a lower electrode to draw ions into a substrate support. The radio frequency power source supplies the radio frequency power as one or more pulses in a period in which the pulsed negative direct-current voltage is not applied to the lower electrode. The radio frequency power source stops supply of the radio frequency power in a period in which the pulsed negative direct-current voltage is applied to the lower electrode. Each of the one or more pulses has a power level that gradually increases from a point in time of start thereof to a point in time when a peak thereof appears.

A plasma control system comprises: a high frequency power source; a first antenna connected at one end to the high frequency power source; a second antenna connected at one end to another end of the first antenna; a first variable reactance element provided between the first antenna and the second antenna; a first drive part for the first variable reactance element; a second variable reactance element connected to another end of the second antenna; a second drive part for the second variable reactance element; a first current detection part detecting the current in the one end of the first antenna; a second current detection part detecting the current between the first antenna and the second antenna; a third current detection part detecting the current in the other end of the second antenna; and a control device controlling the first drive part and the second drive part.

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.

Disclosed is an amplifier circuit for providing an output of at least 100 W, preferably of at least 200 W and most preferably of at least 250 W comprising a field effect transistor. A drain of the field effect transistor is connected with a protective feedback circuit. The protective feedback circuit is arranged to reduce an over-voltage energy at the drain of the field effect transistor if the voltage between the gate and a drain of the field effect transistor exceeds a feedback threshold voltage. Further disclosed is a radio frequency amplifier comprising an amplifier circuit, an electrical radio frequency generator comprising the radio frequency amplifier and a plasma processing system comprising an electrical radio frequency generator. Still further disclosed is a method of protecting a field effect transistor in an amplifier circuit.

A ballast transformer and system using the ballast transformer to couple power to a plasma load. The ballast transformer has a magnetic core, a first primary winding on a primary side of the magnetic core, a secondary winding on a secondary side of the magnetic core, and a second primary winding connected in series with the first primary winding and wound in proximity to the secondary winding on the secondary side of the magnetic core. The first primary winding is connectable to the AC power source, and the secondary winding is connectable to the plasma load via a coaxial cable.

A ballast transformer and system using the ballast transformer to couple power to a plasma load. The ballast transformer has a magnetic core, a first primary winding on a primary side of the magnetic core, a secondary winding on a secondary side of the magnetic core, and a second primary winding connected in series with the first primary winding and wound in proximity to the secondary winding on the secondary side of the magnetic core. The first primary winding is connectable to the AC power source, and the secondary winding is connectable to the plasma load via a coaxial cable.

A matching network for a system having a non-linear load and powered by a first RF power supply operating at a first frequency and a second RF power supply operating at a second frequency. The matching network includes a first matching network section for providing an impedance match between the first power supply and the load. The matching network also includes a second matching network section for providing an impedance match between the second power supply and the load. A the first matching network section includes a first variable reactance, and the variable reactance is controlled in accordance with IMD sensed in the signal applied to the load by the first RF power supply. The variable reactance is adjusted in accordance with the IMD to reduce the detected IMD.