Abstract: A radio frequency variable inductor with a high ratio of inductance variation to minimum inductance is provided by combining both conductive elements and ferromagnetic elements in an inductance variation assembly, which is rotatably mounted inside a coil. This variable inductor is combined with fixed capacitors and a variable transformer using a rotatable primary coil to provide a complete radio frequency match system.

Abstract: A handheld device for sensing and indicating the location of a blood vessel, and marking the skin adjacent to the blood vessel. The operation of the device is based on determining the difference in signal transfer amplitude between two partially overlapping infrared light paths, and moving the device until this difference is zeroed. The sensitivity of the device is enhanced by having an angle in each infrared light path such that the infrared light is primarily reflected, rather than absorbed, by the blood vessel.

Abstract: A plasma etching system includes a radio frequency generator and a parallel plate plasma reactor vessel. A phase inverter circuit is used to couple the RF generator to the electrodes in the plasma reactor so that the electrodes are driven with voltages of substantially equal magnitude but which are 180.degree. out-of-phase. In this way, a maximum potential difference between the electrodes can be achieved while minimizing the potential difference between the individual electrodes and the reactor vessel. Such operation allows higher power levels with reduced occurrence of arcing and stray discharge, and provides a stable, uniform plasma discharge.