A method and apparatus for launching microwave energy to a plasma processing chamber in which the required magnetic field is generated by a permanent magnet structure and the permanent magnet material effectively comprises one or more surfaces of the waveguide structure. The waveguide structure functions as an impedance matching device and controls the field pattern of the launched microwave field to create a uniform plasma. The waveguide launcher may comprise a rectangular waveguide, a circular waveguide, or a coaxial waveguide with permanent magnet material forming the sidewalls of the guide and a magnetization pattern which produces the required microwave electron cyclotron resonance magnetic field, a uniform field absorption pattern, and a rapid decay of the fields away from the resonance zone. In addition, the incorporation of permanent magnet material as a portion of the waveguide structure places the magnetic material in close proximity to the vacuum chamber, allowing for a precisely controlled magnetic field configuration, and a reduction of the amount of permanent magnet material required.

The invention is directed to a frequency selective limiter. A ferrite member supports a signal carrying conductor and magnets establish a transverse magnetic field closely coupled with the conductor through the ferrite. The magnets establish a magnetic field strength versus temperature having a desired characteristic slope. A magnetic shunt, magnetically coupled to the magnets, diverts a portion of the magnetic field lines away from the ferrite for reducing the magnitude of the field coupled with the conductor to a lower value while maintaining the desired characteristic slope of the magnetic field strength with temperature. In a particular embodiment of the invention, the magnetic shunt establishes magnetic field lines within the ferrite which lie at a selected angle with respect to the conductor so that the limiting characteristic of the FSL is relatively flat across the bandwidth.

A flux drive gyromagnetic system such as a gyromagnetic waveguide phase shifter is temperature compensated by measuring the flux change in the gyromagnetic material during a reverse in saturation magnetization, comparing that change to the change under reference conditions and modifying the drive used to set the gyromagnetic material to a non-saturated condition in accordance with the results of the comparison.

A cascade combination of magnetostatic delay line elements operating in different signal propagation modes for the purpose of achieving dispersion cancellation; magnetic bias control of the attained frequency-dependent delay and a magnetic bias field establishing apparatus for providing the tubular, laminar magnetic flux needed for backward volume wave operation of a magnetostatic delay element are also included.

The present invention is for an apparatus and method of fast-switching a dual-toroid microwave ferrite phase shifter. A first circuit is provided for controllably switching the ferrite in one of the toroids between a saturated and partially saturated states. A second conduit is provided for controllably switching the ferrite in the other of the toroids between a saturated and partially saturated states. A control circuit is provided for controlling the first and second circuits such that the ferrite in at least one of the toroids is maintained in the saturated state at any given time such that any desired phase shift may be achieved with only one switching operation for each toroid. The present invention provides new reference states such that there are two reciprocal phase states for any given phase state such that a reciprocal phase state may always be achieved with only one switching operation for each toroid.