Plasma etch processes incorporating etch chemistries which include hydrogen. The mapping unit associates the transmitted data with subcarriers different from predefined multiple subcarriers arranged at even intervals on a frequency axis. The detection is performed by differentiating the axial wind velocity and filtering for a period of time. The output channel is adjacent the input channel. In a first embodiment the second pole piece structure is a single layer and in a second embodiment the second pole piece structure has front and back components with a flat laminated second pole piece yoke layer located therebetween. During an inflation process of the bag, the guide cloth guides the bag so that the bag is inflated upward smoothly without entering a space below the seat spring.