The effect found in the iPad Album application that let you gather many pictures use the same behavior as the pinch gesture (zoom) but without rescaling images.
On the grounds of the pinch-off voltage, the cut-off point of variable resistance area and saturation area can be fixed, so the field effect tube can reliably work in the saturation area.
根据夹断电压能确定可变电阻区与饱和区的分界点，使场效应管可靠地工作在饱和区的原理。
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The pinch-effect will occur in plasma column because magnetic field pressure outside is bigger than thermal pressure inside of the plasma column carrying electric current.