Investigation of slider dynamics under electro-static force

With the continual increase in the areal density of hard disk drives, the head/disk interface engineers are continuously challenged in designing an interface with a lower mechanical clearance between the slider and disk. Although, this has traditionally been achieved by making the disk smoother, some novel ideas have been discussed, where the slider generally flies high, and when necessary, a part of the slider is moved closer to the disk surface. Another method that has been discussed is applying a voltage across the slider and disk to bring the whole slider closer to the disk. However, rapid application of voltages across the interface may lead to undesirable slider oscillations. In this paper, we study the dynamics of the slider when a voltage is applied across the slider and disk. We show that one can easily excite the air-bearing frequency and if the voltage is not well controlled, the slider may also damage the disk. We also identify,the most probable mechanisms of current flow and show that the disk lubricant plays a critical role in initiating current flow.