Abstract
In this study, we investigated how a thermally actuated air bearing slider heats up a fast-spinning storage disk through a highly pressurized nanoscale air gap in a magnetic recording system. A Eulerian-description-based computational approach is developed considering heat conduction through a pressurized air film and near-field radiation across the gap. A set of field equations that govern the air bearing dynamics, slider thermo-mechanics and disk heat dissipation are solved simultaneously through an iterative approach. A temperature field on the same order as the hot slider surface itself is found to be established in the disk. The effective local heat transfer coefficient is found to vary substantially with disk materials and linear speeds. This approach quantifies the magnitude of different thermal transport schemes and the accuracy is verified by an excellent agreement with our experiment, which measures the local slider temperature rise with a resistance temperature sensor. It also demonstrates an effective computational approach to treat transient thermal processes in a system of components with fast relative speed and different length scales. Finally, the investigated thermal transport mechanism leads to a substantial spacing change that has a significant impact on the spacing margin of today’s magnetic storage systems.
Highlights
Heat transfer across a nanoscale gap is of fundamental importance in thermal management of micro and nanoscale devices
The disk is in general considered as an ideal heat sink[12,13,14] due to its much larger size compared to the slider and its high spinning speed, quickly bringing fresh surfaces below the slider
One particular difficulty is that the spinning disk heats up as it moves underneath the slider and cools off as it moves out of the slider-covered area, making this a transient process that is difficult to fit into the widely-adopted steady-state approach
Summary
At ~1 nm gap size, h due to near field radiation reaches the order of 1 × 106 W/m2/K, a magnitude comparable to h due to air film conduction This change deforms the contour shape in Fig. 3(b): as d further reduces below 1 nm, the pressure becomes almost irrelevant and the gap size dominates, indicating the radiative flow overwhelms the conduction flow. Compared to h, the value of he incorporates the impact from the air film interface, and the effects arising from the disk side, including disk materials, configuration and linear speeds
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