Static Flying Characteristics of Heat-Assisted Magnetic Recording Heads in He-Enclosed HDDs

As new magnetic recording techniques, thermal fly height control and heat-assisted magnetic recording have been proposed to increase the recording density of hard disk drives (HDDs). In addition, He-enclosed HDDs can significantly reduce windage loss, disk flutter, and temperature rise, since He has a lower density and higher heat conductivity than air. In this paper, the static lubrication characteristics of a step slider flying in either air or He over a running boundary wall with local temperature distributions are analyzed using the thermo-molecular gas-film lubrication equation. The decreases in minimum spacing for the slider flying in He are significant, because the mean free path of He is approximately three times that of air. The increases in minimum spacing due to laser heating are negligibly small in both air and He, because the heat spot size is very small. In addition, the van der Waals attractive pressure for spacings of less than 10 nm causes the minimum spacing to decrease.