Thermal protrusion of thermally assisted magnetic recording for binary gas mixture with temperature

Thermally assisted magnetic recording (TAMR) system is the most promising next generation magnetic recording technology. In the system, it is important to accurately predict thermal protrusion at near filed transducer (NFT). In this paper, we first constructed an iterative coupled-field analysis process and derived modified heat transfer equation with temperature using diffusion-based effective molecular diameter of gas mixture. Using the simulation process, the thermal protrusion of TAMR head was investigated for various temperature and helium fraction ratios. From the simulation results, the thermal protrusion occurred bigger in low temperature and low helium fraction ratio. And the thermal protrusion of TAMR head with laser diode (LD) was obtained from 3 nm to 1 nm.