5 ms·

Why helium? I know it's inert but there are many other noble gases. Why not some other gas? Also, why not create a vacuum to minimize friction?

• dom0 10y ago
  Vacuum = requires special lubricants or no lubricants at all, since they would dissipate due to the lowered vapour pressure. Lubricant everywhere would likely be problematic. It's also harder to seal in, and would likely require a much more rigid construction to avoid warping of the drive (these are precision devices after all). Lastly, the hovering of the R/W heads over the platters requires an atmosphere - they are lifted by the air/gas accelerated by the platters (this is a well defined lift force and self-regulates the head height relative to the platter).
• SamReidHughes 10y ago
  The drive heads float on air, which is why vacuum doesn't work, and the benefit of helium is that it's light -- not that it's inert.
• jlubawy 10y ago
  "The density of helium is one-seventh that of air, which reduces drag force acting on the spinning disk stack and lowers fluid flow forces affecting the disks and the heads, allowing for platters to be thinner and a larger number to be packed more densely." [0] [0] http://www.anandtech.com/show/10106/western-digital-introduces-its-consumer-helium-drives http://www.anandtech.com/show/10106/western-digital-introduc...
• ridgeguy 10y ago
  In addition to its lower drag, it has higher thermal conductivity than air. Reduces certain heat effects.