"Helium-filled drives are projected to create new opportunities for the HDD industry by increasing drive capacity before next-generation technologies, like heat-assisted magnetic recording, become available.
Current drives using perpendicular magnetic recording technology support up to 4TB in capacity. Helium can extend that to 5TB or even 6TB. The weight or thickness of current HDD products can also be reduced by approximately 30% by stacking platters closer together.
The magic element here is helium, which is lighter than air and has a lower molecular weight. Given its nonreactive nature and lower density, helium is thought to improve the speed of the HDD tracking arm, enhance drive performance through faster spinning of the drive, and eliminate mechanical issues like noise, vibration and turbulence. A better conductor of heat than air, helium also helps produce a more uniform temperature on the platter to raise quality, and protects the coating of the hard disk head and disk to lengthen the life of the drive."