Apple's New Manufacturing Partner, GT Advanced, Uses Particle Accelerator to Cut Sapphire Glass Production Costs: "A particle accelerator bombards these wafers with hydrogen ions, and with exacting control of the voltage of the accelerator, the hydrogen ions accumulate precisely 20 micrometers from the surface of each wafer. A robotic arm then transports the wafers to a furnace where the ions expand into hydrogen gas, which cause the 20-micrometer-thick layer to shear off."