Patent ID: 8597756

Claim:
A method of manufacturing a resistance heated sapphire single crystal ingot, the method comprising: charging polycrystalline alumina into a crucible included in a chamber; heating the crucible by a resistance heating heater to make the polycrystalline alumina as an alumina melt; a cusp magnet applying a magnetic field to the alumina melt in the crucible; contacting a seed crystal with an upper portion of the molten alumina; growing a sapphire single crystal ingot from the seed crystal; and separating the grown ingot from the molten alumina, wherein a zero gauss plane is lowered and a Lorentz force of a seed rotation cell (SR-cell) is increased by adjusting a ratio of currents applied to an upper coil and a lower coil of the cusp magnet in a range of about 1:0.5 to about 1:2.