Patent ID: 8240169

Claim:
A vitreous silica crucible manufacturing apparatus, comprising: a plurality of carbon electrodes configured to heat and melt raw material powder by arc discharge, wherein a value of a ratio R 2 /R 1 of a diameter R 2 of a front end of each of the carbon electrodes to a diameter R 1 of a base end thereof is set in a range of 0.6 to 0.8, a flat surface which is approximately perpendicular to an axis line is formed on the front end of each of the carbon electrodes, each of the carbon electrodes have a diameter reduction portion formed at a front end position and reduced in diameter from a diameter R 3 of a base end side to the diameter R 2 of the front end, and a length L 1 of the diameter reduction portion, the diameter R 2 of the front end, and the diameter R 1 of the base end are set such that a value of L 1 −(X/tan(θ 1 /2)) is set in a range of 50 to 150 mm when an angle between the axis lines of the carbon electrodes is θ 1 and X=(R 1 −R 2 )/2.