Method for manufacturing quartz glass crucible

A method of producing a silica glass crucible, in which silica powder is melted by arc discharge and a silica glass crucible is formed in a rotating mold, comprising the steps of:

• forming an accumulated layer of the silica powder on an inner surface of the mold;
• supplying helium and/or hydrogen gas to the accumulated layer at predetermined positions located in sidewalls and a bottom portion of the mold;
• starting arc discharge, after supplying helium and/or hydrogen gas to the accumulated layer for a predetermined time;
• stopping supply of helium and/or hydrogen gas and degassing the accumulated layer, when a thin film-like melting layer has been formed on the surface of the accumulated layer;
• and
• starting again supply of helium and/or hydrogen gas when the accumulated layer has reached a predetermined vacuum state.

A method of producing a silica glass crucible, in which silica powder is melted by arc discharge and a silica glass crucible is formed in a rotating mold, comprising the steps of:

• forming an accumulated layer of the silica powder on an inner surface of the mold;
• putting a cover on the upper opening portion of the mold when the accumulated layer has been formed and degassing the inside of the mold;
• supplying helium and/or hydrogen gas to the inside of the mold when the inside of the mold has reached a predetermined vacuum state;
• and
• removing the cover and starting arc discharge, after a pressure inside the mold has risen to a predetermined value,
• wherein, after removing the cover, supply of helium and/or hydrogen gas is continued for a predetermined time.

A method of producing a silica glass crucible, in which silica powder is melted by arc discharge and a silica glass crucible is formed in a rotating mold, comprising the steps of:

• forming an accumulated layer of the silica powder on an inner surface of the mold;
• supplying helium and/or hydrogen gas to the accumulated layer through predetermined positions located in a sidewall and a bottom portion of the mold;
• starting arc discharge, after supplying helium and/or hydrogen gas to the accumulated layer for a predetermined time;
• continuing supply of helium and/or degassing the accumulated layer through upper portions of the sidewall of the mold, when a thin film-like melting layer has been formed on the surface of the accumulated layer.

A method of producing a silica glass crucible, in which silica powder is melted by arc discharge and a silica glass crucible is formed in a rotating mold, comprising the steps of:

• forming an accumulated layer of the silica powder on an inner surface of the mold;
• putting a cover on the upper opening portion of the mold when the accumulated layer has been formed and degassing the inside of the mold;
• supplying helium and/or hydrogen gas to the inside of the mold through predetermined positions located in sidewalls and a bottom portion of the mold, when the inside of the mold has reached a predetermined vacuum state;
• and
• removing the cover and starting arc discharge, after a pressure inside the mold has risen to a predetermined value,
• wherein, supplying of helium and/or hydrogen gas is continued and the accumulated layer is degassed at upper portions of the sidewall of the mold, when a thin film-like melting layer has been formed on the surface of the accumulated layer.