Production method for glass preform and production apparatus for glass preform

A production method for a glass preform in a production apparatus,

• the production apparatus including:
• a main chamber configured to produce the glass preform in a state where a glass fine particle deposit is accommodated in the main chamber;
• and
• a preliminary chamber communicating with the main chamber, the preliminary chamber being formed such that the glass fine particle deposit and the glass preform are allowed to be put in and taken out,
• wherein a furnace core tube is accommodated inside the main chamber, the furnace core tube being configured to produce the glass preform in a state where the glass fine particle deposit is accommodated in the furnace core tube,
• the production method comprising:
• a production step of producing the glass preform by consolidating the glass fine particle deposit in the furnace core tube while introducing corrosive gas into the furnace core tube;
• a gas introduction step of introducing gas into the preliminary chamber after the production step;
• and
• a gas discharge step of discharging gas from at least one of the preliminary chamber and the main chamber after the production step,
• wherein the gas introduction step is started before end of the gas discharge step.