Crystal pulling systems having a cover member for covering the silicon charge and methods for growing a melt of silicon in a crucible assembly

A crystal pulling system for growing a monocrystalline ingot from a silicon melt, the system having a pull axis and comprising:

• a housing defining a growth chamber;
• a crucible assembly disposed within the growth chamber for containing the silicon melt, the crucible assembly comprising a bottom and an outer sidewall that extends from the bottom;
• a heat shield that defines a central passage through which the monocrystalline ingot passes during ingot growth;
• and
• a cover member that is moveable within the heat shield along the pull axis, the cover member comprising:
• a first plate having a first plate axis that is parallel to the pull axis, the first plate comprising a hub, the hub having a hub opening;
• a second plate having a second plate axis that is parallel to the pull axis, the second plate being disposed above the first plate;
• one or more insulation layers disposed between the first plate and the second plate, the one or more insulation layers being made of felt, wherein the felt contacts the first plate and the felt contacts the second plate;
• and
• a shaft having an elongated portion and a collar, the collar being connected to and extending radially outward from the elongated portion, the shaft extending through the hub opening, the first plate resting on the collar.