Additive manufacturing system with gas flow head

An additive manufacturing system comprising:

• a build surface;
• one or more laser energy sources;
• an optics assembly movable relative to the build surface and configured to direct laser energy from the one or more laser energy sources toward the build surface, wherein exposure of a layer of material on the build surface to the laser energy melts at least a portion of the layer of material;
• and
• a gas flow head coupled to the optics assembly and defining a partially enclosed volume between the optics assembly and the build surface, the gas flow head comprising:
• a gas inflow through which a supply gas flows into the gas flow head during operation of the gas flow head,
• a gas outflow through which a return gas flows out of the gas flow head during operation of the gas flow head, and
• an aperture arranged to permit transmission of the laser energy through the gas flow head to the build surface, wherein the supply gas and return gas define a gas flow profile within the gas flow head during operation of the gas flow head;
• wherein a first flow rate of the supply gas into the gas flow head is less than a second flow rate of the return gas out of the gas flow head during operation of the gas flow head, and a difference between the first flow rate and the second flow rate causes a scavenge gas to flow into the gas flow head.