An additive manufacturing apparatus comprising: at least a first beam source configured to emit at least a first beam, at least a second beam source configured to emit at least a second beam, and a process chamber housing, wherein the process chamber housing comprises a process chamber, wherein the process chamber has at least: - a bottom, a ceiling and side walls (11, 12, 13), jointly enclosing a volume of the process chamber, - an inert gas inlet configured to provide an inert gas into the process chamber, - an inert gas outlet configured to release the inert gas out of the process chamber, wherein the bottom has an opening, being delimited by opening walls and a vertically movable support for supporting a powder bed and a three dimensional object located in between of the opening walls, and wherein the gas inlet is configured to provide a light inert gas, having a density of less than 1,4 kg/m 3, into the process chamber, characterized in that the additive manufacturing apparatus further comprises a process chamber controlling device configured to control the additive manufacturing apparatus to execute the step of fusing at least - a first location of the powder bed using the first beam, thereby generating a first smoke plume, and - a second location of the powder bed using the second beam, thereby generating a second smoke plume, wherein the first location is closer to the inert gas inlet than the second location and the second location is closer to the inert gas outlet than the first location, while the at least one second beam is controlled to fuse the second location of the powder bed being covered by the first smoke plume being generated by fusing the first location of the powder bed with the at least one first beam, and in that the inert gas inlet and the inert gas outlet are configured to remove the smoke plumes (82, 92) from the process chamber by a main inert gas flow, wherein the main inert gas flow is established by an inert gas comprising at least 20% of He and/or Ne. at least a first beam source configured to emit at least a first beam, at least a second beam source configured to emit at least a second beam, and a process chamber housing, wherein the process chamber housing comprises a process chamber, wherein the process chamber has at least: - a bottom, a ceiling and side walls (11, 12, 13), jointly enclosing a volume of the process chamber, - an inert gas inlet configured to provide an inert gas into the process chamber, - an inert gas outlet configured to release the inert gas out of the process chamber, - a bottom, a ceiling and side walls (11, 12, 13), jointly enclosing a volume of the process chamber, - an inert gas inlet configured to provide an inert gas into the process chamber, - an inert gas outlet configured to release the inert gas out of the process chamber, wherein the bottom has an opening, being delimited by opening walls and a vertically movable support for supporting a powder bed and a three dimensional object located in between of the opening walls, and wherein the gas inlet is configured to provide a light inert gas, having a density of less than 1,4 kg/m 3, into the process chamber, characterized in that the additive manufacturing apparatus further comprises a process chamber controlling device configured to control the additive manufacturing apparatus to execute the step of fusing at least - a first location of the powder bed using the first beam, thereby generating a first smoke plume, and - a second location of the powder bed using the second beam, thereby generating a second smoke plume, - a first location of the powder bed using the first beam, thereby generating a first smoke plume, and - a second location of the powder bed using the second beam, thereby generating a second smoke plume, wherein the first location is closer to the inert gas inlet than the second location and the second location is closer to the inert gas outlet than the first location, while the at least one second beam is controlled to fuse the second location of the powder bed being covered by the first smoke plume being generated by fusing the first location of the powder bed with the at least one first beam, and in that the inert gas inlet and the inert gas outlet are configured to remove the smoke plumes (82, 92) from the process chamber by a main inert gas flow, wherein the main inert gas flow is established by an inert gas comprising at least 20% of He and/or Ne.