An apparatus includes a radiation source that emits a radiation beam that causes substantially all of a quantity of material to evaporate; and structure having first and second surface portions, a first operational mode wherein a greater quantity of a byproduct of the evaporation impinges on the first surface portion, and a second operational mode wherein a greater quantity of the byproduct impinges on the second surface portion. A different aspect involves emitting a radiation beam toward a quantity of material, the radiation beam causing substantially all of the quantity of material to evaporate; operating a structure having first and second surface portions in a first operational mode wherein a greater quantity of a byproduct of the evaporation impinges on the first surface portion; and thereafter operating the structure in a second operational mode wherein a greater quantity of the byproduct impinges on the second surface portion.