A solid material or {HEAD ~ combination} of materials is evaporated in {TAIL ~ the chamber} to form vapor 
is evaporated in
A solid material or { HEAD ~ combination } of materials is evaporated in { TAIL ~ the chamber } to form vapor
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH