The assembly includes a source 24 of {HEAD ~ one or more solid materials} such as silicon, germanium and carbon within {TAIL ~ the chamber} 14 
The assembly includes a source 24 of { HEAD ~ one or more solid materials } such as silicon , germanium and carbon within { TAIL ~ the chamber } 14
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH