the first trap unit further includes a collection unit for collecting {HEAD ~ the debris} molten on {TAIL ~ the surface} of the first trap unit 
molten on
the first trap unit further includes a collection unit for collecting { HEAD ~ the debris } molten on { TAIL ~ the surface } of the first trap unit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH