{TAIL ~ A flange member} is provided on {HEAD ~ an outer wall} of the vacuum chamber to cover an opening in the wall 
{ TAIL ~ A flange member } is provided on { HEAD ~ an outer wall } of the vacuum chamber to cover an opening in the wall
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH