The next step is pumping down the plasma cleaning chamber interior region down to a pre determined pressure, with {HEAD ~ hydrogen} as {TAIL ~ the ambient gas} 
The next step is pumping down the plasma cleaning chamber interior region down to a pre determined pressure , with { HEAD ~ hydrogen } as { TAIL ~ the ambient gas }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL