Problem pquest SNF 2008-04-08 13:09:03: low DC bias

koseki at koseki at
Tue Apr 8 13:09:03 PDT 2008

The DC voltage is low today, and the plasma is dark.
Also, the chamber pressure is way too high, as well as
it is difficult to obtain the impedance matching.
Previous user (mitsuru1) also told me that he got the
dark plasma.
Would you, anyone who knows the machine well, please
improve the situation ? Thank you...
With my Ar/Cl2 recipe (koseki.rcp, initially copied 
from davegaas.rcp)
Yesterday (operated normally)
RF: set 200/ forward 202.9/ reflected 0.4
microwave: set 40/ forward 45/ reflected 1
DC bias: -59.6
pressure: 3.8mtorr
stub: 975/900/50
Today (operating strangely)
RF: set 200/ forward 202.9/ reflected 9.9
microwave: set 40/ forward 46/ reflected 2
DC bias: -27.8
pressure: 94.2mtorr
stub: 1385/1330/1440

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