Hello Huisheng,

   I used for a long time a sputtering system in which the plasma turned
from blue color to purple color depending on the shutter being floating
or at ground potential. The gas was Ar and the pressure 7e-3mbar. The
system had no gas leak, so may be your situation depends also on the
electrical connections inside your chamber.

Best regards,

Javier


Huisheng JIAO escribió:

> Dear Ian, thank you very much for your reply.
> I am using Ar gas and gold target. so could you tell me, if there is no
> leak, the plasma should be in blue? whatever in low temperature or at
> room
> temperature? if I see the purple plasma at room temperature, that means I
> got N2 leaks into my chamber?

________________________________________________________________________________
___________

Dr. Javier Sesé
Investigador del programa Ramón y Cajal
INA - Instituto Universitario de Investigación en Nanociencia de
Aragón (Interfacultades II)
Universidad de Zaragoza
C/ Pedro Cerbuna 12
50009 Zaragoza, SPAIN
tel.: + 34 976 762783
fax: + 34 976 762776