This might be related with the pressure inside of the chamber. Can you
observe it? The blue colored plasma is usually associated with the lower
pressure.

Darius

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Huisheng JIAO
Sent: Monday, July 10, 2006 11:48 AM
To: [email protected]
Subject: [mems-talk] Plasma colour

Dear All:

Anybody can advise me the relationship between the colour of plasma and the
temperature of the vacuum chamber? When sputtering at room temperature, the
plsama shows purple colour; but when the chamber cooled by liquid nitrogen,
plasma changes to bule colour. what is the reason? Thanks in advance,