Hi Huisheng, It sounds like  you have  a leak in the chamber at room temp
and the pink colour of an N2 plasma is adding  to the blue of the Ar? you
are using to sputter. What is the leak up rate at room temperature?
Ian Burnett

----- Original Message -----
From: "Huisheng JIAO" 
To: 
Sent: Monday, July 10, 2006 9:48 AM
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,
> Huisheng JIAO
>
>