Huisheng JIAO,

The plasma will stay the same color for the same gas over a realistic
temperature range for sputtering (20 - 800 degrees C).  If you see
the plasma change color, you are changing the gas chemistry.  This
may be from air leaks in your system as a result of the change in
temperature (portions of the chamber being at liquid nitrogen
temperature and others at room temperature or hotter) or from some of
the liquid nitrogen leaking into your system.

Paul

At 04:48 AM 7/10/2006, you wrote:
>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?
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Paul Sunal, PhD
Senior MEMS Engineer

MEMS and Nanotechnology Exchange / CNRI
1895 Preston White Drive
Suite #100
Reston, VA  20191

Tel: 703.262.5323
Fax: 703.262.5367
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