Hi All,

We have also recently observed something similar in our experiments. We produced
air plasma in parallel plate config. using two different power source in two
seperate but identical reactors. In one reactor we used 40 KHz AC and in other
we used 13.56 MHz RF. keeping all other parameters same.

In result, 40 KHz reactor gave purple color plasma and 13.56 MHz gave pink color
plasma. Here power, pressure and all other cong. except source is same.

what can be the reason of this ? 13.56 MHz plasma is Nitrogen excitation
dominated and 40 KHz some other ? can anyone please through some light on this ?

Thanks & Regards;
Ms. Purvi Kikani Dave (M.Sc. Physics)
Facilitation Center for Industrial Plasma Technologies (FCIPT)
Institute for Plasma Research (IPR)
Department of Atomic Energy,
 Government of India
Gandhinagar, Gujarat,
India Phone # +91 079 23269014(O), +91 9979704390 (M)
Alternate email: [email protected], [email protected]

--- On Thu, 9/9/10, Birol Kuyel  wrote:

From: Birol Kuyel 
Subject: Re: [mems-talk] Argon plasma color
To: "'General MEMS discussion'" 
Date: Thursday, 9 September, 2010, 12:04 AM

Dear Debashish,

At higher energy Ar Plasma color goes to purple to blue: (email me directly
at [email protected]) to see two pictures on
the bottom of the WG where one plate is in Ar plasma the second one is in
the same plasma with -1000V bias.

On the other hand, in sputtering, plasma in front of the magnetron changes
color with the material being sputtered as well; for example Cu would make
the plasma color Green.

Power and pressure relates to brightness of the color (plasma density) but
if you further increase or lower the pressure you would lose the plasma
altogether.

Regards,

Birol Kuyel, Ph.D.
Nano-Master Inc.