Karthik,
        Plasma is simply electrically conductive gas.  As soon as the
gas becomes conductive it starts to absorb electrical energy and then
delivers this energy to a remote locale.  Simplest example is the
fluorescent light, a high voltage source cracks the gas then 110 volts
60 H/z keeps the current flowing.  The gas molecule becomes a gas ion, a
molecule less one or more electrons, and electrons.  Both absorb energy,
the ion vibrates, becomes physically hot and bombards the walls of the
fluorescent tube.  If you coat the tube with a fluoresecent substance it
fluoresces and you get more efficient light.  Common methods of cracking
gas to create an industrial plasma are;- 1) Inductive usually 13.54 MH/z
a coil wrapped round a tube with low pressure gas in the tube.  This
acts like a transformer coupling energy to the inside of the tube. If
the gas is the correct pressure it cracks and starts to absorb energy
and glow.  Capacitively coupled usually 40 to 50 KH/z flat metal
capacitors with about 500 volts between the plates.  Same deal low
pressure crack the gas absorb energy liberate it later as an etching
operation.  Microwave 2.54 MH/z low pressure, beam in microwave, crack
gas, absorb microwave energy.  Lightning 100,000 volt atmospheric gas
cracker.  Aurora Borealis, northern lights low pressure high in the
atmosphere.  At the poles where the earths magnetic field is strongest.
The magnetic field flowing through low pressure moist gas creates
electrical energy cracks gas lots of different gasses lots of different
spectra.
  Hope this is sufficient.  Bill Moffat