Different tools and techniques can be employed to characterize
the discharge plasmas but multi-tip Langmuir probes are considered
to be the most powerful and experimentally the simplest technique
for plasma characterization over a wide range of plasma densities
because they did not require the assumption that plasmas to be
in local thermodynamic equilibrium. Irvin Langmuir was the first
who measured the volt-ampere characteristics by inserting a single
conducting wire into plasma and then using it, he determined the
electron temperature and plasma density . This simple device now
a days commonly used in plasma measurements, called the single
Langmuir probe (SLP). The SLPs have some major drawbacks which
are difficult to overcome particularly when the reference electrode is
absent or when the plasma potential is not well dened. Moreover,
unless the probe area is suffcient small, it may draw large electronic
current by disturbing the discharge conditions when operated close to
the space potential which shows that the single probe method is not suitable for decaying plasmas accompanied by the perturbation of the
discharge plasmas. In order to overcome these difficulties introduced
by the SLP method, the double and triple Langmuir probe methods
are developed which have negligible influence on the discharges and
yield an accurate data for the measurement of plasma parameters in
all types of discharge plasmas .