Measurements have been made of the striation formation time of
an
α-type RF
discharge in nitrogen as a function of pressure, RF frequency, electrode
separation
and input power. A theoretical model is proposed that yields electron energy
and
density and striation formation time, given the measured discharge parameters
of
interelectrode voltage and separation, gas pressure and RF frequency. It
is found
that increasing the pressure and the electrode separation increase the
striation
formation time, while increasing the power and the RF frequency decrease
the
striation formation time. The model predicts that striations in the RF
discharge
are formed when the plasma charge density reaches some critical value at
which
the space charge distorts the interelectrode field.