where V0 is the charge voltage, R is the ballast resistance,
and C is the stray capacitance of the electrode system. With
the time constant of 14 ms obtained from Fig. 2, the stray
capacitance is determined to be about 14 pF. In this case, the
discharge is an arc, however, the amount of plasma is not
sufficient for generating a long plasma torch. Therefore, a
low ballast resistance (20 k) is adopted in order to generate
a strong arc discharge between the electrodes. Consequently,
a high amount of plasma can be produced.