This paper describes characteristics of discharge for the plasma gener
ator in electrothermal-chemical(ETC) launchers by means of both experi
ments and numerical simulations. The dependence of plasma properties o
n the pulse forming network(PFN) and especially, on the capillary size
has been investigated, It has been concluded that there is an optimiz
ed design of plasma generator when the caliber of ETC launcher and the
initial energy stored in PFN are given.