In the case of PJ-2, we could produce higher density plasma jet compared with that in the case of PJ-1, because
we could apply higher voltage and current in the case of PJ-2 under lower gas temperature, such as 38 -C. Such lower
temperature in the PJ-2 was realized due to strong gas flow from one exit of the inner pipe differently from the case of
PJ-1, where gas flow through each hole in the inner pipe was weak because of several gas through-holes.