An experimental study of the plasma effect on the structure of an attached
conical shock front appearing at the front end of a cone-shaped model has b
een carried out in a Mach 2.5 stream. The tip and the body of the model are
designed as the cathode and anode, which are separated by a conical-shaped
ceramic insulator providing a 5 mm gap for gaseous discharge. The electric
field intensity near the cathode is enhanced by the sharpness of the tip.
The experimental results show that the diffused discharge can produce plasm
a distributed symmetrically around the tip in the region in front of the sh
ock wave. It is observed that such plasma can cause shock wave moving upstr
eam with its shock front detached from the model. The shock front is also b
ecoming more and more diffusive and having an increasing shock angle as see
n in the shadow video graphs of the flow. A physical mechanism of the obser
ved plasma effect on this type of shock wave is also presented. (C) 2001 Am
erican Institute of Physics.