It is a concentric electrode with 7 lead points. Of the 15 micron platinum-iridium wires, 1 is symmetrically located in the center and the other 6 around it. This arrangement is mounted in a 185 micron steel tube. The end of the electrode is formed into a symmetrical peak of 45 degrees.
The drain point in the middle is conical, while the 6 wire ends surrounding it are oval in shape.