[en] The plasma is created by high power microwave injection into the MM-2 simple mirror. Simply by using tiny movable probes to measure the floating potential profile, along with diamagnetic and X-ray measurements, the drifting and bouncing motions of hot electrons associated with the formation process of the electron ring are detected. The radius of the hot electron ring is found to be 7 cm; its thickness is about 4 cm. The axial boundary of the ring extends from z = 10 cm to 20 cm, where z is the distance from the central plane of the device. The hot electron temperature is 140 to 170 keV, and the average beta value of the electron ring is about 4 to 5%. (author). 2 refs, 3 figs