The suppression of the potential fluctuation was clearly observed by a gold neutral beam probe (GNBP) during the higher potentials and positive electric fields driven by electron cyclotron heating. The particle flux evaluated from the phase difference between the potential and density fluctuations measured by GNBP showed the radial outward flux and correlates with the decrease in the stored energy. When flux is suppressed by the potential formation, the quick plasma stored energy increase is observed.