Fig. 1. Structure diagram of three-step probes array (floating potential: #3, #4, #7, #8, #11, and #12; positive biased voltage: #1, #5, and #9, negative biased voltage: #2, #6, and #10)

Fig. 2. Discharge parameters(a) Plasma current, (b) Toroidal magnetic field, (c) SMBI signal, (d) Line-averaged density at r/a≈0, (e) Probe displacement, (f) Floating potentials

Fig. 3. Variations of electron density (a), temperature (b), and pressure (c) in the edge plasmas (r/a≈0.88) with time

Fig. 4. Varitions of radial electric field (a), and the contributions of pressure gradients (b) and poloidal flows (c) to the radial electric field with time

Fig. 5. The power spectra of floating potential fluctuations (a), coherency (b) and phase shifts (c) between the floating potential fluctuations measured by poloidally positioned probes

Fig. 6. The auto-bicoherence spectrum (a) and summed bicoherence spectrum (b) of the floating potential fluctuations (color online)

Fig. 7. The spectrogram of floating potential fluctuations (a), and variations of GAM intensity (b), turbulence intensity (c), and ion-ion collisionality (d) with time

Fig. 8. Variations of the velocities of GAMs (a1, a2), the turbulent Reynolds stresses (b1, b2), the gradients of Reynolds stresses (c1, c2), and the Reynolds works of turbulence (d1, d2) with time

Fig. 9. Variations of turbulence intensity (a), radial electric field shear (b), density (c) and temperature (d)gradients with time

Fig. 10. Variations of turbulent particle flux (a), the amplitudes of density (b) and radial velocity (c) fluctuations, and the correlation (d) and the mean (e) and the standard deviation (f) of phase difference between density and radial velocity fluctuations with time