The data that support the findings of this study are available from the corresponding author upon reasonable request. Raw data were generated at the EAST facility. Accepted paper information is listed here: Z. Sun et al 2021 Plasma of Physics. This paper include 13 figures. Captions listed below:
Figure 1 Poloidal and toroidal layouts of main diagnostics: the poloidal cross-section is the reconstructed equilibrium from an upper-single null divertor discharge #85198 @ 6 s;(a) superimposed over the flux plot are the sight lines of 11-channel POINT and EUV and locations of divertor target Langmuir probes; (b) the location of the downward trajectory of injected B powders and 64-channel XUV; (c) locations of Mirnov probes and sightlines of upper and lower Dα arrays; (d) sightlines of midplane Dα arrays and toroidal locations of main diagnostics
Figure 2 (a) reconstructed light intensity profile in the poloidal plane during B injection, with a super-imposed equilibrium boundary shape from #85198@6s on EAST. The trajectory of injected B powder is indicated by the black arrow. Visible color camera images obtained (b) before and (c) during B powder injection.
Figure 3 Comparison of reference ELMy discharge without B powder injection (black) and ELM suppression discharge with B powder injection (red): (a) plasma current Ip, (b) line-averaged electron density ne, (c) total heating power, (d) plasma stored energy WMHD, (e) core W emission WUTA, (f) BV emission from edge plasma, (g) upper divertor Dα emission, (h) Mirnov probe signal, dB/dt, cross-power spectrograms between XUV#55 chord and Dα#U8 for these discharges without (i) and with (j) B injection.
Figure 4 The evolution of BV (a), Dα at the divertor target (b), (c) BV (dashed line) and Dα (solid line) for a discharge in which B powder injection was terminated early, (d) integrated power of the auto-power spectrum power density for XUV#57 fluctuation in frequency range from 2.8 kHz to 15 kHz, which includes the first three harmonics of the EHM, (e) H98(y,2) factor.
Figure 5 B powder injection rate scan for RF-only heated discharges with 3.1 MW auxiliary heating power, showing (a) BV emission, (b) bulk radiated power, (c) H98(y,2) factor, (d) internal inductance, Divertor Dα of #93158 with bule color (e), #93159 with orange color (f), #93179 with yellow color (g), and #93180 with purple color (h). The flow rates of #93158 and #93159 are close to the threshold for ELM suppression while #93179 and #93180 were 6 and 10 times higher than the ELM suppression threshold rate.
Figure 6 Coherence spectrum (coherence coefficient verses frequency – see the text for a description) between XUV#57and Dα#U4, UIIS#5, CMPT#5, POINT#1 for a selected discharge #85198 with the EHM. Stars represent the peak frequency of all harmonics.
Figure 7 Auto-power spectrum of three MPs, locating near inner upper divertor (a), inner lower divertor (b); auto-power spectrum of two POINT channels, horizontally going through the upper(c)and lower (d) parts of plasma. All data are from #85198, the same as in Figure 6. 
Figure 8 (a) poloidal distribution of the line-averaged density fluctuation of the fundamental mode, (b) the ratio of line-averaged density fluctuation in time window of 6-6.5 s to 3-3.5 s without the EHM. All data are from #85198, the same as in Figure 6. 
Figure 9 Auto-power spectrum of three selected channels viewing the upper divertor(a), midplane(b), and lower divertor(c). (d) poloidal profile of the EHM intensity calculated by integrating auto-power intensity over the time window 6-6.5 s and domain frequency (1.8-3.1, 4.3-5.7, 6.8-8.3 kHz) windows of the first 3 harmonics for all XUV channels: Y axis is the height of intersection between each sightline of XUV channel and the vertical line going through the magnetic axis. (e) poloidal profile of averaged coefficient of variation with EHM and B injection (6-6.5 s, orange) and without EHM or B injection (3-3.3 s, blue). All data are from #85198, the same as in Figure 6. 
Figure 10 Averaged coefficient of variation with EHM and B injection (6-6.3 s, diamond) and without EHM (3-3.3 s, cross) for discharge #85198: upper(a) and lower(b) Dα array. All data are from #85198 same as in Figure 6. Diagnostic sight lines are shown in Figure 1(c).
Figure 11 the radial profiles of integrated power over the time window 5.6-6.5 s and frequency window 2-3 kHz, which was calculated by auto-power spectrum of the tangential ‘He-BES’ Dα array at the midplane. All data are from #85198, the same as in Figure 6.
Figure 12 (a) a time sequence of eight oscillation cycles from the signals of XUV57 (black) and ion saturation current (UIIS03) measured by a target Langmuir probe with a band-pass filter (yellow); (b) the cross correlation function between the two signals: the most probable lag time is ~180 μs (maximum coherence). All data are from #85198, the same as in Figure 6.
Figure 13 (a) evolutions of Divertor Dα (left Y axis), WUTA (black) and BV (bule), two WUTA spikes at 4.25 s and 5.4 s represent two spontaneous W droplet injections during ELM and ELM-absent phases. Reconstruction of central the soft x-ray signal with the exponential function Ae(−t/τimp ) + B (red line) in decay phase for two events (b) & (c).