Experimental study of the effect of 2/1 classical tearing mode on (intermediate, small)-scale microturbulence in the core of an EAST L mode plasma

The microturbulence at different scales k⊥=10, 18 and 26 cm−1 (i.e., k^r ~ 2 i , 3.6 and 5.2, respectively. Here, ri is the ion gyroradius and k⊥ is the perpendicular wavenumber) were measured simultaneously by the EAST multi-channel tangential CO2 laser collective scattering diagnostics.

Experimental results confirm that the decrease of microturbulent Doppler shift ( fDoppler = kt vt 2p), inversely correlated to the increase of microturbulent mean frequency (defined in equation (1)), is due to the 2/1 tearing mode. Temporal evolution of frequencyintegrated spectral power Stot of microturbulence, found to be correlated with the width of 2/1 magnetic island, suggests the modulation effect on microturbulence by the tearing mode beyond Doppler shift effect.