Speaker
Description
See the full abstract here http://ocs.ciemat.es/EPS2019ABS/pdf/P5.1090.pdf
An ExB drift poloidal rotation is now considered as an effective mechanism to suppress the plasma instabilities [1]. So, the direct radial electric field Er studies are important ingredient for understanding the role of E_r x B_t shear poloidal rotation in the turbulence suppression. In the -10 tokamak, the mean values of E_r were retrieved via plasma electric potential measured by heavy ion beam probe (HIBP) [2]. On top of that, recent advances in the T-10 HIBP allows us to measure simultaneously the plasma potential and density fluctuations within the frequency domain up to 250 kHz in 5 poloidally shifted sample volumes with the 5-slits energy analyser [3] in the plasma core (0.07 m < r < 0.2 m). Cross-phase θ_ij between density fluctuations in two sample volumes poloidally shifted at Δx_ij, each observed by corresponding analyzer entrance slits with numbers i and j, gives the information on the poloidal turbulence rotation velocity: V_turb =Δxij∙2πf/θij, i, j = 1-5, ixj [4]. The ohmic plasmas with m, B_t = 2.2 T, I_pl = 230 kA, n_e = 1x1019 m -3 were studied. For the stochastic low-frequency fluctuations (SLF) [5] with f_SLF =0-30 kHz, V_SLF ~ 2.5-3 km/s is directed towards the ion diamagnetic drift. For the low-frequency quasi-coherent fluctuations (LFQC) [6], f_LFQC =50200 kHz, V_LFQC ~ -10-15 km/s is directed towards the electron diamagnetic drift. It has been shown that E_r = - 60 V/cm, so E_r X B_t rotation velocity V_ExB equals to ~ -3 km/s and directed to the electron diamagnetic drift. The effect of EC heating on the ExB and turbulence rotation will be also presented.
References
[1] Burrell K.H., Phys. Plasmas 4 (1997) 1499
[2] Melnikov A.V. et al., Rev. Sci. Instrum. 66 (1995) 317
[3] Melnikov A.V. et al., Nucl. Fusion 57 (2017) 115001
[4] Eliseev L.G. et al., Plasma Fusion Res. 7 (2012) 2402064
[5] Vershkov V.A. et al., Nucl. Fusion 45 (2005) S203
[6] Vershkov V.A. et al., Nucl. Fusion 57 (2017) 102017
