in the TUMAN-3M Tokamak S.V. Lebedev1, L.G. Askinazi1, F.V. Chernyshev1, V.E. Golant1, M.A. Irzak1, V.A. Kornev1, S.V. Krikunov1, A.D. Melnik1, D.V. Razumenko1, V.V. Rozhdestvensky1, A.A. Rushkevich2, A.I. Smirnov1, A.S. Tukachinsky1, M.I. Vild’junas1, N.A. Zhubr1 1 Ioffe Physico-Technical Institute, RAS, 194021, St Petersburg, RUSSIA 2 SPb State Polytechnical University, St Petersburg, RUSSIA Threshold power needed to attain H-mode in a tokamak is a critical parameter for designing of future devices and in particular fusion reactor ITER [1]. According to commonly accepted scaling [2] the threshold power increases with average density thr P e n when the

Threshold power needed to attain H-mode in a tokamak is a critical parameter for designing of future devices and in particular fusion reactor ITER [1]. According to commonly accepted scaling [2] the threshold power P-thr increases with average density n(e) when the density exceeds some n(e) (min) at which P-thr is minimal. An increase in the P-thr towards low density was observed in many experiments [3-6], prevents the transition at lower ne as well. Physics of the threshold power increase at low ne is not well understood. Since the radial electric field E-r and E-r x B sheared flow play important roles in the LH transition one could expect these quantities effect the low (n) over bar (e) transitions. Toroidal rotation and radial electric field generation during counter-NBI have been studied in [7] and recently reconsidered theoretically in [8]. Thus, motivation for the presented study is to analyze effect of counter-NBI on the LH transition at low density.