TUMAN-3M is a circular crossection tokamak without divertor. The device has the following parameters: vessel major radius R=0.55m, circular limiter radius a=0.24 m, longitudinal magnetic field B_t<1.2 T, plasma current, I_p<175 kA, line average density <n> < 6.2*10¹⁹ m^-3;, central electron temperature T_e(0)<1.0 keV, central ion temperature T_i(0)<0.4 keV. The vessel and circular limiters are made of Inconel (80% - Ni, 20% - Cr). Sector limiter (30° at the low field side, limiter shadow - 50 mm) is made of molybdenum.

Standard vessel conditioning consists in 3-4 hour AC inductive discharge cleaning with low toroidal current, I_cl~1 kA, and low plasma temperature, <T_e>=3-10 eV in deuterium, followed by 2-3 hour baking with wall temperature ~200°C. The procedure is used for everyday vessel preparation. From time to time (once in 300-2000 shots) boronization is performed. The boronization includes ~ 1 hour of Glow in He with admixture of Carborane (C₂B₁₀H₁₂). Typical Z_eff value in the TUMAN-3M plasma is lower than 2.0. In the freshly boronized vessel (first 300-500 shots) Z_eff is close to 1.0.

TUMAN-3M is equipped with the following diagnostic tools: magnetics (poloidal flux loops and coils, diamagnetic coils, 2 toroidally separated sets of 24 Mirnov coils, Rogovsky coils), microwave interferometry (10 vertical equidistant channels with dR=48 mm, L_rf=2.2 mm), SXR diode array (dR=30 mm at equatorial plane), Thomson scattering (2x4 spatial channels, 5 spectrum channels, single pulse Ruby laser), neutral particle analyzer (2x6 energy channels, mass resolution), microwave reflectometry (f≤26 GHz), D_alpha monitors. Other diagnostic tools are used occasionally (bolometry, heavy ion beam probe, Doppler shift visible spectroscopy, electrostatic probes).

49 time slices have been submitted into the international H-mode confinement database. Submitted into the DB data were collected in the ELM-free ohmic H-mode. In some shots the ohmic H-mode developed spontaneously, but in the majority of the discharges the H-mode was induced by some increase in the working gas puffing rate (deuterium). The ohmic H-mode was obtained at I_p=90-170 kA and q_cyl=2.1-4.3. Submitted data include time slices (one slice per shot) in the shots with I_p=140-165 kA, q_cyl=2.2-2.9, N_e=(0.8-2.7)*10^{19 m -3};. For some shots equilibrium simulations were performed in order to determine plasma geometry parameters. Energy content was measured with diamagnetic loops and was compared with kinetic measurements and equilibrium simulations in some shots. The data agree within 15% accuracy. Transition into the ohmic H-mode results in strong suppression of the particle transport and corresponding increase in the density. Reflectometry and probe measurements have shown significant drop in the peripheral turbulence after the H-mode transition.