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 Bt<1.2
T, plasma current, Ip<175 kA, line average density <n>
< 6.2*1019 m-3;, central electron temperature
Te(0)<1.0 keV, central ion temperature Ti(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, Icl~1 kA,
and low plasma temperature, <Te>=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 Zeff value in the TUMAN-3M plasma is lower than 2.0. In the
freshly boronized vessel (first 300-500 shots) Zeff 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, Lrf=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 Ip=90-170 kA and qcyl=2.1-4.3.
Submitted data include time slices (one slice per shot) in the shots
with Ip=140-165 kA, qcyl=2.2-2.9, Ne=(0.8-2.7)*1019
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.