Speaker
Mr
Leonid Askinazi
(Russian Federation)
Description
Overview of activity of the Plasma Physics Division at the Ioffe Institute in support of fusion program is presented. Experiments on LHCD (100kW, 2.5GHz) at the Globus-M tokamak (R=0.36m, a=0.24m, B_tor=0.4T, I_pl=200kA) with poloidally oriented grill resulted in RF driven current of up to 40 kA, in agreement with the theory predictions. At the FT-2 tokamak (R=0.56m, a=0.08m, B_tor=2.3T, I_pl=30kA) experiments with traditional toroidally oriented grill revealed no dependence of LHCD density limit on H/D ratio in spite of 3 times different LH resonance densities. Microwave Doppler Reflectometry (DR) at the Globus-M, and DR and Heavy Ion Beam Probe measurements at the tokamak TUMAN-3M (R=0.53m, a=0.24m, B_tor=1.0T, I_pl=190kA) demonstrated GAM suppression at the L-H transition. Observations at the FT-2 using Doppler Enhanced Scattering showed that GAM amplitude is anti-correlated both spatially and temporally with electron thermal diffusivity. For the first time turbulence amplitude modulation at GAM frequency was found both experimentally and in global gyrokinetic modeling. A model of L-H transition is proposed based on this effect. The loss mechanisms of energetic ions’ (EI) were investigated in the NBI experiments on Globus-M and TUMAN-3M: orbit losses, sawtooth triggered redistribution of EIs and Alfvenic mode excitation. Non-conservation of adiabatic invariant of EI in small aspect ratio configuration was found numerically to play a role in EI losses. Empirical scaling of 2.5 MeV DD neutron rate for the two devices shows strong dependence on toroidal field (B_tor)^1.29 and plasma current (I_pl)^1.34; this justifies B_tor and I_pl increase by a factor of 2.5 in proposed upgrade of Globus-M. Bursts of ~1MHz Alfvenic type oscillations correlating with sawtooth crashes were observed in OH at the TUMAN-3M. Possibility of low threshold parametric excitation of Bernstein and upper hybrid waves trapped in drift-wave eddies resulting in anomalous absorption in ECRH experiments in toroidal plasmas was discovered theoretically. A novel method of radial correlation Doppler reflectometry is shown to be capable of measuring the turbulence wave-number spectrum in realistic 2D geometry. Progress in design and fabrication of three diagnostics for ITER developed in Ioffe institute is reported: Neutral Particle Analysis, Divertor Thomson Scattering and Gamma Spectroscopy.
| Country or International Organisation | Russian Federation |
|---|---|
| Paper Number | OV/1-1 |
Primary author
Mr
Leonid Askinazi
(Russian Federation)
Co-authors
_ Diagnostic and Theory groups
(Ioffe Institute)
_ FT-2 team
(Ioffe Institute)
_ Globus-M team
(Ioffe Institute)
_ TUMAN-3M team
(Ioffe Institute)
