A heavy ion beam probe diagnostic was installed on T-10 tokamak. Cs+ and Tl+ beams with the energy loo-280 keV and intensity about a few dozen ,uA were used. The diagnostic is able to make two-dimensional measurements of plasma parameters along the detector line, The detector grid covered the first quadrant of the plasma cross section. The measurements are possible with r/a=0.3-1, and o=O"-90" for B=lS T and Cs+ ions. High-voltage stabilizers keep the analyzer and accelerator voltage drift on the level A U/U-10m5. An absolute in situ calibration of the energy analyzer, using He target will allow to make a more accurate absolute referencing of the potential. The time dependence of the local plasma parameters was obtained. A scan along the detector line by variation of injection angle and obtaining the whole profile during one pulse is possible. The diagnostic is also sensitive to poloidal magnetic field. 0 1995 American Institute of Physics.

Convective transport of fast ions in the toroidal field ripples of a tokamak was investigated experimentally and theoretically. Comprehensive numerical computations of this effect were performed on the basis of the previously developed theory. Simultaneously, detailed experimental studies were made of the energetic ions in the T-4 and T-10 tokamaks. The experiments demonstrate that the ion distribution function is substantially different from the Maxwellian one, being strongly enriched with fast particles at the plasma column periphery. The local trapped-ion distribution is, in addition, asymmetric throughout the plasma cross-section. A detailed comparison with the numerical results shows that the observed effects can be explained in terms of the kinetic convective transport theory. Kinetic convection is shown to contribute significantly to energy transport. With increasing ion temperature, convective ripple transport may become dominant. Therefore, the variation of rippling may become an effective means of controlling the temperature and ignition regimes of a thermonuclear reactor. The results obtained demonstrate that transport processes in modern tokamaks have to be described in terms of kinetic theory.

The study of two types of T-10 regime-a regime with low impurity confinement (S regime) and a regime with enhanced impurity confinement (B regime) has been continued in deuterium discharges with A, -Aecrit. In the present experiments the transitions from S to B regimes is obtained by the method of gas puff cut-off. Detailed investigations of the profile evolution of T,(r), Ti(r). n,(r) and carbon density 11, showed, that the ?ze(r) profile greatly changes after gas puff cut-off, while T,(r) and TJr) remain practically unchanged at the central zone of the plasma. This indicates the possibility of a relation between the

The authors report the results of ion temperature measurements in the T-10 tokamak, with allowance for corrections due to the effect of kinetic transport of ions to the energy spectrum of atoms. On the basis of the experimental data they analyse the ion energy balance in the Ohmic heating and ECRH regimes over a broad range of plasma parameters.