Spectral and correlation analysis of microturbulences in the spherical Globus-M/M2 tokamaks

Results of the studies on turbulences carried out on the Globus-M2 and Globus-M tokamaks are presented. The main focus was on the analysis of the data obtained using Doppler backscattering method (DBS). The developed codes for the analysis of DBS signals allowed to study the effects of turbulences on the operational mode of the tokamak. A description of the data processing codes is also included. The analysis performed indicates the suppression of turbulence and the formation of a velocity shear during the L-H transition. It was also successfully used to study density fluctuations during and between edge localized modes (ELMs). Spectral and correlation analysis also led to the discovery of limit-cycle oscillations (LCO) and quasi coherent fluctuations (QCFs) during the I-phase.

Review of Advanced Implementation of Doppler Backscattering Method in Globus-M

Doppler backscattering (DBS) is a microwave diagnostics method typically used to study the plasma rotation velocity. Apart from conventional techniques, more advanced forms of DBS implementation were suggested on Globus-M. More specifically the study of a variety of oscillating processes was performed using DBS. In this review we present a detailed description of all of the methods and techniques employed in Globus-M alongside results obtained using DBS in all the years up until the shutdown of the tokamak. These include research similar to that done on other devices into the properties of such phenomena like geodesic acoustic modes or limit cycle oscillations, along with innovative works regarding the detection and investigation of Alfven eigenmodes and filaments that were the first of their kind and that provided important and novel results. Apart from that, the specific aspects of DBS application on a spherical tokamak are discussed. An in-depth look into the gradual change and improvement of the DBS diagnostics on Globus-M is also presented in this paper.

Materials analysis by ion channeling at "Demokritos"

A new fully automated Goniometer system installed recently at the Institute of Nuclear Physics of "Demokritos" is presented. This system enables to perform materials analysis not only via the Rutherford Backscattering method, which has been used so far at "Demokritos", but also by the ion channeling technique. The first experiments carried out using the Goniometer are also presented.

Tau mass measurement at BES-III

A scan of the threshold region of the process e+ e−→ τ+τ− with integrated luminosity about 140 pb−1 was performed with the BES-III detector at the BEPC-II collider in order to measure the τ-lepton mass. The beam energy was determined by the Compton backscattering method. To verify the measurement accuracy scans of the J/ψ and ψ′ resonances were performed.

Влияние низкочастотных магнитогидродинамических мод на развитие филаментов в токамаке Глобус-М

Experimental data indicating the influence of the magnetohydrodynamic tearing mode in the Globus-M spherical tokamak on the appearance of filamentary structures (filaments) are presented. The filaments were detected by the Doppler backscattering method. Filament groups localized in the toroidal direction were detected, the appearance of which turned out to be synchronized with the spreading of the tearing mode. The possible causes of the influence of low-frequency MHD oscillations on the occurrence of groups of filamentary perturbations are considered.