Fizika plazmy

In a brief review, we discuss the processes associated with plasma self-organization in tokamaks, and the model of the self-consistent pressure profiles formation used in the energy and particle balance equations. Plasma self-organization can be interpreted as the formation of a structure consisting from chain of magnetic islands, each of which can form a self-consistent pressure profile. The convergence of island chains leads to anomalous transport, and their divergence leads to the formation of transport barriers. In the proposed model, the total energy flux Γ consists of two main parts: Γ0 and Γ1, where Γ0 corresponds to a self-consistent pressure profile, and the anomalous turbulent flux Γ1 appears, when the pressure profile is distorted by additional heating/cooling, as well as the neoclassical flux Γneo. The electron pressure profiles obtained by Thomson scattering in plasmas with magnetic islands and the effect of sawtooth oscillations on the anomalous Γ1 flux are analyzed. We present examples of the plasma confinement deterioration due to the nonoptimal deposition of additional heating power, and the confinement improvement due to increased radiation losses at the edge, leading to diminishing the level of magnetic fluctuations, which can be associated with the divergence of the chain of magnetic islands or with a decrease in the size of the islands.

A chromatographic study of atmospheric pressure glow discharge products in a mixture of CO2 and CH4 has been carried out. The discharge has been ignited using a source at a frequency of 50 Hz and a discharge voltage of up to 10 kV. The main gas products at the discharge output are H2 (∼55%) and CO (∼40%). It is shown that the discharge properties are determined by the ratio of CO2 and CH4 consumption at the reactor input. Soot particles are formed in the discharge in addition to gas products at the same CO2 and CH4 consumption at the reactor input. The soot formation is suppressed and water vapor appears in the discharge when in the CO2 content in the mixture increases. The discharge current and voltage oscillograms have been analyzed and the energy required to obtain hydrogen and spent on decomposition of CO2 have been estimated.