A concept of the Globus-3 spherical tokamak with a “warm” copper electromagnetic system, developed jointly by employees of the JSC NIIEFA and the Ioffe Institute, is presented. By increasing the facility parameters to a plasma current of 2 MA, a toroidal magnetic field of 2 T, and an aspect ratio of 1.8, the expected ion temperature can reach thermonuclear values, which opens up prospects for studying the behavior of charged fusion products, including alpha particles. Using the iterative process, the major and minor plasma radii and the parameters of the poloidal magnetic system of the facility have been determined, allowing for achieving the required discharge plateau duration of up to 3 s. The plasma discharge scenarios are simulated. The choice of scenario parameters is based on data obtained during experiments on the Globus-M2 tokamak, as well as on calculations using the GLOBSYS code. The design variant proposed at this stage is recognized as the most preferable for the implementation of the Globus-3 facility with a copper electromagnetic system in the available experimental building of the Ioffe Institute.
An absolute error in measuring the plasma electric potential using the heavy ion beam probe (HIBP) is estimated for the T-15MD tokamak. The main sources of error are analyzed, including the instability of voltage and the inaccuracy of its setting in the high-voltage power supplies of the accelerator and the energy analyzer, the uncertainty in the entrance angle of the secondary ion beam into the analyzer, the noise in the measurement path and the shot noise. The error is calculated for various modes of tokamak operation with the toroidal magnetic field of BТ = 1.2–2.0 T and the chord-averaged electron density of ne = (3–5) × 1019 m–3 for different profiles of electron temperature and density. The radial plasma regions accessible to reliable potential measurement are determined. Two-dimensional distributions of the absolute error for both the average potential and its fluctuations are obtained. It is demonstrated that optimizing the analyzer plate voltage, which reduces the normalized difference in partial currents at the detector, reduces the overall measurement error by approximately a factor of four and substantially expands the sample volume.
Understanding the laws of confinement and transport of plasma at high electron temperature is a key issue in the field of plasma fusion research. The turbulent transport level of edge plasma is studied by using the Langmuir probe in NanChang Spherical Tokamak (NCST). The results show that electron heat conduction dominated by temperature diffusion due to temperature gradient occupies the center of the energy flow in the scrape-off layer (SOL) of NCST. In addition, it is observed that the contribution of electron heat convection resulting from the electron transport process gradually increases during the discharge process, with the ratio of electron thermal convection and electron thermal conduction increasing from about 15 to 44
The potential application of non-thermal plasma in treating textile industrial wastewater motivates researchers to develop innovative techniques at a laboratory scale to achieve the goal of wastewater mineralization. With this objective, a post-dielectric barrier discharge (DBD) plasma reactor with a liquid electrode has been developed to study the degradation of synthetic dye solutions (simulated dye wastewater) at the laboratory scale. The in-house-developed post-DBD plasma reactor is used to assess its applicability for degrading Crystal Violet and other azo dyes in aqueous solution (model wastewater samples). We investigated the roles of solution and reactor parameters in achieving a higher degradation efficiency of Crystal Violet under the given discharge conditions. The reaction kinetics of Crystal Violet degradation were studied by analyzing UV-Vis spectra at different treatment times. The primary results suggest that the proposed post-DBD plasma reactor may offer a more promising solution than a simple DBD plasma reactor for degrading synthetic dyes and organic matter in industrial wastewater.
This study investigates nonlinear ion-acoustic waves (IAWs) in a magnetized multi-ion plasma motivated by cometary plasma environments, where hydrogen ions, oxygen ions, and non-Maxwellian electron populations may coexist due to solar-wind interaction and particle acceleration processes. The distribution is adopted here as an effective model for electrons with superthermal tails, rather than as a universal description of all cometary electron populations. Two scenarios are analyzed: (1) oxygen ions follow Cairns–Tsallis distributions (CTD) while hydrogen ions behave as isothermal fluids, and (2) hydrogen ions adopt CTD while oxygen ions are governed by fluid dynamics. Using 3D fluid equations, reductive perturbation theory (RPT) and samll k perturbation expansion, we derive Zakharov–Kuznetsov (ZK) equations to describe nonlinear IAWs and their three-dimensional instability (TMI). Results reveal that wave features-such as phase speed, amplitude, width and instability growth rates depend critically on nonthermal electron parameter, nonextensivity, magnetic field orientation and basic plasma parameters. Notably, instability arises when specific threshold conditions are met, with growth rates sensitive to wave propagation angles. These findings deepen our understanding of wave dynamics in cometary and other space plasmas with non-Maxwellian components.
