Plasma Physics Reports最新文献

To solve the main problems of designing a thermonuclear tokamak reactor, such as the experimental demonstration of quasi-stationary thermonuclear burning, generation of non-inductive quasi-stationary current; development of plasma technologies and materials of the first wall and divertor, the International Thermonuclear Experimental Reactor ITER is being designed, projects of DEMO demonstration reactors are being developed, and a Tokamak with Reactor Technologies TRT is being developed in Russia. The main components of the ITER (superconducting electromagnetic system (EMS) made of Nb₃Sn and NbTi, the first wall of W coated with a low-Z material, systems for additional plasma heating, experimental modules of a breeder blanket, plasma control systems, etc.) and TRT (EMS of high-temperature superconductors, first wall options of W with B₄C coating, TiB₂–AlN composite and liquid metal lithium, additional heating and quasi-stationary non-inductive current drive systems, innovative divertor, experimental breeder and hybrid blanket modules, reactor-compatible diagnostics and remote plasma control systems, etc.) technology platforms are presented. The technological platforms of the ITER being under construction and the TRT being designed contain an almost complete, according to modern understanding, set of technologies for the future thermonuclear reactor.

High radiation resistance, chemical inertness, the ability to operate at elevated temperatures, high mobility and efficiency of charge-carrier collection are important properties of diamond for designing detectors and spectrometers of ionizing radiation. Currently, diagnostics of neutrons and neutral particle fluxes based on diamond detectors for the ITER thermonuclear reactor are justified and developed. This work presents the results of a Raman spectroscopy and photoluminescence spectroscopy study of the electronic quality of synthesized epitaxial diamond films obtained by vapor deposition in a hydrogen and methane mixture in the ARDIS reactor on boron-doped single-crystal diamond substrates. To confirm their electronic quality, detectors have been made from films selected by spectrometric methods and the charge collection efficiency and energy resolution have been measured when irradiated with alpha particles from a ²⁴¹Am source and 14.7 MeV fast neutrons from the ING-07T2 neutron generator.

A conceptual design for diagnosing erosion of the first wall and divertor plates of a tokamak with reactor technologies TRT is proposed. The principles of constructing a diagnostic complex based on the following systems are developed: laser radar, dual-wavelength digital holographic interferometry and active laser IR thermography. An optical scheme is developed for combining the optical paths to input laser radiation and collect scattered light from diagnostic systems. To view the maximum area of the first wall, a scheme for optical scanning of the surface of the first wall and divertor is proposed. Based on optical simulation, the spatial distribution of the power density and phase of interferometry laser radiation in the illuminated region of the first wall is constructed, and the dimensions of the light fields and power density for IR thermography and laser radar diagnostics are determined. An image formation scheme is proposed and the spatial resolution is determined for interferometry and IR thermography methods. The light scattering function on models of the ITER divertor cladding is studied experimentally. The energy of the collected signal is calculated on the basis on the experimental data for all three diagnostic methods and the requirements for the diagnostic equipment are formulated.

Options for implementing the IR thermography diagnostic system in a TRT facility are considered. Two variants of the optical scheme for measuring the temperature of the first wall and divertor targets are proposed: a wide-angle system combined with two divertor channels and a four-channel viewing system. The optical resolution of both systems and the levels of the collected signal are numerically simulated. On the basis of the calculations performed, conclusions are drawn about the compliance of the systems with the requirements for measuring the temperature of TRT plasma-facing elements. The sources of the temperature measurement error are considered, and the error caused by the reflection of radiation from structural plasma-facing elements by the surface under study is estimated. Calibration issues for IR thermography diagnostics are also discussed.

A short review of the studies carried out at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences (BINP SB RAS) on the photon neutralization of the beams of negative ions is presented. The principal distinctive feature of the presented approach consists in the nonresonant accumulation of photons in a limited space. Their confinement is based on the adiabatic motion of photons in a system of concave mirrors, which is insensitive to the quality of the injected radiation. An analysis is carried out of the possibility of using the neutralizer based on such a nonresonant photon trap in large-scale installations such as ITER and TRT, and a future experiment is described on the photon neutralization using a beam of negative hydrogen ions with energy up to 130 keV and a current of about 10 mA.

The possibility of carrying out measurements of plasma parameters in a tokamak with reactor technologies (TRT) by means of the technique based on the Stark effect by resolving the spectrum of the split lines of Balmer series emitted by fast hydrogen atoms injected into plasma is analyzed. The code containing the models of emission applicable for the high-temperature tokamak plasma, along with the library of functions for the ray-tracing simulation of geometric optics, was used. Simulation of spectra of active neutral beam emission and plasma emission, both as a result of charge exchange on beam atoms and passive one, taking into account reflections from the plasma facing vessel elements, allowed determining parameters of the diagnostic injector and relative position of the light-collection systems and heating injectors for which the useful and background spectra could be separated. The signal gathered by the detector is simulated. The shape of the visual angle along the line of sight, optical properties of the lens materials, the instrumental function of the spectral device, the sensor characteristics, and statistical noise of the signal are taken into consideration. Based on the obtained results, a preliminary concept of the motional Stark effect (MSE) diagnostic for the tokamak with reactor technologies is proposed.

This paper reports on the generation of a directed flux of electromagnetic radiation with an energy content of 10 J in the frequency range of 0.2–0.3 THz at a microsecond pulse duration in a beam–plasma system. The flux is generated when a relativistic electron beam (REB) pumps electron plasma waves in a magnetized plasma column. In the described experiments, this fundamentally new approach to generate terahertz radiation was carried out at the GOL-PET facility in the conditions of varying the beam current density and the plasma density in the appropriate ranges of 1–2 kA/cm² and 10¹⁴–10¹⁵ cm^–3. From the comparison of the flux energy spectrum measured experimentally in the frequency range 0.15–0.45 THz with the calculated one obtained using the previously proposed model of radiation generation in a beam–plasma system it was shown that this process occurs through resonant pumping by REB of precisely the branch of upper-hybrid plasma waves. Mastering this new method to generate terahertz radiation opens the prospect of its use to obtain multi-megawatt radiation fluxes in the frequency range up to 1 terahertz and higher. For such a development approach the most promising beam for pumping plasma oscillations seems to be a kiloampere REB generated in a linear induction accelerator.

The canonical profiles transport model (CPTM), whose coefficients were determined from the T‑10 tokamak database with a standard magnetic field B_T = 2.3–2.5 T, has shown its robustness in ohmic regimes with a reduced magnetic field B_T = 1.55–2.1 T. We used the CPTM for predictions of radial profiles and dependences of the electron and ion temperatures and the energy confinement time on the average plasma density for the T-15MD tokamak at the initial stage of its operation: the ohmic regime in a circular limiter configuration with B_T = 1.0 – 2.0 T and plasma current I_p < 1 MA.

The results of measuring the electron temperature and density spatial distributions in plasma of the Globus-M2 tokamak using the Thomson scattering diagnostics are presented. The diagnostics provides measurements throughout the entire tokamak discharge, starting from time of gas breakdown. The Thomson scattering data were analyzed in order to determine the positions of the last closed flux surface, the plasma magnetic axis, and the radius of inversion during the saw-tooth oscillations. The results of measurements performed during the internal reconnection of magnetic field lines are presents, as well as the dynamics of spatial distributions of electron temperature, density and pressure during the plasma transition to the H-mode. The results of measuring the electron temperature distribution in the scrape-off layer using the Thomson scattering diagnostics are also presented for distances up to 4 cm outside the last closed flux surface.

The results of experiments are presented on the deposition onto silicate glasses of thin refractory-metal-films: molybdenum, tantalum and tungsten. The technique used for manufacturing films was based on the deposition of metal-containing plasma formed when exposing the surface of foils made of refractory metals to high-power plasma and ion pulses. For generation of such pulses, the facility of plasma focus type was used, which makes it possible to obtain ion beams and plasma flows with the energy flux density in the range of 10¹⁰–10¹² W/cm². The most intense central part of the ion-plasma flow was separated using metal di-aphragms with aperture diameters of 2.5, 3.5, and 4.5 mm. Metal Mo, Ta and W films with dimensions of ∅3–5 mm were obtained on the surfaces of glasses. Metal films are characterized by good adhesion, since they coalesce with the glass surface. It was discovered that the planarity of films becomes violated due to the drift of molten metal particles under the glass surface. The relief of films is non-uniform, which can be explained by the presence of micrometer-sized metal particles in the plasma flow.