Vol 50, No 4 (2024)

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.

The paper presents a concept of the ECE diagnostic for the TRT facility and estimates the achievable measurement parameters in the baseline scenario. The target spectral region for the diagnostic corresponds to the first harmonic of the ECR frequency in ordinary polarization (O1) and the second harmonic in extraordinary polarization (X2). It is proposed to carry out measurements from the low-field side along two lines of sight: radial and toroidally oblique. The accessible spectral region in terms of the normalized radial coordinate is approximately estimated as –0.9 to 0.9 and –0.1 to 0.9. It is proposed to shape the input wave beam by means of a quasi-optical focusing system that provides a transverse size of the resolved region of approximately 3—5 cm for O1 and 1.2—3 cm for X2. For measurements, it is proposed to use Fourier transform spectrometers with a time resolution of about 10 ms and multichannel heterodyne receivers with a time resolution of about 1 μs. The minimum radial size of the resolved region is estimated to be 3—5 cm for O1 and 2—4 cm for X2, depending on the coordinate.

The results of model numerical calculations are presented, showing the effect of the TRT vacuum vessel on the amplitudes and phases of the magnetic sensors signals, which are located on the inner and outer vacuum vessel surfaces. It is shown that the characteristic times of loop voltage sensors considerably depend on their position on the TRT vacuum vessel. Therefore, their accurate mutual matching is required, especially in the dynamic stage of the discharge, when high eddy currents are induced in the vacuum vessel. The results of numerical calculations for the case of periodic disturbances in the plasma column are presented. They showed that the vacuum vessel almost completely shields the signals of the magnetic sensors located on the outer surface of the vacuum vessel. Moreover, it affects not only the amplitudes of magnetic sensors signals, but also their phases. Numerical studies brought us to conclusion that it is of priority to install the magnetic sensors just on the inner surface of the TRT vacuum vessel.

The paper discusses the possibility of using the Doppler backscattering (DBS) diagnostic to aid the Tokamak with Reactor Technologies (TRT) with its mission, and also offers ways of installing it in TRT, including the possible technical characteristics of the system. One of the most important advantages of DBS implementation is the ability to investigate various areas of plasma. This requires selecting an appropriate range of probing frequencies to match the scenarios and density profiles expected in TRT. Aspects and advantages of different ways of implementing DBS in the tokamak are discussed. Possible hardware, design and arrangement of the antenna system are presented. There are also system limitations that need to be considered specifically for TRT. The propositions for DBS on TRT are supported by calculations of ray tracing and diagnostic resolution. The wave number values of plasma fluctuations that the system could detect are also estimated.

The possibilities of using active neutral particle diagnostics for measuring local ion temperatures and isotopic ratio of deuterium-tritium plasma at the tokamak with reactor technologies are considered. Options for positioning the neutral particle analyzer relative to the diagnostic injector are presented. The fluxes of deuterium and tritium atoms escaping out of plasma were simulated in a wide range of plasma densities and temperatures. It is shown that the neutral particle analyzer active diagnostics will make it possible to measure the plasma parameters mentioned with the spatial and time resolutions of ~14 cm and ~0.01—0.1 s, respectively.

AbstractOptions 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.