Energy breakeven in thermonuclear fusion. An advanced concept for efficient energy input with positive implications for energy saving and the geoscience of climate change

The motivation of the present study is energy generation with thermonuclear fusion. Specifically, it is the attainment of breakeven conditions with a fusionable plasma whereby the output fusion energy is at least equal to the energy expended in creating the plasma and bringing it to fusionable conditions. This objective has eluded the physics community for the past seven decades. It is here suggested that perhaps the reason is that ever-bigger fusion machines are built, which unfortunately have brought results not in line with the expectations, in terms of desired fusion output. The opposite view is taken here, where attention is paid to the energy input, with the objective of minimizing the energy losses. One of the most important losses is a consequence of the limited thermodynamic efficiency of conventional engines that convert heat to work, thus generating the electricity involved in the energy input. This preliminary study shows that the efficiency can be improved if a novel thermodynamic cycle is used with heat recovery and recirculation. No attention is paid in the present study to the applicability of the novel cycle to a working engine but only to its feasibility. After the delineation of the concept, we use a simulation program to confirm that such approach is promising, and the objective of improving the thermodynamic efficiency of conventional heat-engines by at least 10% is realistic. Finally, the economic benefits are quantified of such substantial efficiency improvement on a world-wide scale. Mitigation of the damage to our environment due to the reduced heat rejection is also quantified.

Thermonuclear Fusion Reactor Plasma-Facing Materials under Conditions of Ion Irradiation and Plasma Flux

A review of experimental studies carried out at the NRC “Kurchatov Institute” on plasma-facing thermonuclear fusion reactor materials is presented in the paper. An experimental method was developed to produce high-level radiation damage in materials simulating the neutron effect by surrogate irradiation with high-energy ions. Plasma-surface interaction is investigated on materials irradiated to high levels of radiation damage in high-flux deuterium plasma. The total fluence of accelerated ions (3–30 MeV, 4He2+, 12C3+, 14N3+, protons) on the samples was 1021–1023 m−2. Experiments were carried out on graphite materials, tungsten, and silicon carbide. Samples have been obtained with a primary defect concentration from 0.1 to 100 displacements per atom, which covers the predicted damage for the ITER and DEMO projects. Erosion dynamics of the irradiated materials in steady-state deuterium plasma, changes of the surface microstructure, and deuterium retention were studied using SEM, TEM, ERDA, TDS, and nuclear backscattering techniques. The surface layer of the materials (3 to hundreds µm) was investigated, and it was shown that the changes in the crystal structure, the loss of their symmetry, and diffusion of defects to grain boundaries play an important role. The most significant results are presented in the paper as an overview of our previous work for many years (carbon and tungsten materials) as well as the relatively recent results (silicon carbide).

Participation in thermonuclear research of EURATOM: results achieved under the HORIZON 2020 program and the prospects for the next EU program for 2021-2027 (transcript of the report at the meeting of the Presidium of NAS of Ukraine, February 17, 2021)

The report emphasizes the importance of developing thermonuclear research in the world, the need for further integration of Ukrainian research institutions into the European research area and increasing the participation of Ukrainian scientists in world-class research in plasma physics and controlled thermonuclear fusion. The urgency and complexity of the problem of controlled thermonuclear fusion, which covers not only various aspects of high-temperature plasma physics as the basis of energy of the future, but also problems of thermonuclear reactors, materials science, engineering aspects of thermonuclear energy, etc. are discussed.

About the modeling of light beam self-focusing in plasma at the irradiation of the target by power UV laser

The peculiarities of light beam expansion in plasma upon irradiation of condensed targets with a powerful UV laser pulse are studied with the help of mathematical modeling. Experiments were carried out at the Lebedev Physical Institute of the Russian Academy of Sciences with the use of GARPUN installation: a powerful KrF laser that irradiated two-layer targets consisting of aluminum foil and a plexiglass layer. Channels stretched along the direction of incidence of the laser beam were found at the bottom of the crater. It was shown on the basis of experimental and calculated data that selffocusing of the laser beam developed in the plasma. As a result, hot spots were produced in vicinity of the plasma critical density, and fast (superthermal) electron flows were generated. The electron flows could produce the channels in the plexiglas. In order to describe the self-focusing effect a physicalmathematical model was developed, and “FOCUS” program was created at the Russian Technological University (MIREA). Numerical simulations were carried out on the gas-dynamic profiles (linear and exponential). It was shown that thermal self-focusing could develop at the conditions of “GARPUN” experiments (~ 1 mm longitudinal plasma, moderate radiation intensity: 1011–1012(W/cm2) × µm2). The parameters of dangerous modes of laser beam perturbations were estimated. The interest in the experimental and mathematical modelling results is related to the laser thermonuclear fusion (LTF) research. Although Nd glass lasers are the basic installations for LTF research, UV gas eximer lasers have some advantages as drivers for future thermonuclear fusion reactors. The interaction of UV laser radiation with plasma has some peculiarities. Thus, developing physical-mathematical models and creating new programs required for the interpretation of modern UV laser – plasma coupling experiments and for the design of large scale facilities based on eximer drivers is a topical problem.

TO THE FIFTIETH ANNIVERSARY OF THE KIPT TORSATRON PROGRAM

The paper is dedicated to the 50th anniversary of controlled thermonuclear fusion studies performed at the KIPT on the specific stellarator-type experimental installations commonly referred to as “the torsatron”. Detailed data are reported on the operating thermonuclear facility “Uragan-2M”, the research results obtained with it, and also, the prospects for its use as a reactor. The advantages of the torsatron of this type are described, among them being the wide-range parameter variation capability. This is of importance for finding out the regularities related to plasma stability, heating and confinement.