V. Belyakov

Some Aspects of Winding Geometry Control for ITER Superconducting Coils Using Magnetic Measurements

A feasibility has been demonstrated for numerical reconstruction of geometrical displacement or deformations of the winding occurred in the manufacture and assembly of magnet coils using magnetic measurements, that is one of the principal issues for the quality control of the magnet. For validations of the proposed approach, test results of reconstruction of possible misalignments and deviations of the ITER coil are presented.

Engineering Problems of Tokamak T-15 Electromagnet System Reconstruction

Currently reconstruction is initiated on the T-15 tokamak at the Institute of Tokamak Physics, NRC “Kurchatov Institute”. The purpose of the reconstruction is to build the facility with a small aspect ratio , elongated cross-section and the divertor with a major radius of 1.67 m, long plasma current pulse of 2 MA up to 10 s and powerful auxiliary plasma heating (up to 15 MW). The facility is intended for demonstration of the plasma steady-state burning with high parameters for physics research to support the ITER program and program for development of volumetric neutron sources. The reconstruction involves replacement of the existing superconducting TF magnet system and cryoresistive PF system by the “warm” system. The developed magnet system provides the above-mentioned tokamak parameters. The magnet system of the new facility use of the T-10 and T-15 infrastructure, thus essentially determining the choice of its main parameters.

Tokamak DEMO-FNS: Concept of magnet system and vacuum chamber

The level of knowledge accumulated to date in the physics and technologies of controlled thermonuclear fusion (CTF) makes it possible to begin designing fusion—fission hybrid systems that would involve a fusion neutron source (FNS) and which would admit employment for the production of fissile materials and for the transmutation of spent nuclear fuel. Modern Russian strategies for CTF development plan the construction to 2023 of tokamak-based demonstration hybrid FNS for implementing steady-state plasma burning, testing hybrid blankets, and evolving nuclear technologies. Work on designing the DEMO-FNS facility is still in its infancy. The Efremov Institute began designing its magnet system and vacuum chamber, while the Kurchatov Institute developed plasma-physics design aspects and determined basic parameters of the facility. The major radius of the plasma in the DEMO-FNS facility is R = 2.75 m, while its minor radius is a = 1 m; the plasma elongation is k95 = 2. The fusion power is PFUS = 40 MW. The toroidal magnetic field on the plasma-filament axis is Bt0 = 5 T. The plasma current is Ip = 5 MA. The application of superconductors in the magnet system permits drastically reducing the power consumed by its magnets but requires arranging a thick radiation shield between the plasma and magnet system. The central solenoid, toroidal-field coils, and poloidal-field coils are manufactured from, respectively, Nb3Sn, NbTi and Nb3Sn, and NbTi. The vacuum chamber is a double-wall vessel. The space between the walls manufactured from 316L austenitic steel is filled with an iron—water radiation shield (70% of stainless steel and 30% of water).

Modeling of magnetic field perturbations in electrophysical devices due to the steel reinforcement of buildings

We have proposed an effective method for modeling the steel reinforcement in the buildings for electrophysical devices to take into account the magnetic field perturbation caused by the magnetization of bars. The reinforcement lattice has been represented by one or several layers of a homogeneous isotropic material with preliminarily calculated equivalent (averaged) magnetic properties. Examples of calculating these magnetic properties have been considered using a simplified analytic approach, as well as by the numerical simulation of the magnetic field in a 3D cell of a periodic reinforcement lattice. The efficiency of the method has been demonstrated based on an important practical example of simulating the perturbation of a uniform magnetic field caused by the reinforced slab. The results have been compared with the simulation data based on different approaches.

Computational Technique for Analysis of Superconductive Fault Current Limiters With Saturated Core

A computational technique is proposed for the analysis and design optimization of inductive-type superconducting fault current limiters (SFCL) with variable impedance for power systems application. The technique is applicable for a wide range of magnet systems. The paper is focused on the analysis of electromagnetic transients. A methodological example of a model SFCL is presented. Numerical experiments are described to study nonlinear effects at saturated and unsaturated states. Results demonstrate that the nonlinear magnetic behavior of the SFCL components affects noticeably the accuracy of predictions.

Modeling Magnetic Effects of Steel Rebar of Concrete Surroundings for Electrophysical Apparatus

The article describes an advanced approach to modelling magnetic properties of reinforced concrete structures taking into account the anisotropic effect due to rod layers orientations. The equivalent model has been validated in the computation of a test problem. For comparison, simulations have been carried out with a detailed 3D FE model that describes each of the steel rods. The equivalent model has required a few times less finite elements than the detailed model. A comparison of the fields obtained has demonstrated a very good match, even for the distances comparable with the rebar rod gaps.

Experience in PF1 Dummy Pancake Manufacturing on the Mobile Facility for Winding and VPI of Large-Scale Superconductive Magnets

This paper describes the experience in PF1 dummy double pancake winding, which was performed in the Russian Federation in 2014-2015. The pancake was wound by the method of “two-in-hand” stress-free winding with continuous chemical cleaning and sandblasting of the conductor surface followed by application of multilayered turn insulation. The winding was accomplished by a mobile flexibly scalable complex of equipment installed within the shortest possible time in a special “clean room.” This complex has a number of advantages, such as mobility, cost effectiveness, independence, minimum attending personnel, synchronization of all operations under a unified automatic control system, continuous control, and possible fast correction of output parameters.

Optimization of currents in ITER correction coils

In tokamaks non-axisymmetric magnetic field perturbations (error fields) can induce in plasma locked modes and cause disruption. In ITER the main contributor to error fields is assembly and manufacturing errors of the magnet system of the machine. To suppress intrinsic error fields and guarantee the expected plasma performance ITER is provided with the proper correction coils (CC). The paper is related to optimization of CC currents. The optimization takes into account as constraints both CC current capacities and an allowable level of error fields.

Field and trajectory analyses and optimization of magnetic shielding for neutral particle diagnostics in ITER

A diagnostic system of the neutral particle analyzer has been developed under the Ioffe Institute supervision for the International Thermonuclear Experimental Reactor (ITER). A numerical experiment is presented aimed to analyze the diagnostics operability in harsh electromagnetic environment and optimize its design and performance. A care was taken to integrate the diagnostic system with the ITER machine structures.