•Duration of DINA-plasma disruption scenarios is limited by the end of plasma CQ.•Using of constant CS and PF coil currents after CQ end may give incorrect results.•Inductive coupling between the CS ...and PF coils and VV.•EM loads on the tokamak components located outside VV.
One of the most crucial issues in the design of the ITER machine is the electromagnetic (EM) loads associated with eddy currents induced in the conducting structures during plasma disruptions. The ITER database contains tens of calculation scenarios for possible plasma disruption events. The duration of these scenarios is usually limited by the end of the plasma current quench when the toroidal plasma current decreases to zero. For further EM analysis, the currents in the poloidal field coils are conventionally assumed constant after the end of the current quench. Such approach is not good for estimation of electromagnetic loads acting on the tokamak components located outside vacuum vessel. A possible way to solve this problem is to employ pre-determined coil current variations over the entire period of observation including time interval after the current quench. This paper describes an approach to such electromagnetic calculations and comparative results for selected cases with/out an extended current-time specification.
Some aspects of electromagnetic (EM) simulation of the central divertor cassettes (CDC) in the ITER tokamak are described. The study is focused on EM loads anticipated on the plasma-facing units ...(PFU) of CDC. The paper is devoted to the EM simulations of the most dangerous scenarios associated with high mechanical stresses: fast downward vertical displacement events of Categories II and III with 36-ms linear current quench (FD VDE-II and FD VDE-III with 36-ms LCQ). The selected events have been analyzed using the original TORNADO code intended for simulation of transient EM processes in 3D solids using the finite element representation. Results of computations include evolutions of EM loads on PFUs in the form of integral EM forces and moments, their peak values and relevant time points.
The main results of numerical simulation of transient electromagnetic processes in the modules of the first and second rows of TRT first wall panels are presented. The study was carried out using the ...TYPHOON software designed for numerical simulation of quasi-stationary eddy currents in conducting shells of complex shape randomly located in space, taking into account their multicoupling and branching. The basic design of the first wall panel and its five modifications are considered. It is determined that the electromagnetic forces and moments for the basic design reach extreme values, and the edge elements of the panel are the most loaded. Options with inserting electrical insulation at the places of contact of the plasma facing elements and the base of the panel, as well as incorporating a shunt between adjacent panels, make it possible to achieve the strongest reduction in loads. These options are accepted as basic for further modification of the panel design and conduction of additional EM analysis.
A neutron collimator is developed to attenuate the neutron flux and reduce the residual induced activity in the interportal space of the diagnostic system of neutral particle analyzers of the ITER ...tokamak reactor. The collimator is installed in the port plug of the ITER vacuum vessel in front of an inlet to the vacuum pipeline of the diagnostic system. The collimator design has a cellular structure with 80% transparency for the neutral atom beam that goes out of the plasma and is recorded by the analyzers. However, because of increased scattering of neutrons in the collimator, their flux in the interportal room in the service zone of diagnostic systems of equatorial port no. 11 is significantly reduced and allows the equivalent dose rate in this zone to be decreased by several times. Thermal analysis showed that, during the reactor operation in modes with generation of the maximum power of 500 MW, the plasma radiation will cause the heating of the collimating grid to a temperature not exceeding 250°C, which makes it possible to select the stainless steel (316L(N)-ITER grade) as a material for manufacturing the collimator. In this case the cyclic strength of the collimator meets the ITER requirements, and it can be used without replacement during the entire deuterium-tritium experiment of the tokamak reactor.
At present, the development of magnetic levitation transportation is conducted based on electromagnetic and electrodynamic suspensions the technical and commercial implementation of which has been ...successfully demonstrated in Korea, China, Japan, and other countries. Sources of an electromagnetic field in suspensions can be normally conducting electromagnets, superconducting magnets and high-coercive permanent magnets. The progress made in the development of new magnetic materials (permanent magnets and high-temperature superconductors) opens up prospects for reducing the energy consumption of levitation transport systems. The authors proposed magnets of all three types, which together ensure the functioning of combined electromagnetic suspension, and created scale models of such magnets. The permanent levitation of suspension models with a load is provided. The correctness of technical solutions is confirmed, software created in the Russian Federation allows one to reliably-scale magnetic systems of suspensions. Thus, all the prerequisites have been completed for the next stage of creating full-scale prototypes of effective levitation systems, in particular, a 50-ton cargo platform.
•A general concept of engineering EM simulator for tokamak application is proposed.•An algorithm is based on influence functions and superposition principle.•The software works with extensive ...databases and offers parallel processing.•The simulator allows us to obtain the solution hundreds times faster.
The paper presents an attempt to proceed to a general concept of software environment for fast and consistent multi-task simulation of EM transients (engineering simulator for tokamak applications). As an example, the ITER tokamak is taken to introduce a computational technique. The strategy exploits parallel processing with optimized simulation algorithms based on using of influence functions and superposition principle to take full advantage of parallelism. The software has been tested on a multi-core supercomputer. The results were compared with data obtained in TYPHOON computations. A discrepancy was found to be below 0.4%. The computation cost for the simulator is proportional to the number of observation points. An average computation time with the simulator is found to be by hundreds times less than the time required to solve numerically a relevant system of differential equations for known software tools.
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.
An optimized magnetic specification has been searched for a PM quadrupole constructed for the DC-140 cyclotron in JINR, Dubna. The field inhomogeneity should be reduced to come closer to an ideal ...distribution. The quad parameters should be determined with very high mechanical and magnetic precision in order to reach the specified gradient. Results of the analytic study based on a 2D model gave initial values for the PM blocks dimensions and orientations. To ensure stringent performance criteria, parametrized 2D and 3D models of the quad were built. These models were used to optimize the magnet configuration, analyze its sensitivity to various errors and derive parameter tolerances. Additional adjustment to suitable field quality is foreseen using results of a trajectory analysis and acceptance inspection. The design parameters for the best suited magnet configuration are presented and the performance criteria are defined. However, an electromagnetic analysis of the selected configuration has revealed that the relative field error adopted previously as the optimization criterion gives low accuracy estimate. Alternative estimations are proposed utilizing the field gradient error as the basic criterion to satisfy the constraint on the field inhomogeneity.
The discreteness of the toroidal field (TF) coils causes toroidally asymmetric perturbations of magnetic field (TF ripple). Maximum value of the TF ripple produced in the plasma by ITER TF coils is ...1.16%. The ripple requirements are determined by loss of fast particles and by potential changes in H-mode characteristics. The fast particle behavior is well known and a maximum TF ripple at the plasma separatrix of <;1% is enough to avoid excessive fast particle losses in all ITER scenarios. The quantitative influence of TF ripple on plasma performance in the H-mode remains the subject of continuing R&D and at this time the prudent approach is to make ripple as small as reasonably achievable. It is shown that optimum distribution of ferromagnetic inserts (FI) allows reduction of the TF ripple to about 0.3% in regular sectors of the ITER vacuum vessel (VV) and to about 0.55% in irregular VV sectors. Error fields produced by irregularity of the FI and currents in correction coils required for their reduction were also calculated.
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