Thermal bending of thick rectangular plates

An analysis with a shear deformation capability for the thermal bending of thick rectangular plates is presented. Formulation of the problem, with appropriate thermal terms incorporated and applicable to the bending of moderately thick plates, has been carried out by using Reissner's plate bending theory. Representative plate bending problems have been considered for illustrating the procedure. Numerical results obtained indicate that thick plate solutions to thermal problems deviate from those of the classical theory in practically the same manner as with mechanical loading cases.     

Limit loads of variable thickness circular plates in bending

This paper presents the results of an investigation of rigid-plastic collapse of simply supported circular plates of variable thickness. The plates are loaded with a uniformly distributed transverse pressure and the material is assumed to yield according to the von Mises criterion. Numerical results for collapse loads and stress fields are given in graphs and the solution for the resulting velocity fields is indicated.     

Estimation of error fields from ferromagnetic parts in ITER

Error fields in tokamaks are small departures from the exact axisymmetry of the ideal magnetic field configuration. Their reduction below a threshold value by the error field correction coils is essential since sufficiently large static error fields lead to discharge disruption.The error fields are originated not only by magnets fabrication and installation tolerances, by the joints and by the busbars, but also by the presence of ferromagnetic elements. It was shown that superconducting joints, feeders and busbars play a secondary effect; however in order to estimate of the importance of each possible error field source, rough evaluations can be very useful because it can provide an order of magnitude of the correspondent effect and, therefore, a ranking in the request for in depth analysis. The paper proposes a two steps procedure. The first step aims to get the approximate magnetization state of ferromagnetic parts; the second aims to estimate the full 3D error field over the whole volume using equivalent sources for magnetic masses and taking advantage from well assessed approximate closed form expressions, well suited for the far distance effects.     

Plasma jet deflection in magnetic fields

We investigated the motion of plasma jets in a quadripole magnetic field produced by four current conductors whose axial lines were bent through 90° (the curvature radius was 30 cm). The maximum strength of the magnetic field in the slit between the current conductors was 6 kOe. The plasma jet, which was produced by means of a coaxial gun, was injected along the axis of the magnetic system. The magnetic system was adequate for defecting the plasma jet, which had an initial velocity of 8×10⁶ cm/sec and a maximum concentration before deflection of 2×10¹⁵ cm^–3. The jet velocity was equal to 7×10⁶ cm/sec. In spite of the considerable loss of particles (due to the presence of slits in the magnetic system), the ion concentration in the jet beyond the turn attained 2×10¹⁴ cm^–3, while the over-all number of particles was as large as 10¹⁷.As a result of deflection, it was possible to eliminate completely the neutral gas accompanying the jet and to obtain virtually totally ionized plasma. The optimum value of the magnetic field's strength was 8 kOe.Translated from Atomnaya Énergiya, Vol. 19, No. 4, pp. 329–335, October, 1965     

A high precision triangular plate bending element for the analysis of thick plates

A high precision triangular plate bending element for the analysis of thick plates is developed in thin paper. The element has three nodes and 12 degrees of freedom per node. Explicit expressions for stiffness coefficients are derived. The superiority of the element is demonstrated by the accuracy of the results obtained by applying it to some typical thick plate problems.     

Geometrical aspects of cylindric magnetic shields in strong static fields

Motivated by rrER (the International Thermonuclear Experimental Reactor),research on a magnetic shield against a strong field has been carried out.In this paper,a cylindric magnetic shield is studied by using the finite element method with a nonlinear magnetization curve.The geometrical aspects of shielding performance are identified and corresponding suggestions for application are provided.Among them,the effects of the edge and cover thickness have not been mentioned elsewhere to our knowledge.     

Effect of an additional ferromagnetic material on the toroidal magnetic field ripple in the ITER

In the ITER tokamak, the toroidal magnetic field (TF) ripple is estimated with TF coils only, with the installation of ferromagnetic inserts (FIs), and with test blanket modules (TBMs) by using a 2-D code for easy and fast calculation. We assessed the effects of the thickness of the FIs on the TF ripple in order to optimize the FI. And we analyzed how the TBMs distort the TF, and calculated the TF ripple for various amounts of a ferromagnetic material and the positions of the TBMs. Even in the case of moving the TBMs outward up to 60-cm, and reducing the ferromagnetic material to 52%, the TF ripple is not decreased below 0.38%. So we had to adopt ripple correction coils. With a 52% reduced amount of the ferromagnetic material in a TBM, we could reduce the TF ripple to 0.28% at a coil current of 100 kA turn per each coil. And with an outward recess of the TBM up to 60 cm, we could reduce the TF ripple to 0.23% at a coil current of 250 kA turn per each coil. As a combined approach, if we reduce the amount of a ferromagnetic material in a TBM to 30%, and recess the TBM to 15 cm, we can efficiently obtain the TF ripple of 0.25% at a coil current of 150 kA turn per each coil.     

Test of piezo-ceramic motor technology in ITER relevant high magnetic fields

In the framework of a Fusion for Energy (F4E) grant, a test campaign started in 2012 in order to assess the performance of the in-vessel viewing system (IVVS) probe concept and to verify its compatibility when exposed to ITER typical working conditions. ENEA laboratories went through with several tests simulating high magnetic fields, high temperature, high vacuum, gamma radiation and neutron radiation.A customized motor has been adopted to study the performances of ultrasonic piezo motors technology in high magnetic field conditions. This paper reports on the testing activity performed on the motor in a multi Tesla magnetic field. The job was carried out in a test facility of ENEA laboratories able to achieve 14 T. A maximum field of 10 T, fully compliant with ITER requirements (8 T), was applied. A specific mechanical assembly has been designed and manufactured to hold the motor in the region with high homogeneity of the field. Results obtained so far indicate that the motor is compatible with high magnetic fields, and are presented in the paper.     

The use of strong-pulsed magnetic fields to weld metals

I. V. Kurchatov Institute of Atomic Energy. Translated from Atomnaya Énergiya, Vol. 73, No. 4, pp. 278–284, October, 1992.     

Non-axisymmetric magnetic field due to ferromagnetic inserts and helium cooled solid breeder test blanket modules in ITER

An analysis is carried out on the three-dimensional modeling and computation of the magnetic field in ITER. The commercial finite element code ANSYS-EM is employed for this study. In particular, an emphasis is put on the analysis of the characteristics of non-axisymmetric magnetic fields produced by ferromagnetic materials, including ferromagnetic inserts (FIs) and helium cooled solid breeder test blanket modules (TBMs). It is found that the ITER design requirement for toroidal field ripple is violated by the presence of TBMs, even in the presence of FIs. Calculations of TBM-produced error fields also show that TBM produces a significant error field at q = 2 surface exceeding the ITER design requirement. Discussions are made of the potential implication of the TBM-produced non-axisymmetric fields on plasma performance and the design of a TBM emulation system.     

A comparative study of variable and constant thickness high precision triangular plate bending elements in the analysis of variable thickness plates

For the analysis of plate bending and vibration problems high precision triangular elements are very attractive. The effect of thickness variation can be included in these elements very easily at the expense of the computer time, for analysing variable thickness plates. On the other hand, variable thickness plates can be analysed as stepped plates with constant thickness elements with less computer time. In this paper a comparative study of the use of variable thickness and constant thickness elements for analysing variable thickness plates is attempted by solving three typical problems. The results show that for static problems there is a marginal accuracy when using variable thickness elements as against average thickness elements. However, for vibration problems even though there is not much difference in the fundamental frequency parameter obtained by using both elements, the higher modes obtained by using variable thickness elements are very accurate.     

Novel quantum phenomena induced by strong magnetic fields in heavy-ion collisions

The relativistic heavy-ion collisions create both hot quark–gluon matter and strong magnetic fields, and provide an arena to study the interplay between quantum chromodynamics and quantum electrodynamics. In recent years, it has been shown that such an interplay can generate a number of interesting quantum phenomena in hadronic and quark–gluon matter. In this short review, we first discuss some properties of the magnetic fields in heavy-ion collisions and then give an overview of the magnetic fieldinduced novel quantum effects. In particular, we focus on the magnetic effect on the heavy flavor mesons, the heavyquark transports, and the phenomena closely related to chiral anomaly.     

Effects of resonant magnetic perturbations on radial electric fields in DIII-D tokamak

Gyrokinetic simulations of DIII-D tokamak equilibrium find that resonant magnetic perturbation (RMP) drives a neoclassical non-ambipolar electron particle flux, which causes a rapid change of equilibrium radial electric fields consistent with experimental observations during the suppression of the edge localized mode (ELM). The simulation results provide a support for the conjecture that RMP-induced changes of radial electric fields lead to the enhanced turbulent transport at the pedestal top during the ELM suppression (Taimourzadeh et al 2019 Nucl. Fusion 59 046005). Furthermore, gyrokinetic simulations of collisionless damping of zonal flows show that resonant responses to the RMP decrease the residual level of the zonal flows and damp the geodesic acoustic mode.     

The influence of stray DC magnetic fields in MeV ion nanobeam systems

This paper evaluates the lens aberrations in microbeam and nanobeam systems caused by stray DC magnetic fields. Stray DC fields are far less influential on focussed beam spots than stray AC fields, but in order to achieve good beam-spot resolution the beamline must be aligned to the stray DC fields in the laboratory. The relative thickness of the optical elements compared to the curvature of the beam in such fields causes aberration where the beam axis differs from the optical axis of the lens system. In this paper numerical ray tracing has been used to study the influence of stray DC magnetic fields on beam resolution at the sub-micron level using typical field strengths for the Earth’s magnetic field as a case study.     

Chiral phase transition of quark matter in the background of parallel electric and magnetic fields

We report on our results about spontaneous chiral symmetry breaking for quark matter in the background of static and homogeneous parallel electric field,E,and magnetic field,B.A Nambu–Jona–Lasinio model is used to compute the dependence of the chiral condensate at finite temperature,E and B.We study the effect of this background on inverse catalysis of chiral symmetry breaking for E and B of the same order of magnitude.We also consider the effect of equilibration of chiral density,n_5,produced by axial anomaly on the critical temperature.The equilibration of n_5 allows for the introduction of the chiral chemical potential,u_5,which is computed selfconsistently as a function of temperature and field strength.We find that even if the chiral medium is produced by the fields the thermodynamics,with particular reference to the inverse catalysis induced by the external fields,it is not very affected by n_5 at least if the average u_5,at equilibrium is not too large.