The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created. The first operation of the European X-ray free-electron laser facility accelerator based on superconducting technology is reported. The maximum electron energy is 17.5 GeV. A laser average power of 6 W is achieved at a photon energy of 9.3 keV.

Presently, the Tokamak T-15 is being upgraded. The magnet system of the Tokamak T-15 upgrade will obtain and confine the hot plasma in the divertor configuration. Plasma parameters are a major radius of 1.48 m, a minor radius of 0.67 m, an elongation of 1.7-1.9 and a triangularity of 0.3-0.4. The magnet system includes the toroidal winding and the poloidal magnet system. The poloidal magnet system generates the divertor with single null and double null magnetic configurations. The power supply system provides the necessary current scenarios in the windings of the magnet system. All elements of the magnet system will be manufactured by the end of 2015. The Tokamak T-15 upgrade should begin operations in 2016. (C) 2015 Elsevier B.V. All rights reserved.

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.

The paper describes the dipole electromagnet XBB to be used in the XFEL systems for longitudinal compression of beam bunches.

The ITER-like Wall Project (ILW) at JET aims at replacing carbon fiber composite (CFC) on plasma-facing surfaces by tungsten and beryllium, which are relevant to the ITER design. The original design of the JET divertor, with CFC tiles, has quite high eddy current-related loads. Tungsten has a much higher electrical conductivity than CFC, and this does not allow a simple replacement of the CFC with solid tungsten in the original design.So-called fishbone- or tree-like shapes, avoiding large loops of eddy currents, have been proposed for the tungsten components and supporting structures. These shapes reduce the eddy current loads drastically and provide well-defined paths for the Halo current.This report describes how the design of the supporting structures is driven by electromagnetic considerations. Analytical and numerical techniques are combined and cross-checked. A study has undertaken for two variable orthogonal magnetic fields, for two cases of Halo current, with three orthogonal background magnetic fields. Then the worst load combinations were identified and used for the calculation of the forces and stresses in fixtures. (C) 2007 Elsevier B.V. All rights reserved.

The work has been carried out at the Efremov Institute according to the new PETRA-III machine optics. Normal-conducting magnets (quadrupole, dipole and corrector magnets) for the PETRA-III project were designed and calculated. Prototypes were built and magnetic measurements were carried out. Two precision quadrupole magnets with asymmetrical yoke lengths were developed. Their apertures are 70 mm and their design gradients 21.5 T/m. The integral field nonlinearity in the good field region (GFR), r o < 25 mm should be less than 0.0005. The new dipole magnets for the PETRA-III project have a H-shaped magnetic yoke with a length of 1 m. In the GFR area of 60 mm times 36 mm a magnetic field of B max = 1 T should be obtained. Within the GFR limits the integral field nonlinearity should be less than 0.0005, which is achieved by profiling the poles (longitudinal chamfers, slants and shims). The vertical correction dipole magnet has a horizontal magnetic field of B X = 0.062 T, its aperture is 112 mm times 50 mm and its total length, including the coil end parts, is limited to L = 200 mm. The authors have designed two versions one with air-cooling and one with water-cooling. Results of the magnetic measurements are given and compared with the simulation

Analytical and numerical approaches for the calculation of eddy currents in mechanical structures of the TEXTOR tokamak in view of operating the dynamic ergodic divertor (DED) coil system fed with the alternating current up to 15 kA at frequencies up to 10 kHz are described. The design of the in-vessel components located close to the DED coils requires detailed investigation of eddy current effects to avoid unacceptable heating and forces. Different approaches depending on skin-layer depths compared with the body dimensions are analyzed. The applied algorithms are based on analytical and simplified numerical methods. Precision and application range of these algorithms have been checked by a numerical code. The simplified technique is rather effective for first step engineering estimation and gives a good understanding for the problem. In a certain parameter range, it results in even precise values and can be used for design optimization of the structures without huge efforts in numerical modeling. After modification of the component's shape prototypes have been manufactured and successfully tested in a full-scale model under the real DED field. The design recommendations resulting from the eddy current studies contributed significantly to the optimized lay out of the DED in-vessel components.

The Dynamic Ergodic Divertor (DED) of the TEXTOR 94 tokamak will work at the regimes of DC current and AC current at frequencies up to 10 kHz. In order to design the mechanical structures supporting the DED coils and the graphite protective tiles it is necessary to take into account the induced eddy currents, especially at high frequencies. The temperature rise and mechanical forces in the structures should be within acceptable limits. The screening effect of the DED coils in the plasma region should be minimized. The modeling of the DED electromagnetic field is discussed. The problem is solved numerically with the ANSYS code. For comparison, some simplified technique is employed. Two approaches are used for the different types of structures: thin shell approach and infinitely thin skin-layer approach. The eddy currents and energy losses in the structures have been defined. The 2-D and 3-D nonstationary thermal problems have been solved and the temperature rise in the structures has been calculated for the steady state regimes. The evaluation of the static and cyclic strength of the structures has been made. Based on parametric studies, the parameters of the coil and tile supporting structures have been optimized.

The results of calculations and the. key design problems for the normal-conducting septum magnet for the Main Extraction Line of the TESLA linear collider are presented. The septum magnet is required to vertically deflect the so-called "spent beam" (after the interaction point) into the extraction line channel, while leaving the incoming (oppositely charged) beam undisturbed. The distance between the incoming beam and the copper septum is about 9 mm. The total length of the magnet core is 16 m. The 0.175 T magnetic field in 85 mm gap is produced by the copper winding and steel core. The septum is 5 mm thick. The stray field should not exceed 1 G. The septum-magnet should operate in the continuous regime. The required distribution of the magnetic field and the pole dimension of the septum-magnets have been calculated and optimized using two-dimensional models. A full-scale mock-up of one section of the septum-magnet has been developed and will be constructed for testing at the D.V. Efremov Scientific Research Institute of Electrophysical Apparatus.

The Dynamic Ergodic Divertor—to be installed inside the vacuum vessel of the TEXTOR 94 tokamak—requires a new liner design. The new liner represents a thin toroidal shell with numerous holes. One-third of the liner shell, facing the ergodic coils, is cut out for purposes of the ergodic divertor structures. To sustain the electromagnetic loads the cut-off edges of the inconel liner shell are reinforced with massive steel structures. Edges of the liner holes are reinforced with different types of steel structures. Calculation of the induced currents in the liner and vacuum vessel and electromagnetic forces on the structures due to interaction of the induced currents with the electromagnetic field during a plasma disruption is presented. The eddy currents in the segments of the vacuum vessel separated by bellows form closed loops. Because of numerous ports in the vacuum vessel and numerous holes in the liner, there are currents flowing perpendicular to the toroidal magnetic field. This leads to bending and twisting of the structures. The calculated electromagnetic forces were used for the subsequent structural analysis.

An accident has been considered when a short circuit takes place in the single ITER toroidal coil. The case has been studied when the current in the shorted coil is 250% of the coil current at normal operation. The current in the rest of the coils drops to 50% of the normal current. The 3D FE stress analysis has been carried out and the main analysis results relating to the structure deformation and the stresses state in the system components are presented. It is shown that the main stress occur in the shorted coil and the value does not exceed similar to 1000 MPa.

The aim of the numerical modelling is to study different regimes of operation of the TEXTOR 94 poloidal magnetic field system. The model allows to take into account the gaps between the parts of joke, nonlinear magnetic characteristics of ferromagnetic, discharge parameters as well as to simulate the operation regime providing scenarios for discharges with equilibrium conditions. The model includes vacuum vessel and liner and makes it possible to study the start up phase. Inductance matrix and efficiencies of the poloidal coils are determined for different levels of the iron magnetization. The results of the coils magnetic field measurements have been compared with the calculated ones. The ways of the stray fields compensation in this region for the start up phase have been proposed. On the basis of the predefined currents in the poloidal field system the possibility is shown to calculate the plasma parameters (current, inner inductance, elongation). The calculated parameters are in a good agreement with the experimental ones. The TEXTOR 94 magnet system incorporates 16 toroidal field coils (TFC). The coil system forms a vault inside to support centripetal forces. At the outside the coils are connected via intercoil structures taking the tilting moments. 2D and 3D finite element stress analyses of the TFC under electromagnetic and thermal loading have been performed for the upgrade system parameters. Contact interaction between the magnet system components has been taken into account.

The magnet QN is a septum quadrupole with a narrow septum coil for focusing the protons with a gradient of 30T/m, needed for the HERA Luminosity upgrade (1). It is 1.93m long and has a pole radius of 35mm. The field error must be limited to 3*10 -4 at 25mm reference radius over the whole excitation range of Gmax=20 Gmin. The required current density in the septum coil is 21A/mm 2 which results in a high power consumption of 124kW and a complicated water cooling system. Additional magnetic shielding between the septum coil and the nearby electron beam reduces the stray field below the limit of 20Gauss. The optimization of the field quality and the detailed design are described here. the magnet midplanes. The magnetic field seen by the electron beam must be less than 20Gauss with a nonlinear content of less than 5Gauss. In order to reduce calculated field value to the required level, a plate of magnetic shielding material is inserted between the coil and the e- beam. In order to suppress the forbidden harmonics due to the distortion of symmetry (odd harmonics, mainly: a3/a2 2 10 -4 ) the shielding needs to be inserted in the other quadrants as well. The shape of these insertions, however, is slightly different from the screen shape to make facilitate the assembling of the magnet. The results of optimization coil and shielding are presented in Fig. 2. The results of numerical simulation for a QN magnet of perfect symmetry are summarized in table 1. Table 1: Results of quadrupole QN computations. S=1-f(Aw)/f((Aw) max)/2, f(Aw)=G/Aw Aw G a6/a2 a10/a2 a14/a2 S KA T/m 10-4 10-4 10-4 10-2 0.7 1.392 1.74 0.29 -0.80 2.3 1.5 3.014 1.78 0.29 -0.80 1.33 3.5 7.095 1.69 0.29 -0.81 0.44 6.0 12.204 1.65 0.30 -0.81 0.10 8.5 17.306 1.60 0.30 -0.81 0 11.0 22.324 1.50 0.30 -0.81 0.35 13.5 26.477 1.24 0.29 -0.80 3.68 15.0 28.549 0.72 0.24 -0.80 6.53 16.0 29.681 0.26 0.21 -0.80 8.89 16.5 30.155 0.03 0.19 -0.79 10.22 The magnet yoke will be produced from laminated magnet steel of 0.75mm thickness and is re-enforced by a rectangular magnet frame made from 10mm strong magnetic steel. This frame is welded to the laminations of the yoke. The mechanical construction is such that the magnet can be separated into two halves inside the HERA tunnel to allow for easy installation of the beam pipes. The magnet also has removable pole tips for optimization of the fringe field. The magnet coils are made from rectangular copper conductors with a specific resistance of not more than 17.2m• /mm 2