Magnetic configuration scans during divertor operation of Wendelstein 7-X

Wendelstein 7-X (Greifswald, Germany) is an advanced stellarator, which uses the modular coil concept to realize a magnetic configuration optimized for fusion-relevant plasma properties. The magnet system of the machine allows a variation of the rotational transform (iota) at the boundary. In the latest Wendelstein 7-X operational phase a dedicated configuration scan has been performed varying the rotational transform between magnetic configurations with iota=5/4 and iota=5/5 at the boundary. This paper presents an overview of the experiments and of the main results with respect to confinement and stability. The main observation is an increase of the plasma energy in several intermediate configurations of the scan when the 5/5-islands are close to the plasma boundary but still inside the last-closed-flux-surface. In addition, these configurations showed marked MHD-activity with a crashing behavior related to the 5/5-islands. The corresponding mode amplitude was correlated with the size of the internal 5/5 islands.

New magnetic flux flows with Heisenberg ferromagnetic spin of optical quasi velocity magnetic flows with flux density

In this article, we first offer the approach of quasi magnetic Lorentz flux of quasi velocity magnetic flows of particles by the quasi frame in 3D space. Eventually, we obtain new optical conditions of quasi magnetic Lorentz flux by using directional quasi fields. Moreover, we determine quasi magnetic Lorentz flux for quasi vector fields. Also, we give new constructions for quasi curvatures of quasi velocity magnetic flows by considering Heisenberg ferromagnetic spin. Finally, magnetic flux surface is demonstrated in a static and uniform magnetic surface by using the analytical and numerical results.

Yokeless Axial Flux Surface-Mounted Permanent Magnets Machine Rotor Parameters Influence on Torque and Back-Emf

The paper presents the results of a 3D FEA simulations series of a dual air gap Axial Flux (AF) electric machine with Surface-Mounted Permanent magnets (SPM) with parameterized rotor geometry. Pole number and pole span influence on back-emf, as well as cogging and ideal electromagnetic torques angular characteristics were investigated for each model with the common segmented yokeless stator with concentric windings. Synchronous and BLDC drives supply were used to estimate back-emf distortion. Ideal torque ripple and cogging torque spectra were analyzed. It was concluded that the number of poles closer to the number of slots with ~0.8 pole span tends to yield good torque density with the lowest cogging torque, back-emf distortion and ideal torque ripple.

DECADAL MIXED LAYER SALINITY IN THE SOUTHEASTERN INDIAN OCEAN

The decadal of mixed layer salinity budget in the southeastern Indian Ocean (SETIO) is evaluated by using monthly gridded reanalysis ocean dataset (Estimated State of Global Ocean for Climate Research (ESTOC)) from January 1960 to December 2014. The evaluation of salinity budget through the examination of atmospheric flux, surface advection, Ekman advection and entrainment terms. The mixed layer salinity (MLS) in the outflow of the ITF shows decadal cycle. The decadal MLS tendency follows the Ekman advection term. The other processes such as atmospheric surface flux, surface advection and entrainment terms are counterbalanced and small correlates to the salinity tendency.

The importance of the classical channel in the impurity transport of optimized stellarators

In toroidal magnetic confinement devices, such as tokamaks and stellarators, neoclassical transport is usually an order of magnitude larger than its classical counterpart. However, when a high-collisionality species is present in a stellarator optimized for low Pfirsch–Schlüter current, its classical transport can be comparable to the neoclassical transport. In this letter, we compare neoclassical and classical fluxes and transport coefficients calculated for Wendelstein 7-X (W7-X) and Large Helical Device (LHD) cases. In W7-X, we find that the classical transport of a collisional impurity is comparable to the neoclassical transport for all radii, while it is negligible in the LHD cases, except in the vicinity of radii where the neoclassical transport changes sign. In the LHD case, electrostatic potential variations on the flux surface significantly enhance the neoclassical impurity transport, while the classical transport is largely insensitive to this effect in the cases studied.