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Investigates the global ideal magnetohydrodynamic (MHD) stability of plasmas with a prescribed helical boundary deformation and nonvanishing toroidal current. Stabilization of external modes by a fixed helical boundary deformation; Finding that current-driven external kink modes are among the dominant MHD instabilities in confinement devices.

Reports on the association of reversed magnetic shear with large negative surface averaged parallel current densities that increase in magnitude towards the plasma edge and guarantee stability at large beta in tokamaks. Dominance of the parallel current density in torsatrons by the Pfirsch-Schluter currents; Expression for the magnetohydrodynamic potential energy.

Investigates the ideal magnetohydrodynamic stability with respect to localized ballooning modes and the Mercier criterion of a quasihelically symmetric stellarator configuration. Configurations with enhanced magnetic mirror and deeper magnetic well; Yields of the Mercier criterion for the standard configuration; Ballooning instabilities near the center of the plasma.

Describes the application of semiclassical quantization to a ten-field period stellarator test case. Use of the ideal magnetohydrodynamics ballooning eigenvalue to provide dispersion relation; Application of the ballooning formalism to low-frequency plasma instabilities; Continuum bands predicted from three-dimensional Wentzel-Kramers-Brillouin theory.

Examines the effect of quadrupole fields on local three-dimensional ideal magnetohydrodynamic (MHD) stability in torsatrons. Vacuum rotational transform profiles in a 12-field torsatron of moderate aspect ratio for the standard configuration; Calculation of the ballooning mode structures.

Presents corrections for the paper 'Spectrum of ballooning instabilities in a stellarator,' published in the 'Physics of Plasmas' in 1996. Displacement vector; Ballooning mode equation.

Abstract: An incompressible variational ideal ballooning mode equation is discretized with the COOL finite element discretization scheme using basis functions composed of variable order Legendre polynomials. This reduces the second order ordinary differential equation to a special block pentadiagonal matrix equation that is solved using an inverse vector iteration method. A benchmark test of BECOOL (Ballooning Eigensolver using COOL finite elements) with second order Legendre polynomials recovers precisely the eigenvalues computed by the VVBAL shooting code. Timing runs reveal the need to determine an optimal lower order case. Eigenvalue convergence runs show that cubic Legendre polynomials construct the optimal ballooning mode equation for intensive computations. [Copyright &y& Elsevier]

Since the identification of anaplastic lymphoma kinase ( ALK) gene rearrangements in non-small cell lung cancer (NSCLC) in 2005, the treatment of ALK-rearranged NSCLC ( ALK+ NSCLC) has evolved at a rapid pace. This molecularly distinct subset of NSCLC has uniquely important biology, clinicopathologic features and mechanisms of drug resistance which impact on the choice of treatment for a patient with this disease. There are multiple ALK tyrosine kinase inhibitors now available in clinical practice with efficacy data continuing to emerge and guide the optimal treatment algorithm. A detailed search of medical databases and clinical trial registries was conducted to capture all relevant articles on this topic enabling an updated detailed overview of the landscape of management of ALK-rearranged NSCLC. [ABSTRACT FROM AUTHOR]

Energetic ions are found to be transported strongly from the core of MAST hybrid-like plasmas during long-lived mode (LLM) magnetohydrodynamic activity. The resulting impact on the neutral beam ion deposition and concurrent current drive is modelled using the guiding-centre approximation in the internal kinked magnetic topology. General coordinate guiding-centre equations are extended for this purpose. It is found that the kinked core spirals around the position of strongest ionization, which remains geometrically centred, so that a large fraction of the population is deposited in the high shear external region where the plasma is almost axisymmetric. Those particles ionized in the low shear region exhibit exotic drift motion due to the strongly non-axisymmetric equilibrium, periodically passing near the magnetic axis and then reflected by the boundary of the kinked equilibrium, which in this respect acts as a confining pinch. Broad agreement is found against experimental measurement of fast ion particle confinement degradation as the MAST LLM amplitude varies. [ABSTRACT FROM AUTHOR]

Kinked saturated m = 1 helical structures are frequently observed in tokamak hybrid plasmas and in reversed field pinches (RFP). These modes occur when an extremum in the safety factor is close to, but necessarily resonant with, a low order rational (typically qmin ≈ 1/1 in tokamaks, and qmax ≈ 1/7 in RFPs). If the exact resonance can be avoided, the essential character of these modes can be modelled assuming ideal nested magnetic flux surfaces. The methods used to characterize these structures include linear and nonlinear ideal magnetohydrodynamic stability calculations, which evaluate the departure from an axisymmetric plasma state, or equilibrium calculations using a 3D equilibrium code. The extent to which these approaches agree in tokamaks and reverse field pinches is investigated, and compared favourably for the first time with an analytic nonlinear treatment that is valid for arbitrary toroidal mode number. [ABSTRACT FROM AUTHOR]

Focuses on a fully kinetic assessment of the stability properties of toroidal drift modes obtained for nonaxisymmetric (stellarator) geometry in the electrostatic limit. Solution of the linearized gyrokinetic equation; Toroidal drift waves destabilized by temperature gradients and/or trapped particle dynamics; Design effort for a quasiaxisymmetric stellarator.

The three-dimensional plasma boundary displacements induced by applied non-axisymmetric magnetic perturbations have been measured in ASDEX Upgrade, DIII-D, JET, MAST and NSTX. The displacements arising from applied resonant magnetic perturbations (RMPs) are measured up to ±5% of the minor radius in present-day machines. Good agreement can be found between different experimental measurements and a range of models—be it vacuum field line tracing, ideal three-dimensional MHD equilibrium modelling, or nonlinear plasma amplification. The agreement of the various experimental measurements with the different predictions from these models is presented, and the regions of applicability of each discussed. The measured displacement of the outboard boundary from various machines is found to correlate approximately linearly with the applied resonant field predicted by vacuum modelling (though it should be emphasized that one should not infer that vacuum modelling accurately predicts the displacement inside the plasma). The RMP-induced displacements foreseen in ITER are expected to lie within the range of those predicted by the different models, meaning less than ±1.75% (±3.5 cm) of the minor radius in the H-mode baseline and less than ±2.5% (±5 cm) in a 9 MA plasma. Whilst a displacement of 7 cm peak-to-peak in the baseline scenario is marginally acceptable from both a plasma control and heat loading perspective, it is important that ITER adopts a plasma control system which can account for a three-dimensional boundary corrugation to avoid an n = 0 correction which would otherwise locally exacerbate the displacement caused by the applied fields. [ABSTRACT FROM AUTHOR]

The three-dimensional plasma boundary displacement induced by long-lasting core magnetohydrodynamic (MHD) instabilities has been measured in JET, MAST and NSTX. Only saturated instabilities are considered here since transient rapidly growing modes which degrade confinement and act as potential triggers for disruptions bring more fundamental concerns than boundary displacements. The measured displacements are usually small, although in extreme cases in MAST when the rotation braking is strong, a significant global displacement can be observed. The instability most likely to saturate and exist for many energy confinement times whilst distorting the boundary of ITER is the saturated internal kink, or helical core, which can be found in plasmas with a wide region of low magnetic shear such as the hybrid scenario. This mode can lead to non-negligible boundary displacements. Nonetheless, the boundary displacement resultant from core MHD instabilities in ITER is predicted to be less than ±1.5% of the minor radius, well within tolerable limits for heat loads to plasma-facing components. [ABSTRACT FROM AUTHOR]