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Peeters, Wim

doi:10.1007/978-3-476-05395-4_30

Cited by 5 publications

(6 citation statements)

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“…The fact that these two lines appear to be more closely associated with the visible nuclear cluster, estimated to be 60 Myr in age [9], than with the IR and radio source of the current starburst, suggests that this gas may be more closely correlated with a B star population than the young O stars. A similar result has been found for PAHs in galaxies [22].…”

Section: Principal Component Analysis Of the Center Of A Normal Spirasupporting

confidence: 88%

Chemical complexity in galaxies

Turner¹,

Meier²

2008

Science With the Atacama Large Millimeter Array

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ALMA will be able to detect a broad spectrum of molecular lines in galaxies. Current observations indicate that the molecular line emission from galaxies is remarkably variable, even on kpc scales. Imaging spectroscopy at resolutions of an arcsecond or better will reduce the chemical complexity by allowing regions of physical conditions to be defined and classified.A rich spectrum of molecular lines is available at millimeter and submillimeter wavelengths for the study of molecular clouds in galaxies. A recent single dish survey in the λ = 2 mm band of the starburst Sc galaxy NGC 253 revealed lines from 25 [1] of the over 35 molecular species detected to date in external galaxies (see contribution by S. Martín in this volume). Within the reach of ALMA will be thousands of transitions of over a hundred molecules, bringing a vast set of potential diagnostics of molecular gas and physical conditions within galaxies.

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Section: Principal Component Analysis Of the Center Of A Normal Spirasupporting

confidence: 88%

Chemical complexity in galaxies

Turner¹,

Meier²

2008

Science With the Atacama Large Millimeter Array

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“…Solved within GKW is the gyro-kinetic set of equations. The full details can be found in [34] and references found therein. Here we outline the basic set of equations that are solved and in the next section the modification and assumptions used in driving the tearing instability.…”

Section: Gyrokinetic Frameworkmentioning

confidence: 99%

On seed island generation and the non-linear self-consistent interaction of the tearing mode With electromagnetic gyro-kinetic turbulence

Hornsby

Migliano

Buchholz

et al. 2015

Plasma Phys. Control. Fusion

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Abstract.The multi-scale interaction of self-consistently driven magnetic islands with electromagnetic turbulence is studied within the three dimensional, toroidal gyrokinetic framework. It can be seen that, even in the presence of electromagnetic turbulence the linear structure of the mode is retained. Turbulent fluctuations do not destroy the growing island early in its development, which then maintains a coherent form as it grows.The island is seeded by the electromagnetic turbulence fluctuations, which provide an initial island structure through nonlinear interactions and which grows at a rate significantly faster than the linear tearing growth rate. These island structures saturate at a width that is approximately ρ i in size. In the presence of turbulence the island then grows at the linear rate even though the island is significantly wider than the resonant layer width, a regime where the island is expected to grow at a significantly reduced non-linear rate.A large degree of stochastisation around the separatrix, and an almost complete break down of the X-point is seen. This significantly reduces the effective island width.Magnetic islands in a tokamak can lead to loss of confinement or even major disruptions of the plasma. The tearing mode [1, 2], specifically the neoclassical tearing mode (NTM) [3] is expected to set the beta limit in a reactor [4,5]. The dynamics of magnetic islands is the result of the interplay of variety of processes. On one hand, their instability is widely believed to be due to neoclassical effects, first of all to the non-linear drive caused by the bootstrap-current perturbation due to the island itself and often the polarisation current is invoked as a mechanism for its threshold [6,7]. Within the singular layer, centred around rational surfaces, (Parallel wave-vector of the mode, k || = 0) the assumptions of ideal MHD break down and magnetic reconnection may take place. For a collisionless mode the mechanism of reconnection is the electron inertia, where the singular layer width, and in turn the growth rate, are related closely to the electron skin depth [8]. When collisions become significant, it is plasma resistivity arXiv:1409.0648v2 [physics.plasm-ph]

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“…The global version of the electromagnetic non-linear gyro-kinetic code GKW [24] was utilised in this study. A full description of the equations solved, and the implementation of the tearing mode current drive can be found in references [25,21].…”

Section: Parameters and Set-upmentioning

confidence: 99%

The non-linear evolution of the tearing mode in electromagnetic turbulence using gyrokinetic simulations

Hornsby

Migliano

Buchholz

et al. 2015

Plasma Phys. Control. Fusion

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The non-linear evolution of a magnetic island is studied using the Vlasov gyro-kinetic code GKW. The interaction of electromagnetic turbulence with a self-consistently growing magnetic island, generated by a tearing unstable ∆ ′ > 0 current profile, is considered. The turbulence is able to seed the magnetic island and bypass the linear growth phase by generating structures that are approximately an ion gyro-radius in width. The non-linear evolution of the island width and its rotation frequency, after this seeding phase, is found to be modified and is dependent on the value of the plasma beta and equilibrium pressure gradients. At low values of beta the island evolves largely independent of the turbulence, while at higher values the interaction has a dramatic effect on island growth, causing the island to grow exponentially at the growth rate of its linear phase, even though the island is larger than linear theory validity. The turbulence forces the island to rotate in the ion-diamagnetic direction as opposed to the electron diamagnetic direction in which it rotates when no turbulence is present. In addition, it is found that the mode rotation slows as the island grows in size.

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Cited by 5 publications

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Chemical complexity in galaxies

Chemical complexity in galaxies

On seed island generation and the non-linear self-consistent interaction of the tearing mode With electromagnetic gyro-kinetic turbulence

The non-linear evolution of the tearing mode in electromagnetic turbulence using gyrokinetic simulations

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