A Monte Carlo Primer

Dupree, S.A.; Fraley, Stanley K.

doi:10.1007/978-1-4419-9036-5

Cited by 9 publications

(9 citation statements)

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“…For an overview of the Monte Carlo method as it pertains to particle transport problems, see e.g. Dupree & Fraley (2002) or, for more advanced topics, Lux & Koblinger (1991). Essentially, Monte Carlo is the 'natural' way of solving the RTE, in the sense that the photons in nature are unaware that they are solving a very difficult equation, they are simply obeying the local conditions.…”

Section: The Monte Carlo Methodsmentioning

confidence: 99%

“…The only requirement on g(x) is that g (x) > 0 for all x for which f (x) > 0. Biasing can be a very effective way of reducing the variance in the results of a Monte Carlo calculation by more effectively sampling the parts of the distribution that are important for the end result (Dupree & Fraley 2002). Juvela (2005) explored different biasing schemes in the context of radiative transfer through a spherically symmetric dust cloud, and found potential increases in efficiency by more than an order of magnitude.…”

Section: Biasingmentioning

confidence: 99%

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SUNRISE: polychromatic dust radiative transfer in arbitrary geometries

Jönsson

2006

Monthly Notices of the Royal Astronomical Society

313

330

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This paper describes sunrise, a parallel, free Monte Carlo code for the calculation of radiation transfer through astronomical dust. sunrise uses an adaptive mesh refinement grid to describe arbitrary geometries of emitting and absorbing/scattering media, with spatial dynamical range exceeding 104, and it can efficiently generate images of the emerging radiation at arbitrary points in space. In addition to the monochromatic radiative transfer typically used by Monte Carlo codes, sunrise is capable of propagating a range of wavelengths simultaneously. This ‘polychromatic’ algorithm gives significant improvements in efficiency and accuracy when spectral features are calculated. sunrise is used to study the effects of dust in hydrodynamic simulations of interacting galaxies, and the procedure for this is described. The code is tested against previously published results.

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Section: The Monte Carlo Methodsmentioning

confidence: 99%

Section: Biasingmentioning

confidence: 99%

SUNRISE: polychromatic dust radiative transfer in arbitrary geometries

Jönsson

2006

Monthly Notices of the Royal Astronomical Society

313

330

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“…The initial number density and electric field is obtained from the exact analytical solution of equations (18,21). [79] The generation of the particle velocity has been obtained using the rejection-method [Dupree and Fraley, 2002]. The distribution function at the point z p is…”

Section: A07206mentioning

confidence: 99%

Model of bifurcated current sheets in the Earth's magnetotail: Equilibrium and stability

Camporeale

Lapenta

2005

J. Geophys. Res.

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[1] Recent observations of CLUSTER have reconfirmed the recurring presence of bifurcated current sheets. The present paper revisits the model of Schindler and Birn (2002) to describe analytically bifurcated current sheets. Our contributions are in order. First, we describe a number of analytical velocity distribution functions that lead to bifurcated current sheets. Second, we derive necessary and sufficient conditions that determine when current sheets can be produced within the mathematical model of Schindler and Birn (2002). Third, we present a class of bifurcated current sheets, and we describe their properties. Fourth, we study the stability of bifurcated current sheets to the tearing instability finding that bifurcated current sheets tend to be more stable. Finally, we investigate the stability of bifurcated current sheets to the lower hybrid drift instability (LHDI) and kinking instability proving their presence. The work reported here is intended to extend and investigate the properties of instabilities from the typical but academic case of the Harris current sheet to current sheet equilibria that are more realisticly representative of the real magnetotail.Citation: Camporeale, E., and G. Lapenta (2005), Model of bifurcated current sheets in the Earth's magnetotail: Equilibrium and stability,

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“…We therefore carried out first 3D radiative transfer calculations utilizing the Monte Carlo method (Wood & Reynolds 1999) which has been updated to include algorithms for particle tracking from Dupree & Fraley (2002) as a follow-up of the work presented in for hydrogen-rich atmospheres. We model the interactions of protons, positive, neutral and negative pions, positive and negative muons, electrons and positrons, and gamma rays with an H2-dominated gas in a three dimensional Cartesian grid representing a homogeneous atmosphere with a radial density-temperature gradient.…”

Section: Non-thermal Processes: Winds Clouds and Cosmic Raysmentioning

confidence: 99%

Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

Helling

Rimmer

Rodriguez-Barrera

et al. 2016

Plasma Phys. Control. Fusion

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Brown dwarfs and giant gas extrasolar planets have cold atmospheres with a rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field B Earth , a chromosphere and aurorae might form as suggested by radio and X-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g., magnetic field induced star spots.

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A Monte Carlo Primer

Cited by 9 publications

References 0 publications

SUNRISE: polychromatic dust radiative transfer in arbitrary geometries

SUNRISE: polychromatic dust radiative transfer in arbitrary geometries

Model of bifurcated current sheets in the Earth's magnetotail: Equilibrium and stability

Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

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