21 Result(s)

Chapter

Electric Current Circuits in Astrophysics

Cosmic magnetic structures have in common that they are anchored in a dynamo, that an external driver converts kinetic energy into internal magnetic energy, that this magnetic energy is transported as Poynting...

Jan Kuijpers, Harald U. Frey… in Multi-scale Structure Formation and Dynami… (2016)

Article

Cycle 23 Variation in Solar Flare Productivity

The NOAA listings of solar flares in cycles 21 – 24, including the GOES soft X-ray magnitudes, enable a simple determination of the number of flares each flaring active region produces over its lifetime. We ha...

Hugh Hudson, Lyndsay Fletcher, Jim McTiernan in Solar Physics (2014)

Article

Solar Particle Acceleration Radiation and Kinetics (SPARK)

Energetic particles are critical components of plasma populations found throughout the universe. In many cases particles are accelerated to relativistic energies and represent a substantial fraction of the tot...

Sarah A. Matthews, David R. Williams, Karl-Ludwig Klein… in Experimental Astronomy (2012)

Article

Comparison of the Energy Spectra and Number Fluxes From a simple Flare Model to Observations

In this paper, we investigate the energy spectra produced by a simple test particle X-point model of a solar flare for different configurations of the initial electromagnetic field. We find that once the recon...

Iain G. Hannah, Lyndsay Fletcher in Solar Physics (2006)

Article

The Observational Motivation for Computational Advances in Solar Flare Physics

A solar flare is a violent and transient release of energy in the corona of the Sun, associated with the reconfiguration of the coronal magnetic field. The major mystery of solar flare physics is the precise n...

Lyndsay Fletcher in Space Science Reviews (2005)

Chapter

Overview of Solar Flares

This chapter reviews the physics of solar flares, with special emphasis on the past decade. During this decade first Yohkoh and then TRACE have drastically improved our observational capabilities for flares, with...

Hugh Hudson, Lyndsay Fletcher, Josef I. Khan… in Solar and Space Weather Radiophysics (2005)

Article

Tracking of TRACE Ultraviolet Flare Footpoints

Solar flares produce bright, compact sources of UV emission in the lower atmosphere, identified as flare footpoints. Observed at high time cadence with the Transition Region and Coronal Explorer, groups of UV ...

Lyndsay Fletcher, Jennifer A. Pollock, Hugh E. Potts in Solar Physics (2004)

Chapter

The Energy Release Process in Solar Flares; Constraints from TRACE Observations

The Transition Region And Coronal Explorer Satellite, TRACE, launched in 1998, has proved a valuable tool in the study of solar flares. UV and EUV observations of the impulsive and gradual phases of many tens ...

Lyndsay Fletcher, Harry P. Warren in Energy Conversion and Particle Acceleratio… (2003)

Article

A Relationship Between Transition Region Brightenings, Abundances, and Magnetic Topology

We present multi-instrument observations of active region (AR) 8048, made between 3 June and 5 June 1997, as part of the SOHO Joint Observing Program 33. This AR has a sigmoid-like global shape and undergoes t...

Lyndsay Fletcher, Marcelo C. López Fuentes, Cristina H. Mandrini… in Solar Physics (2001)

Chapter

High-Resolution Observations of Plasma Jets in the Solar Corona

We present recent observations of coronal jets, made by TRACE and Yohkoh/SXT on 28 May and 19 August 1998. The high spatial resolution of TRACE enables us to see in detail the process of material ejection; in the...

David Alexander, Lyndsay Fletcher in Physics of the Solar Corona and Transition Region (2000)

Article

High-resolution Observations of Plasma Jets in the Solar Corona

We present recent observations of coronal jets, made by TRACE and Yohkoh/SXT on 28 May and 19 August 1998. The high spatial resolution of TRACE enables us to see in detail the process of material ejection; in the...

David Alexander, Lyndsay Fletcher in Solar Physics (1999)

Article

PARTICLE ACCELERATION AND TRANSPORT IN RECONNECTING PLASMAS

We model the behaviour of particles in and around X-type magnetic configurations, a possible solar flare reconnection geometry. Particles are accelerated by a time-varying electric field close to the neutral p...

LYNDSAY FLETCHER, PANAGIOTA PETKAKI in Solar Physics (1997)

Article

Are coronal mass ejections caused by magnetic pum**?

Magnetic pum** in the solar corona is revisited. We derive conditions under which magnetic pum** can be the cause of heating of loops rather than of particle acceleration. Candidate sources for such a proc...

Jan Kuijpers, Lyndsay Fletcher in Solar Physics (1996)

Chapter

The Height Distribution of Hard X-Rays in Impulsive Solar Flares

Matsushita et al. (1992) used the Hard X-ray Telescope on board the Yohkoh satellite to image hard X-ray (HXR) emission in 100 impulsive flares, and found that low energy emission comes from higher in the corona ...

Lyndsay Fletcher in Magnetodynamic Phenomena in the Solar Atmosphere (1996)

Article

Modelling particle transport with stochastic simulations

We use stochastic simulations to calculate the evolution of particle distributions in complex situations. Comparison of numerical and analytical solutions is made, for the case of electrons moving from the cor...

Lyndsay Fletcher in Space Science Reviews (1994)

Article

Foreword

Bert Van Den Oord, Jan Kuijpers, Max Kuperus, A. O. Benz… in Space Science Reviews (1994)