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Litvinenko, Yuri E.

doi:10.1023/a:1026143310271

Cited by 17 publications

(9 citation statements)

References 21 publications

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“…Particles encounter the non-adiabatic region, the process resulting in a Fermi-type acceleration. A similar phenomenon has been noted for a multiple neutral point configuration by Kliem (1994), in the behavior of protons in the presence of an MHD disturbance by Petkaki & Mackinnon (1997), and was explored analytically for time-varying electric field by Litvinenko (2003).…”

Section: Energy Distributions Of Accelerated Electrons and Protonsmentioning

confidence: 53%

“…Recent work studies regular and chaotic dynamics in 3D reconnecting current sheets (Efthymiopoulos et al 2005;Gontikakis et al 2006) or studies particle orbits in the presence of 3D magnetic nulls (Heerikhuisen et al 2002;Dalla & Browning 2005). Particularly relevant here is the exploratory, analytical study of Litvinenko (2003) which looks at charged particle orbits in an oscillating electric field in a magnetic field containing a neutral line.…”

Section: Introductionmentioning

confidence: 99%

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Particle acceleration by fluctuating electric fields at a magnetic field null point

Petkaki

MacKinnon

2007

A&A

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Context. Particle acceleration consequences from fluctuating electric fields superposed on an X-type magnetic field in collisionless solar plasma are studied. Such a system is chosen to mimic generic features of dynamic reconnection, or the reconnective dissipation of a linear disturbance. Aims. We explore numerically the consequences for charged particle distributions of fluctuating electric fields superposed on an X-type magnetic field. Methods. Particle distributions are obtained by numerically integrating individual charged particle orbits when a time varying electric field is superimposed on a static X-type neutral point. This configuration represents the effects of the passage of a generic MHD disturbance through such a system. Different frequencies of the electric field are used, representing different possible types of wave. The electric field reduces with increasing distance from the X-type neutral point as in linear dynamic magnetic reconnection. Results. The resulting particle distributions have properties that depend on the amplitude and frequency of the electric field. In many cases a bimodal form is found. Depending on the timescale for variation of the electric field, electrons and ions may be accelerated to different degrees and often have energy distributions of different forms. Protons are accelerated to γ-ray producing energies and electrons to and above hard X-ray producing energies in timescales of 1 s. The acceleration mechanism is possibly important for solar flares and solar noise storms but is also applicable to all collisionless plasmas.

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Section: Energy Distributions Of Accelerated Electrons and Protonsmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Particle acceleration by fluctuating electric fields at a magnetic field null point

Petkaki

MacKinnon

2007

A&A

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“…In the case of the impulsive events, several processes have been proposed for the modeling of the turbulent acceleration of particles in the flare region. Stochastic acceleration involving interaction of the particles with plasma waves gives a reasonable fit to some of the features of the energy spectra and the abundance ratios for several ions in the impulsive solar flares [35,[39][40][41][42]. However, some of the recent observations have shown that this canonical scenario of different acceleration mechanisms and characteristics for the impulsive and gradual flares is not always valid.…”

Section: High Energy Astroparticle Physics At Ooty and The Grapes-3 Ementioning

confidence: 99%

High Energy Astroparticle Physics at Ooty and the GRAPES-3 Experiment

Gupta¹

2014

Proceedings of the Indian National Science Academy

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The astroparticle studies at Ooty have their roots going way back into the fifties, when studies using cosmic rays were initiated with cloud chambers of progressively larger sizes as the primary detector and measuring device to obtain properties of hadrons at high energies. This study was subsequently strengthened with the installation of a total absorption calorimeter and a modest extensive air shower array to probe the composition of the primary cosmic rays to very high energies. The discovery of pulsars provided a thrust for the exploration of these compact objects as the sources of γ-rays at TeV energies with the aid of atmospheric Cerenkov detectors in the seventies. With the rapid technological advances occurring during the subsequent years in detectors, electronics and computers, physicists world-wide were able to set up very large and remarkably sensitive experiments that were hard to imagine a decade earlier. With the increasing sophistication and complexity the modern experiments require participation of very large teams of scientists. This development has made the formation of collaboration of large number of physicists both experimental and theoretical, engineers, technicians etc., from a number of institutions and universities, a prerequisite for setting up any major experimental facility. The GRAPES-3 experiment is a collaboration of 34 scientists from 13 institutions, including 8 from India and 5 from Japan. The GRAPES-3 experiment contains a dense extensive air shower array operating with ~ 400 scintillator detectors and a 560 m 2 tracking muon detector (Em > 1 GeV), at Ooty in India. 25 % of scintillator detectors are instrumented with two fast photomultiplier tubes (PMTs) for extending the dynamic range to ~ 5x10 3 particles m -2. The scintillators, signal processing electronics and data recording systems were fabricated in-house to cut costs and optimize performance. The muon multiplicity distribution of the EAS is used to probe the composition of primary cosmic rays below the 'knee', with an overlap with direct measurements. Search for multi-TeV γ-rays from point sources is done with the aid of the muon detector. A good angular resolution of 0.7 o at 30 TeV, is measured from shadow of the Moon on the isotropic flux of cosmic rays. Sensitive limit on the diffuse flux of 100 TeV γ-rays is placed by using muon detector to filter out the charged cosmic ray background. The tracking muon detector allows sensitive measurements on the coronal mass ejections and solar flares through Forbush decrease events. We have major expansion plans to enhance the sensitivity of the GRAPES-3 experiment in the areas listed above. PACS

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“…This was shown to be due to the finite width of the nonadiabatic region close to the neutral point which allows particles to gain or lose energy randomly resulting in a Fermi-type stochastic acceleration. Furthermore Petkaki and MacKinnon (2007),2011 found that certain frequencies were more effective at accelerating particles than others, through resonant interactions, since some particles were observed to gain energy outside of the central diffusion region (see also Guo et al (2010) and the analytical discussion of Litvinenko (2003)). …”

Section: Introductionmentioning

confidence: 99%

Particle Acceleration in the Presence of Weak Turbulence at an X-Type Neutral Point

2012

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We simulate the likely noisy situation near a reconnection region by superposing many 2D linear reconnection eigenmodes. The superposition of modes on the steady state X-type magnetic field creates multiple X-and O-type neutral points close to the original neutral point and so increases the size of the non-adiabatic region. We study test particle trajectories of initially thermal protons in these fields. Protons become trapped in this region and are accelerated by the turbulent electric field to energies up to 1 MeV in time scales relevant to solar flares. Higher energies are achieved due to the interaction of particles with increasingly turbulent electric and magnetic fields.

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Untitled

Cited by 17 publications

References 21 publications

Particle acceleration by fluctuating electric fields at a magnetic field null point

Particle acceleration by fluctuating electric fields at a magnetic field null point

High Energy Astroparticle Physics at Ooty and the GRAPES-3 Experiment

Particle Acceleration in the Presence of Weak Turbulence at an X-Type Neutral Point

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