Acceleration of charged particles by gyroresonant surfing at quasi-parallel shocks

Kuramitsu, Yasuhiro; Krasnoselskikh, V.

doi:10.1051/0004-6361:20042283

Cited by 20 publications

(20 citation statements)

References 34 publications

(41 reference statements)

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“…Such trapping was referred to as "nonresonant trapping" in the past study. 12 Since phase velocities of Alfvén waves with significant wave power are close to Alfvén speed ͑V A =1͒, ions are mainly scattered in the v ix − ͉v iЌ ͉ phase space keeping ͑v ix −1͒ 2 + ͉v iЌ ͉ 2 = V 2 = const due to the nonresonant pitch angle scattering. The approximate trapping region is given by the first integral of equation of individual ions 11,12 H = − ͉b͉ ͱ 1 − 2 cos +…”

Section: B Time Evolution Of the Vdfsmentioning

confidence: 99%

“…Recent studies using test particle simulations 6,7,9 and quasilinear theories 8,10 have also demonstrated that the nonresonant scattering by finite-amplitude Alfvén waves 11,12 leads to the perpendicular "pseudoheating" of ions, without dissipation of wave energy. 7,8 Araneda et al 3 have recently proposed an interesting scenario for generating a beam proton distribution when large amplitude Alfvén waves are present.…”

Section: Introductionmentioning

confidence: 99%

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Heating and acceleration of ions in nonresonant Alfvénic turbulence

2010

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Nonlinear scattering of protons and alpha particles during the dissipation of the finite amplitude, low-frequency Alfvénic turbulence is studied. The process discussed here is not the coherent scattering and acceleration, as those often treated in the past studies, but is an incoherent process in which it is essential that the Alfvénic turbulence has a broadband spectrum. The presence of such an Alfvénic turbulence is widely recognized observationally both in the solar corona and in the solar wind. Numerical results suggest that, although there is no apparent sign of the occurrence of any parametric instabilities, the ions are heated efficiently by the nonlinear Landau damping, i.e., trapping and phase mixing by Alfvén wave packets which are generated by beating of finite amplitude Alfvén waves. The heating occurs both in the parallel and in the perpendicular directions, and the ion distribution function which is asymmetric with respect to the parallel velocity is produced. Eventual perpendicular energy of ions is much influenced by the spectrum and polarization of the given Alfvénic turbulence since the turbulence initially possess transverse energy as specified by Walen's relation.

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Section: B Time Evolution Of the Vdfsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heating and acceleration of ions in nonresonant Alfvénic turbulence

2010

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“…The mechanism proposed here can act alone and/or in combination with some other phenomena like shocks that are also known to accelerate particles (Sandroos & Vainio 2009;Kuramitsu & Krasnoselskikh 2005;Aran et al 2007). Together, the two phenomena may transport particles to high altitudes and provide physical explanation for the observations of solar energetic particles at high latitudes.…”

Section: Discussionmentioning

confidence: 99%

Transport and diffusion of particles due to transverse drift waves

Vranjes

2011

A&A

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Transport and diffusion of plasma particles perpendicular and parallel to the magnetic field is discussed in the framework of the transverse drift wave theory. The starting model includes the density and magnetic field gradients perpendicular to the magnetic field vector. In such an inhomogeneous environment the transverse drift wave naturally develops. The transverse drift wave is a low frequency mode, with the frequency far below the ion gyro-frequency, it is driven by these gradients and it propagates perpendicular to them. The mode is also purely perpendicular to the magnetic field and it is electromagnetically transverse, which implies that when its wave vector is perpendicular to the magnetic field vector, the perturbed electric field is along the equilibrium magnetic field, while in the same time the perturbed magnetic field is in the direction of the background gradients. In application to the solar wind, it is shown that very small wave electric field amplitude, of the order of 10 −7 V/m, within one wave period can produce the drift of protons in both directions, perpendicular to the ecliptic plane and also along the background magnetic field, to distances measured in millions of kilometers. The electric field along the magnetic field vector implies particle acceleration in the same direction. When a critical threshold velocity of the particle is achieved, the particle motion becomes stochastic. This is a completely new nonlinear stochastic mechanism which follows from the very specific geometry of the transverse drift mode. Particle drift perpendicular to the magnetic field vector means a diffusion of particles, with the effective diffusion coefficient for ions that is at least 11 orders of magnitude larger than the classic diffusion coefficient. The features of this diffusion are: within certain time interval, initially faster particles will diffuse to larger distances, and the same holds for protons in comparison to heavier ions. For electrons the effective diffusion coefficient can easily match the one obtained from observations, i.e., to become of the order of 10 17 m 2 /s. It is also expected that the wave-induced stochastic motion will considerably increase the effective collision frequency in such an environment which is, with respect to its mean parameters, practically collision-lees. Hence, the solar wind regions affected by such a stochastic acceleration may show various unexpected features that are typical for collisional plasmas.

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“…In general, nonlinear motion of a single particle in a one-dimensional space has been analyzed based on the Hamiltonian for the particle motion (e.g., Kuramitsu and Krasnoselskikh, 2005). In the presence of finite amplitude MHD wave with a single mode, the corresponding Hamiltonian can be described as a time-independent function in phase space coordinates which are pitch angle cosine in the wave rest frame µ and phase ψ between transverse magnetic field fluctuation and transverse velocity vectors.…”

Section: Single Particle Motionmentioning

confidence: 99%

Energetic particle parallel diffusion in a cascading wave turbulence in the foreshock region

Otsuka

Omura

Verkhoglyadova

2007

Nonlin. Processes Geophys.

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Abstract.We study parallel (field-aligned) diffusion of energetic particles in the upstream of the bow shock with test particle simulations. We assume parallel shock geometry of the bow shock, and that MHD wave turbulence convected by the solar wind toward the shock is purely transverse in one-dimensional system with a constant background magnetic field. We use three turbulence models: a homogeneous turbulence, a regular cascade from a large scale to smaller scales, and an inverse cascade from a small scale to larger scales. For the homogeneous model the particle motions along the average field are Brownian motions due to random and isotropic scattering across 90 degree pitch angle. On the other hand, for the two cascade models particle motion is non-Brownian due to coherent and anisotropic pitch angle scattering for finite time scale. The mean free path λ calculated by the ensemble average of these particle motions exhibits dependence on the distance from the shock. It also depends on the parameters such as the thermal velocity of the particles, solar wind flow velocity, and a wave turbulence model. For the inverse cascade model, the dependence of λ at the shock on the thermal energy is consistent with the hybrid simulation done by Giacalone (2004), but the spatial dependence of λ is inconsistent with it.

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Acceleration of charged particles by gyroresonant surfing at quasi-parallel shocks

Cited by 20 publications

References 34 publications

Heating and acceleration of ions in nonresonant Alfvénic turbulence

Heating and acceleration of ions in nonresonant Alfvénic turbulence

Transport and diffusion of particles due to transverse drift waves

Energetic particle parallel diffusion in a cascading wave turbulence in the foreshock region

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