Consequences of strong pitch-angle diffusion of particles in solar flares

Bespalov, P. A.; Зайцев, В. В.; Stepanov, A. V.

doi:10.1086/170127

Cited by 42 publications

(27 citation statements)

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“…Trapping of protons by mirroring at footpoints leads to the escape time of 2ρ 0 (L/v) (e.g., Hulot et al 1989), where ρ 0 is the footpoint mirror ratio. If this time is small relative to the trapping time by self-generated waves, L/(2V A ) (Bespalov et al 1987(Bespalov et al , 1991, one may regard neglecting the footpoint mirroring reasonable (cf. Kocharov et al 1999).…”

Section: The Modelmentioning

confidence: 99%

“…In application to impulsive γ-ray flares, the role of self-generated waves was emphasized by Bespalov et al (1987Bespalov et al ( , 1991. The transport conditions of protons in flaring loops determine the time scale for their precipitation.…”

Section: Introductionmentioning

confidence: 99%

“…Strong interaction with hydromagnetic waves is known to make the trapping of protons inside the loop efficient. Bespalov et al (1987Bespalov et al ( , 1991 studied the proton transport under the assumption that the protons stream away from a source located at the top of the loop, and generate Alfvén waves. They showed that for a sufficiently strong source, the waves would become so intense that the particles would essentially be locked on the waves and convect with them at Alfvén speed towards the footpoints of the loop.…”

Section: Introductionmentioning

confidence: 99%

“…One aspect of the turbulent trapping model missing from the original work of Bespalov et al (1987Bespalov et al ( , 1991 is that it could lead to interesting effects, if the flux tube is asymmetric with respect to the source position, and if transient processes are incorporated in the model. Scattering off self-generated waves at open magnetic field lines may also affect the interplanetary-to-interacting proton ratio.…”

Section: Introductionmentioning

confidence: 99%

“…The purpose of this paper is to study and extend the transport model of Bespalov et al (1987Bespalov et al ( , 1991, using a time-dependent numerical method. To simplify the model at this stage, we perform the study inside a single magnetic flux tube with constant values of the magnitude of the magnetic field and plasma density, and zero bulk speed of the thermal plasma.…”

Section: Introductionmentioning

confidence: 99%

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Proton transport through self-generated waves in impulsive flares

Vainio

Kocharov

2001

A&A

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Abstract. Energetic proton transport through self-generated Alfvén waves in impulsive (γ-ray) flares is studied using the method of Monte Carlo simulations. Protons are traced inside a flux tube after they are released from a point source located inside the loop until they hit the boundary of the 1-D simulation box and escape. As they stream from the source towards the boundaries, the particles generate Alfvén waves through the streaming instability. We consider both open and closed field lines. In the closed field line case, the escaping particles precipitate and produce observable secondary emissions; for the open field line, particles precipitate only from one end of the field line, and escape freely to the interplanetary medium from the other end. For a sufficiently large number of accelerated protons per unit area, n0VA/Ωp where n0 is the plasma density, VA the Alfvén speed, and Ωp the proton gyro-frequency, the particle flux from the source produces a turbulent trap that expands at Alfvén speed in both directions from the source. The resulting γ-ray emission from the loop legs consists of a precursor, related to the quick propagation of particles when the trap has not formed yet, and of a delayed brightening in the loop leg closer to the source, related to the opening of the turbulent trap as the self-generated waves reach the solar surface. For impulsive injections lasting L/(2VA), where L is the loop length, the second emission may be suppressed by adiabatic deceleration in the expanding turbulent trap. For open field lines, our model is capable of producing the small ratio of the numbers of interplanetary-to-interacting protons typically observed in impulsive flares, if the proton source is located close to the Sun.

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