Particle acceleration at an X‐type reconnection site with a parallel magnetic field

Browning, Philippa; Vekstein, G.

doi:10.1029/2001ja900014

Cited by 49 publications

(39 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…their gyro-radii are much smaller than the field's scale length), their energies are approximately the same as for electrons. The small noticeable difference is most likely due to the difference in the initial thermal velocities, which are comparable to the drift velocity u E for protons and much higher than u E for electrons (see discussion in Vekstein & Browning 1997;Browning & Vekstein 2001).…”

Section: Particle Energy Spectramentioning

confidence: 99%

“…This approach has previously been used to study particle acceleration in RCS by many authors (see e.g. Browning & Vekstein 2001;Giuliani et al 2005). It is important to note that the present adiabatic approach is valid because we consider non-neutral RCS; i.e., the magnetic field is non-zero everywhere.…”

Section: Main Equationsmentioning

confidence: 99%

“…Kliem (1994) used the test-particle approach to study acceleration by fragmentary electric field in the reconnection region and shows that particles can be accelerated to near-relativistic energies within ∼10 −2 s. Miller (1997) considered test-particle acceleration by the fast-mode wave and find that pitch angle scattering is essential for electron acceleration. A self-consistent approach combining analytically derived magnetic and electric field configurations with test-particle calculations was used by Browning & Vekstein (2001) to study particle motion in a 2D model and determine the resulting energy spectra. Zharkova & Gordovskyy (2004) considered particle orbits in simple non-neutral CS and show that, in the presence of a strong longitudinal magnetic field, electrons and protons may be ejected separately.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Particle acceleration in a transient magnetic reconnection event

Gordovskyy¹,

Browning²,

Vekstein³

2010

A&A

Self Cite

View full text Add to dashboard Cite

Context. In the present paper, we investigate particle acceleration by direct electric field in solar flares. Aims. Proton and electron kinetics are considered based on MHD simulations of magnetic reconnection, with the aim of determining the properties of accelerated particles in a time-dependent reconnecting event model. Methods. At first, we considered several two-dimensional numerical models of forced reconnection in the initially force-free Harris current sheet. The electric and magnetic fields from these models were then used to study proton and electron motion with the guiding centre, test particle approach. Results. It is shown that protons and electrons can be accelerated to very high energies up to tens of MeV in the present model. The energy spectra for both particle species are combinations of exponential and rather hard power-law shapes. Also, protons and electrons are ejected from the CS in different directions.

show abstract

Section: Particle Energy Spectramentioning

confidence: 99%

Section: Main Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Particle acceleration in a transient magnetic reconnection event

Gordovskyy¹,

Browning²,

Vekstein³

2010

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Typically, these are either (two-dimensional) null point configurations or current sheets, or a combination of both, in many cases including a guide field in the invariant direction (e.g. Bulanov & Sasorov 1976;Bruhwiler & Zweibel 1992;Kliem 1994;Litvinenko 1996;Browning & Vekstein 2001;Zharkova & Gordovskyy 2004Wood & Neukirch 2005;Hannah & Fletcher 2006;Drake et al 2006;Gordovskyy et al 2010a,b).…”

Section: Introductionmentioning

confidence: 99%

Particle acceleration at a reconnecting magnetic separator

Threlfall

Neukirch

Parnell

et al. 2015

A&A

View full text Add to dashboard Cite

Context. While the exact acceleration mechanism of energetic particles during solar flares is (as yet) unknown, magnetic reconnection plays a key role both in the release of stored magnetic energy of the solar corona and the magnetic restructuring during a flare. Recent work has shown that special field lines, called separators, are common sites of reconnection in 3D numerical experiments. To date, 3D separator reconnection sites have received little attention as particle accelerators. Aims. We investigate the effectiveness of separator reconnection as a particle acceleration mechanism for electrons and protons. Methods. We study the particle acceleration using a relativistic guiding-centre particle code in a time-dependent kinematic model of magnetic reconnection at a separator. Results. The effect upon particle behaviour of initial position, pitch angle, and initial kinetic energy are examined in detail, both for specific (single) particle examples and for large distributions of initial conditions. The separator reconnection model contains several free parameters, and we study the effect of changing these parameters upon particle acceleration, in particular in view of the final particle energy ranges that agree with observed energy spectra.

show abstract

“…Speiser 1965Speiser , 1967Bruhwiler & Zweibel 1992;Mori et al 1998;Browning & Vekstein 2001;Zharkova & Gordovskyy 2004;Efthymiopoulos et al 2005;Hannah & Fletcher 2006). The conclusion from these test particle calculations is that with larger electric fields and with additional guiding magnetic fields in the current sheet, particles can be accelerated more efficiently.…”

Section: Introductionmentioning

confidence: 99%

Is the 3-D magnetic null point with a convective electric field an efficient particle accelerator?

Guo

Büchner

Otto

et al. 2010

A&A

View full text Add to dashboard Cite

Aims. We study the particle acceleration at a magnetic null point in the solar corona, considering self-consistent magnetic fields, plasma flows and the corresponding convective electric fields. Methods. We calculate the electromagnetic fields by 3-D magnetohydrodynamic (MHD) simulations and expose charged particles to these fields within a full-orbit relativistic test-particle approach. In the 3-D MHD simulation part, the initial magnetic field configuration is set to be a potential field obtained by extrapolation from an analytic quadrupolar photospheric magnetic field with a typically observed magnitude. The configuration is chosen so that the resulting coronal magnetic field contains a null. Driven by photospheric plasma motion, the MHD simulation reveals the coronal plasma motion and the self-consistent electric and magnetic fields. In a subsequent test particle experiment the particle energies and orbits (determined by the forces exerted by the convective electric field and the magnetic field around the null) are calculated in time.Results. Test particle calculations show that protons can be accelerated up to 30 keV near the null if the local plasma flow velocity is of the order of 1000 km s −1 (in solar active regions). The final parallel velocity is much higher than the perpendicular velocity so that accelerated particles escape from the null along the magnetic field lines. Stronger convection electric field during big flare explosions can accelerate protons up to 2 MeV and electrons to 3 keV. Higher initial velocities can help most protons to be strongly accelerated, but a few protons also run the risk to be decelerated. Conclusions. Through its convective electric field and due to magnetic nonuniform drifts and de-magnetization process, the 3-D null can act as an effective accelerator for protons but not for electrons. Protons are more easily de-magnetized and accelerated than electrons because of their larger Larmor radii. Notice that macroscopic MHD simulations are blind to microscopic magnetic structures where more non-adiabatic processes might be taking place. In the real solar corona, we expect that particles could have a higher probability to experience a de-magnetization process and get accelerated. To trigger a significant acceleration of electrons and even higher energetic protons, however, the existence of a resistive electric field mainly parallel to the magnetic field is required. A physically reasonable resistivity model included in resistive MHD simulations is direly needed for the further investigations of electron acceleration by parallel electric fields.

show abstract

Particle acceleration at an X‐type reconnection site with a parallel magnetic field

Cited by 49 publications

References 23 publications

Particle acceleration in a transient magnetic reconnection event

Particle acceleration in a transient magnetic reconnection event

Particle acceleration at a reconnecting magnetic separator

Is the 3-D magnetic null point with a convective electric field an efficient particle accelerator?

Contact Info

Product

Resources

About