Back to Volume
Paper: Flare Energy Conversion due to Direct Electric Fields Resulting from the Sheared Reconnection
Volume: 369, New Solar Physics with Solar-B Mission
Page: 477
Authors: Hirayama, T.
Abstract: We propose a new mechanism of the main energy conversion of the solar flare. Since a flare inducing prominence (flux tube) rises below Vz ≤ 300 km s−1, lasting plasma ejections with Alfvén speeds of 3000 km s−1 are impossible, requiring to discard the slow shock mechanism.

In a reconnecting morphology, we assume a magnetic component parallel to the photospheric neutral line, i.e. sheared fields By. Then Gauss’s law leads to non-zero electric charges σ: 4πσ = div(E + E||) = −div(V×B/c) ≈ By∂Vz/c∂x where the horizontal inflow velocity Vx change to vertical downflow Vz (e.g. ByBz = 40 G and x ≈ 104 km). Field-aligned electric fields Ek from Coulomb law using this σ are far greater than the Dreicer field (divE|| = 0 holds), and accelerate electrons and protons. Thus the horizontally inflowing Poynting energy flux in area Sx are immediately converted to the kinetic energy of electron beams along the magnetic field in area Sz; VxB2Sx/4π = me(nV3)beamSz/2 (Sx/Sz ≈ 3). The total energy can be supplied by 10 keV electrons and nbeam = 2 × 107 cm−3 for Vx = 40 km s−1, which ensures the short flare duration.

Back to Volume