The helicity, induced electric field and the Poynting flux of AR 11158 and their relationship with the X-class flare

Liu Jihong, liujh@bao.ac.cn, Shijiazhuang University, China
Su jiangtao, National Astronomical Observatories
Zhang hongqi, National Astronomical Observatories

Abstract
With the convnient of the observing data of vector magnetic fields in the potosphere provided by SDO team, the helicity accumulation, induced electric field and the Poynting flux of the solar magnetic field, which have been considered as appropriate representations of the magnetic non-potenciality, have been calculated for AR 11158 by using the local correlation tracking technique. It is found that the helicity accumulation reaches 6000?10^40Mx^2, the average of the mean densities of the induced electric field reaches about 0.15~0.35 V cm^-1, and that of the Poynting flux reaches about 50~240 W m^-2. The X2.2 flare occurred in the increasing phase of the helicity accumulation after its slope changing to a smaller one, in the decreasing phase of the evolution of the averages of induced electric field and the flatness phase of that of the Poynting flux, which had all evolved from increasing phases persisted for about 20 hours and changed 8~9 hours before the flare.