Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.sao.ru/hq/katya/CosmosPh/en/Abstract_Pustilnik_3.txt Дата изменения: Wed Feb 24 16:35:49 2010 Дата индексирования: Tue Oct 2 12:30:28 2012 Кодировка: Поисковые слова: horizon

"Solar Flare Origin - critical analysis"

Lev Pusti'lnik

We analyze current approach to solar flare origin in 3 aspects:
a. Pre-flare equilibrium state of current-magnetic structure above active
region and its evolution to flare state,
b. Possible reasons of stability loss with transition of system in flare
state
c. Flare energy release in turbulent current sheet and particle acceleration
in this system.
We show that standard consideration of pre-flare state base on potential
fields with some force-free adds, generated by motion on photosphere level,
is in evident contradiction with observational facts of the last years: fine
structure of magnetic fields on photosphere level (with dominated part of
magnetic flux concentrated in small part of area in strong field threads/
ropes with conserved fractal dimension) and fine structure of coronal
magnetic-current structure based on numerous magnetic threads-arcs (observed
in X-ray and UV). We show that observed configuration can not be considered
as quasi-static equilibrium, but in opposite, is in very active state of
dynamic equilibrium of ensemble of individual current-magnetic local element
and strong interaction between them.
We consider global current as control parameter, cause catastrophic
transition of the system of currents into flare state and analyze possible
role of external disturbances as possible triggers of flare process.
We consider flare energy release in final .flare. state of current-magnetic
system and show that observed extra high power of flare energy release demand
existing of extremely thin turbulent current sheet (TCS). We show that, from
other side, this TCS is absolutely unstable relative to dissipative modes,
pinch-like modes and overheating modes. In result TCS must disrupt to
numerous domains of .turbulent. and .normal. plasma with very high aand very
low resistance, correspondently. This situation may be described by process
of current percolation through random resistor.s network with dependence
resistance from current of threshold like type. New equilibrium state of
current, percolated through resistor.s network with current. dependent
resistors lead to new state of dynamical equilibrium, controlled by global
current value. This percolation process is base of well known effects of
phase transitions from insulator to conductor or from conductor to
superconductor and may explain different mysterious properties of flare
process: sudden start of flare itself in large volume, precursors and
pre-fluctuation preceded to flare state, power spectrum of amplitude-
frequency distribution, power spectrum of accelerated particles in their
energy.