ISRAEL COSMIC RAY and SPACE WEATHER CENTER
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Pre-Introduction
ISRAEL COSMIC RAY and SPACE WEATHER CENTER
Main Components of ISRAEL SPACE WEATHER CENTER
• Israel-Italy Cosmic Ray Emilio Segre Observatory
• Hermon site of National Network of VLF/ULF/ELF antennas
• Hermon site of the National network of magnetographs
• ConCam optical Meteor Survey Sheffield, 20.03.2015
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PARTICIPANTS and
EQUIPMENT of Space
Weather Center
Israel Cosmic Ray and Space Weather
Center (ICRSWC) of Tel Aviv University
– Cosmic Rays
Geophysics and Planetary Sciences
Department (GPSD) of Tel Aviv
University– Ionosphere, Atmospheric
Discharge
Research Department of Survey Of
Israel (SOI) – magnetometers
Magnetosphere and magnetic storms
Departm. of Natural Science of Open
University (DNSOU) - Ionosphere
Wise Observatory of Tel Aviv University
(WOTAU) - ConCam meteors patrol
- Meteors
Kinneret Limnological Laboratory (KLL)
team of Dr. Alon Rimmer - atmosphere
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Sheffield, 20.03.2015
Price of space weather knowledge for space technology
1. Price of space technology (include space
stations) in 2013 is about
1000,000,000,000$ =1012 $$
Insurance claims: (800 – 1400)*106 yearly
2. 2014 year – more then 400 communication
satellites provide above 2*109 users by mobile
communication + GPS
As example – crash of SkyLab mission 25 m* 7 m with loss 600 millions $$) in 1979.
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Main driver of Space Weather Storms –
Solar Flares
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Solar Flare Origin – critical analysis of existed
picture
Lev Pustil’nik, Israel Cosmic Ray & Space Weather Center, TAU-ISA
Standard approach to system analysis Solar Flare:
1. Equilibrium state – balance of forces 1. Energy Source and pre-flare
Equilibrium State
2. Possibility of catastrophe state :
1. Point of loss of stability with transition 2. Triggers – Instability –
to new physical equilibrium state = (Catastrophe Phase Transition)
phase transition
3. Flare Energy Release itself -
2. Trigger mechanisms
stationary process of abnormal
3. Transition process to new magnetic field dissipation to
equilibrium state plasma turbulence, plasma heating
and particle acceleration.
Sheffield, 20.03.2015
Solar Flare: Source, Pre-flare equilibrium state, Triggers,
Energy release, Particle acceleration
Eth ~ Ekinetic ~ Eparticles
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Sheffield, 20.03.2015
Solar Flare: Source, Triggers, Energy Release, Particle
acceleration
• Magnetic energy, non-potential component ∆H to potential H0
• Source ∆H – development of sunspots, its motion and rotation
• Location – current sheet in contact region between different magnetic fluxes:
• Necessary conditions for flare energy release (Qfl=1029 erg/sec):
( ∆ H )2 1
J2
Q∝ ∝ ⋅
σ d 2
σ
or d→d*
Pre-flare equilibrium state
• Standard approach – quasi-potential magnetic field restored
from boundary condition (photosphere field Hp) and Laplas
equation ∆H 1 = 0 with multi-pole geometry and small adds
of non-potential force-free field with α - constant or smooth
function rotH 2 = αH 2
+ Singular points (X,Y) – lines identified with future current sheet
– it lose mean, if to take into account real magnetic shear (Hz≠0)
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What we see in really: Flare of Bastille Day – numerous
arc-like thin very thin (d=100-500 km) arc-like threads
Sheffield, 20.03.2015 10Basic elements of flare – numerous arc-like threads!
Dynamical equilibrium !!!
11 Sheffield, 20.03.2015Main contradiction with observations:
Direct sequence : absence of force-free equilibrium
in transitions between individual force-free current
magnetic threads (Parker): strong interacted force-
free threads-arcs with dynamic equilibrium of
global structure 12
Sheffield, 20.03.2015Fine current-magnetic structure start from
photosphere
Observations of photosphere magnetic field with high angular
resolution:
numerous magnetic points (1000 G)
– dominated part of the magnetic flux + fractal nature of magnetic
threads in photosphere
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Sheffield, 20.03.2015New approach to pre-flare equilibrium state of current-
magnetic structure above active region
• In spite quasi static equilibrium
global force-free fields with slow
evolution of α we observe
dynamical equilibrium of ensemble
of numerous current-magnetic
threads with strong magnetic field,
with cross interaction between
nearest threads and self organization
of ensemble to equilibrium state and
possibility of critical state.
• Manifestations – statistical
properties of ensemble
Problem 1: Correct description of equilibrium state of unforce-free ensemble
of force-free very thin current-magnetic arcs/threads with constant section
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and strong interaction between contacted threads.
Sheffield, 20.03.2015Triggers=What is a reason for transition to flare state: slow
evolution or external trigger disturbances?
• Possible drivers: Increasing of
global current in system, caused by:
– fast change of photosphere
fields, fast birth and
development of new AR
(October 2003)
– emergency of new magnetic
flux in bottom of old AR,
– collision of magnetic fluxes of
active regions
• Observational statistics: >90%
strong flares preceded birth of new
EMF several hours- tens hours
before flare.
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Sheffield, 20.03.2015Trigger mechanisms of flare – disturbance-initiator
1.New Merged Magnetic Flux (both energy source and trigger)
–Observed in several hours – tens hours before major part of flares
2. External disturbances, generate dstubance Δj near critical state with j≤jcr:
a. Flute instabilities of Quiescent Prominence
overloaded by siphon supply mass in prominence
– typical for 85% flares for Hα class >2 – precursors
“disappeared filaments” 1 hour before flare
(Mikhailutsa, Hinode group, Stepanov-Zaitsev)
b. Flute instability of Coronal Condensations
overheated by corona heating – precursors as pre-flare oscillations in radio and X-ray before
strong proton flares (Kobrin)
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Sheffield, 20.03.2015Energy Release – current dissipation in the turbulent current sheet
Θ=
(
∂ Hξ Hψ ) ≠0
∂z
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Sheffield, 20.03.2015Problems of flare energy release – 2
Instability of the turbulent current sheet
1.Drift-dissipative instabilities (σ ≠∞) like to tearing-mode,
swiping mode (∇σ ≠0), … during cross-dissipation time will s 1− s
split current sheet into set of linear currents τ tearing ≈ τ Aτ d ,
Result – fast disruption of the thin current sheet
into set of linear currents – magnetic islands (τ A = d / VA ; τ d = d 2 ( c 2 4πσ ))
(in 3-d -confusion of current treads)
2. Fast pinch like instabilities of the linear currents in
the disrupted current sheet – “sausage”, “kink”,
“twist” instabilities with
τ pinch ≈ τ A ≈ d / V A
2. Accumulation of linear current in numerous bundles
with u=j/ne>uc , generation of plasma turbulence => fast
current dissipation in the points of a current rupture
(like to explosion in the electric lamp, caused by
glower disruption)
3. Overheating of turbulent domain with suppression instability
4.”Splitting” of boundary of turbulent current sheet
with σ(j)-threshold like
•Final result: disruption of the thin current sheet into
numerous domains of “normal” and “turbulent”
states with current percolation from them:
Flare as Current Percolation through Random Resistor’s Network of turbulent
and normal domains (with threshold dependence of resistance from local
current in elements J/Jcr 18
Sheffield, 20.03.2015Main properties of current percolation through random resistor’s
network –applications to solar flares -1
1. Threshold dependence of global net conductivity Σnet
on the density of “bad” elements pc (global current J0):
Σ net ∝ ( J − J cr ) −α
Flare as phase transition in random resistors network
(semi-conductors, metal/ceramic superconductors, polymer’s chains, neuron nets) with resistance
nonlinearly dependence of elements resistance on local current Jik
This sharp transition is able to explain the mysterious ''flare's''
character of flare itself – flare as a result of current dissipation
in numerous discharges on turbulent “bad” resistors
(“electrostatic double layers”) blocked percolation through net.
1. Self generation of high amplitude
macro-fluctuations of global conductivity
near threshold state (J0≈Jcr)
– explanation of numerous pre-flare bursts and pre-flare heating, observed as activation of micro-
flares in many cases before flare itself.
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Sheffield, 20.03.2015Main properties of current percolation through random resistor’s
network –applications to solar flares -2
•Universal power character of the amplitude-frequency
spectrum for percolated networks
N (W ) ∝ W − n
based on the fundamental property of percolated clustered
resistors network - power dependence of number of
elements in cluster s from domain size x :
N ( x) ∝ x − k
The exponents α,k are determined by the fractal
dimension of the clusters, global dimensions of the system
n, and feedback current-resistance-current.
The same universal amplitude-frequency spectrum is
observed for all flare stars (red dwarfs of UV Ceti type)
and for different manifestations of solar flares, in
microwave bursts and type I noise storms – avalanche
model (Lu & Hamilton; Crosby, Aschwanden & Dennis;
Krasnoselskikh, Lefebvr & Podryadchikova; Vlakhos et
al.)
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Sheffield, 20.03.2015Description of flare process is dynamic equilibrium in
percolated resistors network with saltatory resistance R(j)
• Saltatory dependence of local resistance on local current in element of network
Rik = R0 for jik < jcr ; Rij = Rt ≈ 106 R 0 for jik > jcr ;
• Kirghof laws in resistors network:
ji = ∑ jik = I 0 ; ∆Vik = ∑ jik Rik ≠ f ( sik )
k
• Inputted full current input J0 is control parameter of the system :
J0 = ∑ Ji
i
• Integrated power of flare energy release is
Q* = ∑ J Ri i
2
bad
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Sheffield, 20.03.2015Solar Flare: Source, Triggers, Energy Release, Particle acceleration
Particles acceleration in the turbulent current sheet: charged particles
propagation through ensemble of clusters of “electrostatic double layers”
•Turbulent domain with j>jcr= necSi and abnormal conductivity
σ * = ω02e ( 4πν eff ) = 10 2÷3 Ω 0i (ν eff 0.1 ⋅ Ω 0i )
is electrostatic turbulent double layer with electric field:
E = jcr σ * = ( ne ⋅ cSi ) ( 10 2÷3 Ω 0i )
Effective energy, what particle obtain in the current sheet, included clusters of turbulent domains-electrostatic double layers
will be proportional number of turbulent elements in the way along regular electric field (z-direction) or length of the cluster
of double electric layers, what particle cross: ε ≈ eE*l z with maximal value
−k
ε max ≈ eE* L = 109÷10 ev ⋅ ( n8k T7n Lm9 ) N lz ∝ l z
From the another side probability or number of cluster with size lz in the percolated network of random resistors has power
dependence from the size of cluster: −k
N (ε = eE* l z ) ∝ N ( l z ) ∝ l z ∝ ε −k
So, resulted energetic spectrum of the accelerated particles must be, naturally, power type:
with k depend on dimension of the process in turbulent current sheet and dependence in
dynamics"resistance>current>resistance>…”
So, power spectrum of accelerated particles in the percolated current sheet, included random mixture
of “electrostatic double layers” is direct sequence of power statistics of clusters in percolated random
network near percolated threshold. 22
Sheffield, 20.03.2015Conclusion
• Observed equilibrium state is not potential or force-free magnetic structure with singular
points..
• Observation forced us to consider as basically situation ensemble with numerous thin
magnetic and current threads (forced-free inside and with strong interaction with surrounded
fields) and stabilized by freezing into massive photosphere in bottom.
• The threads interact one with another, percolate and redistribute free magnetic energy and
tension through ensemble with self-organization by percolation. Finally equilibrium is not
static as in standard model, but dynamical with permanent redistribution. Increasing totally
current J0 through system up to critical lead to phase transition and formation of ensemble of
current sheets with reconnection and tubulisation (flare state).
• Dissipative instabilities in formed turbulent current sheet+ overheating of turbulent plasma
by turbulent anomalous heating and splitting of current sheet convert initially current sheet to
percolated resistor’s network with two kind of resistors with salutatory conductivity on
threshold value of the local currents (J=Jcr).
• This approach consider solar flare phenomena as phase transition in random percolated
network of resistors and naturally explain power spectrum of amplitude spectrum of flares
and bursts, and universal power spectrum of accelerated particles.
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