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MODELING AND OBSERVATION OF PARTIALLY IONIZED PLASMA PROCESSES
Elena Khomenko Instituto de Astrofísica de Canarias (IAC), Tenerife, Spain
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MULTI-FLUID CHROMOSPHERE
collisions ion-neutral
collisions neutral-ion
ion cyclotron, B=175 G
ion cyclotron, B=15 G
wave, period 1 sec
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MULTI-FLUID IS CRUCIAL at SMALL SCALES
SHOCKS Vi Vn
INSTABILITIES
Vn
B
RECONNECTION
Vi
Vi
Vi ,Vn
B
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OBSERVATIONS vs MODELS
Leenaarts et al. 2015
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Where do we stand with multi-fluid simulations?
MULI-FLUID EFFECTS
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FAST WAVE SHOCKS by Draine & McKee (1993)
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SLOW WAVE SHOCKS by Hillier et al (2016)
see also Snow and Hillier 2019 for polarity reversal at shock fronts Ballai et al. 2018 for dispersive shocks including Hall currents
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FAST WAVE SHOCKS in the CHROMOSPHERE
Popescu Braileanu et al. 2019
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FAST WAVE SHOCKS in the CHROMOSPHERE
Popescu Braileanu et al. 2019
Strong frictional damping of shocks
Shocks disappear after some height
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FRICTIONAL HEATING
Popescu Braileanu et al. 2019
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FRICTIONAL HEATING: 2D SIMULATIONS
Maneva, Alvarez Laguna, Lani, Poeds (2017)
Interplay between frictional heating and ionization effects Multi-dimensional stratifications bring complexity
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Progress with realistic simulations including generalized Ohms law?
SINGLE-FLUID
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(1) AD increases the temperature in the chromosphere; (2) AD concentrates electrical currents, leading to more violent jets; (3) Formation of longer and faster spicules; (4) Decoupling of the plasma and magnetic field in spicules.
Martínez-Sykora et al. 2012, 2017
2D MAGNETO-CONVECTION & AMBIPOLAR DIFFUSION
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3D DYNAMO SIMULATIONS + AD + HALL EFFECT
Khomenko, Vitas, Collados, de Vicente 2018; Gonázlez-Morales et al. 2019
Seeded by battery effect Saturated field strength ~ 100 G Include chromospheric heights
Ideal MHD (only battery effect)
+ Ambipolar
diffusion
+ Ambipolar diffusion + Hall
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VERTICAL POYNTING FLUX: SPECTRA
V & B vectors
Calculate ideal PF Fourier-transform
Average power over horizontal directions, X-Y
X Y
Z
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POYNTING FLUX
Gonázlez-Morales et al. 2019
AD: Up to 50% absorption of Poynting Flux HALL: Production of Poynting Flux in the form of Alfvén waves
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EFFECT FOR AVERAGE TEMPERATURE
Temperature no ambipolar diffusion
with ambipolar diffusion
Low bond on the chromospheric temperature increase
with ambipolar diffusion & Hall
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Observational confirmation of multi-fluid effects ?
MULI-FLUID EFFECTS
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DIRECTION of CHROMOSPHERIC FILAMENTS
de la Cruz Rodríguez & Socas-Navarro 2011; Asensio Ramos, de la Cruz Rodrigues et al. 2017
Misalignment between chromospheric fibrils and magnetic field
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Martínez-Sykora, De Pontieu, Carlsson et al. 2017
DIRECTION of CHROMOSPHERIC FILAMENTS
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Hα He I D3 Ca II IR
Khomenko, Díaz, Collados (2016)
DIRECT DETECTION of ION-NEUTRAL DRIFTS
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Velocity comparison: Sr II - Na I spectral lines
Wiehr, Stellmacher, Bianda (2019)
DIRECT DETECTION of ION-NEUTRAL DRIFTS
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Velocity comparison: Ca II H, Hε, Hγ, Ca II 8542 A
Anan, Ichimoto & Hillier (2017)
DIRECT DETECTION of ION-NEUTRAL DRIFTS
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CROSS-FIELD DIFFUSION of NEUTRALS
Gilbert et al. (2002, 2008)
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SUMMARY
ü At shocks, producing multi-fluid structure at shock fronts and frictional heating;
ü At current layers, helping efficient dissipation of currents perpendicular to the magnetic field, contributing to the energy balance;
ü By modifying the field structure and favoring production of Alfvén waves; ü In prominences, producing cross-field diffusion, and influencing stability; ü In filaments and spicules, by making the material moving not aligned
with the field; ü For sure in reconnection & turbulence (could not cover the topic due to the lack of time)
Ion-neutral effects definitely play important role in the chromosphere