Partially Ionized Plasma Effect in Dynamic Solar Atmosphere

Partially Ionized Plasma Effect inDynamic Solar AtmosphereNaoki Nakamura2015/07/05Solar Seminar

200MmAsai + (2003)Solar flareChromospheric jets

Hinode CaII HSolar Activity with Emerging flux20 MmSolar chromosphereHinode XRTHinode SOT

Difficulty of observation of chromospherePhotosphere ChromosphereCoronaobservationContinuum +line Line EUV line+ X-ray RadiationOptically thick? Optically thin Local thermodynamic equilibrium (LTE)Yes No No Association with physical variables Source function is nearly equal to Planck function => Intensity is highly relates to local gas temperaturePhotospheric radiation field affect excitation states of atoms , which relates to line.=> Intensity could not determined by local physical variablesEM : is proportional to density squared

Line intensity is highly depend on associate ionization degree, which relates to temperature It is difficult to estimate physical variables from chromosphere observationSolar chromosphereHinode XRTHinode SOT

Chromosphere (partially ionized plasma)Emerging flux activityin solar atmosphereCurrent sheet

Shibata et al. 2007Corona(fully-ionized plasma) Photosphere(weakly ionized plasma) What height and physics are important ?Reconnection is same in all layer?Plasma and magnetic fieldMagnetic fieldLorentz Forcegyration)

-+Charged ParticlesElectric field Frozen inPlasma is frozen into magnetic fieldPlasma-+Break of frozen in -+Plasma pass through fieldNon-ideal effectHall EffectElectron gyration Ion no gyration Magnetic fieldepex1:Difference of Larmor radiusIon Larmor radius > Characteristic scale>Electron Larmor radiusPnnnex2:Collisional frequency difference to neutrals(high density partially ionized plasma)

Charged particle cannot gyrate if collisional frequency to neutral become large

Ion collisional time1000km) Ambipolar[Sunspot]Lower atmosphere: Hall Higher atmosphere (>300 km) Ambipolar

Minimum magnetic structure by non-ideal effect (Quiet Sun)

Time and spatial scale comparable to advection termMinimum magnetic structure by non-ideal effect (Sunspot umbra)Time and spatial scale comparable to advection term

Discussion

From bottom to upper atmosphere Reconnection picture change Sweet-Parker-like (photosphere)

Petschek-like (lower chromosphere)

Sweet-Parker-like (upper chromosphere)Quiet Sun?Dynamic atmosphereSolar Atmosphere is not static =>Dynamic Atmosphere!

What is a effect of dynamic parameterchange in active phenomena?

Carlsson & Stein 1995Temperature change on time

Leake & Arber 2006 Left : fully-ionizedRight : partially-ionizedAmbipolar diffusion effect life up magnetic field moreEmerging flux in partially ionized plasmaParameter change in emerging-flux

Leake & Arber 2006 Thin Solid: fully ionized case, Dashed :with ambipolar diffusion

Plasma parameter greatly change during emerging flux with ambipolar diffusion=>Dynamic atmosphere is necessary to understand chromopheric reconnection Discussion (Dynamic atmosphere)Ambipolar diffusion approximation (single fluid description) assuming plasma pressure and inertia is much less than Local thermodynamic equilibrium (LTE)

Two fluid description is necessary

Summary Solar atmosphere is gravitationally stratified partially ionized plasma and dominant source of non-ideal effect is different with heightPhotosphere: Ohmic diffusionLower chromosphere : Hall effect Upper chromosphere :ambipolar diffusion

Non-ideal effect to magnetic reconnection is difference in Hall and ambipolar effect

Non-static atmosphere, plasma parameters is much difference in static atmosphere. =>Full simulation is important to understand such a phenomenaGravitational stratificationTwo fluid stratification (no-magnetic field)AFR atmosphere equilibrium2 fluid stratification