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NLTE simulations with CRASH code and related issues Fall 2011 Review

NLTE simulations with CRASH code and related issues Fall 2011 Review. Igor Sokolov [with Michel Busquet and Marcel Klapisch (ARTEP)]. Reaction rates in xenon are a possible issue for CRASH . LTE happens when

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NLTE simulations with CRASH code and related issues Fall 2011 Review

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  1. NLTE simulations with CRASH code and related issuesFall 2011 Review Igor Sokolov [with Michel Busquet and Marcel Klapisch (ARTEP)]

  2. Reaction rates in xenon are a possible issue for CRASH • LTE happens when • radiative recombination (red curve) << 3-body collisional recombination (green curve) • Then collisions ensure that Z=Z(Te) only. • Non-LTE happens when • radiation recombination dominates over 3-body recombination • The coronal model then applies: one-source-two-sinks of free electrons, which affect the ionization degree. • For optically thin media, of course • Prof. G.A.Moses raised this issue CRASH density 50 eV Xe Radiative recombination LTE Reaction rate Dielectronic 3-body 1020 1022 1012 Atomic density [per cm3] 1014 1016 1018

  3. NonLTEmay impact the CRASH problem •energy balance : for same Etot, more in electron kinetic energy, and less in ionization "internal" energy • thermal conduction : as average charge is lower, electron conduction (and laser absorption) is reduced • radiative energy : • less coupling of radiation with matter • X-ray conversion of Elaser reduced • x-ray precursor (of shock wave, ...) has larger extent

  4. Principle of the RADIOM model • • Non-LTE of charge state distribution (and excited states to some extent) • is mimicked by an "ionization temperature" Tz • We are able to derive numerically Tz from Ne, Te, {hnu,Erad/Brad} • Non-LTE total energy is a function of Eint(Tz), Zbar(Tz), Te (and ro) :

  5. RADIOM reduces the effective ionization in a manner consistent with the SCROLL model

  6. RADIOM algorithmwith direct EOS done CRASH in progress ro Te {Erad/Brad} estimated Ne Eeff Z* CALTZ EOS(Tz) Tz Zdif= |Z*Ni-Ne| ≈ 0 > 0 ro, Ne [Te],Tz {Erad/Brad} Etot Ptot Cv correct EOS handling Abs. AND Emiss. opacities LUT(ro,Tz) correct Opacities Abs.Coef. Emis.Coef.

  7. The coronal model is not enough for CRASH • In the (solar) corona the “back-lighter” (the photosphere) has a radiation temperature much LOWER than Te in the corona (half eV vs hundreds eV). Contrary to our case. • We may need more electrons, while the coronal model gives us less electrons. • Need to implement the RADIOM/CRASH coupling for the out-of-equilibrium HOT radiation (hundreds eV vs tens eV). • This isnow in progress.

  8. We have made progress on Non-LTE • RADIOM and CRASH codes are coupled now. • “Coronal model” fully implemented • More complete model is under testing • Implementing these models allows us to quantify another source of uncertainties in the CRASH predictions

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