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Line broadening / Atomic physics in plasmas Ladislav Kocbach University of Bergen, Bergen, Norway Atomic physics in laser plasmas and line broadening in laser plasmas Laser-matter interaction High power laser stories ("Laser in protons out") Some basic relations Laser plasmas as source of X-rays Atomic physics in laser plasmas Line shapes, broadening Lorentz, Doppler, Voigt profiles Stark broadening Microfields electron broadening Simulations Why are simulations important Pulse + prepulse How are simulations done Laser-matter interaction what is special Einstein's "error" ATI (High Harmonics) "Laser light in, protons out" Photoeffect (photoionization): The kinetic energy of the electrons is given by the energy of the photons and does not depend on the intensity of the light Multiphoton and Above Threshold Ionization (MPI/ATI) ATI of rare gas atoms, by 800 nm, 100fs pulses with 1013-1014 W/cm2. Example of a typical kinetic energy spectrum of photoelectrons produced by ATI of Xenon. High power laser stories "Laser in protons out" (Future) Medical applications Nuclear beams without accelerators VULCAN NOVA PETAWATT NIF - Monster Lasers Laser Light In, MeV Protons Out (1999) Livermore's Petawatt, the world's most powerful laser, impinges upon a target to generate 30 trillion protons from a tiny spot only 400 microns in size. (Livermore) Table Top Terawat Laser NOVA system Prague Asterix Laser System PALS Laser plasmas as source of X-rays Radiation from laser plasmas Pulse, prepuls Spectrum of soft X-rays from Al-plasma Soft X-ray emission enhanced by a prepulse Spectrum of x-ray in keV-range from Al-plasma 6 Photon energy [keV] 1.55 1.60 16 2 Intensity [arb.] Im = 2.3´10 W/cm 1.50 Ka (Al0+– Al4+) 4 2 Hea (Al11+) Al5+ Al6+ 0 0.78 0.80 0.82 Wavelength [nm] 0.84 X-ray emission enhanced by a prepulse Atomic physics in laser plasmas Laser-electron interaction, heating Heating - high degree ionization Electron-ion collision: ionization recombinations light emission and reabsorption optical thickness Electron temperature Ion temperature Ionization degree Line shapes, broadening Line Broadening: Lorentz, Doppler, Voigt profiles Stark broadening electron broadening Stark broadening due to the fields of neighbouring ions Ion microfields Distribution of microfields (static) Holtsmark 1919 Microfields determine states of the emiter n=2 in hydrogen-like ion (atom) n=3 in hydrogen-like ion (atom) Holtsmark function used to evaluate the distribution of electric field strength due to ions. b is scaled electric field strength. Stark brodened n=2 to n=1 in hydrogenic ion (model, from Holtsmarks distribution) Lya Stark brodened n=3 to n=1 in hydrogenic ion (model, from Holtsmarks distribution) Lyb Broadening due to electron impact Which means also due to the presence of unbound electrons Classical motion (semiclassical model) Quantal: Baranger’s formulation (coherent broadening - single emitor) The perturbing system: Continuum electrons present in the neighboourhood Their density of states Their distribution over these states This makes the multiparticle manifold of perturbing states Generalized formulations several approaches exist (fully quantal, semiclassical) Density matrix formulation (can incorporate both coherent and incoherent broadening) Line shape modeling of multielectron ions in plasmas P.A. LOBODA, I.A. LITVINENKO, G.V. BAYDIN, V.V. POPOVA, and S.V. KOLTCHUGIN Russian Federal Nuclear Center All Russian Institute of Technical Physics Snezhinsk, Chelyabinsk region, Russia Laser and Particle Beams 18 (2000), 275–289. Simulations Why are simulations important Pulse + prepulse How are simulations done Simulations The plasma dynamics is described via one-fluid two-temperature Lagrangian "hydrodynamics" codes. Contains a detailed model of the laser-plasma interaction. Laser absorption is calculated by numerical solution of Maxwell’s equations for laser radiation. A simplified model of atomic physics is included to calculate the mean ion charge Z. The populations of the ion charge states are calculated from the set of atomic rate equations. The rates of the collisional ionization, radiative and three-body recombination, include the depression of the ionization potential in dense plasmas. (one dimensional and 2-dim with cylindrical symmetry) Results Ne, Te, Zav, Ti, Ni (Z) As function of position Spectral codes From Ne, Te, Zav, Ti, (more sofisticated can use Ni (Z) ) Evaluate the spectra 1. evaluate detailed configuration populations 2. evaluate line profiles of all the lines 3. combine the spectra from different positions Conclusion Line shapes, broadening Line Broadening: Lorentz, Doppler, Voigt profiles Stark broadening electron broadening Atomic physics in laser plasmas Laser-electron interaction, heating Heating - high degree ionization Electron-ion collision: ionization recombinations light emission and reabsorption optical thickness Electron temperature Ion temperature Ionization degree Soft X-ray emission enhanced by a prepulse Thanks to Dr. Jiri Limpouch Prof. Ladislav Drska Czech Technical University Eric W. Weisstein http://www.treasure-troves.com/physics/ Thanks, this is the end Thanks, this is the end Thanks, this is the end