#### Transcript Dudnikova_Galina

SHOCK WAVE PARTICLE ACCELERATION in LASERPLASMA INTERACTION G.I.Dudnikova, T.V.Leseykina ICT SBRAS SCT-2012, Novosibirsk, June 8, 2012 Introduction & Motivation The progress in laser technology has led to light sources delivering pulses of femtosecond duration and focused intensities up to 1022 W/cm2 NOVA Laser (1999, LLNL, petawatt) HERCULES (CUOS), Table Top Petawatt Introduction & Motivation Experiments carried out in recent years on the laser-plasma interaction show the possibility of ions acceleration to high energy (tens of MeV) Compact and affordable ion accelerator based on laser produced plasmas have potential applications in many fields of science and medicine (radiography, isotopes generation, cancer therapy, inertial fusion). Two more studied mechanism of ion acceleration are TNSA (60MeV, energy spread 20%), RPA ( 30 Mev, 50%, ). TNSA accelerating ions by ultra-intense laser pulses The light pressure, P=2I/c, from Gigabar to Terabar may compress plasma and generate shock waves that lead to acceleration of ions due to reflection by shock front (monoenergetic component in ion spectra are produced ) Set -up Foil: full ionized H plasma Foil size: 3-20 λ Foil density: 2-100 n*, Laser pulse: circular polarized Amplitude a: 2-50 a=eE/ mcɷ a=sqrt(I/1.35 1018 Wcm -2 (λ/µm) 2) n*= 1.1 10^21 cm^-3, λ=0.8 µm 4 λ< R < 10 λ 5 λ< L < 400 λ 5 λ< X1< 10 λ 2 λ< X2 < 5λ 2 λ< X1 < 10 λ HERCULES (MI), ATF BNL (NY), Sokol-P (Snezhinsk, Russia) Numerical Model Numerical modelling is carried out on the basis of code UMKA2D3V*, allowing to carry out calculations of interaction of laser radiation with plasma of any complex structure and to choose type of boundary conditions for an electromagnetic field (reflection, absorption, periodic conditions). The effective algorithm of parallel calculations is created, and its realization on multiprocessing complexes MBC-15000 (Moscow) is carried out. At the decision it was used 100150 processors of complex MBC-15000, calculation up to the moment of time to the equal 400 laser periods has occupied approximately 5000 hours of processor time. * Vshivkov V.A., Dudnikova G.I. Comput. Technol., 2001. Channel & caviton formation Plasma formations observed in experiment (ATF BNL) and simulated (bottom row) shadowgram and a simulated plasma profile for case filamentation and solitons for ne<n*, postsolitons for ne<n*; ne=2n*; ne=2.5 n* *I. V. Pogorelsky, et.al, Proceedings of IPAC’10, Kyoto, Japan, 2010. Hole-boring and shock formation V=0.06 c Vhb= sqrt((1+k) I / ƍc) Cs=sqrt(kTe /mi) Te=mc2sqrt(1+a2/2) M=1.3 Ion phase space Ion trajectories Distribution function Palmer Charlotte A. J.; Dover N. P.; Dudnikova G. I., et. al Phys. Rev. Lett. 106, 014801 (2011) Flat pulse R-T instability Ion density Proton energy spectra Ion energy phase space T.C.Liu, G. Dudnikova, et.al, Phys.Plasma, 18, 2011 Plasma density temporal evolution. a=32, n=169 n*, d=0.25 λ I=1.4 10 21W/cm2, n=1.9 10 23 cm-3, d=0.25 µm a=32 Energy spectrum Summary • Laser acceleration is potentially an affordable alternative to traditional cyclotron acceleration. Intense, high quality ion beams driven by relativistic laser plasma - the next generation ion accelerators. • Shock-like acceleration due to the ion reflection at the front of the compressed layer in the plasma lets to obtain the quasi-monoenergetic ion bunch. • In realistic geometries there are two independent obstacles to sustain quasi-mono-energetic regime of acceleration: Rayleigh-Taylor instability of plasma sheet lateral expansion of plasma