23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 1 Laser acceleration and transport of intense ion beams Zsolt Lécz, Vladimir Kornilov, Oliver Boine-Frankenheim Beam physics for FAIR Bastenhaus, 6 July 2010

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 2 History of lasers PHELIX

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 3 Usual experimental setup

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 4 PHELIX (Petawatt High Energy Laser for Ion eXperiments ), GSI Target Solenoid RCF Stack e-spectrometer 80 cm Thomson parabola

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 5 Why do we do it? Applications ▪Advantages of ion acceleration: -Table-top size, very high acceleration gradient, high energy 10…100 MeV ▪Outstanding, unique features of the ion beam: -Small transverse emittance (1e-2…1e-1 mm*mrad) -> high laminarity and focusability -Increasing the energy the opening angle is decreasing, due to the decreasing source size - High intensity (current) : 1e13-1e18 ions (1e12 could be collimated) ▪Possible applications: -Nuclear researches -The beams can be used as tools in basic plasma diagnostic research -Injection devices into conventional, large accelerators -Ion therapy for tumor treatments -Inertial fusion (energy research)

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 6 PHELIX Experiment, TW laser beam Pulse duration 700 fs 12x17 micrometer spot size Laser intensity:

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 7 Another experiment Photo-Medical Research Centre, Japan Laser intensity

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 8 What is the laser acceleration? Expanding neutral plasma

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 9 TNSA (Target Normal Sheath Acceleration)

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 10 X(micrometer) TNSA Ponderomotive pressure Proton acceleration Front sideRear side Target 14…95 fs

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 11 Density modulation, electric field Debye sheath

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 12 Typical energy spectrums electrons Cut-off energy of protons t=40 fs !

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 13 Energy absorption ▪The energy of laser pulse can be converted to the hot electron energy through many processes: Resonant absorption, vacuum heating, different skin effects, ponderomotive absorption – high intensity and normal incidence Poynting vector history Power(W) Reflected wave

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 14 Motion of electrons in the laser field Equation of motion in a planar wave: Motion in a non-uniform wave: Don’t gain energy! Exists a gradient in x direction ! gradE X

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 15 Ponderomotive force The laser intensity becomes relativistic when the dimensionless electric field amplitude: a>1 The frequency of the oscillating part of ponderomotive force is twice the laser frequency! Relativistic ponderomotive potential: Kinetic energy:

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 16 ASE light preceding the main pulse ASE=Amplified Spontaneous Emission

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 17 Plasma expansion model Linear dependence of the front-plasma scale length on the pulse-delay.

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 18 Absorption dependence on the scale length On the resonant surface is generated higher harmonic of the laser, which can further heat the plasma. The optimal scale length:(skin depth)

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 19 OOPic Pro, Tech-X Corporation ▪Particle in Cell code, EM field solver, fully relativistic ▪Useful interactive visual diagnostics ▪Easy to write the input file, but no debugging ▪Data of any physical quantity can be dumped ▪Almost any type of boundaries can be applied ▪Used post-processing software: Matlab 9, IDL 6.4

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 20 Simulation parameters ▪Debye length is fixed: 4 nm (initial) ▪Grid size is half of the Debye length ▪In x direction the space is 8-9 micrometer long, in y direction only 4 cells ▪Quasi one-dimensional ▪Courant criterion: ▪The number of macroparticles : 30000, ▪Laser intensity: 1e18…1e20 W/cm^2 ▪Wavelength : 1 micrometer ▪In the calculation of critical density is included the time averaged gamma factor The initial electron temperature increases with the laser intensity

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 21 Simulation result n=4*nc I=10^19 W/cm^2 Te=1keV Ti=0.8keV Pulse Length= 40 fs

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 22 Pulse duration Constant! The dimensionless electric field amplitude varied: 4.66 – 1.47

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 23 Conclusions, next steps ▪The OOPic Pro 2.0 is a good mean for analyzing the laser acceleration processes ▪The hot electron generation and energy absorption in case of normal incidence of intense laser pulses in 1 dimension is well understood ▪The parallelized running of the program is needed in order to increase the precision and speed of the simulations and to extend the simulation space ▪2D simulations are planed with different incidence angle ▪The aim of the work is to provide spatial and energy distribution for the ions (and electrons), which can be used in other simulations (transport, collimation)

The End

23. September 2016 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Prof. Dr.-Ing. Thomas Weiland | 25 Bibliography ▪Nonlinear absorption of a short intense laser pulse in a nonuniform plasma, A.A. Andreev and K. Yu. Platonov, Physics of Plasmas volume 10, number 1, January 2003 ▪Influence of subpicosecond laser pulse duration on proton acceleration, A. Flacco, PHYSICS OF PLASMAS 16, ,2009 ▪Energetic proton generation in ultra-intense laser-solid interactions, S. C. Wilks, Physics of plasmas, 8(2), 2001 ▪Short Pulse Laser Interaction with Matter, Paul Gibbon