Munib Amin Institute for Laser and Plasma Physics Heinrich Heine University Düsseldorf Laser ion acceleration and applications A bouquet of flowers

Munib Amin – ILPP Düsseldorf2 Introduction ●You need  Thin foil target  Short pulse  High intensity  High contrast ●You get  Up to protons  up to about 60 MeV  high laminarity beam  Small virtual source size

Munib Amin – ILPP Düsseldorf3 Overview ●Acceleration ●Beam Properties and Control ●Applications ●Conclusion

Munib Amin – ILPP Düsseldorf4 How to accelerate protons? TNSA! (Target Normal Sheath Acceleration)

Munib Amin – ILPP Düsseldorf5 How to accelerate protons (I)

Munib Amin – ILPP Düsseldorf6 How to accelerate protons (II)

Munib Amin – ILPP Düsseldorf7 Properties (I): Laminarity Virtual source ●Longitudinal laminarity ●Transversal laminarity Fast protons Slow protons Proton generation foil Borghesi et al. (2004) Cowan et al. (2004)

Munib Amin – ILPP Düsseldorf8 Properties (II): Ion species ●Heating ●Ablation Energy [MeV] Ions/MeV F7+ heated F7+ unheated Hegelich et al (2002)

Munib Amin – ILPP Düsseldorf9 Properties (III): Divergence/spectrum ●Focus ●Collimate ●Select energy Laser pulse 2 Metal foil cylinder Protons Toncian et al (2006)

Munib Amin – ILPP Düsseldorf10 Properties (IV): Energy ●Energy increase: Laser piston regime? Esirkepov et al (2004)

Munib Amin – ILPP Düsseldorf11 Applications ●Diagnostics for dense plasmas ●Isochoric heating ●Ion source for conventional particle accelerators ●Fast ignition ●Medical applications Already done Maybe one day

Munib Amin – ILPP Düsseldorf12 Probing (I): Principle Object moving downwards ●Time variation can mapped. Borghesi et al (2001)

Munib Amin – ILPP Düsseldorf13 Probing (II): Electric field Proton trajectories Displace- ment Lower density Higher density ●Measure: Density distribution/displacement of protons having the same energy ●Find out: Temporal evolution of the electric field

Munib Amin – ILPP Düsseldorf14 Probing (III): Deflectometry

Munib Amin – ILPP Düsseldorf15 Probing (IV): Deflectometry ●Identify grid nodes ●Measure their displacement

Munib Amin – ILPP Düsseldorf16 Isochoric heating: Creating WDM ●Hemispherical target 320 µm Al Al-foil Patel et al (2003)

Munib Amin – ILPP Düsseldorf17 Fast ignition Roth et al (2001) Petawatt beams (5ps 6kJ) Conical shaped target Proton beams Primary driver Fuel

Munib Amin – ILPP Düsseldorf18 Medical applications (I): Radioisotopes Ledingham et al (2004)

Munib Amin – ILPP Düsseldorf19 Medical applications (II): Cancer therapy X-raysProtons

Munib Amin – ILPP Düsseldorf20 Conclusion ●Attractive applications are waiting for laser accelerated ion beams ●…if we are able to control their properties.

Munib Amin – ILPP Düsseldorf21 Thank you

Munib Amin – ILPP Düsseldorf22 Detection – radiochromic film stack ●The density distribution of the proton beam is recorded by a stack of radiochromic films. ●Since protons deposit most of their energy in the Bragg peak, one film shows the distribution corresponding to only one specific energy. RCF stack

Munib Amin – ILPP Düsseldorf23 Overview (2) ●Quasi monoenergetic particles can be generated by  A special treatment of the foil target (thin layer or dots containing the particles to be accelerated on the rear surface)  A second target that selects one velocity class of protons: a laser irradiated hollow metal foil cylinder ●The proton beam can be focused by using  A hemispherical proton generation foil  A second target that focuses the divergent proton beam: a laser irradiated hollow metal foil cylinder B. M. Hegelich, et al., Nature, 439, (2006). H. Schwoerer, et al., Nature, 439, (2006). P. K. Patel, et al., Phys. Rev. Lett. 91, (2003). T. Toncian, et al., Science 312, (2006).

Munib Amin – ILPP Düsseldorf24 The RAL experiment – Temporal and spatial field evolution on the target surface ●A proton beam is used to probe the electric field on the surface of a laser irradiated metal foil cylinder. ●The density distribution of the electron beam is recorded by a stack of radiochromic films. Laser pulse 1 Laser pulse 2 RCF stack (detector) Metal foil cylinder Proton generation foil Proton beam

Munib Amin – ILPP Düsseldorf25 Reconstruction of the electric field – an iterative method Experiment 1: StreakingExperiment 2: Imaging Imaging Experimental result Simulation Parameter fit Streaking Experimental result Simulation Parameter fit Modelling Parameter transfer

Munib Amin – ILPP Düsseldorf26 Modelling ●Setting up a one dimensional field configuration from simulations or previously published models or experimental results ●Setting reasonable starting parameters for the analysis of the experimental results ●Generalizing to three dimensions according to the experimental geometry

Munib Amin – ILPP Düsseldorf27 The electric field configuration ●The fraction of laser energy absorbed by hot electrons and the hot electron temperature are estimated depending on laser intensity and wave length according to Fuchs[2006]. ●The electric field is supposed to build up in a plasma expanding into vacuum as described by Mora[2003]. ●Spatial dependence in one dimension and temporal evolution are given by PIC and MHD-simulations conducted by Romagnani[2005]. J. Fuchs, et al., Nature Physics 2, (2006). P. Mora, Phys. Rev. Lett. 90, (2003). L. Romagnani, et al., Phys. Rev. Lett. 95, (2005).

Munib Amin – ILPP Düsseldorf28 One dimensional electric field Field strength / (V/m) Time / s Position / m The field distribution according to Mora[2003] and Romagnani[2006] is modelled in one dimension.

Munib Amin – ILPP Düsseldorf29 Generalizing to more dimensions Front E x E x y Weaker and retarded The field distribution can be generalized to two or three dimensions by assuming the expansion to start later and the electron density to be lower at larger distances from the centre of the interaction.

Munib Amin – ILPP Düsseldorf30 The target geometry t3t3 t2t2 t1t1 x y The one dimensional field distribution is applied along the dashed lines Plain targetCurved or cylindrical target