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Outline. I NTRODUCTION: ultraintense ultrashort (UU) laser pulse interaction with matter - C HARGED PARTICLE ACCELERATION IN PLASMAS: electrons, protons, heavy ions L ASER-ION ACCELERATION : main experimental evidences, potential applications P HYSICS OF THE LASER-BASED ION ACCELERATION :

ernestjwilliams
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  1. Outline • INTRODUCTION: • ultraintense ultrashort (UU) laser pulse interaction with matter • - CHARGED PARTICLE ACCELERATION IN PLASMAS: • electrons, protons, heavy ions • LASER-ION ACCELERATION: • main experimental evidences, potential applications • PHYSICS OF THE LASER-BASED ION ACCELERATION: • Present theoretical understanding.Ion acceleration mechanisms: TNSA, RPA. • MATERIAL SCIENCE FOR LASER-ION ACCELERATION • an example: multi-layered targets with ultra-low density layers • - CONCLUSIONS

  2. Introduction: laser-matter interaction …long story, started after the invention of lasers… Introduction of Chirped Pulsed Amplification (CPA) in 1985 determined a true revolution in the field Basic principle of CPA: “Optics in the relativistic regime” G. Mourou, T. Tajima, S.V. Bulanov, Rev. Mod. Phys.78, 309 (2006)

  3. Typical laser parameters with CPA Laser wavelength (m):≈ 1 (Nd-Yag), 0.8 (Ti-Sa), ≈ 10 (CO2) Intensity (power per unit area): > few times 1018 W/cm2 (max about 1021 W/cm2 ) Power: ≈ 100 TW - few PW (PW lines at LLNL and ILE) Pulse duration: ≈ 10 - 103 fs (at  = 1 m,  = c/ = 3.3 fs) Spot size at focus:down to diffraction limit  typically ø < 10 m  : relativistic factor of the electron population Critical density (P = )

  4. Physical fields vs. laser intensity [M. Lontano, M. Passoni, “Ultraintense electromagnetic radiation in plasmas”, Progress in Ultrafast Intense Laser Science, Springer's review book series, Vol I, (2006)] Electric field associated to the laser pulse: from - atomic field - “relativistic” field - limit for e--e+ equilibrium [Te,hot ≈ 20 mec2, BKZS limit in H: G.S. Bisnovaty, et al., Sov. Astr. Journal15, 17 (1971)] • Schwinger • limit [Vacuum break-down: J. Schwinger, Phys. Rev.82, 664 (1951)]

  5. Intensity (W/cm2) Uranium atom fully stripped 1025 relativistic protons pion production fusion thermal pressure of Sun’s core 1020 Electron positron plasma relativistic electrons CPA 1015 Coulomb binding energy photoionization 1010 vaporization of molecules first lasers room temperature 105 Physical regimes achievable - 1 today I ≤ 10 21 W/cm2 D. Umstadter, Relativistic laser-plasma interactions, J. Phys. D: Appl. Phys. 36, R151 (2006)

  6. Accelerating fields due tolaser-driven charge separation 10 - 100 fs high-intensity laser pulse causes strong charge separation (1m = 3 fs) “electric field rectification” + - - EL - + - - - + - - - - + - - + Eacc + + + - + + + + - + + + - huge quasi-stationary electric (and magnetic) fields are produced EL ≈ Eacc ≈ tens GV/cm  efficient charged particle acceleration

  7. Laser based electron acceleration - compact electron accelerators laser pulse into an underdense plasma laser wakefield accelerator radiation pressure expels electrons • maximum s.s. electric field • A.I. Akhiezer, R.V. Polovin, • Sov. Phys. JETP30, 915 (1956) longitudinal E field @ ne = 1018 cm-3,  =1 m  EM ≈ 8 GV/cm GeV regime experimentally approached! effective negative bullet T. Tajima, J. Dawson, Phys. Rev. Lett. 43, 262 (1979) J.M. Dawson, Plasma Phys. Contr. Fus. 34, 2039 (1992) C. Joshi, Th. Katsouleas, Physics Today6, 47 (2003)

  8. Laser-driven ion acceleration in solid targets If an ultraintense and ultrashort laser pulse hits the surface of a thin solid film, intense and energetic (Multi- MeV!) ion “beams” are effectively produced E. L. Clark et al. Phys. Rev. Lett. 84, 670 (2000) A. Maksimchuk, et al., ibid.84, 4108 (2000) R. Snavely et al. ibid.85, 2945 (2000) Typical physical parameters of the accelerating system: Laser – energy: 0,1-1000 J, pulse duration: 10-1000 fs, intensity: 1018-1021 W/cm2 solid target – type: conductors, insulators, thickness: 0,01-100 m accelerated ions – protons in usual conditions, other ionsin proper conditions

  9. Characteristics of ion emission:“front” vs. “rear” emission - 1 …typical experimental setups to diagnose ion acceleration…fromboth sides of the target E.L. Clark, et al., Phys. Rev. Lett. 85, 1654 (2000) Y. Murakami, et al., Phys. Plasmas8, 4138 (2001) I. Spencer, et al., Phys. Rev. E67, 046402 (2003) M. Zepf, et al., Phys. Plasmas8, 2323 (2001) P. McKenna, et al., Phys.Rev. E70, 036405 (2004)

  10. Characteristics of ion emission:“front” vs. “rear” emission - 4 11 Mackinnon, et al., Phys. Rev. Lett.86, 1769 (2001) (Vulcan-Nd:glass-RAL) Allen, et al., Phys. Rev. Lett.93, 265004 (2004) (JanUSP-Ti:Sa-LLNL) Many indications that energetic ions come from the rear surface (usually protons from contaminants!)

  11. Characteristics of ion emission:direction, maximum energy Laser: Nova (Nd:Glass)-LLNL.Parameters: • = 1.053 m, p ≈ 1 ps, E < 700 J,  ≈ 8-9 m, I ≈ 31020 W/cm2 Au, CH targets, 50-125 m thick laser  hot electrons (l,e ≈ 40-50 %) Thot ≈ 5-6 MeV laser  protons (l,pr ≈ 7 %) 31013 prs.(>1 MeV), Tpr ≈ 6 MeV max ≈ 58 MeV high energy cut-off beam Direction: target normal!! from RC films from magn. deflection spectrometer [ S.P. Hatchett, et al., Phys. Plasmas7, 2076 (2000) R.A. Snavely, et al., Phys. Rev. Lett. 85, 2945 (2000)]

  12. Characteristics of ion emission:ion energy spectra “thermal”+ high energy cut-off + plateau (sometimes…) GEKKO MII CPA LLNL-Ti:Sa A.J. Mackinnon, et al., P.R.L. 88, 215006 (2002) Y. Murakami, et al., Ph. Pl. 8, 4138 (2001) high energy cut-off E.L. Clark, et al., P.R.L. 85, 1654 (2000) A. Fukumi, et al., Ph. Pl. 12, 100701 (2005) Ti:Sa/Nd:Ph-CUOS VULCAN-RAL A. Maksimchuk, et al., P.R.L. 84, 4108 (2000) CRIEPI-Kanagawa plateau

  13. Characteristics of ion emission:dependence on laser parameters - 1 A large number of experiments have been performed to study the dependence of the accelerated ion properties on the laser parameters (rear side acceleration) ...collection of published data... K. Krushelnick, et al., Plasma Phys. Contr. Fus. 47, B451 (2005) M. Borghesi et al., Plasma Phys. Contr. Fus. 50, 024140 (2008)

  14. Characteristics of ion emission:dependence on laser parameters - 2 Experiments show that in general ion properties depend on - intensity - energy - pulse duration - contrast ratio (ASE/pedestal) - polarization: linear vs circular In particular some quite general features can be established: • Maximum ion energy mainly depends on laser intensity: Emax ~I1/2 (…I?) • Energetic spectrum and maximum energy depend also on laser energy • Total number of ions increases with laser energy and pulse duration • Total number with short pulses (10-50 fs) can be increased • exploiting higher repetition rate (Hz)

  15. Characteristics of ion emission:dependence on target thickness - 1 several target thicknesses explored, from less than m (~ ) to hundreds m… indication of an “optimal” thickness depending on pulse properties - mainly pre-pulse pedestal level/contrast ratio - for a given target composition Thickness normalized to areal density Spencer, et al., Phys. Rev. E67, 046402 (2003) (Astra-Ti:SA-RAL) M. Kaluza, et al., Phys.Rev.Lett. 93, 045003 (2004) (ATLAS-MPQ)

  16. Characteristics of ion emission:dependence on target thickness - 2 17 Ultrathin targets (down to few tens nm) investigated (using ultrahigh contrast pulses!) - maximum ion energy can significantly increase reducing thickness - Symmetric acceleration: back/front vs forward/rear A. Henig, et al., Phys.Rev.Lett. 103, 045002 (2009) (TRIDENT-Nd:glass-LANL) T. Ceccotti, et al., Phys.Rev.Lett. 99, 185002 (2007) (UHI100-Ti:Sa-CEA Saclay)

  17. Characteristics of ion emission:summary of the main exp. results • Ions can be effectively accelerated in laser-solid interaction • Protonsare mainly accelerated (from surface contaminants), • unless the target is properly cleaned • Ions are accelerated both at the front and at the rear surface • In usual conditions, ions from the rear surface present better properties: • - total number (depending on conditions, 109 – 1013 protons) • - maximum energy (uo to several tens MeV for protons) • - energetic spectrum (wide spectrum with sharp cut -off) • - beam properties (ultralow-emittance 10-3 mm mrad ps bunches) • There is a dependence on the target conditions • target thickness, transverse extension, density • - more protons from CH (i.e. H rich) targets • - much better properties from metallic targets (role of el. transport)

  18. Potential applications …many applications are foreseen… …this is true especially for laser-accelerated ions! • diagnostics for laser plasmas (proton imaging) • “fast ignitors” for inertial nuclear fusion (electron- orproton-driven) • laser-induced nuclear physics: isotope production, … • medical applications (PET, hadrontherapy) • injectors for larger accelerators …in most cases, beam quality is definitely not enough yet… …A LOT of research is still required to reach real feasibility

  19. Potential applications:“proton imaging” - 1 e.g.: ultrafast measure of localized transient electric fields [M. Borghesi, et al., Phys. Plasmas.9, 2214 (2002)] Vulcan- RAL Relativistic Electromagnetic Soliton ? [M. Borghesi, et al., Phys. Rev. Lett.88, 135002 (2002)]

  20. Set-Up CPA Potential applications:“proton imaging” - 2 Example? diagnostic of the accelerating electric field on the rear side! [L. Romagnani, et al., Phys. Rev. Lett.95, 195001 (2005)] LULI Palaiseau interaction CPA1 I ≈ 3.51018 W/cm2  ≈ 1.5 ps 1 - 40 m, Al, Au bent foils diagnostic CPA2 I ≈ 21019 W/cm2  ≈ 300 fs 10 m, Au foil Te≈ 500 keV int ≈ 6-7 MeV E ≈ 3 1010 V/m

  21. Ion acceleration mechanism - 1 Electrons + + + + + + LaserPulse Np << Nhot Light ions (protons) Target There is common agreement on the fact that in most of the experiments protons areaccelerated by the electrostatic field set up by fast electronspropagating into or leaving the target.

  22. Ion acceleration mechanism - 2 23 SOME CRUCIAL ISSUES: solid target Light ion layer pre-plasma (underdense) 1: laser pulse-front surface interaction - radiation pressure-driven charge separation (& resulting ion acceleration) - possible generation of energetic e- population - role of pulse properties (intensity, energy, prepulse, polarization) - role of target properties (density, profile, thickness, mass) 2: electron propagation in the target - role of electron properties (max. energy, spectrum, temperature) - role of target properties - return current 3: effectivecharge separation - generation of intense electric fields - resulting ion acceleration relativistic e- current Laser pulse return current 2 1 3 main pulse front surface rear surface pre-pulse

  23. Ion acceleration mechanisms:TNSA – RPA 24 IF THE e- POPULATION IS DOMINATED BY A THERMAL SPECTRUM… (quite “natural” experimentally…) …accelerating field due to strong charge separation between hot electrons expanding in vacuum and the bulk target Target Normal Sheath Acceleration mechanism (TNSA) [S.C. Wilks, et al., Phys. Plasmas8, 542 (2001)] IF THE ROLE OF THE THERMAL e- POPULATION IS “SUPPRESSED” (superhigh intensity or CP+normal...is it “feasible” experimentally…?) …accelerating field due charge separation induced by the balance between radiation pressure and electrostatic force Radiation Pressure Acceleration mechanism (RPA) [S.C. Esirkepov, et al., Phys. Rev. Lett. 92, 175003 (2004) A. Macchi et al., Phys. Rev. Lett. 94, 165003 (2005)]

  24. TNSA ion acceleration mechanism 25 Let us simply estimate the field at the rear surface: [S.C. Wilks, et al., Phys. Plasmas8, 542 (2001)] EQN~ From quasineutral (QN) plasma expansion: If charge separation is relevant (Ln=cst << d)… order of magnitude of electron energy ~ Te order of magnitude of el. cloud extention ~ de E~ Estimate of Te : ponderomotive potential is the main mechanism of electron heating (see before)

  25. TNSA ion acceleration mechanism 26 For ultraintense ultrashort laser pulses (I > 1018 W/cm2,  1 m, nenc 1021 cm-3) we have Te~ MeV , de~ m (<< Ln) >>> EQN E ~ such fields can accelerate ions up to several MeV on a micrometer scale length!! It is the TNSA field!

  26. TNSA:some other theoretical References 27 TNSA as plasma expansion into vacuum P. Mora, Phys. Rev. Lett.90, 185002 (2003) V.F. Kovalev, et al., JETP,95, 226 (2002) V. Yu. Bychenkov et al., Phys. Plasmas, 11, 3242 (2004) V. T. Tikhonchuk, et al., Plasma Phys. Controlled Fusion47, B869 (2005) P. Mora, Phys. Rev. E 72, 056401 (2005); Phys. Pl. 12, 112102 (2005) S. Betti, et al., Pl. Phys. Contr. Fus. 47, 521 (2005) Quasi-static TNSA models M.Passoni, M.Lontano, Laser Part. Beams 22, 171(2004) M. Lontano, M. Passoni, Phys.Plasmas 13,042102 (2006) J. Schreiber, et al., Phys. Rev. Lett. 97, 045005 (2006) M. Passoni, M. Lontano, Phys. Rev. Lett. 101, 115001 (2008) B.J. Albright, et al., Phys. Rev. Lett. 97, 115002 (2006) A.P. Robinson, et al., Phys. Rev. Lett.96, 035005 (2006) M. Passoni et al, New J. Phys. 12, 045012 (2010) [refs therein for more References]

  27. Other than TNSA?Radiation Pressure Acceleration 28 Isitpossibletoachieveprocessesotherthan TNSA? In principle, yes, exploiting “directly” the pulseradiationpressure RadiationPressureAcceleration (RPA) How? • if pulse intensity increases beyond 1022 W/cm2 PIC simulations • show that RPA becomes competitive, and above 1023 W/cm2 • is the dominant acceleration process (so-called RPDA...) • [ T. Esirkepov et al., Phys. Rev. Lett. 92, 175003 (2004); ibid. 96 105001 (2006) ] • if fast heated e- are “switched off”, TNSA can be suppressed, • leaving only RPA “in action”: achieved using normal incidence and CP • [A. Macchi et al. Phys. Rev. Lett. 94, 165003 (2005) ]

  28. RPA: general remarks 29 [A. Macchi et al. Phys. Rev. Lett. 94, 165003 (2005) ] • radiationpressurepushes e- inwards • “depletion”, “compression” layersdevelop • balancebetweenradiation and • electrostaticpressure • accelerationofions in the compressionlayer • in principlewiththisprocesswe can have • high conv. efficiency + monoenergeticions

  29. RPA with “thick targets”:“hole boring” RPA regime 30 If the targetisthickerthan the depletion+compressionlayer, the ionbunchis “simply” injected in the solid and crossesit [A. Macchi et al. Phys. Rev. Lett. 94, 165003 (2005) ] Estimate of the maximumenergy the holeboring regime: [A.P.L.Robinsonet al, Plasma Phys. Contr. Fusion51 024004 (2009)] where • Forsolid-densitiesonly a fewMeVenergiesmaybeobtained • (maybenotsufficientevento cross the target), buthigh densitybunches • - withrespectto “Light Sail” (requiringultrathintargets, seenext slide) • the schemeseems more robust and less prone to, e.g., prepulseeffects • - HB works in “preplasma”: lowerdensitiesboostionenergy

  30. RPA with ultrathin targets:“light sail” RPA regime 31 In a ultrathin target, withthickness up to the compressionlayer (nmrange), repeatedaccelerationof the ionlayerby the laser (via e-!) can occur The whole target (evenwithmulti-speciesions) isaccelerated in this way (…as a sail…) Simplemodel: a perfectlyreflecting, rigidmirrorboostedby a light wave (pre-dateslaser-ionacceleration era!!) [ G.Marx, Nature 211, 22 (1966) J.F.L.Simmons & C.R.McInnes, Am.J.Phys.61, 205 (1993) ] (reflectivity R = 1) …still a lottobeproperlyunderstood…

  31. RPDA:Pressure Dominated Regime 32 • If pulse intensity > 1023 W/cm2 (still to come experimentally!) PIC simulations • show that RPA becomes the dominant acceleration process: • the pulse acts as a “relativistic piston”, efficiently accelerating ions • new phenomena, like Rayleigh-Taylor instability & Radiation friction can play a role T. Esirkepov et al., Phys. Rev. Lett. 92, 175003 (2004); ibid. 96 105001 (2006)

  32. RPA: recent theoretical references 33 HoleBoringRPA T.V.Liseikina & A.Macchi, Appl.Phys.Lett.94,165003 (2007) N.Naumovaet al, Phys.Rev.Lett.102,025002 (2009) A.P.L.Robinsonet al, Plasma Phys.Contr.Fus.51,024004 (2009). Light sailRPA X.Zhanget al, Phys. Plasmas14,073101 & 123108 (2007) A.P.L.Robinsonet al, New J. Phys.10,013201 (2008) O.Klimoet al, Phys. Rev. ST-AB11,031301 (2008) X.Q.Yanet al, Phys. Rev. Lett.100, 135003 (2008) B.Qiaoet al, Phys. Rev. Lett. 102,145002 (2009) V.K.Tripathiet al, Plasma Phys. Contr. Fus. 51,024014 (2009) A. Macchi et al, Phys. Rev. Lett. 102,085003 (2009) RPDA F. Pegoraro & S.V. Bulanov, Phys. Rev. Lett. 99, 065002 (2007); Laser Phys. 19, 222 (2009) M. Tamburini et al., New J. Phys.12,123005 (2010)

  33. RPA:first experimental evidences 34 “Hole Boring” Target: H gas jet “Light Sail” Target: 5 nm DLC foils Henig, et al., Phys. Rev. Lett.103, 245003 (2009) (JanUSP -Ti:Sa- LLNL) Palmer, et al., Phys. Rev. Lett.106, 014801 (2011) (ATF- CO2 - BNL)

  34. A road towards enhanced TNSA:materials science for novel targets 35 - Evident interest in “intermediate” conditionsne ~nc Motivation - Scalings predicting moreefficient absorption and fast electron generation [L.Willingale et al. Phys. Rev. Lett96, 245002 (2006)] [L.Willingale et al. Phys. Rev. Lett102, 125002 (2009)] [S.S.Bulanov et al. Phys. Plasmas17, 044105 (2010)] Solid foil Foam layer Possibility to reach an “advanced” TNSA regime with multilayered targets: thin solid foil + low-density layer -Open problems- • Parameter scan of target properties (foam thickness, density..) given a laser configuration • Multilayered target manufacturing • (not easy controlling density, adhesion to solid..)

  35. Fabrication tecnique:Pulsed Laser Deposition (PLD) 36 Configuration under study at Nanolab@Politecnico di Milano: low-density Carbon foam attached onto a solid substrate PLD • Main advantages: • Large choice of materials and • substrates • Good adhesion properties • possibility in obtaining • controlled nanostructures QC- Microbalance • Deposition parameters: • Wavelength: 532 nm • Ar pressure: 0 - 1000 Pa • Target-substrate distance: 8,5 cm • Fluence: 0,8 J/cm2 • Target: Graphite • Substrates: • Si[100] -> test depositions for characterization • Al (10µm) -> target fabrication lens/mirror Nd:YAG pulsed laser substrate target vacuum system HV: 10-3 Pa He/ Ar

  36. Carbon “foam” characterization 37 Carbon foam morphology: SEM analysis Structure at high magnification is clearly very open and porous 1 µm On a mesoscale these structures can arrange in different ways by simply varying one process parameter: Ar pressure 30 Pa 100 Pa 300 Pa 10 µm 10 µm 10 µm 10 µm

  37. Conclusions • ULTRAINTENSE ULTRASHORT (UU) LASER PULSE INTERACTION WITH MATTER • - It is an exciting and growing area of reaserch! • - LASER-DRIVEN ION ACCELERATION IS OF PARTICULAR INTEREST • PHENOMENOLOGY OF THE LASER-ION ACCELERATION: • - many experimental data available • - ion spectrum depends on pulse properties (energy, intensity, pre-pulse) • - ion spectrum depends on target properties (composition, thickness) • A NUMBER OF SIGNIFICANT APPLICATIONS ARE FORESEEN • - diagnostic of ultrafast EM phenomena (proton imaging) • - ion-driven inertial fusion • - medical applications (PET, hadrontherapy) • PHYSICS OF THE LASER-BASED ION ACCELERATION: • - ion acceleration mechanism relies on laser-induced strong charge separation • - need of theoretical understanding…

  38. That’s all! 39 ...but, if you want more information and material... ...a comprehensive and updated review is under preparation... A. Macchi, M. Borghesi, M. Passoni “Ion Acceleration by Superintense Laser Pulses: from Classic Problems to Advanced Applications” Reviews of Modern Physics (under review, 2012) THE END THANK YOU!

  39. BACKUP SLIDES

  40. Numerical results (I) 41 ALaDyn PIC code Explorative 3D simulations [C. Benedetti et al. IEEE Trans. Plasma Sci.36/4, 1790 (2008)] • Pulse design: • p-polarized “clean” pulse (λ=0.8 µm) • Gaussianspatialprofile: w=3 µm • Temporal cos4profile: FWHM=25 fs • Peakintensity: a0=10 I≈2x1020 W/cm2 • Powercontent: P=32 TW • Target design • Idealnon-collisionalionized plasma • Main “solid” foil: lm=0.5 µm ; nm=80nc; • Z/A=1/3 (Al9+) • Contaminantlayer (rear): lr=50 nm; nr=9nc ; Z/A=1 (H+) • Low-density “foam”layer (front): lf=0.5  12µm ; nf=1  4nc ; • Z/A=1/2 (C6+) Full 3D and 2D runswereperformed in the sameconditions: withandwithoutfoam 3D 2D • Proton peakenergygainisfoundtobe ~2.3! • 2D-PIC: Overestimationofmaximumprotonenergy BUT qualitative agreement

  41. Numerical results (II) 42 Laser energy conversion (2D-PIC) Maximumprotonenergy (2D-PIC) • Parameterscanwithfoam • thickness and density • optimum thickness area is • broader at decreasing density Dashedline: EM energy Solidlines: total particleenergy • Dynamicenergybalance @ nf=nc: • Absorptionincreaseswithfoam • thickness, reflectiondecreases • up to 60% energyabsorbedby • particles at optimum thickness(red) • Withoutfoam(black) absorptionis • 10 timessmaller!

  42. Numerical results (III) 43 First physicalinterpretationof the results Largerprotonenergies are justifiedby a strongerelectricfield • 2 contributionsto the longitudinalfield: • chargedisplacement •  “ordinary” TNSA •  electronsfrom the foam • “inductive” component due totransient • magneticfields inside the foam [S.V. Bulanovet al. Phys. Rev. Lett98 049503 (2007)] Between the electrostaticcontributions, the one due tofoamelectronsdominates

  43. Comparison among TNSA models 44 C. Perego, et al., Nucl. Instr. and Meth. A (2011), doi:10.1016/j.nima.2011.01.100 Quasi static models appear to be the most effective tools to describe, simply but effectively, TNSA

  44. Pulse energy – intensity plane:TNSA beyond 1021 W/cm2: ? 45 Example : 100 MeV protons with Ti:Sa (=800 nm); I = 4x1021 W/cm2; EL = 5 J M. Passoni et al, New J. Phys. 12, 045012 (2010)

  45. Predictions for applications:hadrontherapy with TNSA? 46 Possible path to reach 250 MeV protons and 10 nA current with “usual” TNSA: Ti:Sa (=800 nm); I = 1x1022 W/cm2; EL = 50 J; = 15 fs (focal=4 µm) (3 PW system); Rep. rate 5 Hz (with 1010 protons/pulse in the selected energy interval) …these requirements could be even less demanding if “improved” schemes of TNSA (mass limited, ultralow thickness, etc) can be adopted at these laser parameters

  46. Experiments with reduced wavelength and different spot size 47 • - Wavelength: 528 nm (2w) • - Pulse width: 400 fs • - Max intensity (Il2): ~4.8*1018 Wcm-2mm² • Temporal contrast: >1010 • Use of Ellipsoidal Plasma mirror (EPM) to tight focus From J. Fuchs presentations at ULIS ’09 and COULOMB ’09 conferences 1/5 spot 3mm 3mm Spot size (FWHM) ~ 4.4mm Spot size (FWHM) ~ 0.9mm

  47. Experiments with reduced wavelength and different spot size 48 Theoretical interpretation of these experiments… (For a discussion on this subject: M. Passoni et al., NIMA 620, 46 (2010)) • General trend well reproduced • Underling physics seems • to be nicely captured

  48. Characteristics of ion emission:dependence on target structure 49 MICROSTRUCTURED TARGETS H. Schwoerer, et al., Nature439, 445 (2006) (JETI-Ti:Sa-Jena) LOW-DENSITY TARGETS L. Willingale, et al., Phys.Rev.Lett. 102, 125002 (2009) (Vulcan-Nd:glass-RAL) MASS LIMITED TARGETS S. Buffechoux, et al., Phys.Rev.Lett. 105, 015005 (2010) (100TW-Nd:glass-LULI)

  49. Ion spectra:Comparison with experiments - 2 - our model 50 Quasi-monoenergetic MeV carbon beams [B. M. Hegelich et al., Nature439, 441 (2006)] […on this issue see also H. Schwoerer et al. ibid. 439, 445 (2006) ] - our model C5+ ions estimated layer thickness: < 5 nm [T. Ceccotti et al, Phys. Rev. Lett. 99, 185002 (2007)] Use of Ultrahigh-Contrast Laser Pulses and thin targets electron energy distribution (PIC) No fitting parameters used!

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