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International Conference on High Energy Density Physics Electron heating in sub-ps laser plasma-interaction Lorenzo Cialfi Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016 2 Co-authors and Sponsors ENSURE project Supercomputing

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Lorenzo Cialfi ICHEDP2016 25/09/2016

Electron heating in sub-ps laser plasma-interaction

Lorenzo Cialfi

International Conference on High Energy Density Physics

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Lorenzo Cialfi ICHEDP2016 25/09/2016

Co-authors and Sponsors

  • M. PASSONI
  • L. FEDELI
  • V. RUSSO
  • A. MAFFINI

“ENSURE” project Research group (Milano, IT) Supercomputing facility (Bologna, IT)

2

  • A. FORMENTI
  • A. PAZZAGLIA
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Lorenzo Cialfi ICHEDP2016 25/09/2016

Co-authors and Sponsors

  • M. PASSONI
  • L. FEDELI
  • V. RUSSO
  • A. MAFFINI

“ENSURE” project Research group (Milano, IT) Supercomputing facility (Bologna, IT)

  • A. FORMENTI
  • A. PAZZAGLIA

Il Woo CHOI I Jong KIM Karol JANULEWICZ H.W. LEE

  • J. H. SUNG

S.K. LEE

  • C. H. NAM

Experimental campaign (Gwangju, South Korea)

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Outline of the presentation

I. Introduction  Laser induced ion acceleration  Electron heating: state of the art

  • II. Proposal of scaling law for electron temperature

 Different experimental paramenters

  • III. Numerical Campaign

 Parametric study

  • IV. Scaling law & Ion acceleration model

 Benchmark with experimental results

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Laser driven ion acceleration

Interesting features: Compactness Choerence Tunable energy Cheaper (?) Required upgrades: Better performances High repetition rate ( > Hz) Better control over the technique

Laser I > 1019 Τ

𝑋 𝑑𝑛2

Duration < ps Focal spot ~ µm Taget Thickness: µm/nm Foils

Potential applications: Proton imaging/radiography Material irradiation Isotope/neutron production Fast ignition Hadrontherapy

  • A. Macchi, M. Borghesi, M. Passoni,
  • Rev. Mod. Phys., 85 751 (2013)

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Target Normal Sheath Acceleration (TNSA) Many acceleration mechanisms

Target Normal Sheath Acceleration (TNSA)

Electron heating Electron expansion Charge separation Ion acceleration

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Electron heating Target Normal Sheath Acceleration (TNSA) Electron expansion Charge separation Ion acceleration Many acceleration mechanisms

Target Normal Sheath Acceleration (TNSA)

𝑼𝒇 𝑭𝒏𝒃𝒚

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Possible approaches: Quasi stationary models Fluid models Hybrid models 𝐹𝑛𝑏𝑦(𝑗𝑝𝑜𝑡) = 𝑎𝑗𝑙𝑐𝑈

𝑓𝑔(𝑟)

𝐹𝑛𝑏𝑦(𝑗𝑝𝑜𝑡) = 2𝑎𝑗𝑙𝑐𝑈

𝑓𝑚𝑜2 τ +

τ2 + 1 𝐹𝑛𝑏𝑦(𝑗𝑝𝑜𝑡) = 𝑎𝑗𝑙𝑐𝑈

𝑓 φ∗ − 1 + β φ∗,Ϛ 𝐽 φ∗,Ϛ 𝑓Ϛ+φ∗

Modelling TNSA

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  • M. Passoni and M. Lontano, Phys. Rev. Lett., vol. 101, p.

115001 (2008).

  • P. Mora, Physical Review Letters, V 90 N 18 (2003)
  • B. J. Albright, et al., Physical Review Letters, 97:115002

(2006).

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Possible approaches: Quasi stationary models Fluid models Hybrid models 𝐹𝑛𝑏𝑦(𝑗𝑝𝑜𝑡) = 𝑎𝑗𝑙𝑐𝑈

𝑓𝑔(𝑟)

𝐹𝑛𝑏𝑦(𝑗𝑝𝑜𝑡) = 2𝑎𝑗𝑙𝑐𝑈

𝑓𝑚𝑜2 τ +

τ2 + 1 𝐹𝑛𝑏𝑦(𝑗𝑝𝑜𝑡) = 𝑎𝑗𝑙𝑐𝑈

𝑓 φ∗ − 1 + β φ∗,Ϛ 𝐽 φ∗,Ϛ 𝑓Ϛ+φ∗

Modelling TNSA

  • M. Passoni and M. Lontano, Phys. Rev. Lett., vol. 101, p.

115001 (2008).

  • P. Mora, Physical Review Letters, V 90 N 18 (2003)
  • B. J. Albright, et al., Physical Review Letters, 97:115002

(2006).

Electron temperature  key parameter

𝑈

𝑓 [KeV]

𝐽λ2 [Wcm−2µm]

Experiments

  • P. Gibbon; Short Pulse Laser Interaction

with Matter; Imperial college press (2005)

𝐉𝟏.𝟔 I 𝐉𝟏.𝟒 Laser intensity dependence Other dependences ?

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Ponderomotive scaling 𝑈

𝑓 𝑁𝑓𝑊 = 0.511

1 + 𝐽λ(µ𝑛)2 1.37 ∙ 1018 − 1

Electron temperature

Collisional heating  e-i collisions  ν𝑓𝑗 ∝ 𝑎𝑜𝑓 𝑈

𝑓 −3

2 ln Λ , 𝑈

𝑓 ∝ 𝐽1/3𝑢1/6  not efficient for

high intensities and short pulses Resonance heating  𝑈

𝑓 ∝ 𝐽λ2 1/3 efficient for long pulses (~ps) and plasma gradients (µm)

Ultra-intense laser (I > 1018𝑋/𝑑𝑛2) + Sharp-edged micrometric solid targets jxB heating Brunel effect Interaction efficiency η = 1 π𝑏0 1 + 𝑔2𝑏0

2𝑡𝑗𝑜2θ 1/2 − 1 𝑡𝑗𝑜θ

𝑑𝑝𝑡θ 𝑏0

2

2

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Collisionless

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Resonance heating  𝑈

𝑓 ∝ 𝐽λ2 1/3 efficient for long pulses (~ps) and plasma gradients (µm)

Collisional heating  e-i collisions  ν𝑓𝑗 ∝ 𝑎𝑜𝑓 𝑈

𝑓 −3

2 ln Λ , 𝑈

𝑓 ∝ 𝐽1/3𝑢1/6  not efficient for

high intensities and short pulses

Electron temperature

Ultra-intense laser (I > 1018𝑋/𝑑𝑛2) + Sharp-edged micrometric solid targets jxB heating Brunel effect Ponderomotive scaling 𝑈

𝑓 𝑁𝑓𝑊 = 0.511

1 + 𝐽λ(µ𝑛)2 1.37 ∙ 1018 − 1 Interaction efficiency η = 1 π𝑏0 1 + 𝑔2𝑏0

2𝑡𝑗𝑜2θ 1/2 − 1 𝑡𝑗𝑜θ

𝑑𝑝𝑡θ 𝑏0

2/2

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Collisionless

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Micrometric plain solid targets: scaling law proposal

  • jxB heating

 hp: No angular dependence  Ponderomotive scaling Brunel effect  interaction efficiency  𝑈

𝑓 𝛽 η 𝐹𝑚𝑏𝑡𝑓𝑠 𝑂𝑓

Hp: combined heating 𝑈

𝑓[𝑁𝑓𝑊] = 0.511 ∙ 𝐷1 𝑏0, 𝑞𝑝𝑚 ∙

1 + 𝑏02 2 −1 + 0.511 ∙ 𝐷2 𝑏0, 𝑞𝑝𝑚 ∙ 1 + 2𝑏0

2𝑡𝑗𝑜2 θ −1 ∙ tan θ

𝑫𝟐 𝑏0, 𝑞𝑝𝑚 & 𝑫𝟑 𝑏0, 𝑞𝑝𝑚 : ?  Numerical simulations  Temperature fit

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Particle In Cell (PIC) simulations: Electron temperature

Target

Composition : 𝐵𝑚9+ + 𝐼+ (contaminants) Thickness : 0,5 µm and 50 nm contaminants Density: 80 𝑜𝑑 and 4 𝑜𝑑

Laser

Intensity: 1.5 < 𝑏0 < 15 Incidence angle : 0 – 15 – 30 – 45 - 60° Polarization: P-, C-, S-

10 20 30 40 50 60

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5

Electron Temperature (MeV) Incidence angle (°)

a0= 15 a0= 5 a0= 10 a0= 3 a0= 7.5 a0= 1.5

2D results: P polarization

Angular dependence: P and C polarization S polarization (requires 3D simulations) constant temperature

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10 20 30 40 50 60 0,00 0,25 0,50 0,75 1,00 1,25 1,50 1,75 2,00

2D results: C polarization

Electron Temperature (MeV) Incidence angle (°)

a0= 15 a0= 5 a0= 10 a0= 3 a0=7.5 a0= 1.5

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Particle In Cell (PIC) simulations: Electron temperature

Laser

Intensity: 1.5 < 𝑏0 < 15 Incidence angle : 0 – 15 – 30 – 45 - 60° Polarization: P-, C-, S-

10 20 30 40 50 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

3D results

Electron Temperature (MeV) Incidence angle (°)

P pol a0=10 C pol a0=10 S pol a0=10 C pol a0= 5 C pol a0=15 C pol a0= 3 C pol a0=14.4

Angular dependence: P and C polarization S polarization (requires 3D simulations) constant temperature

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Target

Composition : 𝐵𝑚9+ + 𝐼+ (contaminants) Thickness : 0,5 µm and 50 nm contaminants Density: 80 𝑜𝑑 and 4 𝑜𝑑

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𝐷1, 𝐷2 constant for 𝑏0 > 3 𝐷2(pol S) = 0 (no Brunel) 𝐷1(pol S) = 𝐷1(pol P)

Estimation of 𝑫𝟐 and 𝑫𝟑 coefficients

Numerical fit: 𝑈

𝑓 = 𝐷1 𝑏0, 𝑞𝑝𝑚 𝑈 𝑓(𝐊x𝐂) + 𝐷2 𝑏0, 𝑞𝑝𝑚 𝑈 𝑓(Brunel)

2 4 6 8 10 12 14 16 0,0 0,1 0,2 0,3 0,4 0,5

Fit coefficients Normalized laser amplitude (a0)

C2 C1

C polarization

2 4 6 8 10 12 14 16 0,0 0,2 0,4 0,6 0,8 1,0

Fit coefficients Normalized laser amplitude (a0)

C2 C1

P polarization

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𝐷1, 𝐷2 constant for 𝑏0 > 3 𝐷2(pol S) = 0 (no Brunel) 𝐷1(pol S) = 𝐷1(pol P)

Estimation of 𝑫𝟐 and 𝑫𝟑 coefficients

Numerical fit: 𝑈

𝑓 = 𝐷1 𝑏0, 𝑞𝑝𝑚 𝑈 𝑓(𝐊x𝐂) + 𝐷2 𝑏0, 𝑞𝑝𝑚 𝑈 𝑓(Brunel)

2 4 6 8 10 12 14 16 0,0 0,1 0,2 0,3 0,4 0,5

Fit coefficients Normalized laser amplitude (a0)

C2 C1

C polarization

2 4 6 8 10 12 14 16 0,0 0,2 0,4 0,6 0,8 1,0

Fit coefficients Normalized laser amplitude (a0)

C2 C1

P polarization

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Numerical results: electron trajectories

Interaction: I. Normal oscillations

  • II. Kick along the laser direction
  • III. Injection at 2ω

Thicker targets: Similar temperatures (20% decrease) No 𝑓− recirculation  less confinement 0.5 µm thick Al 15 µm thick Al

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jxB injection at 2ω + Brunel injections at ω

Numerical results: electron trajectories

0,0 0,3 0,6 0,9

Electrons number (a.u.)

Thick foil normal incidence Thick foil 45° incidence

1 2 3 4 5 6 7 8 9 10 0,0 0,3 0,6 0,9 Travelling distance (x/)

Interaction: I. Normal oscillations

  • II. Kick along the laser direction
  • III. Injection at 2ω

jxB heating Thicker targets: Similar temperatures (20% decrease) No 𝑓− recirculation  less confinement 0.5 µm thick Al 15 µm thick Al

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Benchmarks with experiments

0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4 8 12 16 20 24

Maximum proton energy (MeV) Intensity on target (10

20 W/cm 2)

Experimental results Proposed scaling law Ponderomotive scaling

P polarization

Benchmark with experimental results

1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 4 6 8 10 12 14 16 18 20 22

Intensity on target (10

20 W/cm 2)

Maximum proton energy (MeV)

Experimenta results Ponderomotive scaling = Proposed scaling

S polarization

0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 2 4 6 8 10 12 14 16 18 20

Intensity on target (10

20 W/cm 2)

Maximum proton energy (MeV)

Experimental results Proposed scaling law Ponderomotive scaling

C polarization

Target: Simple plain foil Compositions: Al Thickness: 0.75 µm 30° Laser: Ti:Sapphire I < 4.2 ∙ 1020 Τ

𝑋 𝑑𝑛2

Laser polarization: P-, S-, C-

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Foam-attached targets

Foam deposition: Pulsed Laser Deposition (PLD) Micrometric-scale near-critical density Nanometric (~ 20-30 nm) over-dense clusters

LASER PULSE ACCELERATED IONS FAST ELECTRONS

SOLID FOIL + LOW DENSITY LAYER Volume & Surface interaction mechanisms

NEARCRITICAL LAYER

  • T. Nakamura et al., Phys. Plasmas, 17 113107 (2010)
  • A. Sgattoni et al., Phys. Rev. E, 85 036405 (2012)

Enhanced TNSA Higher laser energy absorption Enhanced electron production Enhanced number and maximum energy of accelerated ions

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Experimental results

Role of Foam thickness (p-pol.) 𝐹𝑛𝑏𝑦 ∝ 𝐽 Foam targets: no pol dependence Best coupling with 8 µm foam

Higher energies More Ions (>50%)

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Role of laser polarization

0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 4 8 12 16 20 24 28 32

Maximum proton energy (MeV) Intensity on target (10

20 W/cm 2) 8 m foam Al (0.75 m) 36 m foam 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5 10 15 20 25 30

P- pol (Al 0.75 m) S- pol (Al 0.75 m)

Maximum proton energy (MeV) Intensity on target (10

20 W/cm 2)

C- pol (Al 0.75 m) P-, C-, S- polarization C foam (8 µm, 1.2 nc)

  • n Al substrate (0.75 µm)
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Pulse erosion 𝑈

𝑓~𝐽

Ponderomotive expulsion 𝑈

𝑓~𝐽1/2

Electron heating in near critical plasmas

Magnetic dipole generation Self focussing Filamentations Two stream instabilities Simplified physical picture:

𝑓−

Richer physics

𝑞 ~ 𝑞⊥ α 𝑏0 𝑞 ~ 𝑞// α 𝑏0

2

  • Y. J. Gu, et al.; Physics Of Plasmas 21,

063104 (2014) A P L Robinson et al; Plasma Phys. Control. Fusion 53 (2011) 065019

  • L. Willingale et al; Physics of Plasmas 18,

056706 (2011)

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Interaction with foam attached targets

Homogeneous foam Nanostructured foam

Homogeneous foam 𝑜𝑓 = 𝑜𝑑 Random spheres 𝑆𝑡 = 10 𝑜𝑛 𝑜𝑓 = 100 𝑜𝑑 Average density: 𝑜𝑓=𝑜𝑑 17

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Interaction with foam attached targets

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Interaction with foam attached targets

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Interaction with foam attached targets

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Interaction with foam attached targets

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Interaction with foam attached targets

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Interaction with foam attached targets

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Interaction with foam attached targets

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Interaction with foam attached targets

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Interaction with foam attached targets

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Interaction with foam attached targets

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Electron heating in foam attached targets

y/λ x/λ

Two populations: Fast escaping electrons Confined electrons

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Two populations: Fast escaping electrons Confined electrons

y/λ x/λ

Electron heating in foam attached targets

Fast electrons Prompt escape (t < 100fs) 𝑞𝑛𝑏𝑦 α 𝑏0

2

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y/λ x/λ

Electron heating in foam attached targets

Confined electrons: More energetic than solid foil 𝑓− Spectrum dependant to the nanostructure Long confinement time (> 100 fs) Two populations: Fast escaping electrons Confined electrons

Hp: confined electrons  enhanched TNSA

5 10 15 20 25 30 35 40 45 50

10 10

1

10

2

10

3

10

4

10

5

10

6

10

7

Intensity (a.u.) Energy (MeV)

Homogeneous all electrons Nanostructured all electrons Homogeneous confined e

  • Nanostructured confined e
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Temperature scaling and benchmark

𝑈

𝑓 = 𝐷3𝑈𝑞𝑝𝑜𝑒 + 𝐷4

Hp: ponderomotive heated confined electrons Electron heating dependant to the target nanostructure Nanostructure  lower electron temperature

2 4 6 8 10 12 14 16 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5

Electron Temperature (MeV) a0

Homogeneous foam Nanostructured foam Solid target

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Temperature scaling and benchmark

𝑈

𝑓 = 𝐷3𝑈𝑞𝑝𝑜𝑒 + 𝐷4

Hp: ponderomotive heated confined electrons

0,5 1,0 1,5 2,0 2,5 3,0 3,5 5 10 15 20 25 30 35

Maximum proton energy (MeV) Intensity on target (10

20 W/cm 2) Experimental results Nanostructured foam Homogeneous foam

Electron heating dependant to the target nanostructure Nanostructure  lower electron temperature

Experimental results and benchmarks

2 4 6 8 10 12 14 16 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5

Electron Temperature (MeV) a0

Homogeneous foam Nanostructured foam Solid target

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Conclusion and future perspectives

Interaction with over-dense plasma: Brunel effect and jxB heating  combined heating Ponderomotive scaling over-estimates electron temperture in this regime Very good agreement with TNSA experiments Interaction with near-critical plasma: Production of fast-escaping and confined electrons TNSA should be due to the confined electrons Nanostructure is a key parameter in laser-matter interaction Future prespectives: I. Numerical 3D campaign with foam attached targets

  • II. More realistic nanostructure design
  • III. Theoretical model for ponderomotive heating in near critical targets

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Pubblished works

I. L Cialfi, L Fedeli and M Passoni, Electron heating in sub-picosecond laser interaction with

  • ver-dense and near-critical plasmas, submitted.

II. M Passoni, A Sgattoni, I Prencipe, et al., Toward high-energy laserdriven ion beams: Nanostructured double-layer targets, Physical Review Accelerators and Beams 19, 061301 (2016).

  • III. I Prencipe, A Sgattoni, M Passoni et al., Development of foam-based layered targets for

laser-driven ion beam production, Plasma Physics and Controlled Fusion 58, 034019 (2016).

Recent works

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Thank you for your attention

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Sub picosecond ultra-intense lasers

Laser parameters considered: I > 1019 Τ

𝑋 𝑑𝑛2

Pulse duration (FWHM) < 100 fs Focal spot ~ µm P > 100 TW Pulse energy > J

  • I. Matter ionization  Laser- plasma interaction
  • II. Critical density

𝑜𝑑 = γ

𝑛𝑓ω2 4π𝑓2

for Ti:Saphire 𝑜𝑑~ ൗ

𝑛𝑕 𝑑𝑛2

 n > 𝑜𝑑 : Over dense plasma  n < 𝑜𝑑 : Under dense plasma Relativistic transparency I  𝑜𝑑

  • III. Skin depth

λ𝑡𝑒 = 𝑑γ/ω𝑞𝑓 ( ~ 10 − 50 𝑜𝑛) Example: CoReLS, IBS (Gwangju, S. Korea) Laser wavelenght: 800 nm (Ti:Sapphire) 0.5 ∙ 1020 Τ

𝑋 𝑑𝑛2< I < 4.2 ∙ 1020

Τ

𝑋 𝑑𝑛2

Pulse duration (FWHM) < 30 fs Focal spot = 5 µm 1 < Energy on target > 7.5 J

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1 2 3 4 5 6 7 8 9 10 11 12 13 10

1

10

2

10

3

10

4

10

5

10

6

10

7

Intensity (a.u.)

Energy (MeV)

𝑈

𝑓 = −

1 𝑡𝑚𝑝𝑞𝑓 ∙ ln(10)

Electron temperature estimation

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Acceleration experiment @ PULSER I GIST

Role of target properties (s-polarization, full power) nearcritical foam thickness: Al (0.75 µm) + foam (6.8 mg/cm3, 0-36 µm) ↑ proton temperature 7.3 MeV (vs 3.5 MeV for Al) ↑ number of protons (gain factor 7.3 above 5 MeV (vs s))

4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 10

1

10

2

10

3

10

4

10

5

Intensity (a.u.) Energy (MeV)

Al foam 12 foam 8

Afoam 8 m/AAl(E>5 MeV) = 7,3 Afoam 12 m/AAl(E>5 MeV) = 3,1

6 12 18 24 30 36 8 10 12 14 16 18 20 22 24 26 28 30

C

6+ maximum energy (MeV)

H

+ maximum energy (MeV)

H

+ maximum energy

Target thickness (m)

H

+ maximum energy

C

6+ maximum energy

S polarization (peak intensity)

20 40 60 80 100 120 140 160 180

↑ Emax protons: 30 MeV [vs 18 MeV (s), 22 MeV (p)] ↑ Emax C6+: 130-140 MeV [vs 80 MeV (s), --- MeV (p)]

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Lorenzo Cialfi ICHEDP2016 25/09/2016

Acceleration experiment @ PULSER I GIST

Role of target properties (s-polarization, full power) foam density: Al (0.75 µm) + foam (6.8 – 25 mg/cm3, 12 µm)

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 27.5

Intensity on target (10

20 W/cm 2)

4,3 nc 1,2 nc Maximum proton energy (MeV)

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Lorenzo Cialfi ICHEDP2016 25/09/2016

Acceleration experiment @ PULSER I GIST

Role of target properties (s-polarization, full power) substrate thickness: Al (0.75 and 1.5 µm) + foam (6.8 mg/cm3, 12 µm)

1 2 3 4 5 6 8 10 12 14 16 18 20 22 24 26

Intensity on target (10

20 W/cm 2)

Maximum proton energy (MeV) 0.75 m 1.5 m

1 2 3 4 5 6 8 10 12 14 16 18 20 22 24 26

Maximum proton energy (MeV) Intensity on target (10

20 W/cm 2)

0.75 m 1.5 m

Bare Al targets Foam-attached targets

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Foam attached targets: production

PYROLITIC GRAPHITE TARGET SUBSTRATE Si <100> Al (0.7-12 μm) C (3 nm) LASER BEAM 532 nm 0.8 J cm-2 5-7 ns 10 Hz BUFFER GAS Ar/He 0-1000 Pa 4.5 – 8.5 cm

  • A. Zani et al., Carbon, 56 358 (2013); I. Prencipe et al., J. Phys. Conf. Ser., (2015)

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

More realistic: nanostructured-foam layer

  • Limited Diffusion Aggregation (LDA) model
  • same mean thickness & density
  • nanoparticles: 50 nc (2%filling factor)

laser

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

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Lorenzo Cialfi ICHEDP2016 25/09/2016

3D-PIC simulations of the experiment

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Lorenzo Cialfi ICHEDP2016 25/09/2016

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