Emittance growth mechanisms for laser-accelerated proton beams

Kemp, Andreas; Fuchs, Julien; Sentoku, Y.; Sotnikov, V. I.; Bakeman, M.; Antici, P.; Cowan, T. E.

doi:10.1103/physreve.75.056401

Cited by 31 publications

(13 citation statements)

References 38 publications

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“…Furthermore, dynamic control of mega-ampere electron currents in metals using ionization-driven resistive magnetic fields has been proposed by Sentoku et al, 15 and collimation, hollowing, or filamentation of the electron beams have been found in experiments and simulations. Kemp et al 16 investigated the origin for the low emittance of laser-accelerated proton beams and found that the dominant source is filamentation of the laser-generated hot electron jets that drive the ion acceleration. Recently, hybrid and particle-in-cell (PIC) methods have been used to study resistivity effects on the behavior of the hot electron transport through different target materials [17][18][19][20] or density gradients, 21 and their effect on proton acceleration at the target rear side.…”

Section: Introductionmentioning

confidence: 99%

Effect of resistivity gradient on laser-driven electron transport and ion acceleration

et al. 2013

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The effect of resistivity gradient on laser-driven electron transport and ion acceleration is investigated using collisional particle-in-cell simulation. The study is motivated by recent proton acceleration experiments [Gizzi et al., Phys. Rev. ST Accel. Beams 14, 011301 (2011)], which showed significant effect of the resistivity gradient in layered targets on the proton angular spread. This effect is reproduced in the present simulations. It is found that resistivity-gradient generation of magnetic fields and inhibition of electron transport is significantly enhanced when the feedback interaction between the magnetic field and the fast-electron current is included. Filamentation of the laser-generated hot electron jets inside the target, considered as the origin of the nonuniform proton patterns observed in the experiments, is clearly suppressed by the resistive magnetic field. As a result, the electrostatic sheath field at the target back surface acquires a relatively smooth profile, which contributes to the superior quality of the proton beams accelerated off layered targets in the experiments. V C 2013 AIP Publishing LLC. [http://dx.

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Section: Introductionmentioning

confidence: 99%

Effect of resistivity gradient on laser-driven electron transport and ion acceleration

et al. 2013

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“…The rear-surface acceleration ͑RSA͒ ϳTV/ m electric field ionizes atoms and accelerates ions ͑that expand together with the electrons in a quasineutral beam͒ normal to the surface. 13,20 FSA produces a low-quality beam, 21 because of the stochastic nature of the laser-plasma interaction and hence of the charge separation field at the critical density interface. FSA has been clearly identified by nuclear activation 22 and neutron spectroscopy 23 techniques.…”

Section: Introductionmentioning

confidence: 99%

Comparative spectra and efficiencies of ions laser-accelerated forward from the front and rear surfaces of thin solid foils

et al. 2007

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The maximum energy of protons that are accelerated forward by high-intensity, short-pulse lasers from either the front or rear surfaces of thin metal foils is compared for a large range of laser intensities and pulse durations. In the regime of moderately long laser pulse durations (300–850fs), and for high laser intensities [(1−6)×1019W∕cm2], rear-surface acceleration is shown experimentally to produce higher energy particles with smaller divergence and a higher efficiency than front-surface acceleration. For similar laser pulse durations but for lower laser intensities (2×1018Wcm−2), the same conclusion is reached from direct proton radiography of the electric fields associated with proton acceleration from the rear surface. For shorter (30–100fs) or longer (1–10ps) laser pulses, the same predominance of rear-surface acceleration in producing the highest energy protons is suggested by simulations and by comparison of analytical models with measured values. For this purpose, we have revised our previous analytical model of rear-surface acceleration [J. Fuchs et al., Nat. Phys. 2, 48 (2006)] to adapt it to the very short pulse durations. Finally, it appears, for the explored parameters, that rear-surface acceleration is the dominant mechanism.

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“…35,36 If heating of the target is performed prior to the laser irradiation in order to eliminate the hydrogen contaminants as much as possible, the acceleration of heavier ions is favored. 39 Detailed analysis of the acceleration mechanism 39 has shown that these values are the lowest achievable values, limited by scattering of protons in magnetic filaments present on the target rear surface. As the laser is switched off, electrons cool down by adiabatic energy transfer to the ions, 37 leading to a decrease in the driving electric field.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of a linear accelerator using laser-generated proton beams as a source

Antici¹,

Fazi²,

Lombardi³

et al. 2008

Journal of Applied Physics

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The injection of laser-generated protons through conventional drift tube linear accelerators (linacs) has been studied numerically. For this, we used the parameters of the proton source produced by ultraintense lasers, i.e., with an intrinsic high beam quality. The numerical particle tracing code PARMELA [L. M. Young and J. H. Billen, LANL Report No. LA-UR-96-1835, 2004] is then used to inject experimentally measured laser-generated protons with energies of 7+-0.1 MeV and rms un-normalized emittance of 0.180 mm mrad into one drift tube linac tank that accelerated them to more than 14 MeV. The simulations exhibit un-normalized emittance growths of 8 in x direction and 22.6 in y direction, with final emittances lower than those produced using conventional sources, allowing a potential luminosity gain for the final beam. However, the simulations also exhibit a limitation in the allowed injected proton charge as, over 0.112 mA, space charge effect worsens significantly the beam emittance

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Emittance growth mechanisms for laser-accelerated proton beams

Cited by 31 publications

References 38 publications

Effect of resistivity gradient on laser-driven electron transport and ion acceleration

Effect of resistivity gradient on laser-driven electron transport and ion acceleration

Comparative spectra and efficiencies of ions laser-accelerated forward from the front and rear surfaces of thin solid foils

Numerical study of a linear accelerator using laser-generated proton beams as a source

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