Numerical modelling of production of ultrahigh-current-density ion beams by short-pulse laser-plasma interaction (original) (raw)
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Production of ultrahigh-current-density ion beams by short-pulse skin-layer laser–plasma interaction
Applied Physics Letters, 2004
We report experimental evidence, supported by a simple theory and numerical calculations, that the skin-layer subrelativistic interaction of a short ͑ഛ1 ps͒ low-energy ͑Ͻ1 J͒ laser pulse with a thin preplasma layer in front of a solid target can produce a collimated fast ion flux of extremely high ion current density (ജ10 10 A/cm 2 close to the target), comparable to those predicted for ballistically focused ion beams from relativistic laser-plasma interactions.
High-energy ion generation in interaction. of short laser pulse with high-density plasma
Applied Physics B, 2002
Multi-MeV ion production from the interaction of a short laser pulse with a high-density plasma, accompanied by an underdense preplasma, has been studied with a particle-in-cell simulation and good agreement is found with experiment. The mechanism primarily responsible for the acceleration of ions is identified. Comparison with experiments sheds light on the ion-energy dependence on laser intensity, preplasma scale length, and relative ion energies for a multi-species plasma. Two regimes of maximum ion-energy dependence on laser intensity, I, have been identified: subrelativistic, µ I ; and relativistic, µ √ -I. Simulations show that the energy of the accelerated ions versus the preplasma scale length increases linearly and then saturates. In contrast, the ion energy decreases with the thickness of the solid-density plasma.
Laser and Particle Beams, 2006
In this paper we present the analytical description of two processes dealing with the skin-layer ponderomotive acceleration method of fast ion generation by a short laser pulse: ion density rippling in the underdense plasma region and generation of ion beams by trapped electromagnetic field in plasma. Some numerical examples of hydrodynamic simulation illustrating these processes are shown. The effect of using the laser pulse consisting of different frequency components on the ion density rippling and on phenomena connected with trapped electromagnetic field is analyzed.
Energetic ion production from short-laser-pulse interaction with high density plasmas
Multi-MeV ion production from the interaction of a short laser pulse with a high-density plasma, accompanied by an underdense preplasma, has been studied with a particle-incell simulation and good agreement is found with experiment. The mechanism primarily responsible for the acceleration of ions is identified. Comparison with experiments sheds light on the ion-energy dependence on laser intensity, preplasma scale length, and relative ion energies for a multi-species plasma. Two regimes of maximum ion-energy dependence on laser intensity, I, have been identified: subrelativistic, ∝ I; and relativistic, ∝ √ I . Simulations show that the energy of the accelerated ions versus the preplasma scale length increases linearly and then saturates. In contrast, the ion energy decreases with the thickness of the solid-density plasma.
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Laser and Particle Beams, 2004
Energetic ion beams are produced during the interaction of ultrahigh-intensity, short laser pulses with plasmas. These laser-produced ion beams have important applications ranging from the fast ignition of thermonuclear targets to proton imaging, deep proton lithography, medical physics, and injectors for conventional accelerators. Although the basic physical mechanisms of ion beam generation in the plasma produced by the laser pulse interaction with the target are common to all these applications, each application requires a specific optimization of the ion beam properties, that is, an appropriate choice of the target design and of the laser pulse intensity, shape, and duration.
Effect of a nanometer scale plasma on laser-accelerated ion beams
New Journal of Physics, 2009
Energies of laser-accelerated ions from thin foils in the so-called 'ultra-high-contrast' regime have been measured for various preformed plasma sizes on the non-irradiated foil surface. Whereas energies of protons accelerated in the laser counter-propagating direction remain almost constant for plasma scale length up to 300 nm, we found that plasmas as short as a few tens of nanometers reduce the maximum energy of ions accelerated in the laser direction. These experimental measurements are numerically confirmed with two-dimensional particle-in-cell simulations coupled to hydrodynamic calculation. Moreover, our experimental results, supported by simulations, provide evidence for the occurrence of ion wave breaking, and demonstrate its ability to mitigate the ion energy reduction due to the plasma gradient. This wave breaking is observed and characterized for both proton and carbon ion components.
Longitudinal Ion Acceleration From High-Intensity Laser Interactions With Underdense Plasma
Plasma Science, …, 2008
Longitudinal ion acceleration from high-intensity (I ∼ 10 20 Wcm −2 ) laser interactions with helium gas jet targets (n e ≈ 0.04n c ) have been observed. The ion beam has a maximum energy for He 2+ of (40 +3 −8 ) MeV and was directional along the laser propagation path, with the highest energy ions being collimated to a cone of less than 10 • . 2D particle-in-cell simulations have been used to investigate the acceleration mechanism. The time varying magnetic field associated with the fast electron current provides a contribution to the accelerating electric field as well as providing a collimating field for the ions. A strong correlation between the plasma density and the ion acceleration was found. A short plasma scale-length at the vacuum interface was observed to be beneficial for the maximum ion energies, but the collimation appears to be improved with longer scale-lengths due to enhanced magnetic fields in the ramp acceleration region.
Ion Acceleration by Collisionless Shocks in High-Intensity-Laser–Underdense-Plasma Interaction
Physical Review Letters, 2004
Ion acceleration by the interaction of an ultraintense short-pulse laser with an underdense-plasma has been studied at intensities up to 3 10 20 W=cm 2 . Helium ions having a maximum energy of 13:2 1:0 MeV were measured at an angle of 100 from the laser propagation direction. The maximum ion energy scaled with plasma density as n 0:700:05 e . Two-dimensional particle-in-cell simulations suggest that multiple collisionless shocks are formed at high density. The interaction of shocks is responsible for the observed plateau structure in the ion spectrum and leads to an enhanced ion acceleration beyond that possible by the ponderomotive potential of the laser alone.
Plasma physics with intense laser and ion beams
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2000
The unique combination of an intense heavy ion beam and a high-energy Nd:glass laser system at Gesellschaft f ur Schwerionenforschung (GSI-Darmstadt) facilitates pioneering beam-plasma interaction experiments and thus allows to address basic physics issues associated with heavy ion-driven inertial fusion. The deposition power of the intense heavy ion beam from the synchrotron has recently been increased to 1 kJ/g. The hydrodynamic response of solid targets was measured. A comparison with detailed numerical simulations attributes the target response to a pressure pulse of 3 GPa at a maximum temperature of 2500 K. Beam plasma interaction experiments to measure the stopping power of laser plasmas for heavy ion beams have been performed and show an increased energy loss for Ni ions in a 60 eV dense carbon plasma. Subsequently performed time-resolved charge-state measurements indicate that the increased stopping power can partially be attributed to a high charge state of the beam ions traversing the plasma. Improved plasma diagnostic by high-resolution spectroscopy revealed the unexpected existence of He-like resonance and intercombination lines (He a 1s2p 3 P 1 ±1s 2 and Y a 1s2p 3 P 1 ±1s 2 ) of¯uorine even for a modest laser intensity of 5´10 11 W/cm 2 . Ó