15 research outputs found
Kinetic and finite ion mass effects on the transition to relativistic self-induced transparency in laser-driven ion acceleration
We study kinetic effects responsible for the transition to relativistic
self-induced transparency in the interaction of a circularly-polarized
laser-pulse with an overdense plasma and their relation to hole-boring and ion
acceleration. It is demonstrated using particle-in-cell simulations and an
analysis of separatrices in single-electron phase-space, that ion motion can
suppress fast electron escape to the vacuum, which would otherwise lead to
transition to the relativistic transparency regime. A simple analytical
estimate shows that for large laser pulse amplitude the time scale over
which ion motion becomes important is much shorter than usually anticipated. As
a result, the threshold density above which hole-boring occurs decreases with
the charge-to-mass ratio. Moreover, the transition threshold is seen to depend
on the laser temporal profile, due to the effect that the latter has on
electron heating. Finally, we report a new regime in which a transition from
relativistic transparency to hole-boring occurs dynamically during the course
of the interaction. It is shown that, for a fixed laser intensity, this dynamic
transition regime allows optimal ion acceleration in terms of both energy and
energy spread.Comment: Added new material. 15 pages, 12 figure
Comment on “Temporal Dynamics of ICP, CPP, PRx, and CPPopt in High-Grade Aneurysmal Subarachnoid Hemorrhage and the Relation to Clinical Outcome”
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Pay Attention to Blood Pressure and Oxygen Supply for Neurocritically Ill Patients: Each Pathology Deserves a Specific Treatment
Laser-driven collisionless shock acceleration of protons
Experimental and numerical results have shown that collisionless shock acceleration is promis-ing for generation of high energy proton beams. There are many potential applications for suchbeams, for example: isotope generation for medical applications, ion therapy and proton radio-graphy. In this work, we use 1D1P Eulerian Vlasov-Maxwell simulations to study shock waveacceleration. Vlasov-Maxwell modeling allows for high resolution of the distribution functionand is highly suitable in cases where effects of low-density tails in the distribution function needto be resolved accurately.We find that combining collisionless shock acceleration with a strong, quasi-stationary sheath-field may be a way to reach even higher maximum proton energies and optimize the ion spec-trum. We show that a layered plasma target with a combination of light and heavy ions leads toa strong quasi-static sheath-field, which induces an enhancement of the energy of shock-waveaccelerated ions, without broadening their energy spectrum, if the heavy ion layer has highdensity
Kinetic effects on the transition to relativistic self-induced transparency in laser-driven ion acceleration
We study kinetic effects responsible for the transition to relativistic self-induced transparency in the interaction of a circularly-polarized laser-pulse with an overdense plasma and their relation to hole-boring and ion acceleration. It is shown, using particle-in-cell simulations and an analysis of separatrices in single-particle phase-space, that this transition is mediated by the complex interplay of fast electron dynamics and ion motion at the initial stage of the interaction. It thus depends on the ion charge-to-mass ratio and can be controlled by varying the laser temporal profile. Moreover, we find a new regime in which a transition from relativistic transparency to hole-boring occurs dynamically during the course of the interaction. It is shown that, for a fixed laser intensity, this dynamic transition regime allows optimal ion acceleration in terms of both energy and energy spread
Kinetic effects on the transition to relativistic self-induced transparency in laser-driven ion acceleration
We study kinetic effects responsible for the transition to relativistic self-induced transparency in the interaction of a circularly-polarized laser-pulse with an overdense plasma and their relation to hole-boring and ion acceleration. It is shown, using particle-in-cell simulations and an analysis of separatrices in single-particle phase-space, that this transition is mediated by the complex interplay of fast electron dynamics and ion motion at the initial stage of the interaction. It thus depends on the ion charge-to-mass ratio and can be controlled by varying the laser temporal profile. Moreover, we find a new regime in which a transition from relativistic transparency to hole-boring occurs dynamically during the course of the interaction. It is shown that, for a fixed laser intensity, this dynamic transition regime allows optimal ion acceleration in terms of both energy and energy spread
Kinetic effects on the transition to relativistic self-induced transparency in laser-driven ion acceleration
We study kinetic effects responsible for the transition to relativistic self-induced transparency in the interaction of a circularly-polarized laser-pulse with an overdense plasma and their relation to hole-boring and ion acceleration. It is shown, using particle-in-cell simulations and an analysis of separatrices in single-particle phase-space, that this transition is mediated by the complex interplay of fast electron dynamics and ion motion at the initial stage of the interaction. It thus depends on the ion charge-to-mass ratio and can be controlled by varying the laser temporal profile. Moreover, we find a new regime in which a transition from relativistic transparency to hole-boring occurs dynamically during the course of the interaction. It is shown that, for a fixed laser intensity, this dynamic transition regime allows optimal ion acceleration in terms of both energy and energy spread