اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدPrepulse and amplified spontaneous emission effects on the interaction of a petawatt class laser with thin solid targets
226
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
When a finite contrast petawatt laser pulse irradiates a micron-thick foil, a prepulse (including amplified spontaneous emission) creates a preplasma, where an ultrashort relativistically strong portion of the laser pulse (the main pulse) acquires higher intensity due to relativistic self-focusing and undergoes fast depletion transferring energy to fast electrons. If the preplasma thickness is optimal, the main pulse can reach the target generating fast ions more efficiently than an ideal, infinite contrast, laser pulse. A simple analytical model of a target with preplasma formation is developed and the radiation pressure dominant acceleration of ions in this target is predicted. The preplasma formation by a nanosecond prepulse is analyzed with dissipative hydrodynamic simulations. The main pulse interaction with the preplasma is studied with multi-parametric particle-in-cell simulations. The optimal conditions for hundreds of MeV ion acceleration are found with accompanying effects important for diagnostics, including high-order harmonics generation.
قيم البحث
اقرأ أيضاً
We report spatially and temporally resolved measurements of magnetic fields generated by petawatt laser-solid interactions with high spatial resolution, using optical polarimetry. The polarimetric measurements map the megagauss magnetic field profile
s generated by the fast electron currents at the target rear. The magnetic fields at the rear of a 50 $mu$m thick aluminum target exhibit distinct and unambiguous signatures of electron beam filamentation. These results are corroborated by hybrid simulations.
Using two-dimensional (2D) and three-dimensional (3D) kinetic simulations, we examine the impact of simulation dimensionality on the laser-driven electron acceleration and the emission of collimated $gamma$-ray beams from hollow micro-channel targets
. We demonstrate that the dimensionality of the simulations considerably influences the results of electron acceleration and photon generation owing to the variation of laser phase velocity in different geometries. In a 3D simulation with a cylindrical geometry, the acceleration process of electrons terminates early due to the higher phase velocity of the propagating laser fields; in contrast, 2D simulations with planar geometry tend to have prolonged electron acceleration and thus produce much more energetic electrons. The photon beam generated in the 3D setup is found to be more diverged accompanied with a lower conversion efficiency. Our work concludes that the 2D simulation can qualitatively reproduce the features in 3D simulation, but for quantitative evaluations and reliable predictions to facilitate experiment designs, 3D modelling is strongly recommended.
Effects of ionization injection in low and high Z gas mixtures for the laser wake field acceleration of electrons are analyzed with the use of balance equations and particle-in-cell simulations via test probe particle trajectories in realistic plasma
fields and direct simulations of charge loading during the ionization process. It is shown that electrons appearing at the maximum of laser pulse field after optical ionization are trapped in the first bucket of the laser pulse wake. Electrons, which are produced by optical field ionization at the front of laser pulse, propagate backwards; some of them are trapped in the second bucket, third bucket and so on. The efficiency of ionization injection is not high, several pC/mm/bucket. This injection becomes competitive with wave breaking injection at lower plasma density and over a rather narrow range of laser pulse intensity.
Developments in quantum technologies lead to new applications that require radiation sources with specific photon statistics. A widely used Poissonian statistics are easily produced by lasers; however, some applications require super- or sub-Poissoni
an statistics. Statistical properties of a light source are characterized by the second-order coherence function g^(2)(0). This function distinguishes stimulated radiation of lasers with g^(2)(0)=1 from light of other sources. For example, g^(2)(0)=2 for black-body radiation, and g^(2)(0)=0 for single-photon emission. One of the applications requiring super-Poissonian statistics (g^(2)(0)>1) is ghost imaging with thermal light. Ghost imaging also requires light with a narrow linewidth and high intensity. Currently, rather expensive and inefficient light sources are used for this purpose. In the last year, a superluminescent diode based on amplified spontaneous emission (ASE) has been considered as a new light source for ghost imaging. Even though ASE has been widely studied, its photon statistics has not been settled - there are neither reliable theoretical estimates of the second-order coherence function nor unambiguous experimental data. Our computer simulation clearly establishes that coherence properties of light produced by ASE are similar to that of a thermal source with g^(2)(0)=2 independent of pump power. This result manifests the fundamental difference between ASE and laser radiation.
The propagation of ultra intense laser pulses through matter is connected with the generation of strong moving magnetic fields in the propagation channel as well as the formation of a thin ion filament along the axis of the channel. Upon exiting the
plasma the magnetic field displaces the electrons at the back of the target, generating a quasistatic electric field that accelerates and collimates ions from the filament. Two-dimensional Particle-in-Cell simulations show that a 1 PW laser pulse tightly focused on a near-critical density target is able to accelerate protons up to an energy of 1.3 GeV. Scaling laws and optimal conditions for proton acceleration are established considering the energy depletion of the laser pulse.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
