Event calendar file
Department of Nuclear and Atomic Physics Seminars
Controlled Laser Acceleration of Electrons
by Dr. Brijesh P. (ENSTA-CNRS-Ecole Polytechnique, Palaiseau, France)
Monday, December 26, 2011
from
to
(Asia/Kolkata)
at Colaba Campus ( P305 )
at Colaba Campus ( P305 )
| Description |
High-intensity, ultrafast laser technology has enabled the development of compact electron sources in the range of KeV to MeV energy scales. Energetic electrons can be generated by the interaction of the intense laser with a gas-target either through the mechanism of ponderomotive acceleration or laser-plasma acceleration, depending on specific laser and target density parameters. The energy gain by ponderomotive acceleration in near-vacuum target conditions is directly due to the electromagnetic fields of the laser focus whereas in the laser-plasma acceleration mechanism, the accelerating structure is the plasma bubble generated in the wake of the laser-pulse propagating in an underdense plasma. However both these mechanisms of electron acceleration suffer from certain limitations in terms of the characteristics of the final electron quality such as angular divergence, maximum energy gain and energy spread. In this talk, experimental and modeling results1 are presented to demonstrate as a proof of concept that three-dimensional shaping of spatial-intensity distribution of the laser focal volume can lead to reduced electron ejection angle and greater energy gain compared to ponderomotive acceleration with a Gaussian focus. An optical system to generate a “horseshoe” shaped longitudinal focal profile that can control the electron dynamics is described and electron-trajectory simulation data including measurements of electron energy spectrum obtained from the shaped focal volume of a Terawatt scale laser system is shown in support of the concept. In the second part of the talk dealing with a laser-plasma accelerator2, plasma density-gradients along the laser-propagation direction is shown to induce controlled injection of electrons into the plasma bubble leading to accelerated electrons with narrower energy spread compared to acceleration in a homogeneous plasma. Based on this technique, we demonstrate fine tune control of the final electron energy by varying the axial location of the density perturbation. 1 Research performed at Laboratory for Laser Energetics, University of Rochester, New York-USA 2 Research performed at Laboratoire d’Optique Appliquee, ENSTA-Ecole Polytechnique, Palaiseau-France |
| Organised by | Dr. Vaibhav Prabhudesai |
