Time: Monday, Apr. 20, 10:00 am
Venue: ZJU Ding Talk
Speaker: O. Rahman
Title: High-quality proton beam generation using multi-laser pulses plasma interactions
Abstract:
A multi-laser pulses plasma interaction scheme is proposed to generate a high-quality mono-energetic proton beam. In this scheme, three linearly polarized Gaussian laser pulses are used to irradiate the double-layer target with different angles of incidences. Initially, two identical laser pulses heat the target obliquely with equal but opposite incidence angles and form two hot electrons bunches by changing the electron distributions of the pre-target. The reflection of the main pulse is significantly reduced, as a result, it can merge these two bunches into a highly dense single bunch and derive them in the forward direction due to the intense radiation pressure similar to the snowplow, which drags the protons to much higher energy. Using two-dimensional particle-in-cell simulations, it is shown that a collimated proton beam of ~1.2 GeV peak energy with immensely low energy spread ~4% and small divergence ~50 can be obtained at intensities of 1021 Wcm-2, which is one order lower as compared with recently proposed some other schemes.
Speaker: Xiaochuan Ning
Title: Transport of an intense ion beam in Plasma
Abstract:
Through accelerator technology, we have been able to obtain intense ion beams, which can be used in many fields. However, due to Coulomb expansion, ion beams can't travel for a long distance in vacuum. Using plasma electrons to neutralize an ion beam is a popular way to restrain its expansion, but during this process, we find a beam-plasma instability arises. The instability can seriously affect an ion beam's propagation. Therefore, it becomes important to study how the instability affects an ion beam's propagation and how to suppress this instability.