Effect of pulse profile and chirp on a laser wakefield generationстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:A laser wakefield driven by an asymmetric laser pulse with/without chirp is investigated
analytically and through two-dimensional particle-in-cell simulations. For a laser pulse with an
appropriate pulse length compared with the plasma wavelength, the wakefield amplitude can be
enhanced by using an asymmetric un-chirped laser pulse with a fast rise time; however, the growth
is small. On the other hand, the wakefield can be greatly enhanced for both positively chirped laser
pulse having a fast rise time and negatively chirped laser pulse having a slow rise time.
Simulations show that at the early laser-plasma interaction stage, due to the influence of the fast
rise time the wakefield driven by the positively chirped laser pulse is more intense than that driven
by the negatively chirped laser pulse, which is in good agreement with analytical results. At a later
time, since the laser pulse with positive chirp exhibits opposite evolution to the one with negative
chirp when propagating in plasma, the wakefield in the latter case grows more intensely. These
effects should be useful in laser wakefield acceleration experiments operating at low plasma
densities.