L'impact du glissement en fréquence lors de l'accélération directe d'électrons par le faisceau laser
|Abstract:||Direct electron acceleration using ultrashort radially polarized laser pulses in strong focusing conditions exhibits unique properties for the production of ultrashort electron bunches. However, several aspects of this acceleration scheme are still left to investigate in order to ensure our complete understanding of the processes taking place. The present master’s thesis studies the use of TM01 chirped pulses in this acceleration scheme. Exact closed-form expressions for the description of all the components of the electromagnetic field of the TM01 chirped pulse are established by the generalization of the Poisson-like spectrum. It is, to the best of our knowledge, the first exact analytical model of an ultrashort non paraxial chirped pulse. These expressions are then used for on-axis “test particle” simulations, considering, at first, a constant pulse energy and, as a second case, a constant field maximum. Results reveal that chirp pulses seem to cause a decrease of the maximum energy gain achievable using this acceleration scheme; a decrease of the efficiency of tens of percents was observed. Additionnaly, numerical simulations show that down-chirp and up-chirp do not lead to the same results: we find that down-chirped pulses produce a slightly larger energy gain than up-chirped pulses, while still being less efficient than Fourier-transform-limited laser pulses|
|Document Type:||Mémoire de maîtrise|
|Open Access Date:||24 April 2018|
|Collection:||Thèses et mémoires|
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