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Archivio digitale delle tesi discusse presso l’Università di Pisa

Tesi etd-07032017-103429


Tipo di tesi
Tesi di dottorato di ricerca
Autore
PALLA, DANIELE
URN
etd-07032017-103429
Titolo
Self-injection in a moderately relativistic LWFA regime
Settore scientifico disciplinare
FIS/01
Corso di studi
FISICA
Relatori
tutor Dott. Gizzi, Leonida Antonio
correlatore Dott. Londrillo, Pasquale
Parole chiave
  • downramp
  • ionization injection
  • LWFA
  • moderately relativistic
  • nitrogen ionization
  • self-focusing
  • self-injection
Data inizio appello
23/08/2017
Consultabilità
Completa
Riassunto
My thesis work is centered on the study of the injection properties of LWFA using gas target with different
ionization properties including He an N2.
The study is centered on experimental work performed at the Intense Laser Irradiation Laboratory (ILIL) in Pisa where application of LWFA including radiobiology and secondary radiation sources studies are being developed. For the thesis, a moderately relativistic LWFA regime was considered, characterized by a maximum intensity on target of I0=2×10^18W/cm 2 with a normalized vector potential a0 =0.96 and a pulse duration of τ=40fs .
In these experimental conditions self-focusing allows the main pulse to remain focused along the entire acceleration length without external guiding. In addition to that, self-focusing also leads to a significant increase of the laser intensity enabling ultrarelativist regime. Background plasma is created via tunneling ionization during the interaction between the laser pulse leading front and the gas targets.
The different ionization properties of nitrogen and helium, combined with the strong dependence of laser pulse intensity upon plasma density, produce substantial differences in the accelerated electron bunch properties. Selected experiments designed to identify the role of ionization in the injection mechanism will be described. In addition, a preliminary experimental
study of the role of tailored density profile will also be presented.
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