This thesis reports on a theoretical investigation aimed at assessing the degree of reliability of methods for the simulation of laser-driven neutron sources. More precisely, neutron generation in a pitcher-catcher scheme is considered. The theoretical tools available for the study of such systems include analytical and numerical methods. As regards these latter, the dynamics of ion acceleration and the neutron generation processes are modelled, respectively, by means of the particle-in-cell code Piccante and of the Monte-Carlo-based Geant4 toolkit. By properly combining the two above-mentioned codes, it is possible to obtain a comprehensive numerical tool able to perform multi-physics simulations of the whole system. Simulations are supported by analytical methods, which are employed for making simple estimates. After having ascertained, by means of a benchmark against experimental data suitably chosen from the literature, the possibility and the limits of the employment of theoretical methods, these have been used for the study of systems of actual interest,i.e. compact laser-driven neutron sources. This activity implied the necessity to introduce optimized features inside the system, especially concerning the pitcher and catcher architecture. i
Questo lavoro di tesi riporta un’indagine teorica volta ad appurare il grado di affidabilità di metodi per la simulazione di sorgenti di neutroni da laser. Più precisamente, viene considerata la generazione di neutroni per mezzo di uno schema pitcher-catcher. Gli strumenti teorici disponibili per lo studio di questi sistemi includono metodi analitici e numerici. Con riferimento a questi ultimi, la dinamica dell’accelerazione di ioni e il processo di generazione dei neutroni vengono modellati facendo uso, rispettivamente, del codice particle-in-cell piccante e del toolkit Geant4, basato sul metodo Monte Carlo. Combinando opportunamente tra loro i codici sopra citati, è possibile ottenere uno strumento numerico complessivo in grado di eseguire simulazioni dell’intero sistema. A questo strumento si affiancano metodi analitici, per stime semplificate di grandezze caratteristiche. Dopo aver accertato, mediante un benchmark con dati sperimentali opportunamente selezionati, la possibilità e i limiti nell’utilizzo di metodi teorici, questi sono stati impiegati per lo studio di sistemi di attuale interesse, ossia le sorgenti di neutroni da laser compatte. Ciò ha comportato la necessità di introdurre elementi di ottimizzazione nel sistema, in particolare per quanto riguarda il design del pitcher e del catcher.
Compact laser-driven neutron sources : a theoretical investigation
ARIOLI, FRANCESCA MARIA
2017/2018
Abstract
This thesis reports on a theoretical investigation aimed at assessing the degree of reliability of methods for the simulation of laser-driven neutron sources. More precisely, neutron generation in a pitcher-catcher scheme is considered. The theoretical tools available for the study of such systems include analytical and numerical methods. As regards these latter, the dynamics of ion acceleration and the neutron generation processes are modelled, respectively, by means of the particle-in-cell code Piccante and of the Monte-Carlo-based Geant4 toolkit. By properly combining the two above-mentioned codes, it is possible to obtain a comprehensive numerical tool able to perform multi-physics simulations of the whole system. Simulations are supported by analytical methods, which are employed for making simple estimates. After having ascertained, by means of a benchmark against experimental data suitably chosen from the literature, the possibility and the limits of the employment of theoretical methods, these have been used for the study of systems of actual interest,i.e. compact laser-driven neutron sources. This activity implied the necessity to introduce optimized features inside the system, especially concerning the pitcher and catcher architecture. iFile | Dimensione | Formato | |
---|---|---|---|
main_FRANCESCA_ARIOLI.pdf
accessibile in internet per tutti
Descrizione: testo della tesi
Dimensione
8.74 MB
Formato
Adobe PDF
|
8.74 MB | Adobe PDF | Visualizza/Apri |
I documenti in POLITesi sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/10589/142386