ﺎرﻣﻮﻧﯿﮏ ﻫﺎي ﺑﺎﻟﺎ ﺑﺎ اﺳﺘﻔﺎده از ﺗﺎﺑﺶ ﻟﯿﺰر ﻓﻤﺘﻮﺛﺎﻧﯿﻪ ﺑﺮروي ﭘﻠﺎﺳﻤﺎي ﭼﮕﺎل ﺗﻮﻟﯿﺪ ﺷﺪه از ﻫﺪف ﺟﺎﻣﺪ

High-order harmonic generation from over dense plasma by interaction of intense femtosecond laser pulses with solids

در اﯾﻦ ﻣﻘﺎﻟﻪ ﺑﻪ ﺑﺮرﺳﯽ ﻧﻈﺮي ﺗﻮﻟﯿﺪ ﻫﺎرﻣﻮﻧﯿﮏ ﻫﺎي ﺑﺎﻟﺎ در اﻧﺪر ﮐﻨﺶ ﻟﯿﺰر ﭘﺮ ﺷﺪت ﺑﺎ اﻫﺪاف ﺟﺎﻣﺪ و ﭘﻠﺎﺳﻤﺎي ﻓﻮق ﭼﮕﺎل ﭘﺮداﺧﺘﻪ ﺷﺪه اﺳﺖ. ﻣﺸﺎﻫﺪه ﻣﯽ ﺷﻮد ﮐﻪ ﺑﺎزده اﺷﻌﻪ اﯾﮑﺲ ﺗﻮﻟﯿﺪي در اﯾﻦ ﺣﺎﻟﺖ ﺑﯿﺸﺘﺮ از ﺗﻮﻟﯿﺪ آن ﺑﺎ اﺳﺘﻔﺎده از ﻫﺪف ﻫﺎي ﮔﺎزي ﻣﯽ ﺑﺎﺷﺪ. ﺗﺎﺛﯿﺮ ﭘﺎراﻣﺘﺮﻫﺎي ﻣﺨﺘﻠﻒ ﻟﯿﺰر و ﭘﻠﺎﺳﻤﺎ در ﺷﺪت ﻫﺎرﻣﻮﻧﯿﮏ ﻫﺎي ﺗﻮﻟﯿﺪ ﺷﺪه ﺗﻮﺳﻂ ﮐﺪ ﺷﺒﯿﻪ ﺳﺎزي ذره در ﺳﻠﻮل ﺑﺮرﺳﯽ ﺷﺪه اﺳﺖ. ﺑﻪ ﺑﺮرﺳﯽ ﺗﺎﺛﯿﺮ ﻋﻮاﻣﻞ ﻣﺨﺘﻠﻒ ﺑﺮ روي ﭘﻬﻨﺎي زﻣﺎﻧﯽ ﺗﭗ ﻫﺎي آﺗﻮ ﺛﺎﻧﯿﻪ ﺣﺎﺻﻞ از ﻫﺎرﻣﻮﻧﯿﮏ ﻫﺎي ﺑﺎﻟﺎ ﭘﺮداﺧﺘﻪ ﺷﺪه اﺳﺖ. ﻫﻤﭽﻨﯿﻦ راﻧﺪﻣﺎن ﺗﻮﻟﯿﺪ اﺷﻌﻪ اﯾﮑﺲ درﺷﺪت ﻫﺎي ﻣﺨﺘﻠﻒ ﻟﯿﺰر در ﻧﺎﺣﯿﻪ ﻏﯿﺮ ﻧﺴﺒﯿﺘﯽ و ﺷﺪت ﻫﺎي ﻧﺴﺒﯿﺘﯽ را ﺑﺮرﺳﯽ ﺷﺪه اﺳﺖ. اﯾﻦ ﺷﺒﯿﻪ ﺳﺎزي را در ﻗﻄﺒﺶ ﻫﺎي ﻣﺨﺘﻠﻒ ﻧﯿﺰ اﻧﺠﺎم داده و داﻣﻨﻪ ﺑﺪﺳﺖ آﻣﺪه را ﻧﯿﺰ ﻣﻘﺎﯾﺴﻪ ﮐﺮدﯾﻢ و ﺑﻪ اﯾﻦ ﻧﺘﯿﺠﻪ رﺳﯿﺪﯾﻢ ﮐﻪ داﻣﻨﻪ ﻧﻮﺳﺎﻧﺎت ﺳﻄﺢ ﭘﻠﺎﺳﻤﺎ در ﻗﻄﺒﺶ ﺑﯿﺸﺘﺮ از ﻗﻄﺒﺶ ﻣﯽ ﺑﺎﺷﺪ. ﻋﻠﺎوه ﺑﺮ آن ﻃﻮل ﺑﻬﯿﻨﻪ ﭘﻠﺎﺳﻤﺎ را ﺑﺮاي ﻫﺎرﻣﻮﻧﯿﮏ ﻫﺎي ﻫﺸﺘﺎدم ﺑﺎ ﻣﻄﺎﻟﻌﻪ ﻃﻮل رﻣﭗ ﻫﺎي ﻣﺨﺘﻠﻒ را ﺑﺪﺳﺖ آوردﯾﻢ.

in this work high harmonic generations by interaction of intense lasers with solid targets and ultra-dense plasma is studied. It is notice that the X rays have produced with higher efficiencies with these targets in comparison with gas jets. In this thesis also the effect of various parameters on the width of generated atto-second pulses in high harmonic is investigated. The efficiency of produced x rays are calculated versus laser intensity both in relativistic and under relativistic regions. The current simulation is also carried out in various laser pulse polarizations and in this found that the amplitude of plasma oscillations are higher in p-polarization in comparison to the one with s-polarization. Furthermore, the optimum plasma length is defined by testing various plasma ramps.