Author: Su, J.-J.
Paper Title Page
THPS013 Radiation Pressure Acceleration of Multi-ion Thin Foil 3448
 
  • T.-C. Liu, G. Dudnikova, M.Q. He, C.-S. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su
    UMD, College Park, Maryland, USA
 
  Ra­di­a­tion pres­sure ac­cel­er­a­tion (RPA) is con­sid­ered as an ef­fi­cient way to pro­duce quasi-mo­noen­er­get­ic ions, in which an ul­tra-thin foil is ac­cel­er­at­ed by high in­ten­si­ty cir­cu­lar­ly po­lar­ized laser. Our sim­u­la­tion study shows that an im­por­tant fac­tor lim­it­ing this ac­cel­er­a­tion pro­cess is the Rayleigh-Tay­lor in­sta­bil­i­ty, which re­sults in the ex­po­nen­tial growth of the foil den­si­ty per­tur­ba­tion dur­ing the ac­cel­er­a­tion and hence the in­duced trans­paren­cy of the foil and broad­en­ing of the par­ti­cle en­er­gy spec­trum. We will study RPA of mul­ti-ion thin foil made of car­bon and hy­dro­gen and in­ves­ti­gate the pos­si­bil­i­ty of using abun­dant elec­trons sup­plied from car­bon to delay the foil from be­com­ing trans­par­ent, en­hance the ac­cel­er­a­tion of pro­tons and there­fore im­prove the en­er­gy of quasi-mo­noen­er­get­ic pro­ton beam. We will show the de­pen­dence of the en­er­gy of quasi-mo­noen­er­get­ic pro­ton and car­bon beam on the den­si­ty and con­cen­tra­tion ratio of car­bon and hy­dro­gen in the foil as well as foil thick­ness for RPA.  
 
THPS014 Laser Thin Gas Target Acceleration for Quasi-monoenergetic Proton Generation 3451
 
  • M.Q. He, G. Dudnikova, C.-S. Liu, T.-C. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su
    UMD, College Park, Maryland, USA
  • Z.M. Sheng
    Shanghai Jiao Tong University, Shanghai, People's Republic of China
 
  We pro­pose a scheme of laser thin gas tar­get ac­cel­er­a­tion for quasi-mo­noen­er­get­ic pro­ton gen­er­a­tion. The scheme uses gas tar­get of thick­ness about sev­er­al laser wave­lengths with gas den­si­ty spa­tial dis­tri­bu­tion of Guas­sian or square of sine shape. We per­formed Par­ti­cle-In-Cell sim­u­la­tion using cir­cu­lar­ly po­lar­ized laser of nor­mal­ized max­i­mum am­pli­tude ~5 and hy­dro­gen gas tar­get of thick­ness ~5 laser wave­length with peak den­si­ty three times of the crit­i­cal den­si­ty. The sim­u­la­tion demon­strates sev­er­al key phys­i­cal pro­cess­es in­volved in the laser thin gas tar­get ac­cel­er­a­tion and the ob­ser­va­tion of quasi-mo­noen­er­get­ic pro­tons. Dur­ing the early phase of the laser plas­ma in­ter­ac­tion, elec­tron and ion cav­i­ties are ob­served. A com­pressed plas­ma layer is formed. The re­flect­ed pro­tons in front of the com­pressed layer are ac­cel­er­at­ed and thus a bunch of quasi-mo­noen­er­get­ic pro­tons are ob­tained. The com­pressed layer is fi­nal­ly de­stroyed due to Rayleigh-Tay­lor in­sta­bil­i­ty. The ac­cel­er­a­tion of the quasi-mo­noen­er­get­ic pro­ton then stops with max­i­mum en­er­gy about 8 MeV. It is also found that gas tar­get thick­ness plays an im­por­tant role for ef­fi­cient quasi-mo­noen­er­get­ic pro­ton gen­er­a­tion.