A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z  

Fukuda, Y.

Paper Title Page
MOPEA059 Laser Acceleration of Negative Ions by Coulomb Implosion Mechanism 211
 
  • T. Nakamura, S.V. Bulanov, H. Daido, T. Esirkepov, A. Faenov, Y. Fukuda, Y. Hayashi, T.K. Kameshima, M. Kando, T. Pikuz, A.S. Pirozhkov, M. Tampo, A. Yogo
    JAEA/Kansai, Kyoto
  
 

In­tense laser pulse is uti­lized to gen­er­ate com­pact sources of elec­trons, ions, x-rays, neu­trons. Re­cent­ly, high en­er­gy neg­a­tive ions are also ob­served in ex­per­i­ments using clus­ter or gas tar­get*. To ex­plain the ac­cel­er­a­tion of neg­a­tive ions from laser-gen­er­at­ed plas­mas, we pro­posed Coulomb im­plo­sion mech­a­nism**. When clus­ters or un­der­dense plas­mas are ir­ra­di­at­ed by an in­tense laser pulse, pos­i­tive ions are ac­cel­er­at­ed in­side the clus­ters or in the self-fo­cus­ing chan­nel by the Coulomb ex­plo­sion. This could lead to the ac­cel­er­a­tion of neg­a­tive ions to­wards tar­get cen­ter. The max­i­mum en­er­gy of neg­a­tive ions is typ­i­cal­ly sev­er­al times lower than that of pos­i­tive ions. A the­o­ret­i­cal de­scrip­tion and cor­re­spond­ing Par­ti­cle-in-Cell sim­u­la­tions of Coulomb im­plo­sion mech­a­nism are pre­sent­ed. We show the ev­i­dence of the neg­a­tive ion ac­cel­er­a­tion ob­served in our ex­per­i­ments using high in­ten­si­ty laser pulse and the clus­ter-gas tar­gets.


* S.Ter-Avetisyan et al., J. Phys. B 37 (2004) 3633.
** T.Nakamura et al., Phys. Plasmas 16 (2009) 113106.

  
TUPE027 Target Ionization Dynamics by Irradiation of X-ray Free-electron Laser Light 2200
 
  • T. Nakamura, Y. Fukuda
    JAEA/Kansai, Kyoto
  • Y. Kishimoto
    Kyoto Univeristy, Kyoto
  
 

In­ter­ac­tions of x-ray free elec­tron laser (XFEL) light with a sin­gle clus­ter tar­get are nu­mer­i­cal­ly in­ves­ti­gat­ed. The ir­ra­di­a­tion of XFEL light onto ma­te­ri­al leads to the ion­iza­tion of the tar­get by pho­to-ion­iza­tion and gen­er­a­tion of high en­er­gy elec­trons. This re­sults in the fur­ther ion­iza­tion via Auger ef­fect, col­li­sion­al ion­iza­tion, and field ion­iza­tion. The ion­iza­tion rate or time scale of each pro­cess de­pends on the con­di­tion of XFEL (in­ten­si­ty, du­ra­tion, pho­ton en­er­gy) and tar­get size. In order to un­der­stand the ion­iza­tion dy­nam­ics, we used a three-di­men­sion­al Par­ti­cle-in-Cell code which in­cludes the plas­ma dy­nam­ics as well as rel­e­vant atom­ic pro­cess­es such as pho­to-ion­iza­tion, the Auger ef­fect, col­li­sion­al ion­iza­tion/re­lax­ation, and field ion­iza­tion. It is found that as the XFEL in­ten­si­ty in­creas­es to as high as rough­ly 1021 pho­tons/pulse/mm2, the field ion­iza­tion, which is the dom­i­nant ion­iza­tion pro­cess over the other atom­ic pro­cess­es, leads to rapid tar­get ion­iza­tion. The tar­get dam­age due to the ir­ra­di­a­tion by XFEL light is nu­mer­i­cal­ly eval­u­at­ed, which gives an es­ti­ma­tion of the XFEL in­ten­si­ty so as to sup­press the tar­get dam­age with­in a tol­er­a­ble range for imag­ing.


* T. Nakamura, et al., Phys. Rev. A, vol. 80, 053202 (2009)

  

slides icon

Slides