• 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.