Coherent X-ray generation in relativistic laser - Gas jet interactions

A. S. Pirozhkov, M. Kando, T. Zh Esirkepov, P. Gallegos, H. Ahmed, E. N. Ragozin, A. Ya Faenov, T. A. Pikuz, J. K. Koga, H. Kiriyama, P. McKenna, M. Borghesi, K. Kondo, H. Daido, Y. Kato, D. Neely, S. V. Bulanov

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

5 Citations (Scopus)


We present experimental results, theory, and simulations demonstrating two novel sources of coherent X-ray radiation generated in the relativistic laser (>10 18W/cm 2) interaction with easily accessible, repetitive, and debris-free gas jet targets. The first source is based on a relativistic mirror reflecting a counter-propagating laser pulse. A strongly nonlinear breaking wake wave driven by an intense laser pulse can act as a semi-transparent relativistic flying mirror. Such a mirror directly converts counter-propagating laser light into a high-frequency (XUV or X-ray) ultrashort pulse due to the double Doppler effect. In the experimental demonstration with the 9 TW J-KAREN laser, the flying mirror generated in a He gas jet partially reflected a 1 TW pulse, providing up to ∼1010 photons, 60 nJ (∼1012 photons/sr) in the XUV range (12.8-22 nm). The second source is demonstrated with the laser power ranging from 9 to 170 TW in experiments with the J-KAREN and Astra Gemini lasers. The odd and even order harmonics generated by linearly as well as circularly polarized pulses are emitted forward out of the gas jet. The 120 TW laser pulses produce harmonics with ∼3×10 13 photons/sr (∼600 μJ/sr) in the 120±5 eV spectral range. The observed harmonics cannot be explained by previously known mechanisms (atomic harmonics, betatron radiation, nonlinear Thomson scattering, etc.). We introduce a novel mechanism of harmonic generation based on the relativistic laser-plasma phenomena (self-focusing, cavity evacuation, bow wave generation), mathematical catastrophe theory which explains the formation of structurally stable electron density singularities, spikes, and collective radiation of a compact charge driven by a relativistic laser.

Original languageEnglish
Title of host publicationX-Ray Lasers and Coherent X-Ray Sources
Subtitle of host publicationDevelopment and Applications IX
EditorsJames Dunn, Annie Klisnick
Place of PublicationBellingham, WA
Publication statusPublished - 5 Oct 2011
EventX-Ray Lasers and Coherent X-Ray Sources: Development and Applications IX - San Diego, CA, United States
Duration: 23 Aug 201125 Aug 2011


ConferenceX-Ray Lasers and Coherent X-Ray Sources: Development and Applications IX
CountryUnited States
CitySan Diego, CA


  • catastrophe theory
  • coherent X-rays
  • double doppler effect
  • electron spikes
  • high-order harmonics
  • particle-in-cell simulation
  • relativistic flying mirror
  • relativistic laser plasma


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