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Article
Holographic visualization of laser wakefields
New Journal of Physics (2010)
  • Peng Dong
  • Steven A. Reed
  • Sunghwan A. Yi
  • Serguei Y. Kalmykov
  • Zhengyan Y. Li
  • Gennady Shvets
  • Nicholas H. Matlis
  • Christopher McGuffey
  • Stepan S. Bulanov
  • Vladimir Chvykov
  • Galina Kalintchenko
  • Karl Krushelnick
  • Anatoly Maksimchuk
  • Takeshi Matsuoka
  • Alexander G. R. Thomas
  • Victor Yanovsky
  • Michael C. Downer
Abstract

We report ‘snapshots’ of laser-generated plasma accelerator structures acquired by frequency domain holography (FDH) and frequency domain shadowgraphy (FDS), techniques for visualizing quasi-static objects propagating near the speed of light. FDH captures images of sinusoidal wakes in mm-length plasmas of density 1 < n_{e} < 5 x 10^{18} cm^{−3} from phase modulations they imprint on co-propagating probe pulses. Changes in the wake structure (such as the curvature of the wavefront), caused by the laser and plasma parameter variations from shot to shot, were observed. FDS visualizes lasergenerated electron density bubbles in mm-length plasmas of density n_{e} > 10^{19} cm^{−3} using amplitude modulations they imprint on co-propagating probe pulses. Variations in the spatio-temporal structure of bubbles are inferred from corresponding variations in the shape of ‘bullets’ of probe light trapped inside them and correlated with mono-energetic electron generation. Both FDH and FDS average over structural variations that occur during propagation through the plasma medium. We explore via simulations a generalization of FDH/FDS (termed frequency domain tomography (FDT)) that can potentially record a time sequence of quasi-static snapshots, like the frames of a movie, of the wake structure as it propagates through the plasma. FDT utilizes several probe–reference pulse pairs that propagate obliquely to the wake, along with tomographic reconstruction algorithms similar to those used in medical CAT scans.

Keywords
  • Laser wakefield acceleration,
  • plasma wake,
  • frequency-domain holography,
  • frequency-domain shadowgraphy,
  • frequency-domain tomography
Publication Date
Spring April 30, 2010
Citation Information
Peng Dong, Steven A. Reed, Sunghwan A. Yi, Serguei Y. Kalmykov, et al.. "Holographic visualization of laser wakefields" New Journal of Physics Vol. 12 (2010)
Available at: http://works.bepress.com/serguei_kalmykov/10/