Paper
7 May 2009 Comparative study of betatron radiation from laser-wakefield and direct-laser accelerated bunches of relativistic electrons
S. Kneip, C. McGuffey, S. R. Nagel, C. Palmer, C. Bellei, J. Schreiber, C. Huntington, F. Dollar, T. Matsuoka, V. Chvykov, G. Kalintchenko, V. Yanovsky, A. Maksimchuk, K. Ta Phuoc, S. P. D. Mangles, K. Krushelnick, Z. Najmudin
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Abstract
The dynamics of relativistic electrons in a laser driven plasma cavity are studied via measurements of their radiation. For ultrashort laser pulses at comparatively low focused laser intensities (3 < a0 < 10), low density and long f-number of 10, electrons are predominantly accelerated in the wakefield leading to quasi-monoenergetic collimated electron beams and well collimated (< 12 mrad) beams of comparatively soft x-rays (1-10 keV) with unprecedented small source size (2-3 μm). For laser pulses with increasing laser intensity (10 < a0 < 30), density and short f-number (< 5), electrons are accelerated directly by the laser, leading to divergent quasimaxwellian electron beams and divergent (50-95°) beams of hard x-rays (20-50 keV) with relatively large source size (> 100 μm). In both cases, the measured x-rays are well described in the synchrotron asymptotic limit of electrons oscillating in a plasma channel. At low laser intensity transverse oscillations are small as the electrons are predominantly accelerated axially by the laser generated wakefield. At high laser intensity, electrons are directly accelerated by the laser. A betatron resonance leads to a tenfold increase in transverse oscillation amplitude and electrons enter a highly radiative regime with up to 5% of their energy converted into x-rays.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. Kneip, C. McGuffey, S. R. Nagel, C. Palmer, C. Bellei, J. Schreiber, C. Huntington, F. Dollar, T. Matsuoka, V. Chvykov, G. Kalintchenko, V. Yanovsky, A. Maksimchuk, K. Ta Phuoc, S. P. D. Mangles, K. Krushelnick, and Z. Najmudin "Comparative study of betatron radiation from laser-wakefield and direct-laser accelerated bunches of relativistic electrons", Proc. SPIE 7359, Harnessing Relativistic Plasma Waves as Novel Radiation Sources from Terahertz to X-Rays and Beyond, 73590T (7 May 2009); https://doi.org/10.1117/12.820657
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Cited by 19 scholarly publications.
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KEYWORDS
Electrons

X-rays

Plasma

Optical filters

Photons

Pulsed laser operation

Electron beams

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