High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; et al.

New Journal of Physics (Internet), 16(9), p.093003_1 - 093003_30, 2014/09

https://doi.org/10.1088/1367-2630/16/9/093003

Relativistic high harmonic generation in gas jet targets

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.

AIP Conference Proceedings 1465, p.167 - 171, 2012/07

https://doi.org/10.1063/1.4737557

Soft-X-ray harmonic comb from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.

Physical Review Letters, 108(13), p.135004_1 - 135004_5, 2012/03

https://doi.org/10.1103/PhysRevLett.108.135004

We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multi-terawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving J/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.

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

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Koga, J. K.; Kiriyama, Hiromitsu; et al.

Proceedings of SPIE, Vol.8140, p.81400A_1 - 81400A_16, 2011/10

http://doi.org/10.1117/12.892898

Tomography of an ultrafast laser driven proton source

Ter-Avetisyan, S.*; Schnrer, M.*; Nickles, P. V.*; Sandner, W.*; Borghesi, M.*; Nakamura, Tatsufumi; Mima, Kunioki*

Physics of Plasmas, 17(6), p.063101_1 - 063101_6, 2010/06

https://doi.org/10.1063/1.3428740

Using a multichannel Thomson spectrometer we have implemented a tomographic approach allowing the reconstruction of the emission characteristics of a laser driven proton source with high energy and spatial resolution. The results demonstrate the complexity of the temporal and spatial characteristics of such a source. The emitted proton beam, which is laminar and divergent ant high energies, becomes convergent at low energies. This implies that a fraction of the proton beam having this kinetic energy is emitted in a collimated way from the target at the turning point between these tow behaviors. Only a finite fraction of the target surface is contributing to the ion spectrum, which is measured at a specific angle within the beam cone. Therefore the momentum distribution of the protons in the emitted beam at any point in space can be controlled by determining the proton source area.

Dependence of the ion energy on the parameters of the laser pulse and target in the radiation-pressure-dominated regime of acceleration

Echkina, E. Yu.*; Inovenkov, I. N.*; Esirkepov, T. Z.; Pegoraro, F.*; Borghesi, M.*; Bulanov, S. V.

Plasma Physics Reports, 36(1), p.15 - 29, 2010/01

https://doi.org/10.1134/S1063780X10010022

On the ion acceleration by high power electromagnetic waves in the radiation pressure dominated regime

Bulanov, S. V.; Esirkepov, T. Z.; Pegoraro, F.*; Borghesi, M.*

Comptes Rendus Physique, 10(2-3), p.216 - 226, 2009/03

https://doi.org/10.1016/j.crhy.2009.03.001

Laser-driven proton acceleration; Source optimization and radiographic applications

Borghesi, M.*; Bigongiari, A.*; Kar, S.*; Macchi, A.*; Romagnani, L.*; Audebert, P.*; Fuchs, A.*; Toncian, T.*; Willi, O.*; Bulanov, S. V.; et al.

Plasma Physics and Controlled Fusion, 50(12), p.124040_1 - 124040_10, 2008/12

https://doi.org/10.1088/0741-3335/50/12/124040

Highly efficient relativistic-ion generation in the laser-piston regime

Esirkepov, T. Z.; Borghesi, M.*; Bulanov, S. V.; Mourou, G.*; Tajima, Toshiki

Physical Review Letters, 92(17), p.175003_1 - 175003_4, 2004/04

https://doi.org/10.1103/PhysRevLett.92.175003

An intense laser-plasma interaction regime of the generation of high density ultra-short relativistic ion beam is suggested. When the radiation pressure is dominant, the laser energy is transformed effciently into the energy of fast ions.

Observation of high-order harmonics produced by relativistic laser-plasma interaction

Kando, Masaki; Pirozhkov, A. S.; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A.*; Pikuz, T.*; Kawachi, Tetsuya; Sagisaka, Akito; et al.

no journal, , 

When we focus laser pulses to the relativistic intensities (10 W/cm) in helium plasma, modulated spectra in the ultraviolet region (80- 300 eV) are observed in the forward direction. Some spectra contain odd and even high harmonics of the nearly fundamental frequency of the laser, continuum frequencies, and modulated structures. When we use a higher peak power laser (50-170 TW, 50fs), these spectral features are reproduced almost 100% probability. Also these spectra are observed when the laser polarization is changed to circular. The mechanism observed in our experiment is different from usual high-harmonics from gas targets, betatron radiation of electrons in wakefield, or nonlinear Thomson scattering due to above experimental conditions and results. We propose a theoretical model that electron density cusps formed by intense laser pulses radiate coherently. The validity of the model is confirmed with computer simulations.