Bright synchrotron radiation from nano-forest targets

Abstract

This paper proposes an intense x-ray source based on the interactions of intense laser pulses with nanowire targets. The presented electron dynamics and energy scalings have been studied by three dimensional particle-in-cell simulations. The resonance of the electronic betatron oscillations with the incident laser field results in extremely high energy electrons. The scaling of radiation intensity is predicted to be ∼IL5/2, where IL is the laser intensity, using optimal parameters. In this case, the number of photons emitted, via synchrotron radiation, with energies above the keV level with 0.1 rad angular spread is greater than 108/fs for intensities IL>1020 W/cm2. This scaling law suggests that the photon flux production using nanowires of suitable lengths is much greater than in a underdense plasma.

Attosecond bunches of gamma photons and positrons generated in nanostructure targets

“…Here, we show that a suitable large separation (D sp ) between nanorods allows the formation of attosecond electron bunches at every half cycle of the laser field, resulting in the coherent emission of gamma photons in attosecond bunches. This works builds on previous works [17] [20] and analyses the interaction of intense laser pulses (10 22 W/cm 2 < I L < 10 23 W/cm 2 ) with array of nanorods at solid density including the above mentioned QED effects. The laser pulses considered have a FWHM duration of 15 fs while the density of nanorods is 200n cr , where n cr = ω 2 0 m e ǫ 0 /e 2 is the critical density, with a diameter and length of 200 nm and 10 µm, respectively.…”

Laser-induced extreme magnetic field in nanorod targets

“…In the case of thin nanorods (∼100 nm in diameter), the return current (I r ) is spatially limited to the cross section of the rods, and exceeds the Alfén current [6,15] without disturbing the fast electron propagation between the nanorods. The azimuthal magnetic field has a guiding role [12] and Weibel instability can not develop because its amplitude is much higher than the magnetic field induced by hot electrons. Two interaction regimes with different magnetic field distribution and its generation mechanisms can be distinguished and they depend on the target density and laser intensity.…”

“…The definition of effective critical thickness [12] can be used in both regimes to express the self magnetic field in terms of = R r d 2 w cr , which leads to the following function A series of simulations measuring the azimuthal magnetic field from a single nanorod interacting with an intense field have been performed in order to check the reliability of results and to explore the transition between these regimes. The experimental conditions for  ¥ R can be achieved by decreasing a 0 or by increasing n 0 , which means that infinite magnetic field could be generated by using the right parameters.…”

“…The relativistic electrons should be laterally inserted into the nanorod array, parallel with the magnetic field of the laser pulse. It has been shown that intense multi-keV photon burst can be produced in the direction of the laser propagation via interaction with nano-wires [12] but nano-wires are required as efficient synchrotron emissions are relatively long (>10 μm).…”

“…There are several advantages in using nanorods arrays with intense laser pulses which arise from the high energy absorption efficiency [7,8]. Such targets have been used in high energy density matter physics [6,9,10] and in generation of intense x-ray sources via laser-induced synchrotron radiation [11,12]. Their usage, however, has not been considered, in detail, for the generation of extreme magnetic fields for applications or experiments.…”