Analysis of wakefield electron orbits in plasma wiggler

Abstract

International audienceIn relativistic laser plasma interaction, electrons can be simultaneously accelerated and wiggled in an ion cavity created in the wake of an intense short pulse laser propagating in an underdense plasma. As a consequence of their motion, the accelerated electrons emit an intense x-ray beam called laser produced betatron radiation. Being an emission from charged particles, the features of the betatron source are directly linked to the electrons trajectories. In particular, the radiation is emitted in the direction of the electrons velocity. In this article we show how an image of electrons orbits in the wakefield cavity can be deduced from the structure of x-ray spatial profiles

Laser-plasma electron acceleration in dielectric capillary tubes

“…A "spiral-like" feature is observed in the images for many different shots and for different capillaries. Assuming that specular reflections of X-rays from the inside walls are negligible, the spiral shapes might be understood as the X-ray emission characteristics of electrons along a spiral-like trajectory [20]. Features similar to the observed ones correspond to an oscillation amplitude of the order of ∼0.1 µm, which is about one order of magnitude smaller than the ones mentioned in [18,19].…”

Pump requirements for betatron-generated femtosecond X-ray laser at saturation from inner-shell transitions

“…We calculate the betatron spectra according to the following method: we set the driving laser power, the laser wavelength (0.8 µm), and the plasma density, which, according to [18], determine the blowout radius r b (1) and (2), the accelerated charge (equation 10) and the energy (6). The electrons are injected at the back of the ionic cavity with an initial distance r 0 that we set equal to 0.2 × r b , according to previous source size measurements [21]. The initial axial and radial momenta of the injected electrons are set to γ g and γ g /2, respectively (where γ g is the Lorentz factor associated with the velocity of the ionic cavity), such that the trapping condition γ > γ g holds.…”

“…The analysis of electron trajectories [21] shows that the betatron source size is equal to 2-µm FWHM. Concerning the lifetime of the source, sub-picosecond duration has been experimentally demonstrated [26], and Particle-In-Cell simulations [18] have shown that the electron bunch lifetime is about 10 fs.…”

Innovative X–γ ray sources based on laser-produced plasmas

“…[11][12][13][14] an analytical study of the angular distribution of the betatron radiation is done. In Ref.…”