Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userGlobal constant field approximation for radiation reaction in collision of high-intensity laser pulse with electron beam
312
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
In the laser --- electron beam head-on interaction electron energy can decrease due to radiation reaction, i.e. emission of photons. For 10--100~fs laser pulses and for the laser field strength up to the pair photoproduction threshold, it is shown that one can calculate the resulting electron and photon spectra as if the electron beam travels through a constant magnetic field. The strength of this constant field and the interaction time are found as functions of the laser field amplitude and duration. Using of constant field approximation can make a theoretical analysis of stochasticity of the radiation reaction much simpler in comparison with the case of alternating laser field, also, it allows one to get electron and photon spectra much cheaper numerically than by particle-in-cell simulations.
rate research
Read More
The dynamics of energetic particles in strong electromagnetic fields can be heavily influenced by the energy loss arising from the emission of radiation during acceleration, known as radiation reaction. When interacting with a high-energy electron beam, todays lasers are sufficiently intense to explore the transition between the classical and quantum radiation reaction regimes. We report on the observation of radiation reaction in the collision of an ultra-relativistic electron beam generated by laser wakefield acceleration ($varepsilon > 500$ MeV) with an intense laser pulse ($a_0 > 10$). We measure an energy loss in the post-collision electron spectrum that is correlated with the detected signal of hard photons ($gamma$-rays), consistent with a quantum (stochastic) description of radiation reaction. The generated $gamma$-rays have the highest energies yet reported from an all-optical inverse Compton scattering scheme, with critical energy $varepsilon_{rm crit} > $ 30 MeV.
Charged particles accelerated by electromagnetic fields emit radiation, which must, by the conservation of momentum, exert a recoil on the emitting particle. The force of this recoil, known as radiation reaction, strongly affects the dynamics of ultrarelativistic electrons in intense electromagnetic fields. Such environments are found astrophysically, e.g. in neutron star magnetospheres, and will be created in laser-matter experiments in the next generation of high-intensity laser facilities. In many of these scenarios, the energy of an individual photon of the radiation can be comparable to the energy of the emitting particle, which necessitates modelling not only of radiation reaction, but quantum radiation reaction. The worldwide development of multi-petawatt laser systems in large-scale facilities, and the expectation that they will create focussed electromagnetic fields with unprecedented intensities $> 10^{23}~mathrm{W}text{cm}^{-2}$, has motivated renewed interest in these effects. In this paper I review theoretical and experimental progress towards understanding radiation reaction, and quantum effects on the same, in high-intensity laser fields that are probed with ultrarelativistic electron beams. In particular, we will discuss how analytical and numerical methods give insight into new kinds of radiation-reaction-induced dynamics, as well as how the same physics can be explored in experiments at currently existing laser facilities.
It is commonly assumed that in ultrastrong laser fields, when the strong field parameter of the laser field $xi$ is larger than one, the electron radiation is well described by the local constant field approximation (LCFA). We discuss the failure of this conjecture, considering radiation of an ultrarelativistic electron interacting with strong counterpropagating laser waves. A deviation from LCFA, in particular in the high-frequency domain, is shown to occur even at $xigg 1$ because of the appearance of an additional small time scale in the trajectory. Moreover, we identify a new class of LCFA violation, when the radiation formation length becomes smaller than the one via LCFA. It is characterized by a broad and smooth spectrum rather than an harmonic structure. A similar phenomenon is also demonstrated in the scenario of an electron colliding with an ultrashort laser pulse. The relevance to laser-plasma kinetic simulations is discussed.
We investigate the generation of twin $gamma$ ray beams in collision of an ultrahigh intensity laser pulse with a laser wakefield accelerated electron beam by using particle-in-cell simulation. We consider the composed target of a homogeneous underdense preplasma in front of an ultrathin solid foil. The electrons in the preplasma are trapped and accelerated by the wakefield. When the laser pulse is reflected by the thin solid foil, the wakefield accelerated electrons continue to move forward and passing through the foil almost without the influence of the reflected laser pulse and the foil. Consequently, two groups of $gamma$ ray flashes, with tunable time delay and energy, are generated by the wakefield accelerated electron beam interacting with the reflected laser pulse from the foil as well as another counter propagating petawatt laser pulse in the behind the foil. The dependence of the $gamma$ photon emission on the preplasma densities, driving laser polarization and the foil are studied.
We report on an experimental study on the interaction of a high-contrast 40 fs duration 2.5 TW laser pulse with an argon cluster target. A high-charge, homogeneous, large divergence electron beam with moderate kinetic energy (~2 MeV) is observed in the forward direction. The results show, that an electron beam with a charge as high as 10 nC can be obtained using a table-top laser system. The accelerated electron beam is suitable for a variety of applications such as radiography of thin samples with a spatial resolution better than 100 micron.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
