Characteristics of betatron radiation from direct-laser-accelerated electrons

Betatron radiation from direct-laser-accelerated electrons is characterized analytically and numerically. It is shown here that the electron dynamics is strongly dependent on a self-similar parameter S(equivalent to n(e)/n(c)a(0)). Both the electron transverse momentum and energy are proportional to the normalized amplitude of laser field (a(0)) for a fixed value of S. As a result, the total number of radiated photons scales as a(0)(2)/root S and the energy conversion efficiency of photons from the accelerated electrons scales as a(0)(3)/S. The particle-in-cell simulations agree well with the analytical scalings. It is suggested that a tunable high-energy and high-flux radiation source can be achieved by exploiting this regime.National Natural Science Foundation of China [91230205, 11575031, 11575298, 11175026]; National Basic Research Program of China (973 Program) [2013CBA01500, 2013CB834100]; National High-Tech 863 Project; Thousand Young Talents Program of China; STFC Central Laser Facility; Scientific Computing Department; SCARF computing cluster at STFC Rutherford-Appleton Laboratory; China Scholarship CouncilSCI(E)PubMedARTICLEalex.robinson@stfc.ac.uk; zcangtao@iapcm.ac.cn; bqiao@pku.edu.cn60632039