Direct Laser Acceleration And X-ray Radiation Generation Driven By Ultra-fast Intense Laser

High-energy particle accelerators and radiation sources play an irreplaceable role in various disciplines like basic scientific research,industrial material testing,medical imaging and treatment,of which the demands are continually increasing.With the development of high-power laser technology,especially Chirped Pulse Amplification technology,laser plasma acceleration and radiation sources have become more mature while a series of milestone progresses have been demonstrated.Owing to its ultra-high acceleration gradient,short pulse width,ultra-high brightness and small source size,laser plasma accelerators and correlated radiation sources have been considered as important alternatives in the miniaturization and even extensive usage of advanced X-ray light sources and high energy particle accelerators.This dissertation presents the Ph D study on direct laser acceleration and X-ray radiation driven by ultra-fast high-power lasers and is organized as follows:The first part is the introduction.As the basis of this dissertation,it introduces the principle and research status of laser plasma acceleration.Specifically,principle of high-power femtosecond lasers,laser propagation and generation of acceleration structures and the physics of various acceleration mechanism and electron injection methods are introduced.The second part presents a laser driven short-period high strength magnetic field undulator and correlated high-brightness X-ray radiation source.This part concerns the energy spread problems of laser plasma accelerated electrons when driving high-brightness X-ray light sources and even free electron lasers.By analytical theory and simulations,a novel scenario of short period high strength helical undulator is shown.High brightness and tunable mono-energetic undulator radiation combing this undulator and laser wake-field accelerators is calculated and the benefits for free electron laser Pierce parameter and gain length are also analyzed.The third part presents the theoretical and experimental study of direct laser acceleration by chirped laser pulses.First the basic physics and research status of direct laser acceleration is introduced and reviewed.Then the interaction of chirped laser pulses with high density plasma on the enhancement of electron charge,electron energy and the optimal chirp strength is also suggested.The experimental results are interpretated by analytical theory and particle in cell simulations and conclude that the maximal enhancement of electron energy and total charge will be obtained when second order dispersion generates the highest chirp strength.The fourth part presents the experimental study of the interaction between PW femtosecond laser and near-critical density plasma with the aim of high flux and energy conversion efficiency X-ray generation.The orders of magnitudes enhanced energy conversion efficiency of laser to X-ray(10^-4)is demonstrated experimentally,which is attributed to the high field strength of the PW laser and enhanced absorption of laser energy by near critical plasmas.With the aid of PIC simulations,the importance of the steep plasma density gradient for electron energy enhancement is compared and emphasized.The fifth part is about the experimental diagnosis research,concerning focusing and spectrum diagnostics of ultra-fast X/Gamma rays.This part includes a Compton Gamma-ray Spectrometer,a Betatron warm dense matter absorption spectroscopic System and a Von-Hamos crystal spectrometer.The last part present a summary and prospect.