Numerical Investigation Of Electron Acceleration In The Wakefield Driven By Combined Laser Pulses And Likely Materials As Substrate For Dielectric Grating Accelerators

This thesis have included two small topics: Numerical investigation of electron acceleration in the wakefield driven by combined laser pulses; Numerical investigation of likely materials as a substrate for dielectric grating structures.1) Plasma based Laser particle accelerators have a great potential to decrease the size and cost of conventional accelerators which are based on micro-wave technology. Plasma doesn’t have an electric field breakdown threshold value, since it is an ionized medium. Many experiments proved the super-high accelerating gradient(up to ～100Ge V/m) of the laser wakefield. In this thesis, electron acceleration in the first cycle of a plasma wakefield driven by combined two laser pulses with different intensity and pulse duration is investigated analytically and numerically. It is found that the combined laser pulses can efficiently modify the plasma wakefield potential and phase portrait of the electron dynamics. The optimum combination of two laser pulses to maximize the net energy gain of the accelerated electrons is discussed. The effect of asymmetry of laser pulses on the electron wakefield acceleration is also studied.2) Structure based dielectric laser accelerators are also considered another attractive way to realize compact accelerators. Dielectric laser accelerators(DLAs) show great potential for a number of applications, as they can generate acceleration gradients in the range of ～GeV/m and produce attosecond electron bunches. In this thesis, the accelerating capability of dielectric grating structures which are made of Al2O3 and Y2O3 have been investigated numerically. The optimum dielectric pillar height and vacuum channel width have been determined. Requirement for initial particle energy has been estimated.