Plasma Filled Raman-type Fel Amplifier Characteristics

Free electron laser (FEL) has a vast prospective in many fields.Many science and research institutes home and abroad have lay investigation on it and got some important achievements. At present, researchers have focused on those FEL with broad width, small size, low cost and high even power. Among them size has become the key factor of restricting the development of FEL. Plasma filled high-power microwave apparatus can improve its characteristics, which has been demonstrated in some experiments. With the help of MAGIC program, a new coaxial hybrid wiggler FEL amplifier was investigated in this paper. According to the characteristic of the wiggler magnetic field in this amplifier, proper magnetic field input method is chosen in the process of PIC simulated research. It analyzes the bandwidth, gain and saturation distance, etc. and studies how gains increase when parameters vary gradually in this FEL. The results of PIC simulation research are agreement with the theoretical results. With the help of MAGIC program, this paper studies the characteristics ofcoaxial hybrid wiggler FEL through particle simulation, and analyses theinfluence of plasma filling on its bandwidth, saturation distance and gain etc.The simulation experiment shows that there exists a critical plasma density,and if the density exceeds critical one, light-wave cannot interact with electronsynchronically. The PIC simulated research shows that the result tallies withthe theoretical result. Through the PIC simulation and theoretical research on coaxialwaveguide FEL and the effect of plasma filling on the apparatus, someachievements in theory and application have been obtained. 1).Studies coaxial hybrid wiggler FEL through PIC simulation, analysesits gain, bandwidth, efficiency, etc. and studies the influence on output whenparameters change gradually. 2)Studies the characteristics of coaxial hybrid wiggler FEL when filledwith plasma through particle simulation. The result shows that though powerdoesn't increase evidently, the bandwidth increases when filled with plasmaand it helps to reduce saturation distance in a proper density. Theory and PICsimulation show that there exists a critical plasma density, and if the densityexceeds critical one, light-wave cannot interact with electron synchronically.