Filled With Plasma Theory Of The Raman-type Free-electron Laser

Free-Electron Laser (FEL) is potentially utilized in many fields becauseit has broad frequency band, tunable frequency, good quality of beam light,high efficiency. It has been investigated in many countries these years. It is animportant branch of plasma-loaded Free-Electron Laser, which can improvethe characteristic of FEL, and many achievements have been improved.The plasma-loaded Raman FEL is widely and thoroughly studied in thispaper. The main content includes: thermal plasma-loaded FEL, plasma-loadedFEL with an axial guide magnetic field (AGMF), and two-stream FEL with anAGMF.In this paper, the basic principle of FEL is introduced and the lineartheory is described in brief firstly. The dispersion relation of thermalplasma-loaded FEL is derived and the plasma effect on the characteristic ofFEL is investigated by numerical calculation.The effect of an axial guide magnetic field (AGMF) on plasma isdescribed as a cyclotron frequency in the plasma-loaded FEL with AGM.F,and the dispersion relation is derived. The influence of guide field on the FELgrowth rate is investigated by numerical calculation. On the other hand,supposing that background plasma has an initial velocity, a novel two-streamFEL model with an AGMF is presented. The influence of two-streamseparation velocity on FEL growth rate is studied.The plasma-loaded Raman FEL is investigated in this paper, and someuseful results are obtained as following:Firstly, the effect of the thermal background plasma on FEL growth rateis analyzed. The results show that growth rate of FEL can be suitablyimproved with plasma temperature presented, and growth rate of FEL canreach the maximum while there is an optimal plasma temperaturecorresponding toγ.Secondly, the characteristic of both plasma-loaded FEL and two-streamFEL with an axial magnetic field is studied. Dispersion relations are obtainedby employing fluid theory and the effect of guide field on FEL growth rate is...