SIMULATION ANALYSIS OF THE EFFECT OF BEAM PIPES AND MULTIMODE COMPETITION IN THE STANDING-WAVE FREE-ELECTRON LASER 2-BEAM ACCELERATOR

In this paper, we present simulation results of an array of standing-w ave free-electron lasers (SWFELs) in the standing-wave free-electron l aser two-beam accelerator (SWFEL/TBA) configuration. The influence of betatron motion on the stability of rf output energy is analyzed. The effects of beam pipes and finite emittance on rf output power are exam ined, and an investigation is made of a possible mode competition. It is shown that for an array of SWFELs with 9 cavities and a 100.6-ns, 0 .5-kA, 7.98-MeV, 2.0 X 10(-4) pi m normalized-emittance electron beam, prebunched at 17.1 GHz, an averaged energy output of 12.3 J/m can be obtained with a fluctuation of less than 6.5%. It is also shown that p otential competitive longitudinal modes can be suppressed by inserting irises along the electric field direction at some node points of the electric field of the operating mode.