Laser induced electron acceleration in a tapered magnetic wiggler

The acceleration of electrons by a laser pulse, in the presence of a magnetic wiggler, in vacuum and plasma is studied. The vector potentials of the laser pulse and magnetic wiggler are taken as A(L)=-(x) over capA(0) sin(omegat-kz)exp[-(t-(z-z(L))/v(g))(2)/tau(L)(2)] and A(w)=(x) over capA(0w) sin[k(w)z/(1+alphaz)], respectively, where alpha is the tapering parameter. For a specific value of k/k(w), the inverse free-electron laser resonance condition is satisfied and energy gained by the electron increases. The resonance condition is sensitive to the electron energy and the electron density of the medium. It can be maintained for longer duration for a suitably tapered wiggler period and the electron can gain much higher energy. The wiggler period increases with initial electron energy and with the decrease in plasma density. Energy gained by the electron decreases with plasma density. (C) 2004 American Institute of Physics.