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Equilibrium orbit analysis in a free-electron laser with a coaxial wiggler

B. Maraghechi·B. Farrokhi·J. E. Willett·U. -H. Hwang
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Abstract

An analysis of single-electron orbits in combined coaxial wiggler and axial guide magnetic fields is presented. Solutions of the equations of motion are developed in a form convenient for computing orbital velocity components and trajectories in the radially dependent wiggler. Simple analytical solutions are obtained in the radially-uniform-wiggler approximation and a formula for the derivative of the axial velocity $v_{\|}$ with respect to Lorentz factor $γ$ is derived. Results of numerical computations are presented and the characteristics of the equilibrium orbits are discussed. The third spatial harmonic of the coaxial wiggler field gives rise to group $III$ orbits which are characterized by a strong negative mass regime.

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B. Maraghechi, B. Farrokhi, J. E. Willett, U. -H. Hwang. 2000-02-17. Equilibrium orbit analysis in a free-electron laser with a coaxial wiggler. https://doi.org/10.1103/physreve.61.7046

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