Analysis of an FEL oscillator at zero detuning length of an optical cavity in the early stage of the field evolution

光共振器の完全同期長におけるFEL発振の解析

西森 信行

Nishimori, Nobuyuki

完全同期長における高強度極短パルスFEL生成のメカニズムについて理論解析を行う。共振器型FELの最初のパスで形成される電場はSelf Amplified Spontaneous Emission(SASE)と同じであり、FELパラメーターで特徴づけられる。完全同期長でnパス後に、このSASE電場と電子のFEL相互作用で得られる電場は、FELパラメーターとパス数nで特徴づけられるSASEとよく似た電場であることを示す。

The evolution of the field of an FEL oscillator at zero detuning length of an optical cavity (dL = 0) is studied analytically. The field on the leading edge at the first round trip is the same as that of a self-amplified spontaneous emission (SASE) FEL characterized by an FEL parameter. The field evolves with round trips by interaction with electrons. The field in the early stage of the evolution is found to scale with the FEL parameter and the round-trip number, and is similar to that of SASE with high electron beam density.