Giannessi L, Bellaveglia M, Chiadroni E, Cianchi A, Couprie M E, Del Franco M, Di Pirro G, Ferrario M, Gatti G, Labat M, Marcus G, Mostacci A, Petralia A, Petrillo V, Quattromini M, Rau J V, Spampinati S, Surrenti V
ENEA C.R. Frascati, Via E. Fermi, 45 00044 Frascati, Roma, Italy.
INFN-LNF, Via E. Fermi, 40 00044 Frascati, Roma, Italy.
Phys Rev Lett. 2013 Jan 25;110(4):044801. doi: 10.1103/PhysRevLett.110.044801. Epub 2013 Jan 23.
We report measurements demonstrating the concept of the free-electron laser (FEL) superradiant cascade. Radiation (λ(rad) = 200 nm) at the second harmonic of a short, intense seed laser pulse (λ(seed) = 400 nm) was generated by the cascaded FEL scheme at the transition between the modulator and radiator undulator sections. The superradiance of the ultrashort pulse is confirmed by detailed measurements of the resulting spectral structure, the intensity level of the produced harmonics, and the trend of the energy growth along the undulator. These results are compared to numerical particle simulations using the FEL code GENESIS 1.3 and show a satisfactory agreement.
我们报告了一些测量结果，这些结果展示了自由电子激光（FEL）超辐射级联的概念。在短而强的种子激光脉冲（λ(seed) = 400 nm）的二次谐波处的辐射（λ(rad) = 200 nm）是由级联FEL方案在调制器和辐射器波荡器段之间的过渡处产生的。通过对所得光谱结构、产生的谐波强度水平以及沿波荡器的能量增长趋势进行详细测量，证实了超短脉冲的超辐射特性。这些结果与使用FEL代码GENESIS 1.3进行的数值粒子模拟结果进行了比较，显示出令人满意的一致性。
