Development of a Tunable Gas-Loaded Free-Electron Laser

本研究计划的目的是调查 自由电子激光器的性能，其中气体介质具有 被引入摇摆器或波动磁场的区域 领域 在自由电子激光摇摆器中加入气体改变了相位匹配 条件 这是由于气体引入了 折射率，其延迟的相速度， 电磁波 通过改变气体的压力， 改变折射率，振荡波长可以是 调谐，可能从红外线到紫外线， 改变电子束或摇摆器的能量 参数 除了可调谐性之外，气体还允许 光束能量显著降低，从而降低成本， 加速器的尺寸，以及加速器的每单位长度的更高增益。 FEL。 作为使用气体的自由电子激光性能计划的一部分， 是一项调查的影响，操作附近的电子 气体中的共振。 在这种情况下，高折射率可以是 在相对低的气体密度下获得。 也会有一项研究 使用带同轴孔的干涉镜的可能性 以便于开发紧凑的串联高增益系统。 在 此外，实验将提供有关 皮秒电子束在气体中的传播 大气压力;研究增加自由电子激光增益的方法 高发射率光束;并研究光学特性， 具有同轴孔的干涉仪。

The objective of this research program is to investigate the performance of a free-electron laser for which a gaseous medium has been introduced into the region of the wiggler, or undulating magnetic field. Placing a gas in an FEL wiggler alters the phase matching condition. This is a consequence of the fact that the gas introduces an index of refraction which retards the phase velocity of the electromagnetic wave. By changing the pressure of the gas, and so changing the index of refraction, the oscillation wavelength can be tuned, potentially from the infrared to the ultraviolet, without altering either the energy of the electron beam or the wiggler parameters. In addition to the tunability, the gas allows for a significant reduction in beam energy, resulting in a lower cost and size for the accelerator, and a higher gain per unit length for the FEL. As part of the program on FEL performance with a gas, there will be an investigation of the effects of operating near an electronic resonance in the gas. In this case a high refractive index can be obtained at relatively low gas densities. There will also be a study of the possibility of using interferometer mirrors with on-axis holes to facilitate development of a compact in-line, high-gain system. In addition, the experiments will provide information concerning the propagation of picosecond electron beams through gases at up to one atmosphere pressure; investigate methods for increasing FEL gain with high emittance beams; and study the optical properties of interferometers with on-axis holes.