Development of an Infrared Free Electron Laser for User Experiments

我们正在修改自由电子激光器的基础上的L波段直线加速器在科学和工业研究所，奥萨拉大学，以开发一个红外自由电子激光器的用户实验。我们对自由电子激光器进行了改进，扩大了激光器的波长范围，特别是向长波方向扩展，并发展了相应的技术;对摇摆器进行了改造，使其磁隙可变，不仅使波长连续可调，而且使工作在大K值下成为可能。对扭摆器上、下游侧的偏转磁铁进行了改造，并安装了垂直尺寸较大的真空室，从而减小了长波长区的衍射损耗。我们检测到的激光与Ge：Ga探测器在波长区域长于50 μ m。为了从激光的时间演化推导出自由电子激光的增益和损耗，我们测量了自由电子激光器的时间分辨率， 关于我们 使用由来自直线加速器的单个聚束束发射的相干同步辐射的检测系统。在自由电子激光实验中，我们使用了一种阴极面积较小的特殊电子枪。最近，在通常的操作中使用的电子枪被替换为更高亮度的电子枪，认为新枪的输出电流与旧枪相当。我们已经发现，这是可能的自由电子激光实验也与新枪。因此，我们可以在很短的机器时间内进行实验。我们使用晶体石英板作为窗口，用于从真空中的光学谐振器中取出波长大于50 μ m的光。我们用15 MeV能量的电子束观察到了136 μ m的自由电子激光振荡，这是迄今为止用射频直线加速器自由电子激光获得的最长波长。我们仍在修改自由电子激光，将更换光学谐振腔的镜夹，使用更大的镜，并正在制作新的真空光路。在这些改进完成后，我们将在更长的波长范围内进行自由电子激光实验。少

We are modifying the free electron laser based on the L-band linac at the Institute of Scientific and Industrial Research, Osala University in order to develop an infrared free electron laser for user experiments. We have modified the free electron laser to expand the wavelength region, especially to the longer wavelength side, and have developed related technologies for it. We have remodeled the wiggler to make the magnet gap variable, which makes not only the wavelength continuously tunable but also operation at a large K-value possible. The bending magnets on the upstream and the downstream sides of the wiggler were remodeled and new vacuum chambers with larger verticalsizes were installed, so that the diffraction loss in the longer wavelength region is made smaller. We detected laser light with a Ge : Ga detector in the wavelength region longer than 50 mum. In order to derive the FEL gain and the loss from the time evolution of laser light, we measured the time resolution of the de … More tection system using coherent synchrotron radiation emitted by a single bunch beam from the linac. In FEL experiments, we used a special electron gun with a smaller cathode area. Recently the electron gun used in usual operation was replaced with a higher brightness electron gun thought the output current from the new gun is comparable to the old one. We have found that it is possible to conduct FEL experiments also with the new gun. As a result, we can carry out experiments even in a short machine time. We use a crystal quartz plate as a window for taking light out from the optical resonator in vacuum in the wavelength region longer than 50 mum. We have observed FEL oscillation at 136 mum using an electron beam of 15 MeV energy, which is the longest wavelength so far obtained with the FELs using RF linacs.We are still modifying the FEL.The mirror folders for the optical resonator will be replaced, larger mirrors will be used, and a new evacuated optical path is being made. After these modifications are completed, we will conduct FEL experiments further longer wavelength region. Less