Development of an Infrared Free Electron Laser for User Experiments

我们正在奥萨拉大学科学与工业研究所L波段直线加速器的基础上对自由电子激光器进行改造，以开发一种用于用户实验的红外自由电子激光器。我们对自由电子激光器进行了改进，以扩大波长范围，特别是向更长的波长侧扩展，并开发了相关技术。我们改装了摇摆器，使磁隙可变，不仅使波长连续可调，而且使大K值工作成为可能。对摇摆器上下游的弯曲磁铁进行了改造，并安装了垂直尺寸更大的新真空室，从而减小了较长波长区的衍射损失。我们用Ge：Ga探测器探测波长大于50微米的激光。为了从激光的时间演化中得到自由电子激光的增益和损耗，我们测量了De…的时间分辨率使用来自直线加速器的单束束发射的相干同步辐射的更多保护系统。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，尽管新电子枪的输出电流与旧电子枪相当，但通常使用的电子枪被更高亮度的电子枪所取代。我们发现，用这种新枪也可以进行自由电子激光实验。因此，我们甚至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，在超过50微米的波长范围内，在真空中将光从光学谐振腔中取出。我们已经用15 MeV的电子束观察到136微米的自由电子激光振荡，这是迄今为止使用射频激光器获得的最长波长。我们仍在修改FEL。光学谐振器的镜片将被更换，将使用更大的镜片，并正在制作新的真空光路。在这些改造完成后，我们将在更长的波长范围内进行自由电子激光实验。较少

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