Development of an Infrared Free Electron Laser for User Experiments

我们正在利用奥萨拉大学科学与工业研究所的l波段直线加速器对自由电子激光器进行改进，以开发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，扩大了波长范围，特别是向长波方向扩展，并开发了相关技术。我们对摆动器进行了改造，使磁隙可变，不仅可以连续调谐波长，而且可以在大k值下工作。对摆动器上下游两侧的弯曲磁体进行了改造，并安装了垂直尺寸更大的新真空室，从而减小了长波长区域的衍射损失。我们用Ge: Ga探测器在波长大于50 μ m的区域探测激光。为了从激光的时间演化中推导出FEL的增益和损耗，我们利用直线加速器发出的单束相干同步辐射测量了de…More探测系统的时间分辨率。在FEL实验中，我们使用了阴极面积较小的特殊电子枪。最近在常规操作中使用的电子枪被替换为更高亮度的电子枪，认为新电子枪的输出电流与旧电子枪相当。我们发现用新枪也可以进行FEL实验。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，在波长大于50 μ m的真空区域中从光学谐振器中取出光。我们用15 MeV能量的电子束观察到了136 μ m的FEL振荡，这是迄今为止使用RF直线加速器获得的最长波长的FEL。我们还在修改FEL。光学谐振器的反射镜文件夹将被替换，使用更大的反射镜，并正在制作新的真空光路。在这些修改完成后，我们将在更长的波长区域进行FEL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