Rudy on Ge V-electron acceleration with table top ultrashort high peak power lasers

本计画的目标是产生GeV电子：1。10 TW激光系统输出功率的稳定和指向;电子等离子体波白色光探针观测技术的建立。强激光在长空心毛细管中的传播及其观测; 10 TW激光脉冲泵浦下长毛细管产生GeV电子，是一个需要解决的技术问题和物理问题。为了产生GeV的驻极体束流，我们必须准备一个长的加速长度。在此基础上，我们研制了一种具有中空纤维的毛细管靶系统。我们用细空心纤维划分了一个靶室。通过使用细的中空纤维，靶室被差分抽气。这样，我们就可以在聚焦侧保持足够高的真空度，而中空毛细管可以填充有足够密度的气体靶。由于目标可以一枪一枪地交换，因此应尽可能容易地进行对准。然后，我们准备了适当的对齐机制。亚mJ量级的飞秒脉冲成功地通过了大气中的空心毛细管靶，而GeV电子失速没有加速。通过这种5 mm的传输产生了强白光连续谱。其次，我们对GeV电子能谱仪的成像板探测器进行了绝对定标。在这次校准中，我们使用了Spring-8同步加速器环的直线加速器。最后，我们产生了亚十飞秒探测脉冲，用于观察电子等离子体波的动力学。该实验在日本原子能机构关西光子科学研究所进行。JUTE 10激光系统用于产生超短脉冲。大坂大学的激光系统进行了改进，准备了洁净室和两个大的YAG激光器作为末级放大器。

The aim of this project was followings for generating GeV electrons: 1. Stabilization of output power and pointing of 10TW laser system, 2. Establishment of the observation technique for electron plasma wave with white light probe, 3. Propagation of intense laser light in a long hollow capillary tube, and its observation, and 4. GeV electron generation with a long capillary pumped by 10TW laser pulses.For the sake of these themes, we have to solve a technical problems and physical problems. For generating GeV electreon beam, we have to prepare a long acceleration length. Then we developed a capillary target system with a hollow fiber. We divided a target chamber with a fine hollow fiber. By using a fine hollow fiber, a target chamber is differentially pumped down. Then we can keep comparatively high enough vacuum at the focusing side, while the hollow capillary could be filled with a gaseous target with enough density. As the target could be exchanged shot by shot, the alignment should be performed as easy as possible. Then, we have prepared the adequate alignment mechanism. The sub-mJ class femtosecond pulses were successfully passed though the hollow capillary target at the atmosphere, while the GeV electrons stall not accelerated. The strong while light continuum have been generated by this 5mm propagation. Next, we have performed the absolute calibration of the Imaging Plate (IP) detector which is used for the electron spectrometer (ESN) of GeV electrons. For this calibration, we have used the linac for Spring-8 synchrotron ring. Finally, we have generated sub-ten femtosecond probe pulse for observing the dynamics of electron plasma wave. This experiment was held at Kansai Photon Science Institute, JAEA. JUTE 10 laser system was used for generating this ultrashort prove pulse. The laser system in Osaka University was improved by preparing clean room and two big YAG lasers for final amplifier.