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

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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.