A Novel technique for monitoring the reproducibility of laser tape-target interactions using an X-ray pinhole camera

Ogura, Koichi; Fukumi, Atsushi*; Li, Z.*; Orimo, Satoshi; Sagisaka, Akito; Nishiuchi, Mamiko; Kado, Masataka; Mori, Michiaki; Yogo, Akifumi; Hayashi, Yukio; Daido, Hiroyuki; Bulanov, S. V.; Oishi, Yuji*; Nayuki, Takuya*; Fujii, Takashi*; Nemoto, Koshichi*; Nakamura, Shu*; Iwashita, Yoshihisa*; Noda, Akira*

For accurate control of relativistic laser-plasma interaction under the repetitive operation, we have to measure and control the laser irradiation conditions such as laser parameters, the target shooting accuracy and so on as well as measuring proton parameter on each laser shot. The displacement of the laser shooting position on a tape target, that are used in the high energy proton generation using an ultra-short Ti:sapphire laser system, is measured by observing an X-ray image from laser plasma with an X-ray pinhole camera for each laser shot. The displacement of the shooting position on the target is about 20micron and the accuracy of the target positioning is within 20micron which is small enough for present laser focusing optics with an F number of 3.6 (f=179mm). The technique contributes to accurate control of a repetitive laser driven proton accelerators.