The effects of ASE contrast and beams mutual alignment on the γ-ray yield in laser-plasma interactions with artificial prepulse
| Autor: | S. A. Shulyapov, I. N. Tsymbalov, K.A. Ivanov, G. A. Gospodinov, R. V. Volkov, Andrey B. Savel'ev |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Journal of Physics: Conference Series. 1692:012023 |
| ISSN: | 1742-6596 1742-6588 |
| DOI: | 10.1088/1742-6596/1692/1/012023 |
| Popis: | We present experimental study of the bremsstrahlung γ-rays generation in a plasma interacting with 50 fs laser pulse in slightly relativistic regime (intensity ∼2-1018 W/cm2). A pre-plasma layer on the surface of the molybdenum target is formed by an additional laser pulse with a duration of 8 ns and an intensity of ∼2-1012 W/cm2. The energy and intensity of the artificial pre-pulse exceed those of the amplified spontaneous emission (ASE) pedestal of the main pulse by ∼103 and 10 times (for contrast 10−7), respectively. It was shown that the low ASE contrast (>10−7) is the crucial condition for increasing (in comparison to the case without artificial pre-pulse) of the integral γ-rays yield when the nanosecond pulse is ahead of the femtosecond one by >20 ns. Interferometry data show that the reason of the γ-rays yield increasing is a pre-plasma layer initially produced by artificial pre-pulse and re-created by the ASE. The optimum conditions for γ-rays yield achieved if (i) the pre-pulse comes ∼25 ns in advance, (ii) ASE contrast is 10−7 and lower and (iii) the femtosecond focal point is shifted by ∼100 μm from the center of the nanosecond pre-pulse focal spot and by ∼100 μm above the target surface. |
| Databáze: | OpenAIRE |
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