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Интеллектуальная Система Тематического Исследования НАукометрических данных |
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Self-induced second harmonic used as diagnostic of microfocus X-ray source size produced by tightly focused femtosecond fiber laser beam at copper targetтезисы доклада
- Авторы: Garmatina A.A., Mareev E.I., Semenov T.A., Krivonosov Yu S., Minaev N.V., Asadchikov V.E., Gordienko V.M.
- Сборник: Book of Abstracts VII International Conference on Ultrafast Optical Science
- Тезисы
- Год издания: 2023
- Место издания: Lebedev Physical Institute Moscow
- Первая страница: 98
- Аннотация: Radiographic phase-contrast imaging using X-rays is a valuable tool in various fields,including basic research, industry, materials science, and medical diagnostics. In this study, we implemented a novel approach for a microfocus X-ray laser-plasma source. This system is based on a low-energy, high repetition rate femtosecond fiber laser (1030 nm, 280 fs, repetition rate 500kHz - 2,2 MHz, 20 W, pulse energy up to 40 µJ) that is tightly focused (NA≈0.2,vacuum intensity I ≈ 10^14 W/cm2) on a rotated copper target. To achieve online control of the source size, we utilized backreflected second optical harmonic generated in the nearsurface plasma by fiber laser. To observe microplasma a microscope was assembled, and a calibrated image was captured with CCD camera. Than profile of the beam was plotted and approximate with Gaussian curve. It has been observed that blowing with helium (compared to air) leads to an increase in the X ray yield and a decrease in the size of the X-ray source due to minimization of the ionization effect in the near-surface medium. We revealed that X ray yield is maximized at the level of 2x10^9 ph/s/2π at 2 MHz, pulse energy 10 µJ. Measurements of the microplasma show that size slowly decrease with growing pulse repetition rate from 500 kHz to 2,2 MHz (and pulse energy from 40 µJ to 8 µJ) and constant power of 20 W. Source size turns out to be about 8,5±1,5 microns at 1/e2 level at optimal condition of 2 MHz, 10 µJ. These results fulfill the requirements for source size for phase contrast measurements.
- Добавил в систему: Гордиенко Вячеслав Михайлович