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arXiv · 2112.10757

Absolute keV X-ray yield and conversion efficiency in over dense Si petawatt laser plasma

Sergey N. Ryazantsev·Artem S. Martynenko·Maksim V. Sedov·Igor Yu. Skobelev·Mikhail D. Mishchenko·Yaroslav S. Lavrinenko·Christopher D. Baird·Nicola Booth·Phil Durey·Leonard N. K. DÖhl·Damon Farley·Kathryn L. Lancaster·Paul Mckenna·Christopher D. Murphy·Tatiana A. Pikuz·Christopher Spindloe·Nigel Woolsey·Sergey A. Pikuz
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Abstract

Laser-produced plasmas are bright, short sources of X-rays often used for time-resolved imaging and spectroscopy. Absolute measurement requires accurate knowledge of laser-to-x-ray conversion efficiencies, spectrum, photon yield and angular distribution. Here we report on soft X-ray emission from a thin Si foil irradiated by a sub-PW picosecond laser pulse. These absolute measurements cover a continuous and broad spectral range that extends from 4.75 to 7.5 Angstroms (1.7-2.6 keV). The X-ray spectrum consists of spectral line transitions from highly charged ions and broadband emission with contributions from recombination, and free-free processes that occur as electrons decelerate in plasma electromagnetic fields. These quantitative measurements are compared to particle-in-cell simulations allowing us to distinguish bremsstrahlung and synchrotron contributions to the free-free emission. We found that experiment and simulation estimations of laser-to-bremsstrahlung conversion efficiency are in a good agreement. This agreement illustrates the accuracy of experiment and physical interpretation of the measurements.

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Sergey N. Ryazantsev, Artem S. Martynenko, Maksim V. Sedov, Igor Yu. Skobelev, Mikhail D. Mishchenko, Yaroslav S. Lavrinenko, Christopher D. Baird, Nicola Booth, Phil Durey, Leonard N. K. DÖhl, Damon Farley, Kathryn L. Lancaster, Paul Mckenna, Christopher D. Murphy, Tatiana A. Pikuz, Christopher Spindloe, Nigel Woolsey, Sergey A. Pikuz. 2021-12-20. Absolute keV X-ray yield and conversion efficiency in over dense Si petawatt laser plasma. https://doi.org/10.1088/1361-6587%2Fac8b33

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