Ultrafast electron kinetics in short pulse laser-driven dense hydrogen. (25th September 2015)

• Record Type: Journal Article
• Authors: Zastrau, U; Sperling, P; Fortmann-Grote, C; Becker, A; Bornath, T; Bredow, R; Döppner, T; Fennel, T; Fletcher, L B; Förster, E; Göde, S; Gregori, G; Harmand, M; Hilbert, V; Laarmann, T; Lee, H J; Ma, T; Meiwes-Broer, K H; Mithen, J P; Murphy, C D; Nakatsutsumi, M; Neumayer, P; Przystawik, A; Skruszewicz, S; Tiggesbäumker, J; Toleikis, S; White, T G; Glenzer, S H; Redmer, R; Tschentscher, T
• Is Part Of: Journal of physics. Volume 48:Number 22(2015:Nov. 15)
• Publication Date: 2015-09-25
• Subjects: electron collisions -- emission -- absorption -- and scattering of electromagnetic radiation -- plasma production and heating by laser beams; Atoms -- Periodicals; Molecules -- Periodicals; Optics -- Periodicals; Nuclear physics -- Periodicals; 539.6
• DOI: 10.1088/0953-4075/48/22/224004
• Languages: English
• ISSNs: 0953-4075

Abstract

Abstract: Dense cryogenic hydrogen is heated by intense femtosecond infrared laser pulses at intensities of W cm −2 . Three-dimensional particle-in-cell (PIC) simulations predict that this heating is limited to the skin depth, causing an inhomogeneously heated outer shell with a cold core and two prominent temperatures of about and for simulated delay times up to after the laser pulse maximum. Experimentally, the time-integrated emitted bremsstrahlung in the spectral range of 8–18 nm was corrected for the wavelength-dependent instrument efficiency. The resulting spectrum cannot be fit with a single temperature bremsstrahlung model, and the best fit is obtained using two temperatures of about 13 and eV. The lower temperatures in the experiment can be explained by missing energy-loss channels in the simulations, as well as the inclusion of hot, non-Maxwellian electrons in the temperature calculation. We resolved the time-scale for laser-heating of hydrogen, and PIC results for laser–matter interaction were successfully tested against the experiment data.