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- ItemX-ray spectroscopy of super-intense laser-produced plasmas for the study of nonlinear processes. Comparison with PIC simulations(Bristol : IOP Publ., 2017) Dalimier, E.; Ya Faenov, A.; Oks, E.; Angelo, P.; Pikuz, T.A.; Fukuda, Y.; Andreev, A.; Koga, J.; Sakaki, H.; Kotaki, H.; Pirozhkov, A.; Hayashi, Y.; Skobelev, I.Yu.; Pikuz, S.A.; Kawachi, T.; Kando, M.; Kondo, K.; Zhidkov, A.; Tubman, E.; Butler, N.M.H.; Dance, R.J.; Alkhimova, M.A.; Booth, N.; Green, J.; Gregory, C.; McKenna, P.; Woolsey, N.; Kodama, R.We present X-ray spectroscopic diagnostics in femto-second laser-driven experiments revealing nonlinear phenomena caused by the strong coupling of the laser radiation with the created plasma. Among those nonlinear phenomena, we found the signatures of the Two Plasmon Decay (TPD) instability in a laser-driven CO2 cluster-based plasma by analyzing the Langmuir dips in the profile of the O VIII Lyϵ line, caused by the Langmuir waves created at the high laser intensity 3 1018Wcm-2. With similar laser intensities, we reveal also the nonlinear phenomenon of the Second Harmonic Generation (SHG) of the laser frequency by analyzing the nonlinear phenomenon of satellites of Lyman δ and ϵ lines of Ar XVII. In the case of relativistic laser-plasma interaction we discovered the Parametric Decay Instability (PDI)-induced ion acoustic turbulence produced simultaneously with Langmuir waves via irradiation of thin Si foils by laser intensities of 1021Wcm-2.
- ItemA compact laboratory transmission X-ray microscope for the water window(Bristol : Institute of Physics Publishing, 2013) Legall, H.; Stiel, H.; Blobel, G.; Seim, C.; Baumann, J.; Yulin, S.; Esser, D.; Hoefer, M.; Wiesemann, U.; Wirtz, M.; Schneider, G.; Rehbein, S.; Hertz, H.M.In the water window (2.2-4.4 nm) the attenuation of radiation in water is significantly smaller than in organic material. Therefore, intact biological specimen (e.g. cells) can be investigated in their natural environment. In order to make this technique accessible to users in a laboratory environment a Full-Field Laboratory Transmission X-ray Microscope (L-TXM) has been developed. The L-TXM is operated with a nitrogen laser plasma source employing an InnoSlab high power laser system for plasma generation. For microscopy the Ly α emission of highly ionized nitrogen at 2.48 nm is used. A laser plasma brightness of 5 × 1011 photons/(s × sr × μm2 in line at 2.48 nm) at a laser power of 70 W is demonstrated. In combination with a state-of-the-art Cr/V multilayer condenser mirror the sample is illuminated with 106 photons/(μm2 × s). Using objective zone plates 35-40 nm lines can be resolved with exposure times < 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W. These exposure times enable cryo tomography in a laboratory environment.
- ItemSubwavelength population density gratings in resonant medium created by few-cycle pulses(Bristol : IOP Publ., 2017) Arkhipov, R.M.; Arkhipov, M.V.; Pakhomov, A.V.; Babushkin, I.; Demircan, A.; Morgner, U.; Rosanov, N.N.We consider theoretically recently proposed a new possibility of creation, erasing and ultrafast control of population density grating. Such grating can be created in resonant medium when ultrashort pulses with duration smaller than relaxation times in the resonant medium (coherent light matter interactions) propagate without overlapping in this medium. Possible applications in the ultrafast optics such as optical switcher and laser beam deflector are discussed.
- ItemReal-time spatial characterization of micrometer-sized X-ray free-electron laser beams focused by bendable mirrors(Washington, DC : Soc., 2022) Mercurio, Giuseppe; Chalupský, Jaromír; Nistea, Ioana-Theodora; Schneider, Michael; Hájková, Věra; Gerasimova, Natalia; Carley, Robert; Cascella, Michele; Le Guyader, Loïc; Mercadier, Laurent; Schlappa, Justine; Setoodehnia, Kiana; Teichmann, Martin; Yaroslavtsev, Alexander; Burian, Tomáš; Vozda, Vojtĕch; Vyšín, Luděk; Wild, Jan; Hickin, David; Silenzi, Alessandro; Stupar, Marijan; Torben Delitz, Jan; Broers, Carsten; Reich, Alexander; Pfau, Bastian; Eisebitt, Stefan; La Civita, Daniele; Sinn, Harald; Vannoni, Maurizio; Alcock, Simon G.; Juha, Libor; Scherz, AndreasA real-time and accurate characterization of the X-ray beam size is essential to enable a large variety of different experiments at free-electron laser facilities. Typically, ablative imprints are employed to determine shape and size of μm-focused X-ray beams. The high accuracy of this state-of-the-art method comes at the expense of the time required to perform an ex-situ image analysis. In contrast, diffraction at a curved grating with suitably varying period and orientation forms a magnified image of the X-ray beam, which can be recorded by a 2D pixelated detector providing beam size and pointing jitter in real time. In this manuscript, we compare results obtained with both techniques, address their advantages and limitations, and demonstrate their excellent agreement. We present an extensive characterization of the FEL beam focused to ≈1 μm by two Kirkpatrick-Baez (KB) mirrors, along with optical metrology slope profiles demonstrating their exceptionally high quality. This work provides a systematic and comprehensive study of the accuracy provided by curved gratings in real-time imaging of X-ray beams at a free-electron laser facility. It is applied here to soft X-rays and can be extended to the hard X-ray range. Furthermore, curved gratings, in combination with a suitable detector, can provide spatial properties of μm-focused X-ray beams at MHz repetition rate.
- ItemA transportable Paul-trap for levitation and accurate positioning of micron-scale particles in vacuum for laser-plasma experiments(Melville, NY : American Institute of Physics, 2018) Ostermayr, T.M.; Gebhard, J.; Haffa, D.; Kiefer, D.; Kreuzer, C.; Allinger, K.; Bömer, C.; Braenzel, J.; Schnürer, M.; Cermak, I.; Schreiber, J.; Hilz, P.We report on a Paul-trap system with large access angles that allows positioning of fully isolated micrometer-scale particles with micrometer precision as targets in high-intensity laser-plasma interactions. This paper summarizes theoretical and experimental concepts of the apparatus as well as supporting measurements that were performed for the trapping process of single particles.