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Intensed pulsed laser

L B Ju, C T Zhou, T W Huang, K Jiang, H Zhang, S Z Wu, B Qiao, S C Ruan
It was shown that in the interactions of ultra-intense circularly polarized laser pulse with the near-critical plasmas, the angular momentum can be transferred efficiently from the laser beam to electrons through the resonance acceleration process. The transferred angular momentum increases almost linearly with the acceleration time t_{a} when the electrons are resonantly accelerated by the laser field. In addition, it is shown analytically that the averaged angular momentum of electrons is proportional to the laser amplitude a_{L}, and the total angular momentum of the accelerated electron beam is proportional to the square of the laser amplitude a_{L}^{2} for a fixed parameter of n_{e}/n_{c}a_{L}...
May 2017: Physical Review. E
Suo Tang, Naveen Kumar, Christoph H Keitel
Plasma high-order-harmonic generation from an extremely intense short-pulse laser is explored by including the effects of ion motion, electron-ion collisions, and radiation reaction force in the plasma dynamics. The laser radiation pressure induces plasma ion motion through the hole-boring effect, resulting in frequency shifting and widening of the harmonic spectra. The classical radiation reaction force slightly mitigates the frequency broadening caused by the ion motion. Based on the results and physical considerations, parameter maps highlighting the optimum regions for generating a single intense attosecond pulse and coherent XUV radiation are presented...
May 2017: Physical Review. E
G M Petrov, J P Palastro, J Peñano
An intense, short laser pulse incident on a transparent dielectric can excite electrons from the valence to the conduction band. As these electrons undergo scattering, both from phonons and ions, they emit bremsstrahlung. Here we present a theory of bremsstrahlung emission appropriate for the interaction of laser pulses with dielectrics. Simulations of the interaction, incorporating this theory, illustrate characteristics of the radiation (power, energy, and spectra) for arbitrary ratios of electron collision frequency to radiation frequency...
May 2017: Physical Review. E
Zhi Luo, Ji'an Duan, Chunlei Guo
We demonstrate an efficient method for fabricating high-quality cylindrical microlens arrays (CMLAs) on the surface of fused silica, fully based on spatially shaping of a femtosecond laser beam from Gaussian to Bessel distribution. As the envelope of shaped spatial intensity distribution matches the profile of cylindrical microlens perfectly, a CMLA with more than 50 uniform microlenses is fabricated by simple line scanning. The radius and height of these microlens units can be finely controlled by adjusting the power of laser pulses...
June 15, 2017: Optics Letters
U Masood, T E Cowan, W Enghardt, K M Hofmann, L Karsch, F Kroll, U Schramm, J J Wilkens, J Pawelke
Proton beams may provide superior dose-conformity in radiation therapy. However, the large sizes and costs limit the widespread use of proton therapy (PT). The recent progress in proton acceleration via high-power laser systems has made it a compelling alternative to conventional accelerators, as it could potentially reduce the overall size and cost of the PT facilities. However, the laser-accelerated beams exhibit different characteristics than conventionally accelerated beams, i.e. very intense proton bunches with large divergences and broad-energy spectra...
July 7, 2017: Physics in Medicine and Biology
Carolina Marciela Herpich, Ernesto Cesar Pinto Leal-Junior, Cid Andre Fidelis de Paula Gomes, Igor Phillip Dos Santos Gloria, Ana Paula Amaral, Maitê de Freitas de Rocha Souza Amaral, Fabiano Politti, Daniela Aparecida Biasotto-Gonzalez
OBJECTIVES: The aim of the present study was to evaluate the immediate and short-term effects of phototherapy on pain intensity, the pressure pain threshold (PPT), maximum vertical mandibular movement, and the electrical activity of the masseter and temporal muscles in women with temporomandibular disorder (TMD). METHODS: Sixty women were randomly allocated to four different groups and submitted to phototherapy with a combination of super-pulsed laser (905 nm), red (640 nm), and infrared (875 nm) light emitting diodes in the same equipment on the masseter (three points) and temporal (two points) muscles bilaterally in a single session...
June 11, 2017: Disability and Rehabilitation
Justin Tian, Xu Wang, J H Eberly
The lack of analytical solutions for the exit momentum in the laser-driven tunneling theory is a well-recognized problem in strong field physics. Theoretical studies of electron momentum distributions in the neighborhood of the tunneling exit depend heavily on ad hoc assumptions. In this Letter, we apply a new numerical method to study the exiting electron's longitudinal momentum distribution under intense short-pulse laser excitation. We present the first realizations of the dynamic behavior of an electron near the so-called tunneling exit region without adopting a tunneling approximation...
May 26, 2017: Physical Review Letters
E Irani, A Anvari, R Sadighi-Bonabi, M Monfared
The multielectron dissociative ionization of CH4 and CH2O molecules has been investigated using optimum convolution of different dual tailored short laser pulses. Based on three dimensional molecular dynamics simulations and TDDFT approach, the dissociation probability is enhanced by designing the dual chirped-chirped laser pulses and chirped-ordinary laser pulses for formaldehyde molecule. However, it is interesting to notice that the sensitivity of enhanced dissociation probability into different tailored laser pulses is not significant for methane molecule...
May 31, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
X Vaisseau, A Morace, M Touati, M Nakatsutsumi, S D Baton, S Hulin, Ph Nicolaï, R Nuter, D Batani, F N Beg, J Breil, R Fedosejevs, J-L Feugeas, P Forestier-Colleoni, C Fourment, S Fujioka, L Giuffrida, S Kerr, H S McLean, H Sawada, V T Tikhonchuk, J J Santos
Collimated transport of ultrahigh intensity electron current was observed in cold and in laser-shocked vitreous carbon, in agreement with simulation predictions. The fast electron beams were created by coupling high-intensity and high-contrast laser pulses onto copper-coated cones drilled into the carbon samples. The guiding mechanism-observed only for times before the shock breakout at the inner cone tip-is due to self-generated resistive magnetic fields of ∼0.5-1  kT arising from the intense currents of fast electrons in vitreous carbon, by virtue of its specific high resistivity over the range of explored background temperatures...
May 19, 2017: Physical Review Letters
A Sanchez-Gonzalez, P Micaelli, C Olivier, T R Barillot, M Ilchen, A A Lutman, A Marinelli, T Maxwell, A Achner, M Agåker, N Berrah, C Bostedt, J D Bozek, J Buck, P H Bucksbaum, S Carron Montero, B Cooper, J P Cryan, M Dong, R Feifel, L J Frasinski, H Fukuzawa, A Galler, G Hartmann, N Hartmann, W Helml, A S Johnson, A Knie, A O Lindahl, J Liu, K Motomura, M Mucke, C O'Grady, J-E Rubensson, E R Simpson, R J Squibb, C Såthe, K Ueda, M Vacher, D J Walke, V Zhaunerchyk, R N Coffee, J P Marangos
Free-electron lasers providing ultra-short high-brightness pulses of X-ray radiation have great potential for a wide impact on science, and are a critical element for unravelling the structural dynamics of matter. To fully harness this potential, we must accurately know the X-ray properties: intensity, spectrum and temporal profile. Owing to the inherent fluctuations in free-electron lasers, this mandates a full characterization of the properties for each and every pulse. While diagnostics of these properties exist, they are often invasive and many cannot operate at a high-repetition rate...
June 5, 2017: Nature Communications
David Popp, N Duane Loh, Habiba Zorgati, Umesh Ghoshdastider, Lu Ting Liow, Magdalena I Ivanova, Mårten Larsson, Daniel P DePonte, Richard Bean, Kenneth R Beyerlein, Cornelius Gati, Dominik Oberthuer, David Arnlund, Gisela Brändén, Peter Berntsen, Duilio Cascio, Leonard M G Chavas, Joe P J Chen, Ke Ding, Holger Fleckenstein, Lars Gumprecht, Rajiv Harimoorthy, Estelle Mossou, Michael R Sawaya, Aaron S Brewster, Johan Hattne, Nicholas K Sauter, Marvin Seibert, Carolin Seuring, Francesco Stellato, Thomas Tilp, David S Eisenberg, Marc Messerschmidt, Garth J Williams, Jason E Koglin, Lee Makowski, Rick P Millane, Trevor Forsyth, Sébastien Boutet, Thomas A White, Anton Barty, Henry Chapman, Swaine L Chen, Mengning Liang, Richard Neutze, Robert C Robinson
A major goal for X-ray free-electron laser (XFEL) based science is to elucidate structures of biological molecules without the need for crystals. Filament systems may provide some of the first single macromolecular structures elucidated by XFEL radiation, since they contain one-dimensional translational symmetry and thereby occupy the diffraction intensity region between the extremes of crystals and single molecules. Here, we demonstrate flow alignment of as few as 100 filaments (Escherichia coli pili, F-actin, and amyloid fibrils), which when intersected by femtosecond X-ray pulses result in diffraction patterns similar to those obtained from classical fiber diffraction studies...
June 2, 2017: Cytoskeleton
Henry N Chapman
The intense X-ray pulses from free-electron lasers, of only femtoseconds duration, outrun most of the processes that lead to structural degradation in X-ray exposures of macromolecules. Using these sources it is therefore possible to increase the dose to macromolecular crystals by several orders of magnitude higher than usually tolerable in conventional measurements, allowing crystal size to be decreased dramatically in diffraction measurements and without the need to cool the sample. Such pulses lead to the eventual vaporization of the sample, which has required a measurement approach, called serial crystallography, of consolidating snapshot diffraction patterns of many individual crystals...
2017: Methods in Molecular Biology
A Rudenko, L Inhester, K Hanasaki, X Li, S J Robatjazi, B Erk, R Boll, K Toyota, Y Hao, O Vendrell, C Bomme, E Savelyev, B Rudek, L Foucar, S H Southworth, C S Lehmann, B Kraessig, T Marchenko, M Simon, K Ueda, K R Ferguson, M Bucher, T Gorkhover, S Carron, R Alonso-Mori, J E Koglin, J Correa, G J Williams, S Boutet, L Young, C Bostedt, S-K Son, R Santra, D Rolles
X-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10(20) watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities...
June 1, 2017: Nature
Yun Sun Byun, Jee Hee Son, Yong Se Cho, Bo Young Chung, Hee Jin Cho, Chun Wook Park, Hye One Kim
Discoid lupus erythematosus (DLE) is a chronic form of cutaneous lupus that can cause permanent scarring. Treatment of DLE includes protection from sunlight and artificial sources of ultraviolet light, as well as systemic and topical medications. The first-line standard therapies are antimalarials and topical steroids. Other systemic therapies include systemic steroid, azathioprine, dapsone, and immunosuppressive agents. Topical tacrolimus and pimecrolimus have also been evaluated. Recent studies reported that several treatments, including pulsed dye laser, CO2 laser, intense pulsed light (IPL), and 1,064-nm long-pulse neodymium-doped yttrium aluminum (Nd:YAG) have been used for the cosmetic treatment of DLE...
June 2017: Annals of Dermatology
Juan S Totero Gongora, Andrey E Miroshnichenko, Yuri S Kivshar, Andrea Fratalocchi
Nanophotonics is a rapidly developing field of research with many suggestions for a design of nanoantennas, sensors and miniature metadevices. Despite many proposals for passive nanophotonic devices, the efficient coupling of light to nanoscale optical structures remains a major challenge. In this article, we propose a nanoscale laser based on a tightly confined anapole mode. By harnessing the non-radiating nature of the anapole state, we show how to engineer nanolasers based on InGaAs nanodisks as on-chip sources with unique optical properties...
May 31, 2017: Nature Communications
Tim Plath, Christoph Lechner, Velizar Miltchev, Philipp Amstutz, Nagitha Ekanayake, Leslie Lamberto Lazzarino, Theophilos Maltezopoulos, Jörn Bödewadt, Tim Laarmann, Jörg Roßbach
Free-electron lasers are unique sources of intense and ultra-short x-ray pulses that led to major scientific breakthroughs across disciplines from matter to materials and life sciences. The essential element of these devices are micrometer-sized electron bunches with high peak currents, low energy spread, and low emittance. Advanced FEL concepts such as seeded amplifiers rely on the capability of analyzing and controlling the electron beam properties with few-femtosecond time resolution. One major challenge is to extract tomographic slice parameters instead of projected electron beam properties...
May 25, 2017: Scientific Reports
Elke Beyreuther, Kerstin Brüchner, Mechthild Krause, Margret Schmidt, Rita Szabo, Jörg Pawelke
BACKGROUND: The long-term aim of developing laser based particle acceleration towards clinical application requires not only substantial technological progress, but also the radiobiological characterization of the resulting ultra-short and ultra-intensive particle beam pulses. After comprehensive cell studies a mouse ear tumour model was established allowing for the penetration of low energy protons (~20 MeV) currently available at laser driven accelerators. The model was successfully applied for a first tumour growth delay study with laser driven electrons, whereby the need of improvements crop out...
2017: PloS One
Yiyang Luo, Jianwei Cheng, Bowen Liu, Qizhen Sun, Lei Li, Songnian Fu, Dingyuan Tang, Luming Zhao, Deming Liu
Physics phenomena of multi-soliton complexes have enriched the life of dissipative solitons in fiber lasers. By developing a birefringence-enhanced fiber laser, we report the first experimental observation of group-velocity-locked vector soliton (GVLVS) molecules. The birefringence-enhanced fiber laser facilitates the generation of GVLVSs, where the two orthogonally polarized components are coupled together to form a multi-soliton complex. Moreover, the interaction of repulsive and attractive forces between multiple pulses binds the particle-like GVLVSs together in time domain to further form compound multi-soliton complexes, namely GVLVS molecules...
May 24, 2017: Scientific Reports
Tsukasa Takanashi, Kosuke Nakamura, Edwin Kukk, Koji Motomura, Hironobu Fukuzawa, Kiyonobu Nagaya, Shin-Ichi Wada, Yoshiaki Kumagai, Denys Iablonskyi, Yuta Ito, Yuta Sakakibara, Daehyun You, Toshiyuki Nishiyama, Kazuki Asa, Yuhiro Sato, Takayuki Umemoto, Kango Kariyazono, Kohei Ochiai, Manabu Kanno, Kaoru Yamazaki, Kuno Kooser, Christophe Nicolas, Catalin Miron, Theodor Asavei, Liviu Neagu, Markus Schöffler, Gregor Kastirke, Xiao-Jing Liu, Artem Rudenko, Shigeki Owada, Tetsuo Katayama, Tadashi Togashi, Kensuke Tono, Makina Yabashi, Hirohiko Kono, Kiyoshi Ueda
Coulomb explosion of diiodomethane CH2I2 molecules irradiated by ultrashort and intense X-ray pulses from SACLA, the Japanese X-ray free electron laser facility, was investigated by multi-ion coincidence measurements and self-consistent charge density-functional-based tight-binding (SCC-DFTB) simulations. The diiodomethane molecule, containing two heavy-atom X-ray absorbing sites, exhibits a rather different charge generation and nuclear motion dynamics compared to iodomethane CH3I with only a single heavy atom, as studied earlier...
May 22, 2017: Physical Chemistry Chemical Physics: PCCP
Omid Zandi, Kyle J Wilkin, Yanwei Xiong, Martin Centurion
We have constructed an experimental setup for gas phase electron diffraction with femtosecond resolution and a high average beam current. While gas electron diffraction has been successful at determining molecular structures, it has been a challenge to reach femtosecond resolution while maintaining sufficient beam current to retrieve structures with high spatial resolution. The main challenges are the Coulomb force that leads to broadening of the electron pulses and the temporal blurring that results from the velocity mismatch between the laser and electron pulses as they traverse the sample...
July 2017: Structural Dynamics (Melville, N.Y.)
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