Download or read book Nonlinear Increase of X ray Intensities from Thin Foils Irradiated with a 200 TW Femtosecond Laser written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report, for the first time, that the energy of femtosecond optical laser pulses, E, with relativistic intensities I> 1021 W/cm2 is efficiently converted to X-ray radiation, which is emitted by "hot" electron component in collision-less processes and heats the solid density plasma periphery. As shown by direct high-resolution spectroscopic measurements X-ray radiation from plasma periphery exhibits unusual non-linear growth ~E4-5 of its power. The non-linear power growth occurs far earlier than the known regime when the radiation reaction dominates particle motion (RDR). Nevertheless, the radiation is shown to dominate the kinetics of the plasma periphery, changing in this regime (now labeled RDKR) the physical picture of the laser plasma interaction. Although in the experiments reported here we demonstrated by observation of KK hollow ions that X-ray intensities in the keV range exceeds ~1017 W/cm2, there is no theoretical limit of the radiation power. Therefore, such powerful X-ray sources can produce and probe exotic material states with high densities and multiple inner-shell electron excitations even for higher Z elements. Femtosecond laser-produced plasmas may thus provide unique ultra-bright X-ray sources, for future studies of matter in extreme conditions, material science studies, and radiography of biological systems.
Download or read book Relativistically Intense Laser Microplasma Interactions written by Tobias Ostermayr and published by Springer. This book was released on 2019-07-16 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation covers several important aspects of relativistically intense laser–microplasma interactions and some potential applications. A Paul-trap based target system was developed to provide fully isolated, well defined and well positioned micro-sphere-targets for experiments with focused peta-watt laser pulses. The laser interaction turned such targets into microplasmas, emitting proton beams with kinetic energies exceeding 10 MeV. The proton beam kinetic energy spectrum and spatial distribution were tuned by variation of the acceleration mechanism, reaching from broadly distributed spectra in relatively cold plasma expansions to spectra with relative energy spread as small as 20% in spherical multi-species Coulomb explosions and in directed acceleration processes. Numerical simulations and analytical calculations support these experimental findings and show how microplasmas may be used to engineer laser-driven proton sources. In a second effort, tungsten micro-needle-targets were used at a peta-watt laser to produce few-keV x-rays and 10-MeV-level proton beams simultaneously, both measured to have only few-μm effective source-size. This source was used to demonstrate single-shot simultaneous radiographic imaging with x-rays and protons of biological and technological samples. Finally, the dissertation discusses future perspectives and directions for laser–microplasma interactions including non-spherical target shapes, as well as thoughts on experimental techniques and advanced quantitative image evaluation for the laser driven radiography.
Download or read book X Ray Lasers 2016 written by Tetsuya Kawachi and published by Springer. This book was released on 2018-02-23 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings comprise a selection of invited and contributed papers presented at the 15th International Conference on X-Ray Lasers (ICXRL 2016), held at the Nara Kasugano International Forum, Japan, from May 22 to 27, 2016. This conference was part of an ongoing series dedicated to recent developments in the science and technology of x-ray lasers and other coherent x-ray sources with additional focus on supporting technologies, instrumentation and applications. The book showcases recent advances in the generation of intense, coherent x-rays, the development of practical devices and their applications across a wide variety of fields. It also discusses emerging topics such as plasma-based x-ray lasers, 4th generation accelerator-based sources and higher harmonic generations, as well as other x-ray generation schemes.
Download or read book X ray Spectroscopy of Buried Layer Foils Irradiated with an Ultra High Intensity Short Pulse Laser written by Sophia Nan Chen and published by . This book was released on 2009 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Relativistic short pulse laser matter interactions are of great interest in the area of high energy density physics which includes the fields of astrophysics, inertial confinement fusion (ICF), and fast ignition (FI). Such interactions can result in the creation of hot dense matter at keV temperatures near solid density which is crucial for the studying radiation transport, understanding particle transport processes, and benchmarking of computer models in this plasma regime. The plasma by short pulse lasers, with intensity greater than 1019 W/cm2 and picosecond pulses, exists for only several tens of picoseconds, has a nonuniform temperature and density, and has a non-Maxwellian electron distribution thus making characterization a challenge. This work presents for the first time a systematic study of the temperature gradient inside of micron thick solid targets using K-shell spectroscopic techniques and demonstrates the importance of energetic electrons, temporal evolution of the plasma and opacity in the analysis of high intensity short pulse laser plasmas. Tamped titanium foils were with a short-pulse laser with intensity greater than 1019 W/cm2. Target parameters such as size, tamper material, and tamper thickness were varied to optimize heating and uniformity of the titanium plasma. Comparison of measured titanium K-shell spectra, from a 250 x 250 x 5 [mu]m3 titanium foil tamped with aluminum, with a collisional radiative model indicated that the front ~0.2 [mu]m reached a peak temperature of Tb>e, peak= 1300 eV at solid density. The remaining bulk material had temperature Te, bulk= 100 eV. This experimental result is consistent with previous observations and the use of a tamper greatly enhances the density uniformity of the plasma. Further reduction of the lateral and longitudinal target dimensions was needed to refine the analysis and prompted a second experiment. Five targets, with dimensions of 100 x 100 x 0.4 [mu]m3, had a copper foil were buried at different depths (i.e. 0-1.5 [mu]m) and irradiated with a short pulse laser with intensities greater than 1020 W/cm2. The measured K-shell spectra again indicated a temperature gradient in the longitudinal direction inside the target. Analysis using a hydrodynamic code and a collisional radiative atomic code showed that the hot electron population, time dependent plasma conditions, and opacity significantly alters the calculated K-shell line ratios thus producing up to a factor of two error in plasma temperature.
Download or read book Establishing Nonlinearity Thresholds with Ultraintense X ray Pulses written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: X-ray techniques have evolved over decades to become highly refined tools for a broad range of investigations. Importantly, these approaches rely on X-ray measurements that depend linearly on the number of incident X-ray photons. The advent of X-ray free electron lasers (XFELs) is opening the ability to reach extremely high photon numbers within ultrashort X-ray pulse durations and is leading to a paradigm shift in our ability to explore nonlinear X-ray signals. However, the enormous increase in X-ray peak power is a double-edged sword with new and exciting methods being developed but at the same time well-established techniques proving unreliable. Consequently, accurate knowledge about the threshold for nonlinear X-ray signals is essential. Here in this paper we report an X-ray spectroscopic study that reveals important details on the thresholds for nonlinear X-ray interactions. By varying both the incident X-ray intensity and photon energy, we establish the regimes at which the simplest nonlinear process, two-photon X-ray absorption (TPA), can be observed. From these measurements we can extract the probability of this process as a function of photon energy and confirm both the nature and sub-femtosecond lifetime of the virtual intermediate electronic state.
Download or read book Laser matter Interactions at Extreme Irradiance written by Anders Sjögren and published by . This book was released on 2002 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterisation and Application of a Laser based Hard X ray Source written by Matthias Grätz and published by . This book was released on 1998 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Short Pulse Laser Interactions With Matter An Introduction written by Paul Gibbon and published by World Scientific. This book was released on 2005-09-05 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book represents the first comprehensive treatment of the subject, covering the theoretical principles, present experimental status and important applications of short-pulse laser-matter interactions.Femtosecond lasers have undergone dramatic technological advances over the last fifteen years, generating a whole host of new research activities under the theme of “ultrafast science”. The focused light from these devices is so intense that ordinary matter is torn apart within a few laser cycles. This book takes a close-up look at the exotic physical phenomena which arise as a result of this new form of “light-matter” interaction, covering a diverse set of topics including multiphoton ionization, rapid heatwaves, fast particle generation and relativistic self-channeling. These processes are central to a number of exciting new applications in other fields, such as microholography, optical particle accelerators and photonuclear physics.Repository for numerical models described in Chapter 6 can be found at www.fz-juelich.de/zam/cams/plasma/SPLIM/./a
Download or read book Emission of the Continous X ray Energy from Thin Aluminum Foils written by Howard Richard Kelly and published by . This book was released on 1940 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Feed out Process written by D. Palmer Smitherman and published by . This book was released on 1998 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental X ray Spectra from Ti V Mn and Ni Foils Irradiated with the Z Beamlet Laser written by and published by . This book was released on 2011 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Intense Picosecond X Rays from Structured Targets written by Gábor Kulcsár and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser plasmas from a new type of nanostructured surface are studied. This nanowire surface is especially useful as a very high absorption target for high power (1 TW) subpicosecond laser-matter interaction. The ensemble of oriented 10-200 nm metallic fibers of this material have linear absorption of 1 m m light greater than 95%. When irradiated by 1 ps pulses at intensities up to 1017 W/cm-2, these targets produce a pulse of x-rays (average energy > 1.5 keV) 30 times more efficiently than do uniform solid targets, while preserving several-picosecond emission times. X-ray conversion efficiencies from the nanowire target and from previously investigated grating and 'smoke' targets are compared to those of flat targets for various angles of incidence and polarizations. Streak camera results show that a bright picosecond measure x-ray pulse is emitted from the near-solid density plasma created from the nanowire target. The measured x-ray pulse length is resolution-limited ( = 6.5 ps) for emission above 1.5 keV and is 20-25 ps for soft x rays. An absorbing uniaxial material model of the nanowire target yields an effective dielectric constant for the structured layer. This model helps to optimize structure parameters for: (1) minimum Fresnel losses on the vacuum/structured-target interface; and, (2) highest light absorption in the structured layer in the small-signal regime. A possible extension of this model into the plasma absorption regime is discussed. As part of this research a state-of-the-art 1 TW chirped pulse amplification (CPA) laser system was constructed. The Nd:glass system is based on a feedback-controlled mode-locked oscillator capable of providing high contrast 1 ps pulses at a wavelength of 1.054 m/f m, with energies up to 5 m J/pulse. The characteristics of the CPA system are described. A new detector was developed to measure absolute x-ray yield, in various spectral ranges, radiated from the solid-density plasma. A calibrated silicon PIN photodiode connected to a charge-sensitive amplifier circuit allows x-ray yield measurements from picosecond pulses. If properly filtered the detector can measure the amount of x-rays radiated in a narrow spectral range. The electrical and spectral characteristics of the PIN photodiode detectors are given.
Download or read book Measurements of Laser Imprint by XUV Radiography Using an X ray Laser written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have developed a technique for studying the imprint of a laser beam on a thin foil using an x-ray laser as an XUV backlighter and XUV multilayer optics. This technique allows us to measure small fractional variations in the foil thickness due to hydrodynamics imprinted by direct laser irradiation. We present results of imprinted modulation and growth due to a low intensity 0.53[mu]m drive beam incident on a 2[mu]m Al foil using a germanium x-ray laser at the Vulcan facility. We present measurements of the modulation due to static RPP, SSD smoothed, and ISI smoothed speckle patterns at 0.53[mu]m irradiation.
Download or read book Absolute X Ray Yields From Laser Irradiated Ge Doped Low Density Aerogels written by and published by . This book was released on 2009 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have used the OMEGA laser (Laboratory for Laser Energetics, University of Rochester) to measure the X-ray yields from laser-irradiated germanium-doped ultra-low-density aerogel plasmas in the energy range from sub-keV to ≈ 15 keV. They have studied the targets X-ray yields with variation in target size, aerogel density, laser pulse length and laser intensity. For targets that result in plasmas with electron densities in the range of ≈ 10% of the critical density for 3[omega] light, one can expect 10-11 J/sr of X-rays with energies above 9 keV, and 600-800 J/sr for energies below 3.5 keV. In addition to the X-ray spectral yields, they have measured the X-ray temporal waveforms and found that the emitted X rays generally follow the delivered laser power, with late-time enhancements of emitted X-ray power correlated with hydrodynamic compression of the hot plasma. Also, they find the laser energy reflected from the target by plasma instabilities to be 2-7% of the incident energy for individual beam intensities ≈ 1014-1015 W/cm2. They also have characterized the propagation of the laser heating in the target volume with two-dimensional imaging. They find the source-region heating to be correlated with the temporal profile of the emitted X-ray power.
Download or read book Frequency Conversion of High intensity Femtosecond Laser Pulses written by Paul Stuart Banks and published by . This book was released on 1997 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Experimental Evidence of Back Surface Acceleration from Laser Irradiated Foils written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Au foils were irradiated with a 100-TW, 100-fs laser at intensities greater than 102° W/cm2 producing proton beams with a total yield of H"1011 and maximum proton energy of> 9 MeV. Removing contamination from the back surface of Au foils with an Ar-ion sputter gun reduced the total yield of accelerated protons to less than 1% of the yield observed without removing contamination. Removing contamination the front surface (laser-interaction side) of the target had no observable effect on the proton beam. We present a one-dimensional particle-in-cell simulation that models the experiment. Both experimental and simulation results are consistent with the back-surface acceleration mechanism described in the text.
Download or read book The Physics Of Laser Plasma Interactions written by William Kruer and published by CRC Press. This book was released on 2019-08-20 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the physics of laser plasma interactions and presents a complementary and very useful numerical model of plasmas. It describes the linear theory of light wave propagation in plasmas, including linear mode conversion into plasma waves and collisional damping.
