Using Extreme Light : Entering New Frontiers with Petawatt-Class Lasers III . Research Using Extreme Light : Entering New Frontiers with Petawatt-Class Lasers (original) (raw)
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Review of physics and applications of relativistic plasmas driven by ultra-intense lasers
Physics of Plasmas, 2001
As tabletop lasers continue to reach record levels of peak power, the interaction of light with matter has crossed a new threshold, in which plasma electrons at the laser focus oscillate at relativistic velocities. The highest forces ever exerted by light have been used to accelerate beams of electrons and protons to energies of a million volts in distances of only microns. Not only is this acceleration gradient up to a thousand times greater than in radio-frequency-based sources, but the transverse emittance of the particle beams is comparable or lower. Additionally, laser-based accelerators have been demonstrated to work at a repetition rate of 10 Hz, an improvement of a factor of 1000 over their best performance of just a couple of years ago. Anticipated improvements in energy spread may allow these novel compact laser-based radiation sources to be useful someday for cancer radiotherapy and as injectors into conventional accelerators, which are critical tools for x-ray and nuclear physics research. They might also be used as a spark to ignite controlled thermonuclear fusion. The ultrashort pulse duration of these particle bursts and the x rays they can produce, hold great promise as well to resolve chemical, biological or physical reactions on ultrafast ͑femtosecond͒ time scales and on the spatial scale of atoms. Even laser-accelerated protons are soon expected to become relativistic. The dense electron-positron plasmas and vast array of nuclear reactions predicted to occur in this case might even help bring astrophysical phenomena down to Earth, into university laboratories. This paper reviews the many recent advances in this emerging discipline, called high-field science. new field of physics, known as high-field science. It is not intended to be comprehensive, but rather to be restricted to a discussion of some of the highlights, mainly over the last 5 years, in the relativistic regime of laser-plasma interactions. Several reviews have already been published on highintensity laser development and applications, 2-4 relativistic nonlinear optics, 4,5 laser accelerators, 6 and intense laserplasma interactions. The paper is organized as follows. A brief basic theoretical overview of relativistic laser-plasmas interactions, with references only to early work, is presented in Sec. II. Recent results and references to more recent theoretical and numerical work are discussed in Sec. III A; experimental results are presented in Sec. III B. Prospects and applications are reviewed in Sec. IV.
Ultra-intense laser interaction with nanostructured near-critical plasmas
Scientific Reports
Near-critical plasmas irradiated at ultra-high laser intensities (I > 10 18 W/cm 2) allow to improve the performances of laser-driven particle and radiation sources and to explore scenarios of great astrophysical interest. Near-critical plasmas with controlled properties can be obtained with nanostructured low-density materials. By means of 3D Particle-In-Cell simulations, we investigate how realistic nanostructures influence the interaction of an ultra-intense laser with a plasma having a near-critical average electron density. We find that the presence of a nanostructure strongly reduces the effect of pulse polarization and enhances the energy absorbed by the ion population, while generally leading to a significant decrease of the electron temperature with respect to a homogeneous nearcritical plasma. We also observe an effect of the nanostructure morphology. These results are relevant both for a fundamental understanding and for the foreseen applications of laser-plasma interaction in the near-critical regime. Laser interaction with near-critical plasmas (NCPs) 1,2 at relativistic intensities, i.e. high enough (I > 10 18 W/cm 2) to accelerate electrons to relativistic energies in a single laser cycle, is studied for a wide range of applications, including advanced laser-driven sources (ions 3-15 , electrons 16-19 and high-energy photons 20-23), generation of dense pair plasmas 24 , generation of ion Weibel-mediated collisionless shocks 25 , High-order Harmonic emission 26 , plasma optics 11,27 and inertial confinement fusion 28. This interaction regime is characterized by a variety of physical processes, such as efficient laser absorption, excitation of bulk plasmons and relativistic solitons, strong self-focusing, channel formation, and betatron electron acceleration, which have been the object of extensive theoretical investigations 1,29-32. NCPs are defined as having an electron density close to the critical density n c (λ), which marks the transparency threshold for the propagation of an electromagnetic wave with wavelength λ. The critical density n c is the electron density n e which satisfies ω L = ω p (n e), where ω L = 2π/λ is the laser frequency and n ne m
Radiation Physics and Chemistry, 2004
The increasing proliferation of 100 TW class ultrashort pulse lasers and the near completion of a number of petawatt class lasers world wide is opening many frontiers in laser science. Some of the most exciting frontiers rest in high energydensity science and high field physics. A multi-TW laser can create heated matter with pressure in excess of a Gbar and can create electric fields of ten to one hundred atomic units. In this paper some of the recent advances in high energy density science and high field physics made using high intensity short pulse lasers will be reviewed with illustrative examples from work performed at the University of Texas and Lawrence Livermore National Laboratory. r
Dense and Relativistic Plasmas Produced by Compact High‐Intensity Lasers
The Astrophysical Journal Supplement Series, 2000
High-intensity lasers interacting with plasmas are used to study processes in the laboratory that would otherwise only occur in astrophysics. These include relativistic plasmas, electron acceleration in ultrahigh Ðeld-gradient wake Ðelds, pressure ionization and continuum lowering in strongly coupled plasmas, and X-ray line emission via Raman scattering.
Extreme plasma states in laser-governed vacuum breakdown
Scientific reports, 2018
Triggering vacuum breakdown at laser facility is expected to provide rapid electron-positron pair production for studies in laboratory astrophysics and fundamental physics. However, the density of the produced plasma may cease to increase at a relativistic critical density, when the plasma becomes opaque. Here, we identify the opportunity of breaking this limit using optimal beam configuration of petawatt-class lasers. Tightly focused laser fields allow generating plasma in a small focal volume much less than λ3 and creating extreme plasma states in terms of density and produced currents. These states can be regarded to be a new object of nonlinear plasma physics. Using 3D QED-PIC simulations we demonstrate a possibility of reaching densities over 1025 cm-3, which is an order of magnitude higher than expected earlier. Controlling the process via initial target parameters provides an opportunity to reach the discovered plasma states at the upcoming laser facilities.
New Journal of Physics, 2020
The coupling of laser energy to electrons is fundamental to almost all topics 14 in intense laser-plasma interactions, including laser-driven particle and radiation 15 generation, relativistic optics, inertial confinement fusion and laboratory astrophysics. 16 We report measurements of total energy absorption in foil targets ranging in thickness 17 from 20 µm, for which the target remains opaque and surface interactions dominate, to 18 40 nm, for which expansion enables relativistic-induced transparency and volumetric 19 interactions. We measure a total peak absorption of ∼80% at an optimum thickness of 20 ∼380 nm. For thinner targets, for which some degree of transparency occurs, although 21 the total absorption decreases, the number of energetic electrons escaping the target 22 increases. 2D particle-in-cell simulations indicate that this results from direct laser 23 acceleration of electrons as the intense laser pulse propagates within the target volume. 24 The results point to a trade-off between total energy coupling to electrons and efficient 25 acceleration to higher energies. 26 1. Introduction 27 Energy absorption and coupling to electrons in dense targets irradiated by high intensity 28 laser pulses is fundamentally important to the development of ultra-bright sources of 29 high energy ions [1, 2], neutrons [3, 4], positrons [5, 6] and photons [7], to advanced 30 schemes for inertial confinement fusion [8], and in the generation of transient states of 31 warm dense matter [9, 10]. The efficiency with which laser energy is coupled to electrons within the plasma is a crucial aspect in optimising the properties of the particles and 33 radiation generated. The electrons accelerated by the laser directly produce photons and 34 positrons, and their displacement establishes the strong electrostatic fields responsible 35 for ion acceleration. The case of laser energy absorption and coupling to electrons in 36
Acceleration of heavy Ions to MeV/nucleon Energies by Ultrahigh-Intensity Lasers
2002
In this thesis the acceleration of heavy ions to multi-MeV energies by means of a laser is demonstrated for the first time. Using an ultrahigh-intensity laser, with focal intensities exceeding 5 x 10^19 W/cm^2, the laser-plasma interaction becomes relativistic and a strong electron current is driven in laser direction. These relativistic electrons penetrate the target foil and set up a quasistatic electric field at the target rear surface. This field is of the order of TV/m and accelerated Fluorine ions to energies of 100 MeV, i.e. about 10 % light speed, within 300 fs. While a normal accelerator needs a distance of roughly 100 m to reach these energies, the laser-driven acceleration achieves this in about 10 microns. Within the scope of this work, a technique was developed to select a specific ion species. The energy spectra and charge state distributions of several different species were measured and used to analyze the acceleration mechanism. The measured results were than compar...
Topical issue on Fundamental physics and ultra-high laser fields: Editorial
European Physical Journal D, 2009
This special issue is dedicated to the investigation of the new physics that has been opened up in the last decade by our recently acquired ability to produce relativistic plasmas in the laboratory [1]. Relativistic plasmas [2] are systems of charged long-range interacting particles in which either their disordered (thermal) kinetic energy or their ordered (fluid) kinetic energy is at least as large as the rest mass energy of the lighter particles (the electrons in general).