Referierte Publikationen

2016

O. Culfa, G. J. Tallents, A. K. Rossall, E. Wagenaars, C. P. Ridgers, C. D. Murphy, R. J. Dance, R. J. Gray, P. McKenna, C. D. R. Brown, S. F. James, D. J. Hoarty, N. Booth, A. P. L. Robinson, K. L. Lancaster, S. A. Pikuz, A. Ya. Faenov, T. Kämpfer, K. S. Schulze, I. Uschmann, and N. C. Woolsey
Plasma scale-length effects on electron energy spectra in high-irradiance laser plasmas
Phys. Rev. E, 93 :043201 (April 2016)
Abstract:
An analysis of an electron spectrometer used to characterize fast electrons generated by ultraintense (10^20 Wcm^−2) laser interaction with a preformed plasma of scale length measured by shadowgraphy is presented. The effects of fringing magnetic fields on the electron spectral measurements and the accuracy of density scale-length measurements are evaluated. 2D EPOCH PIC code simulations are found to be in agreement with measurements of the electron energy spectra showing that laser filamentation in plasma preformed by a prepulse is important with longer plasma scale lengths (>8 μm).
P.-M. Hillenbrand, S. Hagmann, J. M. Monti, R. D. Rivarola, K.-H. Blumenhagen, C. Brandau, W. Chen, R. D. DuBois, A. Gumberidze, D. L. Guo, M. Lestinsky, Yu. A. Litvinov, A. Müller, S. Schippers, U. Spillmann, S. Trotsenko, G. Weber, and T. Stöhlker
Strong asymmetry of the electron-loss-to-continuum cusp of multielectron U²⁸⁺ projectiles in near-relativistic collisions with gaseous targets
Phys. Rev. A, 93 :042709 (April 2016)
Abstract:
The process of electron-loss to the continuum (ELC) has been studied for the collision systems U28+ -> H2 at a collision energy of 50 MeV/u, U28+ -> N2 at 30 MeV/u, and U28+ -> Xe at 50 MeV/u. The energy distributions of cusp electrons emitted at an angle of 0∘ with respect to the projectile beam were measured using a magnetic forward-angle electron spectrometer. For these collision systems far from equilibrium charge state, a significantly asymmetric cusp shape is observed. The experimental results are compared to calculations based on first-order perturbation theory, which predict an almost symmetric cusp shape. Some possible reasons for this discrepancy are discussed.
P. Hansinger, G. Maleshkov, I. L. Garanovich, D. V. Skryabin, D. N. Neshev, A. Dreischuh, and G.G. Paulus
White light generated by femtosecond optical vortex beams
J. Opt. Soc. Am. B, 33 :681 (April 2016)
Abstract:
In this work we report detailed experimental and numerical investigation of the white light generation by singly and doubly charged optical vortices propagating in a Kerr medium, where spectral broadening and transfer of topological charge (TC) into emerging spectral satellites take place due to self-phase modulation and degenerate four-wave frequency mixing (FWFM). Experiments performed with different pump beams show excellent agreement with theory. Singly and doubly charged white light vortices are observed within more than ±200  nm bandwidth after nonlinear propagation in Argon gas. Our experiment and theory data confirm that the TC transformation of the newly generated spectral components follows a law analogous to the one for energy conservation in the FWFM process. We also present results on the white light vortex stability.
D. Seipt, V. Kharin, S. Rykovanov, A. Surzhykov, and S. Fritzsche
Analytical results for nonlinear Compton scattering in short intense laser pulses
J. Plasma Phys., 82 :655820203 (March 2016)
Abstract:
We study in detail the strong-field QED process of nonlinear Compton scattering in short intense plane wave laser pulses of circular polarization. Our main focus is placed on how the spectrum of the backscattered laser light depends on the shape and duration of the initial short intense pulse. Although this pulse shape dependence is very complicated and highly nonlinear, and has never been addressed explicitly, our analysis reveals that all the dependence on the laser pulse shape is contained in a class of three-parameter master integrals. Here we present completely analytical expressions for the nonlinear Compton spectrum in terms of these master integrals. Moreover, we analyse the universal behaviour of the shape of the spectrum for very high harmonic lines.
S. G. Rykovanov, C. G. R. Geddes, C. B. Schroeder, E. Esarey, and W. P. Leemans
Controlling the spectral shape of nonlinear Thomson scattering with proper laser chirping
Phys. Rev. Accel. Beams, 19 :030701 (March 2016)
Abstract:
Effects of nonlinearity in Thomson scattering of a high intensity laser pulse from electrons are analyzed. Analytic expressions for laser pulse shaping in frequency (chirping) are obtained which control spectrum broadening for high laser pulse intensities. These analytic solutions allow prediction of the spectral form and required laser parameters to avoid broadening. Results of analytical and numerical calculations agree well. The control over the scattered radiation bandwidth allows narrow bandwidth sources to be produced using high scattering intensities, which in turn greatly improves scattering yield for future x- and gamma-ray sources.
H. Gies, and G. Torgrimsson
Critical Schwinger Pair Production
Phys. Rev. Lett., 116 :090406 (March 2016)
Abstract:
We investigate Schwinger pair production in spatially inhomogeneous electric backgrounds. A critical point for the onset of pair production can be approached by fields that marginally provide sufficient electrostatic energy for an off-shell long-range electron-positron fluctuation to become a real pair. Close to this critical point, we observe features of universality which are analogous to continuous phase transitions in critical phenomena with the pair-production rate serving as an order parameter: electric backgrounds can be subdivided into universality classes and the onset of pair production exhibits characteristic scaling laws. An appropriate design of the electric background field can interpolate between power-law scaling, essential Berezinskii-Kosterlitz-Thouless-type scaling, and a power-law scaling with log corrections. The corresponding critical exponents only depend on the large-scale features of the electric background, whereas the microscopic details of the background play the role of irrelevant perturbations not affecting criticality.
T. Kämpfer, I. Uschmann, Z. W. Wu, A. Surzhykov, S. Fritzsche, E. Förster, and G.G. Paulus
Linear polarization of the characteristic x-ray lines following inner-shell photoionization of tungsten
Phys. Rev. A, 93 :033409 (March 2016)
Abstract:
The linear polarization of the characteristic lines Lα1 (3d5/2→2p3/2) and Lα2 (3d3/2→2p3/2), following inner-shell photoionization of neutral tungsten, is analyzed both experimentally and theoretically. In the experiment, a tungsten target is photoionized by the primary emission of an x-ray tube with incident photon energies in the range of 10.2–30 keV. The σ and π components of the emitted fluorescence are measured by using a spectropolarimeter, based on x-ray diffraction at Bragg angles close to 45∘. The degree of linear polarization of the Lα1 and Lα2 lines is determined to be +(1.6±0.5)% and −(7±2)%, respectively. In addition, this degree of polarization is calculated within the framework of the density-matrix theory as a function of the incident photon energy. These calculations are in good agreement with the experimental results and show only a weak dependence of the degree of polarization on the energy of the incident photoionizing photon.
A. V. Bogatskaya, E. A. Volkova, V. Y. Kharin, and A. M. Popov
Polarization response in extreme nonlinear optics: when can the semiclassical approach be used?
Laser Phys. Lett., 13 :045301 (March 2016)
Abstract:
Availability of the semiclassical approach in strong-field physics and extreme nonlinear optics is analyzed. It is found that it is valid for calculation of the emission to the initially populated bound state only if population of this state is close to unity during the pulse and in the after pulse regime. If the initial level is depleted, the semiclassical approach fails and should be replaced by quantum-electrodynamical calculations. Also it is demonstrated that the bremsstrahlung spectrum cannot be correctly described in the frames of the semiclassical approach.
S. Hädrich, J. Rothhardt, S. Demmler, M. Tschernajew, A. Hoffmann, M. Krebs, A. Liem, O. d. Vries, M. Plötner, S. Fabian, T. Schreiber, J. Limpert, and A. Tünnermann
Scalability of components for kW-level average power few-cycle lasers
Appl. Opt., 55 :1636 (March 2016)
Abstract:
In this paper, the average power scalability of components that can be used for intense few-cycle lasers based on nonlinear compression of modern femtosecond solid-state lasers is investigated. The key components of such a setup, namely, the gas-filled waveguides, laser windows, chirped mirrors for pulse compression and low dispersion mirrors for beam collimation, focusing, and beam steering are tested under high-average-power operation using a kilowatt cw laser. We demonstrate the long-term stable transmission of kW-level average power through a hollow capillary and a Kagome-type photonic crystal fiber. In addition, we show that sapphire substrates significantly improve the average power capability of metal-coated mirrors. Ultimately, ultrabroadband dielectric mirrors show negligible heating up to 1 kW of average power. In summary, a technology for scaling of few-cycle lasers up to 1 kW of average power and beyond is presented.
W. Cayzac, A. Frank, A. Ortner, V. Bagnoud, M. Basko, S. Bedacht, A. Blazevic, O. Deppert, D. Gericke, L. Hallo, A. Knetsch, D. Kraus, G. Malka, K. Pépitone, G. Schaumann, T. Schlegel, D. Schumacher, An. Tauschwitz, J. Vorberger, F. Wagner, and M. Roth
Simulations of the energy loss of ions at the stopping-power maximum in a laser-induced plasma
J. Phys.: Conf. Ser., 688 :012009 (March 2016)
Abstract:
Simulations have been performed to study the energy loss of carbon ions in a hot, laser-generated plasma in the velocity region of the stopping-power maximum. In this parameter range, discrepancies of up to 30% exist between the various stopping theories and hardly any experimental data are available. The considered plasma, created by irradiating a thin carbon foil with two high-energy laser beams, is fully-ionized with a temperature of nearly 200 eV. To study the interaction at the maximum stopping power, Monte-Carlo calculations of the ion charge state in the plasma are carried out at a projectile energy of 0.5 MeV per nucleon. The predictions of various stopping-power theories are compared and experimental campaigns are planned for a first-time theory benchmarking in this low-velocity range.
A. Gopal, A. H. Woldegeorgis, S. Herzer, G.G. Paulus, P. Singh, W. Ziegler, and T. May.
Smith–Purcell radiation in the terahertz regime using charged particle beams from laser–matter interactions
Laser Part. Beams, 34 :187 (March 2016)
Abstract:
We report on the experimental observation of Smith–Purcell (SP) radiation generation by charged particle beam from laser–matter interactions. High-power laser pulses were focused onto a thin metal foil target to generate proton beams with energies up to 1.7 MeV via the target normal sheath acceleration (TNSA) process. The particle beam from the TNSA process was sent close to a periodic structure to generate SP radiation. Sub-μJ terahertz pulses were recorded using a pyroelectric detector. Simultaneous measurement of the ion spectra allowed us to estimate the power of the emitted radiation and compare it with the experimental results. The distance between the grating and the particle beam was varied and its effect on the emitted radiation was studied.
S. Keppler, A. Sävert, J. Körner, M. Hornung, H. Liebetrau, J. Hein, and M. Kaluza
The generation of amplified spontaneous emission in high-power CPA laser systems
Laser Photon. Rev., 10 :264 (March 2016)
Abstract:
An analytical model is presented describing the temporal intensity contrast determined by amplified spontaneous emission in high-intensity laser systems which are based on the principle of chirped pulse amplification. The model describes both the generation and the amplification of the amplified spontaneous emission for each type of laser amplifier. This model is applied to different solid state laser materials which can support the amplification of pulse durations ≤350 fs . The results are compared to intensity and fluence thresholds, e.g. determined by damage thresholds of a certain target material to be used in high-intensity applications. This allows determining if additional means for contrast improvement, e.g. plasma mirrors, are required for a certain type of laser system and application. Using this model, the requirements for an optimized high-contrast front-end design are derived regarding the necessary contrast improvement and the amplified “clean” output energy for a desired focussed peak intensity. Finally, the model is compared to measurements at three different high-intensity laser systems based on Ti:Sapphire and Yb:glass. These measurements show an excellent agreement with the model.
D. Seipt, A. Surzhykov, S. Fritzsche, and B. Kämpfer
Caustic structures in x-ray Compton scattering off electrons driven by a short intense laser pulse
New J. Phys., 18 :023044 (February 2016)
Abstract:
We study the Compton scattering of x-rays off electrons that are driven by a relativistically intense short optical laser pulse. The frequency spectrum of the laser-assisted Compton radiation shows a broad plateau in the vicinity of the laser-free Compton line due to a nonlinear mixing between x-ray and laser photons. Special emphasis is placed on how the shape of the short assisting laser pulse affects the spectrum of the scattered x-rays. In particular, we observe sharp peak structures in the plateau region, whose number and locations are highly sensitive to the laser pulse shape. These structures are interpreted as spectral caustics by using a semiclassical analysis of the laser-assisted QED matrix element, relating the caustic peak locations to the laser-driven electron motion.
A. Titov, B. Kämpfer, A. Hosaka, T. Nousch, and D. Seipt
Determination of the carrier envelope phase for short, circularly polarized laser pulses
Phys. Rev. D, 93 :045010 (February 2016)
Abstract:
We analyze the impact of the carrier envelope phase on the differential cross sections of the Breit- Wheeler and the generalized Compton scattering in the interaction of a charged electron (positron) with an intensive ultrashort electromagnetic (laser) pulse. The differential cross sections as a function of the azimuthal angle of the outgoing electron have a clear bump structure, where the bump position coincides with the value of the carrier phase. This effect can be used for the carrier envelope phase determination.
J. W. Wang, W. Yu, M. Y. Yu, H. Xu, J. J. Ju, S. X. Luan, M. Murakami, M. Zepf, and S. Rykovanov
High-energy-density electron beam from interaction of two successive laser pulses with subcritical-density plasma
Phys. Rev. Accel. Beams, 19 :021301 (February 2016)
Abstract:
It is shown by particle-in-cell simulations that a narrow electron beam with high energy and charge density can be generated in a subcritical-density plasma by two consecutive laser pulses. Although the first laser pulse dissipates rapidly, the second pulse can propagate for a long distance in the thin wake channel created by the first pulse and can further accelerate the preaccelerated electrons therein. Given that the second pulse also self-focuses, the resulting electron beam has a narrow waist and high charge and energy densities. Such beams are useful for enhancing the target-back space-charge field in target normal sheath acceleration of ions and bremsstrahlung sources, among others.
A. V. Volotka, V. A. Yerokhin, A. Surzhykov, T. Stöhlker, and S. Fritzsche
Many-electron effects on x-ray Rayleigh scattering by highly charged He-like ions
Phys. Rev. A, 93 :023418 (February 2016)
Abstract:
The Rayleigh scattering of x rays by many-electron highly charged ions is studied theoretically. The many-electron perturbation theory, based on a rigorous quantum electrodynamics approach, is developed and implemented for the case of the elastic scattering of (high-energetic) photons by heliumlike ions. Using this elaborate approach, we here investigate the many-electron effects beyond the independent-particle approximation (IPA) as conventionally employed for describing the Rayleigh scattering. The total and angle-differential cross sections are evaluated for the x-ray scattering by heliumlike Ni^26+, Xe^52+, and Au^77+ ions in their ground state. The obtained results show that, for high-energetic photons, the effects beyond the IPA do not exceed 2% for the scattering by a closed K shell.
S. Fuchs, C. Rödel, A. Blinne, U. Zastrau, M. Wünsche, V. Hilbert, L. Glaser, J. Viefhaus, E. Frumker, P. Corkum, E. Förster, and G.G. Paulus
Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation
Sci. Rep., 6 :20658 (February 2016)
Abstract:
Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1 μm, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence lengths corresponding to the spectral transmission windows of, e.g., silicon samples. The axial resolution of coherence tomography is thus improved from micrometers to a few nanometers. Tomographic imaging with an axial resolution better than 18 nm is demonstrated for layer-type nanostructures buried in a silicon substrate. Using wavelengths in the water transmission window, nanometer-scale layers of platinum are retrieved with a resolution better than 8 nm. XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window.
B. Dromey, M. Coughlan, L. Senje, M. Taylor, S. Kuschel, B. Villagomez-Bernabe, R. Stefanuik, G. Nersisyan, L. Stella, J. Kohanoff, M. Borghesi, F. Currell, D. Riley, D. Jung, C.-G. Wahlström, C. L. S. Lewis, and M. Zepf
Picosecond metrology of laser-driven proton bursts
Nat. Commun., 7 :10642 (February 2016)
Abstract:
Tracking primary radiation-induced processes in matter requires ultrafast sources and high precision timing. While compact laser-driven ion accelerators are seeding the development of novel high instantaneous flux applications, combining the ultrashort ion and laser pulse durations with their inherent synchronicity to trace the real-time evolution of initial damage events has yet to be realized. Here we report on the absolute measurement of proton bursts as short as 3.5±0.7 ps from laser solid target interactions for this purpose. Our results verify that laser-driven ion acceleration can deliver interaction times over a factor of hundred shorter than those of state-of-the-art accelerators optimized for high instantaneous flux. Furthermore, these observations draw ion interaction physics into the field of ultrafast science, opening the opportunity for quantitative comparison with both numerical modelling and the adjacent fields of ultrafast electron and photon interactions in matter.
T. Nousch, D. Seipt, B. Kämpfer, and A. I. Titov
Spectral caustics in laser assisted Breit–Wheeler process
Phys. Lett. B, 755 :162 (February 2016)
Abstract:
Electron–positron pair production by the Breit–Wheeler process embedded in a strong laser pulse is analyzed. The transverse momentum spectrum displays prominent peaks which are interpreted as caustics, the positions of which are accessible by the stationary phases. Examples are given for the superposition of an XFEL beam with an optical high-intensity laser beam. Such a configuration is available, e.g., at LCLS at present and at European XFEL in near future. It requires a counter propagating probe photon beam with high energy which can be generated by synchronized inverse Compton backscattering.
S. Cousens, B. Reville, B. Dromey, and M. Zepf
Temporal Structure of Attosecond Pulses from Laser-Driven Coherent Synchrotron Emission
Phys. Rev. Lett., 116 :083901 (February 2016)
Abstract:
The microscopic dynamics of laser-driven coherent synchrotron emission transmitted through thin foils are investigated using particle-in-cell simulations. For normal incidence interactions, we identify the formation of two distinct electron nanobunches from which emission takes place each half-cycle of the driving laser pulse. These emissions are separated temporally by 130 as and are dominant in different frequency ranges, which is a direct consequence of the distinct characteristics of each electron nanobunch. This may be exploited through spectral filtering to isolate these emissions, generating electromagnetic pulses of duration ~70 as.
M. Schäfer, I. Huet, and H. Gies
Worldline numerics for energy-momentum tensors in Casimir geometries
J. Phys. A, 49 :135402 (February 2016)
Abstract:
We develop the worldline formalism for computations of composite operators such as the fluctuation induced energy-momentum tensor. As an example, we use a fluctuating real scalar field subject to Dirichlet boundary conditions. The resulting worldline representation can be evaluated by worldline Monte-Carlo methods in continuous spacetime. We benchmark this worldline numerical algorithm with the aid of analytically accessible single-plate and parallel-plate Casimir configurations, providing a detailed analysis of statistical and systematic errors. The method generalizes straightforwardly to arbitrary Casimir geometries and general background potentials.
A. Blinne, and E. Strobel
Comparison of semiclassical and Wigner function methods in pair production in rotating fields
Phys. Rev. D, 93 :025014 (January 2016)
Abstract:
We present a comparison of two methods to compute the momentum spectrum and the Schwinger pair creation rate for pulsed rotating electric fields: a numerical method based upon the real-time Dirac-Heisenberg-Wigner formalism and a semiclassical approximation based on a scattering ansatz. For the semiclassical method we propose to either perform numerical calculations or an additional approximation based on an analytical solution for the constant rotating field. We find that the two numerical methods are complementary with respect to computation time as well as accuracy. The approximate method shows the same qualitative features while being computationally much faster. We additionally find that the unequal production of pairs in different spin states reported for constant rotating fields with the scattering method is in agreement with the Wigner function method.
J. Braun, F. Karbstein, S. Rechenberger, and D. Roscher
Crystalline ground states in Polyakov-loop extended Nambu-Jona-Lasinio models
Phys. Rev. D, 93 :014032 (January 2016)
Abstract:
Nambu–Jona-Lasinio-type models have been used extensively to study the dynamics of the theory of the strong interaction at finite temperature and quark chemical potential on a phenomenological level. In addition to these studies, which are often performed under the assumption that the ground state of the theory is homogeneous, searches for the existence of crystalline phases associated with inhomogeneous ground states have attracted a lot of interest in recent years. In this work, we study the Polyakov-loop extended Nambu–Jona-Lasinio model using two prominent parametrizations and find that the existence of a crystalline phase is stable against a variation of the parametrization of the underlying Polyakov loop potential.
S. G. Podorov, and E. Förster
Direct inversion of digital 3D Fraunhofer holography maps
Appl. Opt., 55 :A150 (January 2016)
Abstract:
Differential Fourier holography (DFH) gives an exact mathematical solution of the inverse problem of diffraction in the Fraunhofer regime. After the first publication \[Opt. Express15, 9954 (2007)OPEXFF1094-408710.1364/OE.15.009954\], DFH was successfully applied in many experiments to obtain amplitude and phase information about two-dimensional images. In this paper, we demonstrate numerically the possibility to apply DFH also for investigation of unknown three-dimensional objects. The first simulation is made for a double-spiral structure plus a line as a reference object.
I. C. E. Turcu, F. Negoita, D. A. Jaroszynski, P. McKenna, S. Balascuta, D. Ursescu, I. Dancus, M. O. Cernaianu, M. V. Tataru, P. Ghenuche, D. Stutman, A. Boianu, M. Risca, M. Toma, C. Petcu, G. Acbas, S. R. Yoffe, A. Noble, B. Ersfeld, E. Brunetti, R. Capdessus, C. Murphy, C. P. Ridgers, D. Neely, S. P. D. Mangles, R. J. Gray, A. G. R. Thomas, J. G. Kirk, A. Ilderton, M. Marklund, D. F. Gordon, B. Hafizi, D. Kaganovich, J. P. Palastro, E. D'Humieres, M. Zepf, G. Sarri, H. Gies, F. Karbstein, J. Schreiber, G.G. Paulus, B. Dromey, C. Harvey, A. Di Piazza, C. H. Keitel, M.C. Kaluza, S. Gales, and N. V. Zamfir
High Field Physics and QED Experiments at ELI-NP
Rom. Rep. Phys., 68 :S145 (January 2016)
Abstract:
ELI-NP facility will enable for the first time the use of two 10 PW laser beams for quantum electrodynamics (QED) experiments. The first beam will accelerate electrons to relativistic energies. The second beam will subject relativistic electrons to the strong electromagnetic field generating QED processes: intense gamma ray radiation and electron-positron pair formation. The laser beams will be focused to intensities above 10^21 W/cm^2 and reaching 10^22–10^23 W/cm^2 for the first time. We propose to use this capability to investigate new physical phenomena at the interfaces of plasma, nuclear and particle physics at ELI-NP. This High Power Laser System Technical Design Report (HPLS-TDR2) presents the experimental area E6 at ELI-NP for investigating high field physics and quantum electrodynamics and the production of electron-positron-pairs and of energetic gamma-rays. The scientific community submitted 12 commissioning runs for E6 interaction chamber with two 10 PW laser beams and one proposal for the CETAL interaction chamber with 1 PW laser. The proposals are representative of the international high field physics community being written by 48 authors from 14 European and US organizations. The proposals are classified according to the science area investigated into: Radiation Reaction Physics: Classical and Quantum; Compton and Thomson Scattering Physics: Linear and Non Linear Regimes; QED in Vacuum; Atoms in Extreme Fields. Two pump-probe colliding 10 PW laser beams are proposed for the E6 interaction chamber. The focused pump laser beam accelerates the electrons to relativistic energies. The accelerated electron bunches interact with the very high electro-magnetic field of the focused probe laser beam. We propose two main types of experiments with: (a) gas targets in which the pump laser-beam is focused by a long focal length mirror and drives a wakefield in which the electron bunch is accelerated to multi-GeV energies and then exposed to the EM field of the probe laser which is tightly focused; (b) solid targets in which both the pump and probe laser beams are focused on the solid target, one accelerating the electrons in the solid and the other, delayed, providing the high electric field to which the relativistic electrons are subjected. We propose four main focusing configurations for the pump and probe laser beams, two for each type of target: counter-propagating 10 PW focused laser beams and the two 10 PW laser beams focused in the same direction. For solid targets we propose an additional configuration with plasma-mirror on the pump laser beam: the plasma mirror placed between the focusing mirror and target. It is proposed that the 10 PW laser beams will have polarization control and focus control by means of adaptive optics. Initially only one 10 PW may have polarization control and adaptive optics. In order to accommodate the two laser beams and diagnostics the proposed interaction chamber is quasi-octagonal with a diameter of 4.5 m. A large electron-spectrometer is proposed for multi-GeV electrons. Other diagnostics are requested for: gamma-rays, electrons and positrons, protons and ions, plasma characterization, transmitted and reflected laser beam. Targets will be provided by the ELI-NP Target Laboratory or purchased. The E6 experiments and diagnostics will benefit from the ELI-NP Electronics Laboratory, the Workshop and the Optics Laboratory. In order to ensure radiation-protection, a large beam-dump is planned for both multi-GeV electrons and multi-100 MeV protons.