This conference will be dedicated to new developments on the laser acceleration of electrons, protons, and ions. This includes methods based on the interaction of intense lasers with structures and plasmas at gas and solid densities. Experiments, diagnostics, theory, and numerical modeling of laser accelerators will be discussed. Papers are solicited on the following topics:

  • interaction of intense laser pulses with structures, gases, and solid targets
  • generation of large amplitude plasma waves with intense laser pulses
  • self-guiding and channel guiding of intense laser pulses
  • intense laser-plasma instabilities
  • particle acceleration with lasers
  • particle injection techniques for laser accelerators
  • particle beam interaction with plasmas
  • particle beam quality in laser accelerators
  • staging of laser accelerators
  • diagnostics for laser accelerators and ultra-short particle bunches
  • theoretical and numerical modeling of laser accelerators.
  • ;
    In progress – view active session
    Conference 11779

    Laser Acceleration of Electrons, Protons, and Ions VI

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    View Session ∨
    • Special Focus: Three Pillars of ELI Research Infrastructure-World's Most Advanced Short-pulse Lasers
    • Welcome and Monday Plenary Presentation I
    • Monday Plenary Presentation II
    • Tuesday Plenary Presentation III
    • Tuesday Plenary Presentation IV
    • Wednesday Plenary Presentation V
    • Thursday Plenary Presentation VI
    • 1: Laser Wakefield Acceleration of Electrons I
    • 2: Laser Wakefield Acceleration of Electrons II
    • 3: Laser Ion Acceleration I
    • 4: Laser Ion Acceleration II
    Special Focus: Three Pillars of ELI Research Infrastructure-World's Most Advanced Short-pulse Lasers
    Livestream: 19 April 2021 • 09:00 - 11:05 CEST | Zoom



    9:00 to 9:05
    Welcome and Introduction
    Bedřich Rus, ELI Beamlines, Institute of Physics of the CAS (Czech Republic)
    Symposium Chair

    This event occurred in the past.
    Click
    here for Status of lasers and experiments at ELI-Beamlines
    here for ELI ALPS: the next generation of attosecond sources
    here for Status of high-power lasers and experiments at ELI-Nuclear Physics, Romania
    to now view in the SPIE Digital Library.
    11777-501
    Author(s): Georg Korn, ELI Beamlines (Czech Republic)
    On demand | Presented Live 19 April 2021
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    We are reviewing the high-average and high peak-power fs-laser sources and experimental areas currently in operation and preparation for user operation. This includes the 1 kHz, 15fs, 50mJ, Allegra laser based on OPCPA-technology. Short pulse 5ps-CPA thin disc lasers pump a series of OPCPA crystals ensuring a high contrast output. The Allegra laser enters the experimental area E1 with a number of end-stations for user experiments. The HAPLS (sub-30fs, Ti: Sapphire) laser pumped by a high-average power frequency converted DPSSL is currently delivering 500 TW, 3.3 Hz pulses via a stable vacuum beam transport system with a pointing stability around 1rad to the experimental areas for plasma physics experiments (E3) and ion acceleration (E4) with the ELIMAIA station. Both areas are fully equipped with target chambers and focusing optics for experimental operation and user assisted commissioning. The Nd:Glass laser Aton provides 1.5 kJ pulses and is currently being compressed to 10 PW in a large compressor tank. A second oscillator allows shaped pulse ns-operation at kJ level or future combination of 1 PW pulses and kJ shaped ns-pulses for advanced WDM or fusion experiments in the E3 area. A new laser disc liquid cooling technology enables repetition rates of 1 shot/minute allowing a much higher data acquisition for this kind of experiments. Furthermore we will report on the first experiments and the future experimental plans as well as on the prospects for user operation.
    11777-502
    Author(s): Katalin G. Varju, Univ. of Szeged (Hungary)
    On demand | Presented Live 19 April 2021
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    The Extreme Light Infrastructure – Attosecond Light Pulse Source (ELI-ALPS), the Hungarian pillar of ELI, is the first of its kind that operates by the principle of a user facility, supporting laser based fundamental and applied researches in physical, biological, chemical, medical and materials sciences at extreme short time scales. This goal is realized by the combination of specialized primary lasers which drive nonlinear frequency conversion and acceleration processes in more than twelve different secondary sources. Any light pulse source can act as a research tool by itself or, with femtosecond synchronization, in combination with any other of the sources. Thus a uniquely broad spectral range of the highest power and shortest light pulses becomes available for the study of dynamic processes on the attosecond time scale in atoms, molecules, condensed matter and plasmas. The ground-breaking laser systems together with the subsequent outstanding secondary sources generate the highest possible peak power at the highest possible repetition rate in a spectral range from the E-UV through visible and near infrared to THz. The facility – besides the regular scientific staff - will provide accessible research infrastructure for the international scientific community user groups from all around the world. The attosecond secondary sources are based on advanced techniques of Higher-order Harmonic Generation (HHG). Other secondary sources provide particle beams for plasma physics and radiobiology. A set of state-of-the-art endstations will be accessible to those users who do not have access or do not wish to bring along their own equipment. Step by step the lasers are now commissioned, trialed and handed over for user operation. References S. Kuhn et al., “The ELI-ALPS facility: the next generation of attosecond sources.”, Topical Review, Journal of Physics B, 50 (2017) 132002
    11777-503
    Author(s): Kazuo A. Tanaka, Extreme Light Infrastructure Nuclear Physics (Romania)
    On demand | Presented Live 19 April 2021
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    Founded by the European Strategy Forum on Research Infrastructure (ESFRI), three state-of-art laser-based institutes in Romania, Hungary, and the Czech Republic were commissioned in the Extreme Light Infrastructure (ELI). Construction for the three sites started in 2012 and, as of 2020, all sites are operational. ELI-NP (Extreme Light Infrastructure: Nuclear Physics) is located 10km south of Bucharest in Romania. Its flagship installation is two beams of 10 PW, each providing 230 J output energy at a 23 fs laser pulse width. The capability to provide a 10 PW output was recently demonstrated in a live performance. We were able to show that the 10 PW laser shots can be delivered for 10 minutes at a rate of one shot every minute. A total of 230 Zoom participants worldwide, including Prof G Mourou and Prof D Strickland, the Physics Nobel Laureates in 2018, witnessed this breakthrough demonstration. An early experiment at the 100 TW laser station at ELI-NP has already been completed. We successfully demonstrated an electron acceleration of up to 300 MeV, either resulting in monoenergetic or broadband spectra, depending on the well controllable experimental conditions we set. Operations at the 1 PW and 10 PW experimental stations will start soon. External user access will be tested with the early and commissioning experiments and will be formulated coherently within the framework of the IMPULSE project guided by ELI-DC. Reference Current status and highlights of the ELI-NP program research program, KA Tanaka, K Spohr, D Balabanski, et al., Matter Rad. Extremes, 5, 024402 (2020): doi.10.1063/1.5093535
    Session PL1: Welcome and Monday Plenary Presentation I
    Livestream: 19 April 2021 • 15:00 - 16:00 CEST | Zoom
    Monday Plenary Presentation I and Monday Plenary Presentation II are part of the same webinar session with a break in between.

    Times for this live event are all Central European Summer Time, CEST (UTC+2:00 hours)


    Welcome and Opening Remarks
    Bedřich Rus, ELI Beamlines, Institute of Physics of the CAS (Czech Republic)

    This event occurred in the past. Click here to now view in the SPIE Digital Library.
    11775-601
    New technologies for new astronomy (Plenary Presentation)
    Author(s): John C. Mather, NASA Goddard Space Flight Ctr. (United States)
    On demand | Presented Live 19 April 2021
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    We’ve come a long way since 1609, from spectacle lenses to mirrors in space, from twitching frog legs to the Event Horizon Telescope observing a black hole. But far more is possible. On the ground, a new generation of optical telescopes is under construction, up to 39 m in diameter. Adaptive optics compensates for the turbulent atmosphere, but could work far better with an orbiting reference beacon in space. Bright chemiluminescent emission lines in the upper atmosphere interfere with observations, but could be blocked by fiber optic filters. Energy-resolving photon counting detectors promise far greater sensitivity. New ways of making mirrors offer far better resolution for space X-ray telescopes. Coronagraphs can suppress starlight enough to reveal exoplanets in direct imaging, or starshades can cast star shadows on telescopes to do the same thing. New generations of far IR detectors with large cryogenic telescopes in space can reveal the cool and cold universe. Radio telescopes on the quiet far side of the Moon can overcome the limits of the ionosphere and intense local interference to see events in the early universe as it heated up again after the Big Bang expansion cooled everything. Neutrino telescopes can see stars being shredded by black holes, and gravitational wave detectors see merging neutron stars and black holes. Atom wave gravimeters can measure the internal structure of planets and asteroids, and sample return missions are already bring back distant bits of the solar system. What will happen next? I don’t know but it will be glorious.
    Session PL2: Monday Plenary Presentation II
    Livestream: 19 April 2021 • 17:00 - 18:00 CEST | Zoom
    Monday Plenary Presentation I and Monday Plenary Presentation II are part of the same webinar session with a break in between.

    Times for this live event are all Central European Summer Time, CEST (UTC+2:00 hours)


    Welcome and Introduction
    Ivo Rendina, CNR/Istituto per la Microelettronica e Microsistemi (Italy)
    Symposium Chair

    This event occurred in the past. Click here to now view in the SPIE Digital Library.
    11770-602
    Author(s): Anna C. Peacock, Univ. of Southampton (United Kingdom)
    On demand | Presented Live 19 April 2021
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    The nascent field of semiconductor core fibres is attracting increased interest as a means to exploit the excellent optical and optoelectronic functionality of the semiconductor material directly within the fibre geometry. Compared to their planar counterparts, this new class of waveguide retains many advantageous properties of the fibre platforms such as flexibility, cylindrical symmetry, and long waveguide lengths. Furthermore, owing to the robust glass cladding it is also possible to employ standard fibre post-processing procedures to tailor the waveguide dimensions and reduce the optical losses over a broad wavelength range, of particular use for nonlinear applications. This presentation will review progress in the development of nonlinear devices from the semiconductor core fibre platform and outline exciting future prospects for the field.
    Session PL3: Tuesday Plenary Presentation III
    Livestream: 20 April 2021 • 15:00 - 16:00 CEST | Zoom
    Times for this live event are all Central European Summer Time, CEST (UTC+2:00 hours)


    Welcome and Introduction
    Saša Bajt, Deutsches Elektronen-Synchrotron (Germany)
    Symposium Chair
    11776-603
    Author(s): Nina Rohringer, Max-Planck-Institut für Physik komplexer Systeme (Germany)
    On demand | Presented Live 20 April 2021
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    X-ray free-electron lasers, delivering x-ray pulses of femtosecond duration, are available for experiments for more than a decade and allow for hitherto unachievable x-ray intensities on sample, reaching up to 1021 W/cm2 for hard x-rays. At these intensities, the probability of a single atom or molecule to absorb a photon of an impinging x-ray pulse reaches unity. Moreover, several interactions of photons and matter within the duration of the x-ray pulse – nonlinear x-ray matter interactions – become possible, opening the pathway to nonlinear x-ray optics. For a macroscopic ensemble of atoms, molecules, nanometer-sized clusters or a solid, the interaction with a strongly focused x-ray beam can create macroscopic, highly excited states of matter, far from equilibrium. In particular, saturated absorption with a high-intensity x-ray pulse can result in transient states, present for roughly one femtosecond, with the characteristic feature, that every single atom in the interaction region is in a population inverted state with missing population in the innermost electronic shell. This macroscopic population inversion can lead to collective radiative decay mechanisms, such as amplified spontaneous emission or superfluorescence. In this presentation I will give you an overview over our experimental and theoretical investigations of these single-pass x-ray laser amplifiers in the x-ray spectral domain. I will address applications of this phenomenon in the area of chemical x-ray emission spectroscopy, a new concept of an x-ray laser oscillator, and will highlight recent theoretical developments to describe collective spontaneous emission in the x-ray spectral domain.
    Session PL4: Tuesday Plenary Presentation IV
    Livestream: 20 April 2021 • 17:00 - 18:00 CEST | Zoom
    Times for this live event are all Central European Summer Time, CEST (UTC+2:00 hours)


    Welcome and Introduction
    Bedřich Rus, ELI Beamlines, Institute of Physics of the CAS (Czech Republic)
    Symposium Chair
    11777-604
    Author(s): Gilliss Dyer, SLAC National Accelerator Lab. (United States)
    On demand | Presented Live 20 April 2021
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    The Matter in Extreme Conditions (MEC) instrument at LCLS pioneered the use of the hard X-ray free electron laser (XFEL) in combination with high-power optical lasers to advance high energy density science. Commissioned in 2012 as an open-access scientific capability, this application of the powerful XFEL diagnostic has driven a rich array of high-profile scientific results, providing new insight into atomic and structural properties of dynamic plasma and high-pressure material states. Aided in part by the success of MEC and other high power laser facilities, there has been a strong call from the research community over the past 5 years for increased national investments in high power lasers combined with existing national lab infrastructure. In response to a mission need statement from the US Department of Energy, Fusion Energy Sciences, SLAC has developed a conceptual design for a project to build a new HED science facility combining high rep-rate (10Hz) petawatt laser systems and high energy (1kJ) long pulse lasers with the LCLS XFEL. Combined with flexible and high efficiency experimental systems, this facility will enable a world-unique set of scientific capabilities complementing the new emerging generation of high-power laser facilities, including the pillars of ELI and new HED end stations at European XFEL and SACLA. In this talk, I will present an overview of the facility conceptual design and place it in the context of the growing field of high-power laser science.
    Session PL5: Wednesday Plenary Presentation V
    Livestream: 21 April 2021 • 17:00 - 18:00 CEST | Zoom
    Times for this live event are all Central European Summer Time, CEST (UTC+2:00 hours)

    Welcome and Introduction
    Ivo Rendina, CNR/Istituto per la Microelettronica e Microsistemi (Italy)
    Symposium Chair
    11775-605
    Author(s): Mona Jarrahi, UCLA Samueli School of Engineering (United States)
    On demand | Presented Live 21 April 2021
    Session PL6: Thursday Plenary Presentation VI
    Livestream: 22 April 2021 • 09:00 - 10:00 CEST | Zoom
    Times for this live event are all Central European Summer Time, CEST (UTC+2:00 hours)


    Welcome and Introduction
    Saša Bajt, Deutsches Elektronen-Synchrotron (Germany)
    Symposium Chair
    11776-606
    New research opportunities with FELs (Plenary Presentation)
    Author(s): Claudio Masciovecchio, Elettra-Sincrotrone Trieste S.C.p.A. (Italy)
    On demand | Presented Live 22 April 2021
    Session 1: Laser Wakefield Acceleration of Electrons I
    11779-1
    Author(s): Simon M. Hooker, Aarón Alejo, Christopher Arran, Alexander von Boetticher, Univ. of Oxford (United Kingdom); Nicolas Bourgeois, STFC Rutherford Appleton Lab. (United Kingdom); Laura Corner, Univ. of Liverpool (United Kingdom); Linus Feder, George Hine, Univ. of Maryland, College Park (United States); James A. Holloway, Oscar Jakobsson, Univ. of Oxford (United Kingdom); Harry Jones, Univ. of Liverpool (United Kingdom); Jakob Jonnerby, Univ. of Oxford (United Kingdom); Howard M. Milchberg, Univ. of Maryland, College Park (United States); Alexander Picksley, Univ. of Oxford (United Kingdom); Lewis R. Reid, Univ. of Liverpool (United Kingdom); Aimee J. Ross, Robert J. Shalloo, Univ. of Oxford (United Kingdom); Christopher Thornton, STFC Rutherford Appleton Lab. (United Kingdom); Roman Walczak, Univ. of Oxford (United Kingdom)
    On demand
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    In a multi-GeV laser-driven plasma accelerator the driving laser pulse must remain focused as it propagates through tens of centimetres of plasma of density 1017 cm-3. This distance is orders of magnitude greater than the Rayleigh range, and hence the laser pulse must be guided with low losses. Since many applications of laser-plasma accelerators will require that the pulse repetition rate is in the kilohertz range, methods for guiding relativistically-intense laser pulses at high repetition rates must be developed. We describe the development of hydrodynamic optical-field-ionized (HOFI) plasma channels and conditioned HOFI channels, which can meet all of these challenging requirements. We present experiments and numerical simulations that show that hydrodynamic expansion of optical-field-ionized plasma columns can generate channels at low plasma densities. We show that guiding a conditioning pulse in a HOFI channel leads to the formation of long, very low loss plasma channels via ionization of the collar of neutral gas which surrounds the HOFI channel. We describe proof-of-principle experiments in which we generated conditioned HOFI (CHOFI) waveguides with axial electron densities of ne0 ≈ 1×1017 cm−3 and a matched spot size of approximately 30 μm. We present hydrodynamic and particle-in-cell simulations which demonstrate that meter-scale, low-loss CHOFI waveguides could be generated with a total laser pulse energy of about 1 J per meter of channel.
    11779-4
    Author(s): Diana Gorlova, Ivan Tsymbalov, M. V. Lomonosov Moscow State Univ. (Russian Federation), Institute of Nuclear Research (Russian Federation); Konstantin Ivanov, Akim Zavorotnyi, M. V. Lomonosov Moscow State Univ. (Russian Federation); Vladimir Nedorezov, Institute of Nuclear Research (Russian Federation); Andrei Savel'ev, M. V. Lomonosov Moscow State Univ. (Russian Federation)
    On demand
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    Efficient injection of electrons into a propagating relativistic laser pulse with normalized vector potential a0~2 is demonstrated experimentally in a thin plasma layer with density 0.15-0.3 of the critical value. This plasma configuration was obtained by evaporation of ~16 µm thick audiotape by an artificial nanosecond prepulse. Numerical simulations suggest that the injection mechanism is wavebreaking of parametric plasma waves of hybrid SRS-TPD instability. The trapped particles gain multi-MeV (up to 20 MeV) energies by the Direct Laser Acceleration (DLA) in the plasma channel formed by the laser pulse in the lower density plasma tail. Experiments were carried out at the 1 TW Ti:Sa laser facility of the International Laser Center of Lomonosov MSU. We experimentally observed an electron beam with a divergence of ~0.05 rad, a charge of ~50 pC for particles with E>1.7 MeV, and temperature ~2 MeV with the pulse energy as low as 30-50 mJ. This value is 5 times higher than reported in our previous work [1] and 1nC/J efficiency was reached on the table-top laser system.
    11779-5
    Author(s): Dominika Mašlárová, Institute of Plasma Physics of the CAS, v.v.i. (Czech Republic), Czech Technical Univ. in Prague (Czech Republic); Vojtěch Horný, LULI - CNRS, CEA (France); Qiang Chen, Junzhi Wang, Shaoxian Li, Donald Umstadter, Univ. of Nebraska-Lincoln (United States)
    On demand
    11779-7
    Author(s): Petr Valenta, Czech Technical Univ. in Prague (Czech Republic); Gabriele M. Grittani, Carlo M. Lazzarini, ELI Beamlines (Czech Republic); Ondrej Klimo, ELI Beamlines, Institute of Physics of the CAS, v.v.i. (Czech Republic); Sergei V. Bulanov, ELI Beamlines (Czech Republic)
    On demand
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    Using analytical methods and computer simulations, we investigate physical processes which lead to the formation of ring-shaped electromagnetic and electron structures in laser-plasma interaction. We observe that as the intense laser pulse excites a nonlinear Langmuir wave in an underdense plasmas, a significant portion of the pulse is refracted outwards the propagation direction due to the interactions with thin, high-density electron walls surrounding the wave cavities. Because of the radial symmetry, the refracted light forms a distinct electromagnetic ring that encircles the driver pulse. The efficiency of the energy transfer to the electromagnetic ring is relatively high, so that the ring can generate its own Langmuir wave and trigger the electron self-injection, which results in a ring-shaped beam of high-energy electrons. The properties of the ring-shaped electromagnetic and electron beams depend on the parameters of the Langmuir wave cavity walls, thus they can be controlled by tuning the parameters of the laser and plasma. The ring structures could be applied as a drivers for acceleration of positively charged particles, or as a diagnostic to determine regimes and the overall efficiency of the laser-wakefield accelerator.
    Session 2: Laser Wakefield Acceleration of Electrons II
    11779-8
    Author(s): Howard M. Milchberg, Bo Miao, Linus Feder, Jaron Shrock, Andrew Goffin, Univ. of Maryland, College Park (United States)
    On demand
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    I will present recent results from 2 sets of laser plasma acceleration experiments spanning 4 orders of magnitude in plasma density. In near critical density hydrogen plasmas using 5 fs, < 3mJ laser pulses , we have demonstrated acceleration of few pC monoenergetic electron bunches up to 15 MeV at 1 kHz, at a record low beam divergence <10 mrad [1]. Mitigation of carrier envelope phase slip is key to this result. At the other extreme of plasma density, we have demonstrated 2 techniques [2,3] for generation of metre-scale low density plasma waveguides up to several hundred Rayleigh ranges in length, with recent preliminary results showing guiding of up to several hundred terawatts. [1] Laser-accelerated, low divergence 15 MeV quasi-monoenergetic electron bunches at 1 kHz, F. Salehi, M. Le, L. Railing, and H. M. Milchberg, submitted for publication [2] Optical Guiding in Meter-Scale Plasma Waveguides, B. Miao, L. Feder, J. E. Shrock, A. Goffin, and H. M. Milchberg, PHYSICAL REVIEW LETTERS 125, 074801 (2020) [3] Self-waveguiding of relativistic laser pulses in neutral gas channels, L. Feder, B. Miao, J. E. Shrock, A. Goffin, and H. M. Milchberg, PHYSICAL REVIEW RESEARCH 2, 043173 (2020)
    11779-9
    Author(s): Gabriele M. Grittani, ELI Beamlines (Czech Republic)
    On demand
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    The laser wakefield acceleration program at ELI-Beamlines benefits from the future availability of four unique high power laser systems that make possible the investigation of LWFA in a broad range of parameters, ranging from mJ to kJ in pulse energy. The experiments driven by the PW-class laser systems L3-HAPLS (Ti:Sapph, 30 J, 30 fs, 10 Hz) and L4-Aton (Nd:glass, 1.5 kJ, 150 fs, 0.01 Hz) are performed at the ELI-ELBA beamline, and aim at the counter-propagation of laser-accelerated GeV electron beams with high intensity laser pulses. These experiments are designed to study novel regimes of electromagnetic field interaction with matter and quantum vacuum. The flagship experiment of ELI-ELBA is the experimental measurement of synergic Cherenkov-Compton radiation, which will reveal the properties of the vacuum predicted by nonlinear quantum electrodynamics and will require the operation of L3-HAPLS and L4-Aton at full power. The LWFA experiments driven by the TW-class high rep-rate laser systems L1-Allegra (100 mJ, 15 fs, 1 kHz) and L2-Duha (>3J, 25 fs, 50 Hz) are oriented towards laser-driven FEL development and applications in the biomedical field, and to investigation of interaction of high power lasers with near critical density plasmas. In the presentation, the actual status of the ELI-ELBA GeV electron beamline will be presented, along with the schedule leading to the commissioning and full operations. The activity in the field of high repetition rate LWFA will be also presented, including recent theoretical and simulation results, and the description of the experiments planned. Finally, recent design work towards a laser-driven VHEE radiotherapy device will be presented.
    11779-10
    Author(s): Jérôme Faure, Lab. d'Optique Appliquée (France); Neil Zaim, Lab. d'Optique Appliquée (France), CEA-Paris-Saclay (France); Diego Guenot, Lund Univ. (Sweden), Lab. d'Optique Appliquée (France); Ludovic Chopineau, Adrien Denoeud, CEA-Paris-Saclay (France); Olle Lundh, Lund Univ. (Sweden); Henri Vincenti, CEA-Paris-Saclay (France); Fabien Quéré, CEA-Grenoble (France)
    On demand
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    We present experimental results of vacuum laser acceleration (VLA) of electrons using radially polarized laser pulses interacting with a plasma mirror. Tightly focused, radially polarized laser pulses have been proposed for electron acceleration because of their strong longitudinal electric field, making them ideal for VLA. However, experimental results have been limited until now because injecting electrons into the laser field has remained a considerable challenge. Here, we demonstrate experimentally that using a plasma mirror as an injector solves this problem and permits us to inject electrons at the ideal phase of the laser, resulting in the acceleration of electrons along the laser propagation direction while reducing the electron beam divergence compared to the linear polarization case. We obtain electron bunches with few-MeV energies and a 200-pC charge, thus demonstrating, for the first time, electron acceleration to relativistic energies using a radially polarized laser. High-harmonic generation from the plasma surface is also measured, and it provides additional insight into the injection of electrons into the laser field upon its reflection on the plasma mirror. Detailed comparisons between experimental results and full 3D simulations unravel the complex physics of electron injection and acceleration in this new regime: We find that electrons are injected into the radially polarized pulse in the form of two spatially separated bunches emitted from the p-polarized regions of the focus. Finally, we leverage on the insight brought by this study to propose and validate a more optimal experimental configuration that can lead to extremely peaked electron angular distributions and higher energy beams.
    11779-11
    Author(s): Valeria Istokskaia, Vojtěch Stránský, Czech Technical Univ. in Prague (Czech Republic), ELI Beamlines (Czech Republic); Lorenzo Giuffrida, ELI Beamlines (Czech Republic); Roberto Versaci, ELI Beamlines (Czech Republic); Veronika Olšovcová, ELI Beamlines (Czech Republic); Sushil Singh, Institute of Plasma Physics of the Czech Academy of Sciences (Czech Republic), Institute of Physics of the Czech Academy of Sciences (Czech Republic); Michal Krupka, Institute of Plasma Physics of the Czech Academy of Sciences (Czech Republic), Institute of Physics of the Czech Academy of Sciences (Czech Republic), Czech Technical Univ. in Prague (Czech Republic); Roman Dudžák, Josef Krása, Institute of Physics of the Czech Academy of Sciences (Czech Republic); Daniele Margarone, ELI Beamlines (Czech Republic), Queen's Univ. Belfast (United Kingdom)
    On demand
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    With the development of high-intensity and high-repetition-rate laser systems, it has become crucial to be able to measure and characterize the high-energy gamma radiation from laser-matter interaction in real-time. Therefore, a scintillator-based electromagnetic calorimeter aimed at high-energy electron and photon detection under high-repetition rate is being developed at the ELI Beamlines facility. Together with an ad hoc created unfolding technique, it is possible to reconstruct energies/temperatures of one or two thermal populations present in the radiation. A preliminary test of the device performed at the PALS experimental facility together with the corresponding signal unfolding is here presented.
    11779-12
    Author(s): Maxwell LaBerge, The Univ. of Texas at Austin (United States), Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Omid Zarini, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Alex H. Lumpkin, Fermi National Accelerator Lab. (United States); Alexander Debus, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Andrea Hannasch, The Univ. of Texas at Austin (United States); Jurjen Couperus Cabadağ, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Brant Bowers, The Univ. of Texas at Austin (United States); Alexander Koehler, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Rafal Zgadzaj, The Univ. of Texas at Austin (United States); Ulrich Schramm, Arie Irman, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Michael Downer, The Univ. of Texas at Austin (United States)
    On demand
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    The low transverse emittance of electron bunches from laser plasma accelerators (LPAs) makes these advanced accelerators attractive for compact FELs and colliders. To date, direct measurement of this emittance has proven difficult due to the micron-scale beam waist near the accelerator. Here we present single-shot coherent transition radiation (CTR) imaging and interferometry data from electron bunches only ~1 mm after emerging from a 300 MeV LPA. Using eight cameras with different wavelength bandpass filters, we image CTR emitted from a foil placed directly after the LPA. At each of these wavelengths, we observe radially polarized annular distributions, albeit with detailed shape variations, but sharing a strong central minimum, consistent with CTR. These images help us to characterize the micron-scale transverse beam shape. We employ a multioctave spectrometer to measure the spatially averaged TR spectrum from IR to near-UV wavelengths to characterize longitudinal beam shape. Wavelength-dependent variations in the size and radial distribution of the TR images can be correlated with features in the reconstructed longitudinal profile. Combining the longitudinal information acquired by the multi-octave spectrometer with multi-wavelength images of the foil, we observe features in the 3D beam that are unresolvable using other techniques, and, with the aid of physically reasonable assumptions about the bunch profile, we reconstruct the 3D electron bunch distribution.
    11779-13
    Author(s): Guoqian Liao, Institute of Physics, Chinese Academy of Sciences (China)
    On demand
    11779-14
    Author(s): Pavel Gajdos, Institute of Plasma Physics of the CAS, v.v.i. (Czech Republic), Czech Technical Univ. in Prague (Czech Republic); Miroslav Krus, Institute of Plasma Physics of the CAS, v.v.i. (Czech Republic)
    On demand
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    With the recent development of ultrashort laser pulse generation, many laser facilities around the world can routinely accelerate stable, high-energy electron bunches with a duration in the order of several femtoseconds in a very short distance. Due to the short bunch duration, they are suitable for various femtosecond and sub-picosecond applications. However, one of the less favorable properties of this acceleration is a relatively large electron bunch energy spread which causes the increase in the bunch duration when propagating a long distance in space. Hence, for utilizing them in such applications, they need to be compressed back down to the femtosecond duration. In this work we present a design of the electron beam transport line preserving the femtosecond bunch duration. The transport line including the final focusing system consists of commonly used, standard types of electron optical devices – dipoles, quadrupoles and sextupoles. The design exploits setups in conventional radiofrequency accelerators for beams with low energy spread, including chromaticity correction. Our design focuses on the transport of electron bunches with relatively large energy spread, while maximizing the transport line acceptance for given beam parameters, as energy, relative energy spread and emittance.
    Session 3: Laser Ion Acceleration I
    11779-15
    Author(s): Karl Zeil, Constantin Bernert, Florian-Emanuel Brack, Marco Garten, Lennart Gaus, Thomas Kluge, Stephan D. Kraft, Florian Kroll, Josefine Metzkes-Ng, Thomas Pueschel, Martin Rehwald, Hans-Peter Schlenvoigt, Ulrich Schramm, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany)
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    We report on experimental investigations of proton acceleration from laser-irradiated solid foils with the DRACOPW laser, where highest proton cut-off energies were achieved for temporal pulse parameters that varied significantlyfrom those of an ideally Fourier transform limited (FTL) pulse. Controlled spectral phase modulation of the driverlaser by means of an acousto-optic programmable dispersive filter enabled us to manipulate the temporal shape ofthe last picoseconds around the main pulse and to study the effect on proton acceleration from thin foil targets. Theresults show that short and asymmetric pulses generated by positive third order dispersion values are favourable forproton acceleration and can lead to maximum energies of 60 MeV at 18 J laser energy for thin plastic foils, effectivelydoubling the maximum energy compared to ideally compressed FTL pulses. The talk will further prove the robustnessand applicability of this enhancement effect for the use of different target materials and thicknesses as well as laserenergy and temporal intensity contrast settings. Assuming appropriate control over the spectral phase of the laser andcomparable temporal contrast conditions, we believe that the presented method can be universally applied to improveproton acceleration performance using any other laser system, particularly important when operating in the PW regime.
    11779-16
    Author(s): Florian Kroll, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Florian-Emanuel Brack, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany), TU Dresden (Germany); Elisabeth Bodenstein, OncoRay - National Ctr. for Radiation Research in Oncology (Germany); Kerstin Brüchner, OncoRay - National Ctr. for Radiation Research in Oncology (Germany), Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Leonhard Karsch, OncoRay - National Ctr. for Radiation Research in Oncology (Germany); Stephan D. Kraft, Elisabeth Lessmann, Sebastian Meister, Josefine Metzkes-Ng, Alexej Nossula, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Jörg Pawelke, OncoRay - National Ctr. for Radiation Research in Oncology (Germany), Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Jens Pietzsch, Marvin Reimold, Ulrich Schramm, Marvin E. P. Umlandt, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany), TU Dresden (Germany); Karl Zeil, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany); Elke Beyreuther, Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany), OncoRay – National Ctr. for Radiation Research in Oncology (Germany)
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    After the rediscovery of the normal tissue sparing effect of high dose rate radiation, i.e. the so-called FLASH effect, by Favaudon et al. in 2014, research activities on this topic have been revived and are flourishing ever since. Yet, the exact biological mechanism as well as the required boundary conditions and radiation qualities to reach said sparing remain mostly unclear. We present a laser-based irradiation platform at the Draco PW facility that enables systematic studies into the FLASH regime using proton peak dose rates of up to 10^9 Gy/s. Besides the PW class laser acceleration source, a key component is a pulsed high-field beamline to transport and shape the laser driven proton bunches spectrally and spatially in order to generate homogeneous dose distributions tailored to match the irradiation sample. Making use of the diverse capabilities of the laser driven irradiation platform a pilot experiment of highest complexity has been conducted – a systematic in-vivo tumor irradiation in a specifically developed mouse model. A plethora of online particle diagnostics, including Time-of-Flight, bulk scintillators and screens as well as ionization chambers, in conjunction with diagnostics for retrospective absolute dosimetry (radiochromic films) allowed for an unprecedented level of precision in mean dose delivery (±10 %) and dose homogeneity (±5 %) for the challenging beam qualities of a laser accelerator. The tailored detector suite is complemented by predictive simulations. The talk addresses how our interdisciplinary team overcame all hurdles from animal model development, over enhancing the laser and laser acceleration stability, to dose delivery and online dose monitoring. Results on radiation induced tumor growth delay by laser driven as well as conventionally accelerated proton beams are critically discussed.
    11779-17
    Author(s): Paul McKenna, Martin King, Matthew J. Duff, Robbie Wilson, Bruno Gonzalez-Izquierdo, Adam Higginson, Samuel D. R. Williamson, Zoë E. Davidson, Remi Capdessus, Univ. of Strathclyde (United Kingdom); Nicola Booth, Steven J. Hawkes, David Neely, STFC Rutherford Appleton Lab. (United Kingdom); Ross J. Gray, Univ. of Strathclyde (United Kingdom)
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    The spatio-temporal and polarisation properties of intense light is important in wide-ranging topics at the forefront of intense light-matter interactions, including laser-driven particle acceleration. In the context of experiments to optimize transparency-enhanced ion acceleration in expanding ultrathin foils, we investigate the polarisation and temporal properties of intense light measured at the rear of the target. An effective change in the angle of linear polarisation of the light results from a superposition of coherent radiation, generated by a directly accelerated bipolar electron distribution, and the light transmitted due to the onset of relativistic self-induced transparency. Simulations show that the generated light has a high-order transverse electromagnetic mode structure in both the first and second laser harmonics that can evolve on intra-pulse time-scales. The mode structure and polarisation state vary with the interaction parameters, opening up the possibility of developing this approach to achieve dynamic control of structured light fields at ultrahigh intensities [1]. We also report on frequency-resolved optical gating measurements of the light which demonstrate a novel and simple approach to diagnose the time during the interaction at which the foil becomes transparent to the laser light. This is a key parameter for optimising ion acceleration in expanding ultrathin foils. Coherent transition radiation produced at the foil rear interferes with laser light transmitted through the foil producing spectral fringes. The fringe spacing enables the relative timing of the onset of transmission with respect to the transition radiation generation to be determined. This self-referencing approach to spectral interferometry provides a route to optically controlling and optimising ion acceleration from ultrathin foils undergoing transparency [2]. [1] M.J. Duff et al., Scientific Reports 10, 105 (2020) [2] S.D.R. Williamson et al., Phys. Rev. Applied 14, 034018 (2020)
    11779-18
    Author(s): Paul McKenna, Timothy P. Frazer, Robbie Wilson, Martin King, Nicholas Butler, Univ. of Strathclyde (United Kingdom); David C. Carroll, STFC Rutherford Appleton Lab. (United Kingdom); Matthew J. Duff, Adam Higginson, Jonathan Jarrett, Zoë E. Davidson, Univ. of Strathclyde (United Kingdom); Chris Armstrong, STFC Rutherford Appleton Lab. (United Kingdom); Hao Liu, Institute of Physics, Chinese Academy of Sciences (China); David Neely, STFC Rutherford Appleton Lab. (United Kingdom); Ross J. Gray, Univ. of Strathclyde (United Kingdom)
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    The maximum energy to which ions are accelerated in the interaction of a high power laser pulse with a thin foil target scales with the laser intensity, with a power-law that varies with the acceleration mechanism and laser pulse parameters. For fixed laser energy and pulse duration, maximizing the intensity by focusing to a smaller focal spot does not, however, necessarily result in higher-energy ions. For the case of relatively thick foil targets, it has been shown that self-generated magnetic fields and unfavourable changes to the temperature and divergence of the fast electron population injected into the target can result in lower-energy sheath-accelerated ions compared to that expected from intensity scaling laws. We report results from an investigation of the influence of laser focusing on ion acceleration in the ultrathin target regime, for which high energy protons have been achieved by our group [1]. We compare the interaction physics resulting from the use of f/3 and f/1 focusing geometries. Although f/1 focusing (achieved using a focusing plasma optic) produces a smaller nominal laser focal spot size and thus higher nominal peak intensity, more efficient ion acceleration to higher energies is achieved with the f/3 geometry for the case of expanding ultrathin foils undergoing relativistic self-induced transparency. Particle-in-cell simulations reveal that self-focusing in the expanding plasma produces a near-diffraction-limited focal spot, resulting in up to an order of magnitude higher focused intensity in the f/3 case. We also report on the extent to which this intensity enhancement is expected in the case of the short-pulse, ultrahigh-intensity regime that will soon be accessible using multi-petawatt lasers. The study is published in reference [2]. [1] A. Higginson et al., Nature Communications 9, 724 (2018) [2] T. P. Frazer et al., Phys. Rev. Research 2, 042015(R) (2020)
    11779-19
    Author(s): Andriy Velyhan, ELI Beamlines (Czech Republic)
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    The availability of the ultra-high intensity (>10^21 W/cm2), PW (30J/30fs) L3-HAPLS laser at ELI-Beamlines allows entering advanced laser-driven ion acceleration regimes, at a repetition rate up to 10 Hz. A sub-aperture of the L3-HAPLS laser beam (1.5J/30fs) was recently used to accelerate protons with energies approaching the 10-MeV level using the relatively thick (10-40 µm) plastic and metallic foils. Ion diagnostics were optimized for a real-time feedback during the experiment through various detectors, such as ion collectors, single-crystal diamond and silicon carbide detectors, Thomson parabola spectrometer and gamma-ray scintillators, along with a set of complementary passive detectors such as radiochromic films (RCF) and solid-state nuclear track films (CR-39). Analysis of large data acquired during the experimental campaign, summary of the key results and optimal conditions for laser-driven ion acceleration will be presented and discussed.
    11779-20
    Author(s): Aodhan McIlvenny, Queen's Univ. Belfast (United Kingdom); Domenico Doria, Extreme Light Infrastructure Nuclear Physics (Romania); Lorenzo Romagnani, Lab. pour l'Utilisation des Lasers Intenses (France); Hamad Ahmed, Queen's Univ. Belfast (United Kingdom); Nicola Booth, Central Laser Facility (United Kingdom); Emma Ditter, Oliver Ettlinger, George Hicks, Imperial College London (United Kingdom); Philip Martin, Queen's Univ. Belfast (United Kingdom); Graeme Scott, Central Laser Facility (United Kingdom); Samuel Williamson, Univ. of Strathclyde (United Kingdom); Andrea Macchi, Univ. di Pisa (Italy); Paul McKenna, Univ. of Strathclyde (United Kingdom); Zulfikar Najmudin, Imperial College London (United Kingdom); David Neely, Central Laser Facility (United Kingdom); Satya Kar, Marco Borghesi, Queen's Univ. Belfast (United Kingdom)
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    11779-21
    Author(s): Jens Hartmann, Thomas Rösch, Felix Balling, Marc Berndl, Leonard Doyle, Lotta Flaig, Sonja Gerlach, Luisa Tischendorf, Jörg Schreiber, Ludwig-Maximilians-Univ. München (Germany)
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    The Centre for Advanced Laser Applications (CALA) in Garching near Munich features the ATLAS 3000 laser system, which can deliver up to 3 PW within a pulse length of 20 fs. It is the driver for the Laser-driven ION (LION) beamline, which aims to accelerate protons and carbons for applications. The laser beam delivery comprises also a full aperture deformable mirror (DM) after the compressor. A 20 degrees off-axis parabolic mirror with a focal length of 1.5 m focusses the 28 cm diameter laser-beam down to a micrometere-sized spot, where a vacuum-compatible wave-front sensor is used for the DM feed-back loop focus optimization. The nano-Foil Target Positioning System (nFTPS) can replace targets with a repetition rate of up to 0.5 Hz and store up to 19 different target foils. A dipole magnet in a wide-angle spectrometer configuration deflects ions onto a CMOS detector for an online read-out. Commissioning started mid 2019 with regular proton acceleration using nm-thin plastic foils as targets. Since then proton cut-off energies above 20 MeV have been regularly achieved. The amount of light traveling backwards from the experiment into the laser is constantly monitored and 5 J on target have been determined as the current limit to prevent damage in the laser. Protons with a kinetic energy of 12 MeV are stably accelerated with the given laser parameters and are suitable for transport with permanent magnet quadrupoles towards our application platform. We have performed parameter scans varying target thicknesses and laser-pulse shape to optimize for highest and most stable proton numbers at 12 MeV kinetic energy, and investigated shot-to-shot particle number stability for the best parameters.
    11779-22
    Author(s): Jan Pšikal, Czech Technical Univ. in Prague (Czech Republic), ELI Beamlines, IoP-ASCR (Czech Republic)
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    Laser-driven acceleration of ions from near-critical density plasma layer, initially inhomogeneous in density in one spatial dimension (along laser propagation direction), was investigated in multidimensional particle-in-cell simulations. Tracking of high-energy accelerated ions in these simulations reveals the evolution of accelerating fields affecting the particles. While the acceleration of ions occurs in a short time interval when a steep (infinite) density gradient was introduced at the back side of the plasma layer, three phases of ion acceleration can be clearly observed when a smooth (Gaussian) density profile was assumed. These phases are attributed to the accelerating field generated by electron bunches carried by the laser wave, by expanding transverse magnetic field, and by the apex of electron filament behind the laser wave, respectively. The accelerating field affecting the most energetic ions has unexpected local maxima about 50 fs after the moment when ultrashort (30 fs) laser pulse completely left the plasma with Gaussian density profile due to this electron filament apex created behind the transmitted laser pulse. Full 3D simulation confirms the observations in 2D simulations in terms of ion acceleration mechanisms. However, it shows a substantial reduction of maximum achievable ion energies and a larger angular spread of accelerated ions compared with 2D approach, which demonstrates the necessity of using computationally demanding full 3D geometry for similar numerical studies.
    Session 4: Laser Ion Acceleration II
    11779-23
    Author(s): Tobias Ostermayr, Lawrence Berkeley National Lab. (United States), Ludwig-Maximilians-Universität München (Germany); Christian Kreuzer, Franz S. Englbrecht, Ludwig-Maximilians-Univ. München (Germany); Johannes Gebhard, Ludwig-Maximilians-University (Germany); Jens Hartmann, Ludwig-Maximilians-Univ. München (Germany); Axel Hübl, Lawrence Berkeley National Lab. (United States); Daniel Haffa, Peter Hilz, Katia Parodi, Ludwig-Maximilians-Univ. München (Germany); Björn M. Hegelich, The Univ. of Texas at Austin (United States); Hai-En Tsai, Anthony J. Gonsalves, Kei Nakamura, Lawrence Berkeley National Lab. (United States); Mario Balcazar, John A. Nees, Yong Ma, Univ. of Michigan (United States); Elizabeth Grace, Lawrence Livermore National Lab. (United States), Georgia Institute of Technology (United States); Raspberry Simpson, Lawrence Livermore National Lab. (United States), Massachusetts Institute of Technology (United States); Paul King, Isabella Pagano, Lawrence Livermore National Lab. (United States), The Univ. of Texas at Austin (United States); Félicie Albert, Lawrence Livermore National Lab. (United States); Alexander G. R. Thomas, Carolyn Kuranz, Univ. of Michigan (United States); Csaba Toth, Carl B. Schroeder, Cameron G. R. Geddes, Lawrence Berkeley National Lab. (United States); Jörg Schreiber, Ludwig-Maximilians-Univ. München (Germany); Eric H. Esarey, Lawrence Berkeley National Lab. (United States)
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    Radiographic imaging is an omnipresent tool in basic research and applications in industry, material science and medical diagnostics. Often, the information contained in more than one modality can be valuable, but difficult to access simultaneously. This talk reviews developments in laser-plasma-accelerators for protons, electrons and x-rays from solid and gas targets for multimodal imaging. Laser-driven ion acceleration and x-ray generation have been investigated using tungsten micro-needle-targets at the Texas Petawatt laser [1]. The experiments and supporting numerical simulations reveal peaked proton spectra around 10 MeV with significant particle count and a strong keV level x-ray source. The source size for both has been measured to be in the few-µm range. Both sources were eventually applied to simultaneous radiographic imaging of biological and technological samples. In recent experiments at BELLA Center’s high repetition rate 100 TW dual-arm laser, steps were taken towards bi-modal x-ray and electron imaging of dynamic events such as hydrodynamic shocks, in which often both density and electro-magnetic fields are important quantities to measure. Here, a shock was driven by a 1 Joule, 200 ps laser focused in a 30 µm wide water jet. A laser wakefield accelerator was driven by a second 2 Joule, 40 fs laser in a gas-jet target, providing both 150 MeV electrons and broadband betatron x-rays up to ˜10 keV for projection imaging. This research aims to leverage unique properties readily available in laser plasma accelerators for applications. Specifically, the emission of pulsed, bright, multimodal bursts of radiation can open new ways in biological imaging (e.g., with ns-synchronized ions and x-rays) and in high-resolution diagnostics for high-energy density science (e.g., with fs-synchronized electrons and x-rays). [1] T. M. Ostermayr et al., “Laser-driven x-ray and proton micro-source and application to simultaneous single-shot bi-modal radiographic imaging,” Nat. Commun., vol. 11, no. 1, pp. 1–9, Dec. 2020. This work was supported by the DFG via the Cluster of Excellence Munich-Centre for Advanced Photonics (MAP) and Transregio SFB TR18. This work has been carried out within the framework of the EUROfusion Consortium and has received funding, through the ToIFE, from the European Union’s Horizon 2020 research and innovation program under grant agreement number 633053. The authors acknowledge funding by the Air Force Office of Scientific Research (AFOSR)(FA9550-14-1-0045, FA9550-17-1-0264). Work supported by DOE FES under grant DE-SC0020237. Work supported by US DOE NNSA DNN R&D, by Sc. HEP, by the Exascale Computing Project and by FES LaserNetUS under DOE Contract DE-AC02-05CH11231.
    11779-24
    Author(s): Martin Matys, ELI Beamlines, Institute of Physics of the CAS, v.v.i. (Czech Republic), Czech Technical Univ. in Prague (Czech Republic); Sergei V. Bulanov, Mariana Kecova, ELI Beamlines (Czech Republic); Milan Kucharík, Czech Technical Univ. in Prague (Czech Republic); Martin Jirka, ELI Beamlines, Institute of Physics of the CAS, v.v.i. (Czech Republic), Czech Technical Univ. in Prague (Czech Republic); Pavel Janecka, ELI Beamlines (Czech Republic); Jan Psikal, Jan Nikl, ELI Beamlines, Institute of Physics of the CAS, v.v.i. (Czech Republic), Czech Technical Univ. in Prague (Czech Republic); Jakub Grosz, ELI Beamlines, Institute of Physics of the CAS, v.v.i. (Czech Republic); Georg Korn, ELI Beamlines (Czech Republic); Ondrej Klimo, ELI Beamlines, Institute of Physics of the CAS, v.v.i. (Czech Republic), Czech Technical Univ. in Prague (Czech Republic)
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    In this work we investigated the use of a plasma shutter in the form of a thin foil for laser-driven ion acceleration enhancement. It is shown with the help of 3D particle-in-cell simulations that the laser pulse intensity can be increased and its profile steepened after burning through the plasma shutter. The enhanced intensity profile has a positive effect on the subsequent ion acceleration from the main foil, significantly increasing the maximal ion energy. The pre-expansion of the plasma shutter caused by prepulses is investigated using 2D hydrodynamic simulations. A scheme using a double plasma shutter configuration (the first one filtering out the prepulses and the second one shaping the main pulse) is proposed.
    11779-26
    Author(s): Thomas F. Rösch, Luisa Tischendorf, Jens Hartmann, Leonard Doyle, Lotta Flaig, Marc Berndl, Felix Balling, Sonja Gerlach, Jonathan Bortfeldt, Jörg Schreiber, Ludwig-Maximilians-Univ. München (Germany)
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    Many applications of laser-accelerated ions require a delivery of the particles to locations remote from the plasma source. Due to the large bunch divergence, achieving experimentally relevant particle fluences at more than a few tens of cm distance requires a dedicated bunch transport system. The most compact solution is a doublet of permanent magnet quadrupoles. Since these quadrupoles have a fixed magnetic field gradient, their focusing properties depend only on their geometric positions and relative rotations which therefore require careful alignment. We performed comprehensive ion optical simulations to characterize gradients and fields of the individual magnets and to identify the sensitivity of the focus shape to various positioning parameters, especially relative distances and rotation. The simulations also allowed devising radiation and laser safety measures for the quadrupoles. Based on these results and thanks to a very stable and reproducible proton source, we could optimize the obtained focus experimentally to a symmetric star like shape. This optimization yielded a proton spot in which the central area of highest fluence had a minimum diameter of approximately 2 mm FWHM, as revealed with spatially resolved scintillator and radiochromic film measurements. Furthermore, we developed a low-material-budget ionization chamber to monitor bunch charge and performed first tests with the aim to quantify the proton focus dosimetrically. The implemented controls and monitoring tools allow now for planning of first application experiments with (sub-) mm proton bunches of (sub-) ns duration.
    11779-27
    Author(s): Felix Balling, Sonja Gerlach, Anna-Katharina Schmidt, Ludwig-Maximilians-Univ. München (Germany); Vincent Bagnoud, Johannes Hornung, Bernhard Zielbauer, GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Katia Parodi, Jörg Schreiber, Ludwig-Maximilians-Univ. München (Germany)
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    The properties of laser-accelerated ion bunches are demanding and require development of suitable beam diagnos- tics. In particular, the short and intense particle bunches with a broad energy spectrum emitted in conjunction with a strong electromagnetic pulse (EMP) are challenging for conventional and well established monitoring systems. An approach based on measuring the acoustic signals of particles depositing their energy in water, re- ferred to as ionoacoustics 12 was recently developed into Ion-Bunch Energy Acoustic Tracing (I-BEAT). I-BEAT allows online detection of single proton bunches while being cost effective and EMP resistant. A simple water phantom equipped with only one ultrasound transducer positioned on the ion axis allows for reconstructing a rather complex energy spectrum that is typical for (manipulated) laser-accelerated ion bunches. To deduce the lateral bunch properties, additional transducers can be added, for example perpendicular to the ion beam axis. This established setup has been adapted for use closely behind the laser target and tested at the PHELIX laser at GSI. The capability of the system to retrieve information about the broad proton spectrum close to the source despite the harsh conditions has been demonstrated. Future improvements are required, most importantly the increase of dynamic range. Nevertheless, I-BEAT holds promise to evolve into an online diagnostic tool particularly suited for laser-driven source development and optimization at high repetition rates. This work was supported by the BMBF under project 05P18WMFA1 and the German Research Foundation (DFG) within the Research Training Group GRK 2274.
    Conference Chair
    Stepan S. Bulanov
    Lawrence Berkeley National Lab. (United States)
    Conference Chair
    Ludwig-Maximilians-Univ. München (Germany)
    Conference Chair
    Carl B. Schroeder
    Lawrence Berkeley National Lab. (United States)
    Program Committee
    Sergei V. Bulanov
    ELI Beamlines (Czech Republic)
    Program Committee
    Min Chen
    Shanghai Jiao Tong Univ. (China)
    Program Committee
    Brigitte Cros
    Univ. Paris-Sud 11 (France)
    Program Committee
    Eric Esarey
    Lawrence Berkeley National Lab. (United States)
    Program Committee
    Leonida A. Gizzi
    Consiglio Nazionale delle Ricerche (Italy)
    Program Committee
    The Univ. of Texas at Austin (United States)
    Program Committee
    National Institutes for Quantum and Radiological Science and Technology, KPSI (Japan)
    Program Committee
    Univ. of Michigan (United States)
    Program Committee
    Ecole Nationale Supérieure de Techniques Avancées (France)
    Program Committee
    Zulfikar Najmudin
    Imperial College London (United Kingdom)
    Program Committee
    Helmholtz-Zentrum Dresden-Rossendorf e. V. (Germany)
    Program Committee
    Shanghai Jiao Tong Univ. (China)
    Program Committee
    Univ. Técnica de Lisboa (Portugal)
    Program Committee
    Vladimir T. Tikhonchuk
    Univ. Bordeaux 1 (France)
    Program Committee
    Queen's Univ. Belfast (United Kingdom)