Relativistic plasma waves driven by high-power ultra-short pulse lasers are providing new opportunities for developing ultra-compact coherent and incoherent radiation sources, which span a broad spectral range from millimetre wavelengths to X-rays and even beyond to gamma rays.

Laser and beam driven plasma wakefield accelerators have acceleration gradients more than a thousand times that of conventional accelerators. These ultra-compact accelerators are now being developed into compact synchrotron sources, free-electron lasers and gamma ray sources. The radial electrostatic forces of plasma waves, and the availability of counter-propagating laser beams, provides a unique opportunity to develop ultra-short period wigglers, thus making possible sources of radiation with photon energies extending to hard X-rays and gamma rays, and of unprecedented brilliance and short pulse duration. Transition, Cherenkov and diffraction radiation from the femtosecond duration electron bunches is opening up the possibility of single cycle radiation fields with unprecedented intensities.

Furthermore, scattering laser radiation from relativistic plasma waves produces high intensity coherent radiation beams, with high efficiency, which can result in high intensity, attosecond duration coherent XUV radiation. Plasma waves are being used to amplify light through Brillouin, Compton and Raman backscattering, which may provide a new route to very high power and efficient parametric amplifiers. They can also be used to produce transient plasma photonic crystals as robust optical elements such as holograms, mirrors and compressors, polarizers, waveplates etc.

Radiation arising from laser-plasma interactions is extending the range of applications of electromagnetic radiation into domains of science that are not usually associated with lasers, which include probing the nucleus, QED, astrophysics and following the evolution of matter on its natural time and space scales.

If these relativistic plasma based sources are developed to maturity they could transform the way science is done-by making them widely available and delivering intense photon beams with unique properties.

Papers are solicited on (not exclusively) the following areas:
  • synchrotron sources and free-electron lasers based on laser and beam driven plasma wakefield accelerators
  • betatron and ion channel sources based on plasma accelerators and plasma wigglers
  • scattering from relativistic plasma waves and ionisation fronts as coherent sources
  • parametric amplification using plasma waves: Brillouin, Compton and Raman amplifiers, compressors
  • transient plasma photonic crystals as robust optical elements
  • terahertz and infrared sources based on laser-plasma interactions
  • applications of laser-plasma radiation sources
  • high-field applications of intense laser fields.
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    In progress – view active session
    Conference 11778

    Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources IV

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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
    • Conference Networking Session
    • 1: Betatron, Plasma Undulator and Conventional Undulator Sources I
    • 2: Betatron, Plasma Undulator and Conventional Undulator Sources II
    • 3: Terahertz Sources
    • 4: High-field Physics
    • 5: Raman, Brillouin and Parametric Plasma Processes
    • 6: Applications of Plasma Accelerators
    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

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    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
    Conference Networking Session
    Livestream: 23 April 2021 • 09:30 - 10:30 CEST | Zoom
    Hosted by:
    Dino A. Jaroszynski, , Univ. of Strathclyde (United Kingdom)
    MinSup Hur, Ulsan National Institute of Science and Technology (Korea, Republic of)

    Join this open session with the conference chairs and speakers, pose your questions or follow up on questions you asked earlier in Slack after viewing the presentations. Become involved, meet new people with similar interests, and join us for this unique opportunity for some interesting networking and discussion. This session is not recorded.
    Session 1: Betatron, Plasma Undulator and Conventional Undulator Sources I
    11778-1
    Author(s): Shao-Wei Chou, Chun-Cheng Chu, Wei-Cheng Liu, National Central Univ. (Taiwan), Ctr. for High-Energy and High-Field Physics (Taiwan); Shih-Hung Chen, National Central Univ. (Taiwan); Ming-Wei Lin, National Tsing Hua Univ. (Taiwan); Hsu-Hsin Chu, National Central Univ. (Taiwan), Ctr. for High-Energy and High-Field Physics (Taiwan)
    On demand
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    We propose a table-top linearly polarized hard X-ray source by using a tilted shock-front injection in a laser wakefield accelerator (LWFA) to achieve comprehensive control of both polarization and energy of X-ray. By using shock-front injection, the electron bunches are injected during a sharp transition of plasma density. The length of density transition is significantly shorter than the plasma wavelength and offers a highly localized injection. In regular injection methods, such as self and ionization injection, the majority of electrons are injected radially symmetrically. Particle-in-cell (PIC) simulations show the tilted shock front breaks radial symmetry of injection and creates coherent in-plane oscillation of electrons. The coherence of electron bunches is maximized around 30 degrees which leads to a linearly polarized betatron radiation. The polarization of the resulting X-ray is analyzed by Bragg diffraction after collimation by a polycapillary lens.
    11778-2
    Author(s): Zsolt Lécz, ELI-ALPS Research Institute (Hungary); Alexander Andreev, ELI-ALPS Research Institute (Hungary), Max-Born-Institut (Germany); Nasr A. M. Hafz, ELI-ALPS Research Institute (Hungary)
    On demand
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    The photon yield obtained during the betatron motion of electrons in the ion cavity is proportional to the number of such oscillations (or wiggling). In the case of high repetition rate laser systems the pulse energy is very limited, thus the laser pulse has to be tightly focused in order to achieve high peak intensity in the focus. In this way narrow gas jets are used, which results in short acceleration length of electrons, thus in low number of betatron oscillations. In order to increase the number of x-ray photons a mixture of clusters and gas target can be used, where the space-charge of nano-meter size droplets forces the electrons to oscillate at much higher frequency leading to the emission of more photons. In this work we present the interaction of such cluster targets with linearly polarized laser pulses and describe some possible positive effects when circular polarization is used.
    11778-3
    Author(s): Myung Hoon Cho, Minseok Kim, Inhyuk Nam, Pohang Accelerator Lab. (Korea, Republic of)
    On demand
    11778-4
    Author(s): Sang Yun Shin, Seong Hee Park, Korea Univ. Sejong Campus (Korea, Republic of)
    On demand
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    The laser wake-field acceleration (LWFA) has been spotlighted as a compact electron accelerator, because of its accelerating gradient being several hundred times higher than conventional RF accelerators. In LWFA, a supersonic gas jet or discharged gas flow in a capillary is typically used as a plasma target, Recently, a plasma plume ablated from a solid target, such as, Teflon, Nylon or Aluminum, using a nano-second or pico-second laser pulse is proposed to maintain high vacuum and possibly operate at high repetition rate. In addition, it was demonstrated that metals, like aluminum, having higher charge states play an important role to increase the electron charge. Compared with the LWFA mechanism using helium or hydrogen gases, the LWFA using metallic targets involves the ionization effects. It boosts more electrons to be injected in a wake cavity, while reduces the acceleration length due to ionization diffraction. As increasing the injected electrons, more dynamic betatron oscillation is observed. For developing the new betatron emitter using LWFA, we suggest a dual-staged LWFA using metallic targets: the first is as a source, an energetic electron bunch, and the second is as a radiator. In this presentation, an overview and a study of the control of the betatron emission via 2D or 3D PIC (Paritlce-in-cell) code simulations are described.
    Session 2: Betatron, Plasma Undulator and Conventional Undulator Sources II
    11778-5
    Author(s): Inhyuk Nam, Myung Hoon Cho, Min Seok Kim, Seong-Hoon Kwon, Pohang Accelerator Lab. (Korea, Republic of); Si Hyun Lee, Gwangju Institute of Science and Technology (Korea, Republic of)
    On demand
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    Laser plasma wakefield accelerations (LWFA) are the most promising candidates for future compact accelerators and also can be used for next-generation free-electron lasers (FELs). However, due to the insufficient electron beam quality, such as a few percent of energy spread, stability, and reproducibility, the electron beam from the LWFA has difficulty to be directly used for FELs with a range from soft X-ray to hard X-ray. To overcome this limitation of the beam quality from the laser wakefield acceleration using various injection techniques, one of the most reliable way is to use the electron beam with short duration, lower energy spread, and emittance from the RF photocathode. This external injection technique is planning with conventional S-band RF photocathode gun and final energy of 70 MeV, few tens fs duration, and lower emittance at Pohang Accelerator Laboratory Injector Test Facility (PAL-ITF). In this presentation, we show a simulation result on the characterization of the electron beam from LWFA using external injection for soft X-ray free-electron lasers.
    11778-6
    Author(s): Samuel R. Yoffe, Bernhard Ersfeld, Univ. of Strathclyde (United Kingdom); Devki N. Gupta, Arohi Jain, University of Delhi (India); Matthew P. Tooley, Numerical Algorithms Group Ltd (United Kingdom); George K. Holt, Dino A. Jaroszynski, Univ. of Strathclyde (United Kingdom)
    On demand
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    The accelerating structure of the laser wakefield accelerator (LWFA) is dynamic and highly sensitive to the local laser and plasma properties. It can expand and contract as it responds to the evolution of the laser and plasma fields. As a result, the position of, and environment within, the LWFA bubble are usually time dependent, which is not ideal for stable acceleration. Variations can have a negative impact on electron bunch properties, and are deleterious for ion channel lasers and plasma wigglers. We demonstrate how a laser pre-pulse improves the stability of the LWFA, and controls the evolution of the laser group and bubble velocity, which are important for determining LWFA dephasing and ultimately the electron bunch energy.
    11778-7
    Author(s): Bernhard Ersfeld, Univ. of Strathclyde (United Kingdom)
    On demand
    Session 3: Terahertz Sources
    11778-8
    Author(s): Dogeun Jang, Pohang Accelerator Lab. (Korea, Republic of)
    On demand
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    High-power terahertz (THz) sources are essential for many applications including THz-driven acceleration of electrons [1], molecular alignment [2], and material science [3]. Among many THz sources, a THz source with two-color laser mixing in gases has attracted much interest due to its capability of producing intense, broadband THz radiation [4]. In this scheme, a femtosecond laser pulse with its second harmonic pulse is focused to ionize a gaseous medium at the focus and create the plasma current, which can produce an intense, broadband THz pulse. With this scheme, we present an experimental study on efficient THz pulse generation from two-color laser filamentation of the mid-infrared laser pulse at 3.9 um in air. We find that mid-infrared yields higher THz energy with a laser-to-THz conversion efficiency of ~1%, which is about 10~100 times larger than conventional values with 800 nm laser pulse [4]. [1] E. A. Nanni et al., Nat. Commun. 6(1), 8486 (2015) [2] T. Kampfrath et al., Nat. Photonics 7(9), 680-690 (2013) [3] D. Nicoletti and A. Cavalleri, Adv. Opt. Photonics 8(3), 401-464 (2016). [4] D. Jang et al., Optica 6(10), 1338-1341 (2019)
    11778-9
    Author(s): Arohi Jain, Devki N. Gupta, Univ. of Delhi (India)
    On demand
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    We develop an analytical model for the generation of terahertz (THz) fields by the propagation of a higher-order Gaussian laser pulse in a magnetized plasma. A higher-mode Gaussian pulse is utilized for this purpose. The plasma nonlinearity is enhanced due to the modified gradient of the Gaussian spatial intensity profile. THz field generated by the transverse wakefields is significantly larger for this kind of laser pulses. The amplitude of THz fields can be enhanced by the flatness parameter of the higher-order Gaussian laser pulse. The five-fold enhancement of the THz field is reported in this study. Furthermore, the applied axial magnetic field also contributes to enhancing the THz field. For higher-order Gaussian laser pulse, the power conversion efficiency of THz field generation in the presence of a magnetized is four times higher than the ordinary Gaussian pulse case. The production of intense THz field with amplitudes belonging to the GV/m range is helpful in various applications such as THz extreme nonlinear optics and probing remote materials efficiently.
    11778-10
    Author(s): Min Sup Hur, Manoj Kumar, Hyungseon Song, Teyoun Kang, Ulsan National Institute of Science and Technology (Korea, Republic of); Sam Yoffe, Bernhard Ersfeld, Dino Jaroszynski, University of Strathclyde (United Kingdom); Paulo Castillo, SUNY (United States); Kwangmin Yu, BNL (United States)
    On demand
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    Radiation sources from Langmuir waves has been a topic of interest for their relevance to experimental approaches in plasma laboratories as well as for estimating physical models to explain cosmic radio bursts. Since the mechanism for converting energy from electrostatic Langmuir waves to electromagnetic waves is complex, diverse scenarios of such energy conversion have been studied, e.g. mode conversion, antenna radiation, nonlinear scattering, etc. Previously, we introduced a novel perspective of plasma dipole oscillation (PDO) which generates strong radiation bursts at the plasma frequency and high harmonics. In this paper, we report our discovery of radiation that result from electron-laser beam driven Langmuir waves and their interactions. In 2-D PIC simulations, we have observed that obliquely colliding Langmuir waves or even a single Langmuir wave generate localized radiation sources at the plasma frequency and high harmonics. These mechanisms differ from conventional two-plasmon mergers, where only the second harmonic of the plasma frequency is dominant: a strong radiation is observed even at the fundamental harmonic. In addition, from 3-D PIC simulations of electron laser beam driven plasma oscillators in magnetized plasma, the radiation from a local plasma oscillator, i.e. PDO, is found to be robust with diverse spectral peaks at the X-mode and the upper-hybrid mode. Nonlinear theory demonstrates that the relative strength of the harmonics of the plasma frequency depends on the shape of the PDO. The studies imply that the PDO has a more complicated internal structure than the simple model of a solid charge. We discuss the potential of the PDO generated from electron-beam driven plasmas or laser-driven plasmas as a radiation source and its relevance to cosmic radio bursts.
    11778-11
    Author(s): Victor V. Kulagin, M. V. Lomonosov Moscow State Univ. (Russian Federation); Vladimir A. Cherepenin, Vladimir N. Kornienko, Kotelnikov Institute of Radio Engineering and Electronics (Russian Federation); Devki N. Gupta, Univ. of Delhi (India)
    On demand
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    Generation of high-field infrared and terahertz radiation during interaction of a super-intense laser pulse with a complex nanodimensional target consisting of nanowires or nanofoils is studied. In the interaction, dense high-charge bunches of electrons are forced out of the target and accelerated in the laser field, generating intense electromagnetic radiation. Depending on the duration and shape of the laser pulse, three interaction modes can be realized. In the first mode, the laser pulse is smooth, and the electrons are only partially displaced from the target. In this case, characteristics of the low-frequency part of the generated radiation are determined by the laser and target parameters. In the second mode, the laser pulse has a large amplitude and a steep front (the amplitude of the first half-cycle is on the order of the maximum pulse amplitude), then, most of the electrons are displaced from the target at the initial moment of interaction. In this mode, unipolar and bipolar pulses with duration of dozens of laser periods can be generated. Changing the target geometry allows one to control the duration of the period and the number of the periods in the generated radiation. Finally, in the intermediate mode of short laser pulses with an insufficiently steep front, oscillations of the formed electron bunches may occur in the attracting field of ions, leading to radiation with a frequency several times lower than the laser one. Using numerical simulation, the characteristics of infrared and terahertz radiation in three interaction modes are found. The role of the target structure is elucidated. It is shown that in modern laser installations, the amplitude of the generated radiation can reach subrelativistic values, and the intensity conversion efficiency can be as high as 1-2 percent. This work was partially supported by the Russian Foundation for Basic Research project 19-52-45035-Ind-a.
    Session 4: High-field Physics
    11778-12
    Author(s): Teyoun Kang, Ulsan National Institute of Science and Technology (Korea, Republic of); Adam Noble, Samuel R. Yoffe, Dino A. Jaroszynski, Univ. of Strathclyde (United Kingdom), Scottish Universities Physics Alliance (United Kingdom); Min Sup Hur, Ulsan National Institute of Science and Technology (Korea, Republic of)
    On demand
    11778-13
    Author(s): Kenan Qu, Princeton Univ. (United States); Sebastian Meuren, Stanford Univ. (United States); Nathaniel J. Fisch, Princeton Univ. (United States)
    On demand
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    QED cascades can generate electron-positron pairs when the electric field or magnetic field substantially exceeds the Schwinger limit. Signatures of collective pair plasma effects in these QED cascades are shown to appear in exquisite detail through, e.g., plasma-induced frequency upshifts in the laser spectrum. Remarkably, these signatures can be detected even in small plasma volumes moving at relativistic speeds. Strong-field quantum and collective pair plasma effects can thus be explored with existing technology, provided that ultra-dense electron beams were co-located with multi-PW lasers. This work was supported by NNSA Grant No. DE-NA0003871, and AFOSR Grant No. FA9550-15-1-0391. 1. K. Qu, S. Meuren, and N. J. Fisch, arXiv:2001.02590 (2020)
    11778-14
    Author(s): Song Li, Nasr A. M. Hafiz, Dániel Papp, Christos Kamperidis, ELI-ALPS Research Institute (Hungary)
    On demand
    11778-15
    Author(s): Adam Noble, Dino A. Jaroszynski, Univ. of Strathclyde (United Kingdom)
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    The next few years will witness the emergence of a new generation of high-power laser facilities, spearheaded by the Extreme Light Infrastructure in Europe, the Exawatt Center for Extreme Light Studies in Russia, and the Station of Extreme Light in China. Such facilities will produce laser pulses with power exceeding 10 petawatts, in which electrons will emit sufficient radiation that the consequent recoil will strongly affect their dynamics. It is therefore more important than ever to properly understand this mysterious effect. The terms "self-force" and "radiation reaction" are often used synonymously, but reflect different aspects of this recoil force. For a particle accelerating in an electromagnetic field, radiation reaction is usually the dominant self-force, but in a scalar field this is not the case. A deeper understanding of scalar self-forces can therefore elucidate the electromagnetic counterpart, as well as having its own intrinsic value, for example in cosmology. In this talk we explore the subtle interplay between radiation reaction and other self-forces, and how this can be understood in terms of the dynamical properties of the particle and of the spacetime it inhabits.
    Session 5: Raman, Brillouin and Parametric Plasma Processes
    11778-16
    Author(s): Kirill V. Lezhnin, Kenan Qu, Nathaniel J. Fisch, Princeton Univ. (United States)
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    For current state-of-the-art terawatt lasers, the primary laser scattering mechanisms in plasma include Forward Raman Scattering (FRS), excitation of plasma waves, and the self-modulational instability (SMI). Using 2D PIC simulations, we demonstrate the dominance of the FRS in the regime with medium-to-low density plasma and non-relativistic laser fields. However, the use of multi-colored lasers with frequency detuning exceeding the plasma frequency suppresses the FRS. The laser power can then be transmitted efficiently.
    11778-17
    Author(s): Gregory Vieux, Univ. of Strathclyde (United Kingdom); Silvia Cipiccia, University College London (United Kingdom), Univ. of Strathclyde (United Kingdom); Gregor H. Welsh, Sam R. Yoffe, Univ. of Strathclyde (United Kingdom); Felix Gaertner, GSI Helmholtzzentrum für Schwerionenforschung (Germany), Goethe-University Frankfurt/Main (Germany); Matthew P. Tooley, Bernhard Ersfeld, Enrico Brunetti, Bengt Eliasson, Univ. of Strathclyde (United Kingdom); MinSup Hur, UNIST (Korea, Republic of); Joao M. Dias, Instituto Superior Técnico, Universidade de Lisboa (Portugal); Thomas Kuehl, GSI Helmholtzzentrum für Schwerionenforschung (Germany); Dino A. Jaroszynski, Univ. of Strathclyde (United Kingdom)
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    11778-18
    Author(s): George K. Holt, Gregory Vieux, Bernhard Ersfeld, Samuel R. Yoffe, James Feehan, Enrico Brunetti, Univ. of Strathclyde (United Kingdom); Min Sup Hur, Ulsan National Institute of Science and Technology (Korea, Republic of); Dino A. Jaroszynski, Univ. of Strathclyde (United Kingdom)
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    High power lasers require large surface area optical components to avoid their damage. This results in large and expensive devices. Plasma is an alternative optically active medium with a very high damage threshold, because it is already broken down. When two moderate intensity, counter-propagating laser pulses collide in underdense plasma, the ponderomotive force of the beat wave can drive electrons into a volume density grating with a space charge force that imparts momentum to the ions, which results in an ion grating. The density grating has an associated photonic band structure and can be used as an optical element, such as a mirror, waveplate or polariser. Here we explore, using particle-in-cell simulations, the formation of a volume plasma density grating and investigate how it can be used to manipulate the polarisation of an ultrashort, high-intensity probing laser pulse.
    Session 6: Applications of Plasma Accelerators
    11778-19
    Author(s): Enrico Brunetti, Antoine Maitrallain, Dino A. Jaroszynski, Univ. of Strathclyde (United Kingdom)
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    Accelerators driven by 10s TW-class lasers can produce electron bunches with femtosecond-scale duration and energy of 100s of MeV. A potential application of such short bunches is high-dose rate radiotherapy, which could transition to FLASH radiotherapy if a sufficiently large dose is delivered in a single shot. Here we present Monte Carlo simulations to study the bunch length evolution of an electron beam propagating in a water phantom. We show that for electron energies above 100 MeV the bunch lengthens to 1--10 ps duration after interaction with a 30 cm long water phantom, both for a collimated and weakly focused geometry. The corresponding dose rates are on the order of 200 Gy/s per primary electron, much higher than in conventional radiotherapy.
    11778-20
    Author(s): Minseok Kim, Myung Hoon Cho, Inhyuk Nam, Pohang Accelerator Lab. (Korea, Republic of); Sihyeon Lee, Hyyong Suk, Gwangju Institute of Science and Technology (Korea, Republic of); Seong-Hoon Kwon, Pohang Accelerator Lab. (Korea, Republic of)
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    Femtosecond MeV electron beam generated by laser-plasma accelerators (LPA) is a promising source for ultrafast electron diffraction (UED) application. Compared to conventional UED instruments which limit temporal resolution to a few tens of fs, plasma electron accelerator-based UED is possible to make sub-10 fs temporal resolution because of no intrinsic time jitter between pump-probe pulses and ultrashort electron bunch length. Some groups have shown that a few MeV electron beam can be produced by using a few mJ laser pulse as it has shorter pulse duration (single- or few-cycle). In this regime, the laser pulse is tightly focused onto gas target, and thus electrons in relatively high density plasma (1020 cm-3) are self-injected and accelerated. However, the electron beam quality like energy spread and emittance should be still improved for applications. Here, we introduce plan of two laser pulses-based plasma electron acceleration research for UED application at Pohang Accelerator Laboratory (PAL). A laser pulse is separated to two pulses that one is used to drive plasma wakefield and the other one is delivered to induce electron injection in a plasma bubble. Since the driving pulse intensity is retained under threshold of self-injection to suppress electron injection, the electron injection occurs in a localized region the injection pulse is focused, resulting in the high quality electron generation. In addition, researches conducting for better electron beam quality are presented in this presentation.
    Conference Chair
    Univ. of Strathclyde (United Kingdom)
    Conference Chair
    Ulsan National Institute of Science and Technology (Korea, Republic of)
    Program Committee
    Min Chen
    Shanghai Jiao Tong Univ. (China)
    Program Committee
    Heinrich-Heine-Univ. Düsseldorf (Germany)
    Program Committee
    Nathaniel J. Fisch
    Princeton Univ. (United States)
    Program Committee
    Punit Kumar
    Univ. of Lucknow (India)
    Program Committee
    Ecole Nationale Supérieure de Techniques Avancées (France)
    Program Committee
    Univ. Técnica de Lisboa (Portugal)
    Program Committee
    Roman Spesyvtsev
    Univ. of Strathclyde (United Kingdom)
    Program Committee
    Hyyong Suk
    Gwangju Institute of Science and Technology (Korea, Republic of)
    Program Committee
    Luca Volpe
    Univ. degli Studi di Milano-Bicocca (Italy)
    Program Committee
    Stefan A. Weber
    Institute of Physics of the CAS, v.v.i. (Czech Republic)
    Program Committee
    Capital Normal Univ., Beijing Advanced Innovation Ctr. for Imaging Technology (China)