Bulletin of the American Physical Society
63rd Annual Meeting of the APS Division of Plasma Physics
Volume 66, Number 13
Monday–Friday, November 8–12, 2021; Pittsburgh, PA
Session JO05: Relativistic High-Energy-Density Physics and High Field PhysicsOn Demand
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Chair: Alex Arefiev, University of California, San Diego Room: Rooms 306-307 |
Tuesday, November 9, 2021 2:00PM - 2:12PM |
JO05.00001: Pump-Probe Measurement of Relativistic Transparency and Relativistic Birefringence Anthony Zingale, Nicholas Czapla, German Tiscareno, Preston B Pozderac, David Hanggi, Derek Nasir, Rebecca L Daskalova, Douglass W Schumacher Relativistic induced transparency (RIT) is the transmission of a laser through an overdense plasma due to the relativistic mass increase of the laser heated plasma electrons. Direct measurements of RIT are difficult and uncommon, limiting comparison to theory. Recent theoretical findings (Stark, et al., Phys. Rev. Lett. 115, 025002 (2015)) predict a new effect, relativistic induced birefringence due to anisotropy in the electron momentum, offering additional motivation for new experiments. We present results of a pump-probe study of RIT carried out at the Scarlet Laser Facility at Ohio State. A pump with peak intensity >1021 W/cm2 was incident on ~23 nm thick liquid crystal targets while a probe was incident from the other side. The transmission of the pump and probe (polarization resolved) was measured over a delay range of about 15 ps. We measured the ultrafast turn-on and turn-off of RIT. The return of the system to opacity resolves the ambiguity of whether RIT was achieved or if there was simply a decrease in plasma density due to target heating and transport. Finally, an average rotation of the probe polarization ellipticity angle of ∼7.8o at zero delay was measured for the highest pump intensities, serving as strong experimental evidence of relativistic birefringence. |
Tuesday, November 9, 2021 2:12PM - 2:24PM |
JO05.00002: PIC modeling of a pump-probe experiment on relativistic induced transparency and laser driven dynamic structures Preston B Pozderac, Anthony Zingale, David Hanggi, Nicholas Czapla, German Tiscareno, Derek Nasir, Ginevra E Cochran, Douglass W Schumacher Relativistic induced transparency (RIT), whereby an intense laser can transmit through an overdense plasma, is critical to understanding intense laser-matter experiments, particularly those using thin targets. This effect is difficult to measure directly (Palaniyappan, et al., Nature Physics 8, 763 (2012) and Bagnoud, et al., Phys. Rev. Lett. 118, 255003 (2017)), especially with femtosecond temporal resolution. Recent theoretical and computational results (Stark, et al., Phys. Rev. Lett. 115, 025002 (2015)) predict a new effect, relativistic induced birefringence, due to anisotropy in electron momentum. Recent pump-probe experiments using the OSU Scarlet laser have measured the ultrafast turn-on and turn-off of RIT as well as relativistic birefringence using liquid crystal targets at intensities up to or exceeding 1021 W/cm2. We describe 3D particle-in-cell (PIC) simulations that explain these results including the role of dynamic structures that evolve during and after the pump and we also show evidence for a scaling law involving laser intensity and target areal density. This work required a careful separation of pump and probe fields and we describe how this was achieved. |
Tuesday, November 9, 2021 2:24PM - 2:36PM |
JO05.00003: Near Field Spatial Mode Modification of Ultraintense Pulse Through Relativistically Transparent Solid Density Targets using Light with and without Orbital Angular Momentum Nicholas Czapla, Anthony Zingale, German Tiscareno, Derek Nasir, Douglass W Schumacher, Mihail O Cernaianu, Petru Chenuche, Domenico Doria, Florin Negoita, David R. R Blackman, Alexey Arefiev, Dan Stutman Relativistic Transparency (RT) in laser-matter interactions occurs when light incident on an opaque plasma becomes intense enough to drive electrons at relativistic speeds, dropping the effective electron density of the plasma below critical so that it becomes transparent. RT in solid-density targets using ultraintense light (>1020 W/cm2) is still an active research area, with many studies focusing on the turn-on time of the interaction [1]. A recent pump-probe experiment performed at the Scarlet Laser Facility has measured the turn-on and turn-off time scale as well as relativistic polarization effects [2]. Here we discuss the effects to the spatial mode of a pump-only transmitted beam through ultrathin (<30 nm) solid-density targets made in situ using liquid crystal films at the Scarlet laser facility. The interaction was performed using a traditional TEM00 beam mode as well as an l=1 Laguerre-Gaussian (LG) beam mode at a peak incident intensity of 0.5-1 x 1021 W/cm2. We describe measurements of the transmitted spatial mode of the TEM00 and LG beams. |
Tuesday, November 9, 2021 2:36PM - 2:48PM |
JO05.00004: High-yield and high-angular-flux neutron generation from deuterons accelerated by laser-driven collisionless shock Chengkun Huang, David P Broughton, Sasi Palaniyappan, Sylvia Ann Junghans, Metodi Iliev, Robert E Reinovsky, Andrea Favalli
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Tuesday, November 9, 2021 2:48PM - 3:00PM |
JO05.00005: Progress on Laser-Driven MeV Electron-Positron Pair Experiments Hui Chen, Matthew R Edwards, Gennady Fiksel, Sheng Jiang, Jens Von Der Linden, Andrew Longman, Jonathan L Peebles, Louise Willingale Relativistic electron-positron (pair) plasmas have unique properties due to their mass symmetry and may play an important role in energetic astrophysics. High-energy ps laser-target interactions have produced a large number (1010 – 1012) of positrons in a small volume (< 3 mm3) [1]. We have recently made significant progress in three areas of manipulating and optimizing these relativistic pairs: a) designed a magnetic mirror using pulsed-power-driven 13 T solenoids and validated the effectiveness of the magnetic mirror by trapping MeV pairs for ns-timescales [2]; b) created a collimated charge-neutral pair beam [3] using a magnetic lens; c) realized pair yield enhancement by a factor of 2 using a micro-structured target [4]. These results and future plans will be presented. |
Tuesday, November 9, 2021 3:00PM - 3:12PM |
JO05.00006: Self-consistent positron creation and acceleration up to a few GeVs in a plasma channel Bertrand Martinez, Marija Vranic Positron acceleration embodies a significant milestone towards the development of a high-energy electron-positron collider. While plasma wakefield acceleration seems a promising way to achieve this goal, it presents limits such as creating and accelerating the beam beforehand, and injecting it with precision in the right phase of plasma wakefield. |
Tuesday, November 9, 2021 3:12PM - 3:24PM |
JO05.00007: Impact of the laser spatio-temporal shape on Breit-Wheeler pair production Mickael Grech, Anthony Mercuri-Baron, Fabien Niel, Anna Grassi, Mathieu Lobet, Antonino Di Piazza We examine the decay of a flash of γ photons into electron-positron pairs as it collides with an intense laser field (non-linear Breit-Wheeler process). We propose a simple semi-analytical model aimed at describing the interaction of the photons with a Gaussian (G) or Laguerre-Gaussian (LG) laser beam of arbitrary polarization [?]. This model allows to estimate the number of primary pairs produced and to explore the role of the laser peak intensity versus the focal spot size and shape at constant laser energy, chosen to match experimental constraints. In the case of LG beams the influence of the order of the LG beams on pair creation is examined and it is found that above a given threshold a higher order of the LG parameter is more favorable than a higher peak intensity. This result is generalised to a Gaussian beam: above the same threshold a larger spot size is preferable to tight focusing. Our results match very well with three-dimensional particle-in-cell simulations and are used to guide upcoming experimental campaigns. |
Tuesday, November 9, 2021 3:24PM - 3:36PM |
JO05.00008: Strong-field QED features in the leptonic beam collision Wenlong Zhang, Thomas Grismayer, Luis O Silva We study the photon emission and pair production from the collision of dense and ultra-relativistic leptonic beams in the strong QED regime (χe ≫ 1 ). Analytical solutions to the yield of photons and pairs are obtained for low disruption regime, with beams having uniform transverse profiles. Analytical solutions for the low and high energy components of the photon spectrum are derived. Distinct spectral features are identified in these two components of the spectrum with distinct signatures associated with the strong QED regime. The yield and the spectrum features are also studied as a function of the bunch length (or disruption parameter). The analytical solutions are verified by both solving the numerical solution of the QED probability equations and via three dimensional particle-in-cell simulations with OSIRIS. |
Tuesday, November 9, 2021 3:36PM - 3:48PM |
JO05.00009: Generation and measurement of extreme magnetic fields Brandon K Russell, Paul T Campbell, Marija Vranic, Kevin M. Schoeffler, Dmitri A Uzdensky, Qian Qian, Jason A Cardarelli, Alexander G Thomas, Louise Willingale Next-generation laser facilities may reach extreme intensities (>1023 W/cm2), allowing for the effects of quantum electrodynamic (QED) processes on plasmas to be studied. In the interaction of such high intensity pulses with solid targets it is expected that ~0.1 MT magnetic fields may be generated, potentially allowing for the experimental study of extreme astrophysical phenomena. Currently, there is no theoretical description for how such extreme laser intensities affect the magnetic field generation and strength. For example, the magnetization that ultra-intense laser interactions will achieve may be limited by QED processes, i.e. radiation reaction, and therefore cannot be accurately predicted. Using the QED module in the OSIRIS particle-in-cell code, we perform several 2D and quasi-3D simulations to study magnetic field generation at these extreme laser intensities. In the expected range of magnetic field strengths standard proton deflectometry techniques cannot be used due to the extremely large deflections of the protons. We propose an electron radiography method to measure the properties of these magnetic fields. |
Tuesday, November 9, 2021 3:48PM - 4:00PM |
JO05.00010: The acceleration-dependent mass increase and acceleration limit of a charged sphere in uniform circular motion Teyoun Kang, Min Sup Hur The equation of motion for a charged particle, though well established, still has many problems. In particular, when the particle is located in strong electromagnetic fields, the equation of motion becomes unsolvable because of the strong radiation reaction (the self-force). Such strong fields can be observed frequently in astrophysical conditions. Nowadays it is becoming feasible to generate such strong fields in laboratories owing to the rapid development of laser technologies. Naturally, it motivates researchers to investigate the radiation reaction experimentally as well as theoretically. We recently published a new theoretical model of the self-force of a charged sphere undergoing uniform acceleration [Phys. Lett. A 407 (2021) 127445]. In this new model, we tried to resolve the historical paradox about the radiation emission of a uniformly accelerated charge by assuming that a particle is a charged sphere embedded with an image of a point charge on its surface. From this assumption, we have found that the effective mass of the sphere increases by its acceleration (not velocity). The radiation reaction on a uniformly accelerated charged particle, missing in the classical model, could be explained by the acceleration-dependent mass increase. In this talk, we present the self-force of a charged sphere in a uniform circular motion. It will be shown that the effective mass of the sphere in the circular motion also increases by the acceleration. We investigate a physical origin of the acceleration-dependent mass increase. Furthermore, we show that the acceleration in a uniform circular motion can potentially have an upper limit, which is an interesting unexpected consequence of the charged-sphere model. Possible link to the Schwinger limit will be discussed briefly. |
Tuesday, November 9, 2021 4:00PM - 4:12PM |
JO05.00011: Effect of radiation-reaction on charged particle motion in an intense focused light wave Shivam K Mishra, Sarveshwar Sharma, Sudip Sengupta Effect of radiation reaction force on charged particle dynamics in an intense plane focussed light wave is investigated using the Hartemann-Luhmann equation of motion [ F. V. Hartemann and N. C. Luhmann, Phys. Rev. Lett. 74, 1107 (1995) ]. It is found that, irrespective of the choice of initial conditions radiation reaction completely nullifies the well known criterion for reflection from the focal region [ P. K. Kaw and R. M. Kulsrud, Physics of Fluids 16, 321 (1973) ] and thereby enhances the energy gained by the particle from the intense plane wave due to focussing alone. This energy gain is found to be independent of the choice of polarization of the wave. These results, which are of relevance to the direct laser acceleration scheme of particle acceleration, agrees with the results obtained using the well known Landau-Lifshitz equation of motion. |
Tuesday, November 9, 2021 4:12PM - 4:24PM |
JO05.00012: Signature of Collective Plasma Effects in Beam-Driven QED Cascades Kenan Qu, Sebastian Meuren, Nathaniel J Fisch QED cascades play an important role in extreme astrophysical environments like magnetars. They can also be produced by passing a relativistic electron beam through an intense laser field. Signatures of collective pair plasma effects in these QED cascades are shown to appear, in exquisite detail, through 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. |
Tuesday, November 9, 2021 4:24PM - 4:36PM |
JO05.00013: Ultra-energetic electron bunches from SPW excitation in the ultra-high intensity regime Michèle RAYNAUD, Paula Kleij, Samuel Marini, François Amiranoff, Mickael Grech, Andrea Macchi, Caterina Riconda Recent experiments [1] have demonstrated that the resonant excitation of surface plasma waves (SPW) by ultra-high intensity fs lasers impinging on a solid-density target strongly enhances the laser-plasma coupling and provides a new path for generating relativistic, high charge electron bunches emitting radiation with interesting characteristics. In this work, we show that laser wavefront rotation (WFR) [2] acts to both shorten the duration (down to very few optical cycles) and increase the intensity of SPW [3], thus favoring the production of ultra-short, energetic electron bunches. Optimal laser parameters were identified analytically and verified by means of Particle-In-Cell (PIC) simulations with the open-source code SMILEI [4]. The laser pulse with WFR was combined with a smart grating target design. In the laser-plasma relativistic regime of interaction (i.e. Iλ2 = 3.4 × 1019 W/cm2 μm2), we show that this set-up may produce SPW with ~3.6 cycles duration which accelerate high-charge (few 10’s of pC), high-energy (up to 70 MeV) electron bunches of few fs duration [5]. Extending this set up, or more in general exploiting the possibility of SPW excitation by forthcoming multi-petawatt laser facilities ( Iλ2 > 1021) implies an in depth understanding of the SPW excitation conditions and lifetime in that regime. Through extensive parametric studies we identify the optimum SPW excitation angle in the ultra-relativistic regime, that coincides with the optimal angle to optimize the electron acceleration along the plasma surface [6]. The dependence on the plasma density and grating shape is also discussed. As a conclusion, we show that excitation of SPW by a grating can hold at the highest laser intensities available, opening the doors to new experiments on forthcoming multi-petawatt laser systems. |
Tuesday, November 9, 2021 4:36PM - 4:48PM |
JO05.00014: Characterizing the growth of current filamentation instability using laser wakefield accelerated beams Jason A Cardarelli, Yong Ma, Paul T Campbell, Andre F Antoine, Meriame Berboucha, Rebecca Fitzgarrald, Reed C Hollinger, Brendan Kettle, Karl M Krushelnick, Stuart P.D. Mangles, John Morrison, Ryan Nedbailo, Qian Qian, Jorge J Rocca, Gianluca Sarri, Daniel Seipt, Huanyu Song, Matthew J. V Streeter, Shoujun Wang, Louise Willingale, Alec G.R. Thomas Relativistic plasma instabilities provide a rich and active focus of research in fields ranging from high energy astrophysics to inertial confinement fusion. Current Filamentation Instability (CFI), characterized by the formation of high-density filaments as a relativistic beam current travels through a cold background plasma, is one such instability which has had a wealth of research to understand its properties in recent years. In this work a laser wakefield accelerator produces a relativistic electron beam which traverses through a cold background plasma of controllable length. Snapshots of the growth of CFI at different times may be captured by tuning the background plasma length. These experimental results are compared to theoretical frameworks for the CFI growth rate that relate the measured filament growth to properties of the beam and background plasma. Measured results are also compared to Particle-in-Cell (PIC) simulations using the OSIRIS 4.0 PIC code. |
Tuesday, November 9, 2021 4:48PM - 5:00PM |
JO05.00015: Wavelength scaling of the high-intensity laser pulse compression dynamics in gas-filled capillaries Garima C Nagar, Bonggu Shim The multimodal carrier-resolved unidirectional pulse propagation equation is solved to study the wavelength-dependent (λ = 1, 2, 3 and 4 μm) spatio-temporal dynamics, particularly pulse self-compression during high-intensity laser pulse propagation in gas-filled capillaries. We find that pulse self-compression in gas-filled capillaries due to plasma is more efficient for short wavelengths in contrast to wavelength-dependent pulse self-compression in laser filamentation [1]. To explain our finding, a detailed analysis is performed by quantifying the contributions of higher-order modes and calculating the temporal delay among modes, which reveals that pulse self-compression at longer wavelengths does not occur due to larger group velocity mismatch between the fundamental and higher-order modes for longer wavelengths [2]. Our study has important implications for the various fields of high-intensity nonlinear optics in gas-filled capillaries such as supercontinuum generation and high-order harmonic generation [3].[1] L. Bergé et al., Phys. Rev. A 88, 023816 (2013). [2] G. Nagar and B. Shim, submitted. [3] T. Popmitchev et al. Science 336, 1287 (2012). |
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