99 documents found, page 1 of 10
Particle-in-cell simulations of pulsar magnetospheres: Transition between elect...
Cruz, F.; Grismayer, T.; Torres, R.; Chen, A. Y.; Spitkovsky, A.; Fonseca, R. A.; Silva, L. O.Aims. Global particle-in-cell (PIC) simulations of pulsar magnetospheres are performed with volume-, surface-, and pair-production-based plasma injection schemes to systematically investigate the transition between electrosphere and force-free pulsar magnetospheric regimes. Methods. We present a new extension of the PIC code OSIRIS that can be used to model pulsar magnetospheres with a two-dimensional axisymmet...
OSIRIS-GR: General relativistic activation of the polar cap of a compact neutro...
Torres, R; Grismayer, T.; Cruz, F.; Fonseca, R. A.; Silva, L. O.We present ab initio global general-relativistic Particle-in-cell (GR-PIC) simulations of compact millisecond neutron star magnetospheres in the axisymmetric aligned rotator configuration. We investigate the role of GR and plasma supply on the polar cap particle acceleration efficiency – the precursor of coherent radio emission – employing a new module for the PIC code OSIRIS, designed to model plasma dynamics ...
Slowdown of interpenetration of two counterpropagating plasma slabs due to coll...
Shulka, N; Schoeffler, K. M.; Vieira, J.; Fonseca, R. A.; Boella, E; Silva, L. O.The nonlinear evolution of electromagnetic instabilities driven by the interpenetration of two e-,e+ plasma clouds is explored using ab initio kinetic plasma simulations. We show that the plasma clouds slow down due to both oblique and Weibel generated electromagnetic fields, which deflect the particle trajectories, transferring bulk forward momentum into transverse momentum and thermal velocity spread. This pr...
Interaction between electrostatic collisionless shocks generates strong magneti...
Boella, E.; Schoeffler, K. M.; Shulka, N.; Innocenti, M. E.; Lapenta, G; Fonseca, R. A.; Silva, L. O.The head-on collision between electrostatic shocks is studied via multi-dimensional particle-in-cell simulations. A strong magnetic field develops after the interaction, which causes the shock velocities to drop significantly. This transverse magnetic field is generated by the Weibel instability, which is driven by pressure anisotropies due to longitudinal electron heating while the shocks approach each other. ...
Quantum electrodynamics vacuum polarization solver
Grismayer, T.; Torres, R.; Carneiro, P.; Cruz, F.; Fonseca, R. A.; Silva, L. O.The self-consistent modeling of vacuum polarization due to virtual electron-positron fluctuations is of relevance for many near term experiments associated with high intensity radiation sources and represents a milestone in describing scenarios of extreme energy density. We present a generalized finite-difference time-domain solver that can incorporate the modifications to Maxwell’s equations due to vacuum pola...
A robust plasma-based laser amplifier via stimulated Brillouin scattering
Alves, E. P.; Trines, R. M. G.; Humphrey K. A.; Bingham, R.; Cairns, R. A.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.Brillouin amplification in plasma is more resilient to fluctuations in the laser and plasma parameters than Raman amplification, making it an attractive alternative to Raman amplification. In this work, we focus on high plasma densities, $n_0 \gt n_{cr}/4$, where stimulated Raman scattering is not possible and laser beam filamentation is the dominant competing process. Through analytic theory and multi-dimensio...
Simulation and experimental study of proton bunch self-modulation in plasma wit...
Morales Guzmán, P. I.; Muggli, P.; Agnello, R.; Ahdida, C. C.; Aladi, M.; Amoedo Goncalves, M. C.; Andrebe, Y.; Apsimon, O.; Apsimon, R.We present numerical simulations and experimental results of the self-modulation of a long proton bunch in a plasma with linear density gradients along the beam path. Simulation results agree with the experimental results reported [F. Braunmller, T. Nechaeva et al. (AWAKE Collaboration), Phys. Rev. Lett. 125, 264801 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.264801]: with negative gradients, the charge of the...
Boosting the performance of Brillouin amplification at sub-quarter-critical dens...
Trines, R. M. G.; Alves, E. P.; Humphrey, K. A.; Bingham, R.; Cairns, R. A.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.Brillouin amplification of laser pulses in plasma has been shown to be a promising approach to produce picosecond pulses of petawatt power. A key challenge is preservation of the quality of the amplified pulse, which requires control of parasitic instabilities that accompany the amplification process. At high plasma densities (>cr/4), ponderomotive filamentation has been identified as the biggest threat to the ...
Transition between instability and seeded self-modulation of a relativistic par...
Batsch, F.; Muggli, P.; Agnello, R.; Ahdida, C. C.; Amoedo Goncalves, M. C.; Andrebe, Y.; Apsimon, O.; Apsimon, R.; Bachmann, A.-M.; Baistrukov, M. A.We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufficient initial amplitude [≥(4.1±0.4) MV/m], the phase of the modulation along the bunch is reproducible from event to event, with 3%-7% (of 2?) rms variations all along the bunch. The phase is not reproducible for lower ...
Analysis of proton bunch parameters in the AWAKE experiment
Hafych, V.; Caldwell, A.; Agnello, R.; Ahdida, C. C.; Aladi, M.; Amoedo Goncalves, M. C.; Andrebe, Y.; Apsimon, O.; Apsimon, R.; Bachmann, A.-M.A precise characterization of the incoming proton bunch parameters is required to accurately simulate the self-modulation process in the Advanced Wakefield Experiment (AWAKE). This paper presents an analysis of the parameters of the incoming proton bunches used in the later stages of the AWAKE Run 1 data-taking period. The transverse structure of the bunch is observed at multiple positions along the beamline us...