arXiv subjects

L. D. Amorim

Publications and source records attributed to L. D. Amorim.

5 recordsLinked to original sources

arXiv2021

Stable Positron Acceleration in Thin, Warm, Hollow Plasma Channels

Hollow plasma channels are attractive for lepton acceleration because they provide intrinsic emittance preservation regimes. However, beam breakup instabilities dominate the dynamics. Here, we show that thin, warm hollow channels can sustain large-amplitude plasma waves ready for high-quality positron acceleration. We verify that the combination of warm electrons and thin hollow channel enables positron focusing structures. Such focusing wakefields unlock beam breakup damping mechanisms. We demonstrate that such channels emerge self-consistently during the long-term plasma dynamics in the blowout's regime aftermath, allowing for experimental demonstration.

physics.plasm-ph↗

arXiv2021

Porting WarpX to GPU-accelerated platforms

WarpX is a general purpose electromagnetic particle-in-cell code that was originally designed to run on many-core CPU architectures. We describe the strategy followed to allow WarpX to use the GPU-accelerated nodes on OLCF's Summit supercomputer, a strategy we believe will extend to the upcoming machines Frontier and Aurora. We summarize the challenges encountered, lessons learned, and give current performance results on a series of relevant benchmark problems.

physics.comp-ph↗

arXiv2021

Analytical Solution to Electron Beam Envelope Evolution in a Plasma Wakefield

Beam-induced ionization injection (B-III) is currently being explored as a method for injecting an electron beam with a controlled density profile into a plasma wakefield accelerator (PWFA). This process is initiated by the fields of an unmatched drive beam where the slice envelope reaches its minimum value, the 'pinch'. To control the injected beam's qualities, it is crucial to study the beam-slice envelope oscillations, especially size and the location of the pinch. In this proceeding, an ansatz based on the harmonic motion is proposed to find the analytical solution to beam-slice envelope evolution in the nonlinear regime. The size of the pinch is then found through the application of energy conservation in the transverse direction. The resulting analytical expressions are shown to be in good agreement with numerical solutions.

physics.acc-ph↗

arXiv2014

Self-modulation instability of ultra-relativistic particle bunches with finite rise times

We study the evolution of the self-modulation instability using bunches with finite rise times. Using particle-in-cell simulations we show that unlike long bunches with sharp rise times, there are large variations of the wake amplitudes and wake phase velocity when bunches with finite rise times are used. These results show that use of bunches with sharp rise times is important to seed the self-modulation instability and to ensure stable acceleration regimes.

physics.plasm-ph↗

arXiv2014

Electron trapping and acceleration by the plasma wakefield of a self-modulating proton beam

It is shown that co-linear injection of electrons or positrons into the wakefield of the self-modulating particle beam is possible and ensures high energy gain. The witness beam must co-propagate with the tail part of the driver, since the plasma wave phase velocity there can exceed the light velocity, which is necessary for efficient acceleration. If the witness beam is many wakefield periods long, then the trapped charge is limited by beam loading effects. The initial trapping is better for positrons, but at the acceleration stage a considerable fraction of positrons is lost from the wave. For efficient trapping of electrons, the plasma boundary must be sharp, with the density transition region shorter than several centimeters. Positrons are not susceptible to the initial plasma density gradient.

physics.plasm-ph↗