The effect of plasma radius and profile on the development of self-modulation instability of electron bunches

Fang, Yun; Vieira, Jorge; Amorim, L. D.; Mori, W. B.; Muggli, P.

doi:10.1063/1.4872328

Cited by 20 publications

(23 citation statements)

References 25 publications

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“…It was shown that the wakefield amplitude cannot exceed the limit imposed by nonlinear elongation of the wave period [32], and the designed operation regime of the AWAKE experiment is close to this limit [33]. A finite plasma radius or weak radial nonuniformity of the plasma have a small effect on the wave growth, if the radial scale of density variation is much greater than the plasma skin depth [34,35]. As selfmodulating beams are many plasma wavelengths long, motion of plasma ions could come into play and hamper wave excitation, if plasma ions are light [36,37].…”

Section: Introductionmentioning

confidence: 99%

Physics of beam self-modulation in plasma wakefield accelerators

Lotov

2015

Physics of Plasmas

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The self-modulation instability is a key effect that makes possible the usage of nowadays proton beams as drivers for plasma wakefield acceleration. Development of the instability in uniform plasmas and in plasmas with a small density up-step is numerically studied with the focus at nonlinear stages of beam evolution. The step parameters providing the strongest established wakefield are found, and the mechanism of stable bunch train formation is identified.

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Section: Introductionmentioning

confidence: 99%

Physics of beam self-modulation in plasma wakefield accelerators

Lotov

2015

Physics of Plasmas

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“…With our choice of plasma radius (r p ), a ±5% variation seems to have no significant effect on the wakefield amplitude. It has been shown that a smaller plasma radius can enhance the wakefield's focusing force and hence the SMI's growth rate by hindering the plasma's shielding response to the charge in the drive bunch [21]. However, this effect only becomes prominent when r p approaches σ rb , which, despite the variations of ±5%, is not the case here.…”

Section: Properties Of the Wakefieldsmentioning

confidence: 65%

Influence of proton bunch parameters on a proton-driven plasma wakefield acceleration experiment

Moreira

Vieira

Muggli

2019

Phys. Rev. Accel. Beams

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We use particle-in-cell (PIC) simulations to study the effects of variations of the incoming 400 GeV proton bunch parameters on the amplitude and phase of the wakefields resulting from a seeded selfmodulation (SSM) process. We find that these effects are largest during the growth of the SSM, i.e. over the first five to six meters of plasma with an electron density of 7 × 10 14 cm −3 . However, for variations of any single parameter by ±5%, effects after the SSM saturation point are small. In particular, the phase variations correspond to much less than a quarter wakefield period, making deterministic injection of electrons (or positrons) into the accelerating and focusing phase of the wakefields in principle possible. We use the wakefields from the simulations and a simple test electron model to estimate the same effects on the maximum final energies of electrons injected along the plasma, which are found to be below the initial variations of ±5%. This analysis includes the dephasing of the electrons with respect to the wakefields that is expected during the growth of the SSM. Based on a PIC simulation, we also determine the injection position along the bunch and along the plasma leading to the largest energy gain. For the parameters taken here (ratio of peak beam density to plasma density n b0 /n0 ≈ 0.003), we find that the optimum position along the proton bunch is at ξ ≈ −1.5 σ zb , and that the optimal range for injection along the plasma (for a highest final energy of ∼1.6 GeV after 10 m) is 5-6 m.

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“…In sec. IV A the dynamics of the beam into the plasma lenses is then computed by a 2D code written to solve the wakefield equations in the linear regime [32]. Finally, the optimization of the collimator system has been conducted to maximize the driver beam dumping by looking at its fundamental interactions with the collimator walls (predicted by GEANT4, see sec.…”

Section: Plasma Lensesmentioning

confidence: 99%

Plasma lens-based beam extraction and removal system for plasma wakefield acceleration experiments

Pompili

Chiadroni

Cianchi

et al. 2019

Phys. Rev. Accel. Beams

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Plasma Wakefield Acceleration represents one of the most promising techniques able to overcome the limits of conventional RF technology and make possible the development of compact accelerators. With respect to the laser-driven schemes, the beam-driven scenario is not limited by diffraction and dephasing issues, thus it allows to achieve larger acceleration lengths. One of the most prominent drawback, conversely, occurs at the end of the acceleration process and consists of removing the depleted high-charge driver while preserving the main features (emittance and peak current) of the accelerated witness bunch. Here we present a theoretical study demonstrating the possibility to reach these goals by using an innovative system consisting of an array of beam collimators and dischargecapillaries operating as active-plasma lenses. Such a system allows to extract and transport the accelerated and highly divergent witness bunch and, at the same time, provides for the removal of the driver. The study is completed by a set of numerical simulations conducted for different beam configurations. The physics of the interaction of particles with collimator is also investigated.

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The effect of plasma radius and profile on the development of self-modulation instability of electron bunches

Cited by 20 publications

References 25 publications

Physics of beam self-modulation in plasma wakefield accelerators

Physics of beam self-modulation in plasma wakefield accelerators

Influence of proton bunch parameters on a proton-driven plasma wakefield acceleration experiment

Plasma lens-based beam extraction and removal system for plasma wakefield acceleration experiments

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