Control of the diocotron instability of a hollow electron beam with periodic dipole magnets

Jo, Yeon Hwa; Kim, J. S.; Stancari, G.; Chung, М.; Lee, Hae June

doi:10.1063/1.5018425

Cited by 15 publications

(11 citation statements)

References 16 publications

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“…During these experiments, the same electron-lens current was seen by the antiprotons at each turn (the so-called "dc mode" of operation). More studies have followed, such as the calculation of the transverse kicks from the hollow electron-lens bends [20], the beam diocotron instability control [21], and the hollow electron gun characterization [22], as well as experimental and numerical studies for a hollow electron-lens system [23][24][25][26][27][28]. The above studies, as well as the existing electron-lens experience from Tevatron and RHIC [29][30][31][32][33][34], provide information for the design of a hollow electron-lens system that meets the halo removal requirements for the HL-LHC, as well as the future applications of beam collimation in the FCC-hh [35] at CERN or Super Proton-Proton Collider (SPPC) [36] in China.…”

Section: Introductionmentioning

confidence: 99%

“…For the pulsed mode, there are concerns about potential emittance growth due to electron beam profile distortions, field asymmetries between the entrance and the exit bending region of the hollow electron-lens system, and beam alignment errors. There currently is an effort ongoing to improve the beam transverse profile via simulation by reducing the hollow electron beam diocotron instability [21].…”

Section: Introductionmentioning

confidence: 99%

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Halo removal experiments with hollow electron lens in the BNL Relativistic Heavy Ion Collider

Fischer

Altinbas

et al. 2020

Phys. Rev. Accel. Beams

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A hollow electron beam has been proposed as an active control tool to remove the beam halo from highenergy, high-current hadron or ion machines (such as the High-Luminosity Large Hadron Collider). To study the halo removal rate and assess the effect on the ion beam core, one of the two electron lenses in the Relativistic Heavy Ion Collider was changed from a Gaussian beam profile to a hollow profile. We describe the design and verification of the hollow electron beam parameters as well as the methods to minimize the hollow beam profile distortions, which can result in an ion beam emittance increase. The hollow beam alignment with the ion beam by using a backscattered electron detector has been demonstrated. Furthermore, experiments were carried out to explore the efficiency of the halo removal by scanning the current and inner radius of the hollow electron beam, which is pulsed either every turn or every nth turn. The effects of the hollow electron beam on the ion beam emittance and luminosity were also assessed experimentally by scanning the inner radius of the electron beam.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Halo removal experiments with hollow electron lens in the BNL Relativistic Heavy Ion Collider

Fischer

Altinbas

et al. 2020

Phys. Rev. Accel. Beams

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“…A two-dimensional radial-azimuthal explicit and electrostatic particle-in-cell code [39] was utilized to investigate the instability development and spoke dynamics. The code was extensively benchmarked and validated [40,41,42] and the convergence was also verified with different time steps, cell sizes and particles per cell in our study. An equidistant computational grids 64 × 512 in the radial and azimuthal dimensions was used.…”

Section: Pic/mcc Model Descriptionmentioning

confidence: 91%

Direct evidence of the gradient drift instability being the origin of a rotating spoke in a crossed field plasma

Xu,

Eremin,

Brinkmann

2021

Preprint

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A plasma rotating spoke in a crossed field discharge is studied using 2D radial-azimuthal fully kinetic Particle-In-Cell Monte Carlo Collision (PIC/MCC) simulations. The kinetic model reveals the whole perturbation spectrum of the gradient drift instability in the linear stage: Simon-Hoh, lower-hybrid and ion sound modes, providing direct evidence of the spoke of the gradient drift instability nature. The two-fluid dispersion relation of the gradient drift instability was utilized to analyze the linear development of instabilities in the simulations. The charge separation effect was incorporated in the fluid linear theory and a super-resolution signal processing method (multiple signal classification) was applied to obtain the numerical frequency spectrum. The simulated spectrum and growth rate show excellent agreement with the theoretical dispersion relation (real frequency and imaginary frequency) over investigated cases. The most linearly unstable mode was found to be the lower hybrid instability and the mode transition into the m=1 macroscopic rotating structure after saturation of the linear phase is accompanied by an inverse energy cascade. In the nonlinear stage, the pronounced spoke phenomena can occur when the heating of E θ × B electron flow channeled in the spoke front passage suffices to provide the enhanced ionization.

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“…This instability deforms the initially axisymmetric electron density distribution, leading, in the nonlinear phase, to the formation of a discrete number of vortices, and eventually breakup [46,48]. This test case has importance both from a fundamental physics point of view [11,48,43] as well as in practical applications such as beam collimation [49].…”

Section: D Diocotron Instabilitymentioning

confidence: 98%

Sparse Grids based Adaptive Noise Reduction strategy for Particle-In-Cell schemes

Muralikrishnan,

Cerfon,

Frey

et al. 2020

Preprint

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We propose a sparse grids based adaptive noise reduction strategy for electrostatic particle-in-cell (PIC) simulations. Our approach is based on the key idea of relying on sparse grids instead of a regular grid in order to increase the number of particles per cell for the same total number of particles, as first introduced in [1]. Adopting a new filtering perspective for this idea, we construct the algorithm so that it can be easily integrated into high performance largescale PIC code bases. Unlike the physical and Fourier domain filters typically used in PIC codes, our approach automatically adapts to mesh size, number of particles per cell, smoothness of the density profile and the initial sampling technique. Thanks to the truncated combination technique [2, 3, 4], we can reduce the larger grid-based error of the standard sparse grids approach for non-aligned and non-smooth functions. We propose a heuristic based on formal error analysis for selecting the optimal truncation parameter at each time step, and develop a natural framework to minimize the total error in sparse PIC simulations. We demonstrate its efficiency and performance by means of two test cases: the diocotron instability in two dimensions, and the three-dimensional electron dynamics in a Penning trap. Our run time performance studies indicate that our new scheme can provide significant speedup and memory reduction as compared to regular PIC for achieving comparable accuracy in the charge density deposition.

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Control of the diocotron instability of a hollow electron beam with periodic dipole magnets

Cited by 15 publications

References 16 publications

Halo removal experiments with hollow electron lens in the BNL Relativistic Heavy Ion Collider

Halo removal experiments with hollow electron lens in the BNL Relativistic Heavy Ion Collider

Direct evidence of the gradient drift instability being the origin of a rotating spoke in a crossed field plasma

Sparse Grids based Adaptive Noise Reduction strategy for Particle-In-Cell schemes

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