Neutralization of ion beam by electron injection: Excitation and propagation of electrostatic solitary waves

Lan, Chaohui; Kaganovich, Igor

doi:10.1063/1.5128523

Cited by 14 publications

(18 citation statements)

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“…Experimentally at LBNL and theoretically at Princeton University and Japan, HIB space charge neutralization, focusing and manipulation are studied [65][66][67][68][69][70][71][72]. Plasma electrons are supplied to neutralize the HIB charge from a gas plasma preformed in space or at the material surface by active or passive discharges [65][66][67][68][69][70][71][72]. HIB instabilities were studied inside reactor gas, and the results show that HIB is rather stable during the transport in reactor gas against the two-stream and filamentation instabilities [67,73,74].…”

Section: Concept and Characteristics Of Heavy Ion Inertial Fusionmentioning

confidence: 99%

Direct-drive heavy ion beam inertial confinement fusion: a review, toward our future energy source

Kawata

2021

Advances in Physics: X

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Direct-drive heavy ion beam (HIB) inertial confinement fusion (ICF), or HIF would be a promising future energy source for society. Particle accelerators produce HIBs with precise particle energies, pulse lengths and pulse shapes with high energy efficiencies of ~30-40%. Higher energy driver efficiency means that a lower fusion energy output is required to construct a HIF power station to supply ~1 GW of electricity. A HIF power station could use about 4 to 5 MJ of HIB energy per shot at a shot rate of ~10 Hz. This review is focused on the direct-drive scheme in HIF. In directdrive fuel target HIBs deposit their energy into a shell surrounded by a denser tamping outer layer. The DT (Deuterium-Tritium) fusion fuel, with a total mass of several mg, must be compressed to about one thousand times solid density to reduce the input driver energy and to achieve an adequate burn fraction. Highdensity compression is a major challenge in ICF, requiring that non-uniformity in driver energy deposition be kept lower than a few percent. The axis of an HIB can be made to oscillate sufficiently rapidly to improve the uniformity of energy deposition.

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Section: Concept and Characteristics Of Heavy Ion Inertial Fusionmentioning

confidence: 99%

Direct-drive heavy ion beam inertial confinement fusion: a review, toward our future energy source

Kawata

2021

Advances in Physics: X

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“…For the neutralization process, the ESWs were observed to be very robust: they are ubiquitously excited during the neu- tralization process, survive many collisions between themselves and reflection from the boundaries. [9] These ESWs can be easily recognized as vortex-like structures in the electron phase space, as shown in Fig. 2(a).…”

mentioning

confidence: 97%

“…However, the complexity incurred by the generation of background plasma inside of a high-vacuum accelerator can be avoided by using an external filament electron source, which is easy to install in experiments. The neutralization by a filament electron source, however, leads to the excitation of space-charge waves, such as electrostatic solitary waves (ESWs), which limit the beam's space-charge neutralization [9]. While the ESWs have been studied theoretically for many decades [10][11][12], their behavior has gained recent interest since the discovery of their ubiquitous formation in the process of charge neutralization of ion beams [9,13].…”

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confidence: 99%

“…The neutralization by a filament electron source, however, leads to the excitation of space-charge waves, such as electrostatic solitary waves (ESWs), which limit the beam's space-charge neutralization [9]. While the ESWs have been studied theoretically for many decades [10][11][12], their behavior has gained recent interest since the discovery of their ubiquitous formation in the process of charge neutralization of ion beams [9,13]. The ESWs, which we also observed in our numerical simulations, have mostly been studied in 1D in the past [11,14,15].…”

mentioning

confidence: 99%

“…The two-stream instability between two electron streams results in the formation of ESWs, as was reported in Refs. [9,25,26]. For the neutralization process, the ESWs were observed to be very robust: they are ubiquitously excited during the neu- tralization process, survive many collisions between themselves and reflection from the boundaries.…”

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confidence: 99%

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Excitation of electrostatic solitary waves and surface waves in ion beam neutralization process

Nuwal¹,

Kaganovich²,

Levin³

2022

Preprint

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Unusually long electrostatic solitary waves (ESWs) are discovered in 2D and 3D Particle-in-Cell studies of the process of ion beam neutralization by electron emission from filaments. These ESWs are long because trapped and untrapped electron density perturbations nearly compensate each other. Surface waves were discovered in the process of neutralization but were only observed in 3D simulations. This is because the phase velocity of surface waves in a 2D geometry is higher than in 3D giving the high-energy electrons generated upstream near the electron source enough energy to excite such waves only in 3D cylindrical beams.

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Neutralization of ion beam by electron injection: Accumulation of cold electrons

Lan

Kaganovich

2020

Physics of Plasmas

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Ion beam charge neutralization by electron injection is a complex kinetic process.Recent experiments show that resulting self-potential of the beam after neutralization by plasma could be much lower than the temperature of plasma electrons [Physics of Plasmas 23, 043113 (2016)], indicating that kinetic effects are important and may affect the neutralization of ion beam. We performed a numerical study of the charge neutralization process of an ion beam making use of a two-dimensional electrostatic particle-in-cell code. The results show that the process of charge neutralization by electron injection is comprised of two stages. During the first stage, the self-potential of the beam is higher than the temperature of injected electrons (Te/e). Therefore, the neutralization of the ion beam is almost unaffected by Te, and all injected electrons are captured by the ion beam. At the second stage, with the decline of the beam potential (), hot electrons escape from the ion beam, while cold electrons are slowly accumulated. As a result,  can be much lower than Te/e. It is found in the simulations that during the accumulation of cold electrons,  scales as e T  . In addition, the results show that the transverse position of electron source has a great impact on ion beam neutralization. Slight shift of electron source leads to large increase of the beam potential because of increase in potential energy of injected electrons.

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Neutralization of ion beam by electron injection: Excitation and propagation of electrostatic solitary waves

Cited by 14 publications

References 55 publications

Direct-drive heavy ion beam inertial confinement fusion: a review, toward our future energy source

Direct-drive heavy ion beam inertial confinement fusion: a review, toward our future energy source

Excitation of electrostatic solitary waves and surface waves in ion beam neutralization process

Neutralization of ion beam by electron injection: Accumulation of cold electrons

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