The controlling role of envelope mismatches in intense inhomogeneous charged beams

Souza, Everton Granemann; Endler, Antônio; Pakter, Renato; Rizzato, Felipe Barbedo; Nunes, Roger Pizzato

doi:10.1063/1.3385393

Cited by 16 publications

(18 citation statements)

References 10 publications

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“…We recall that fast wave-breaking occurs when magnetic focusing is strong and waves break in less than an oscillatory cycle, with slow wave-breaking occurring only after a series of oscillatory cycles. 13,21 V. CONCLUSIONS…”

Section: B Space-charge Effectsmentioning

confidence: 98%

“…As far as particle dynamics is concerned, the setting is relatively similar to the wave-breaking process in the case of magnetically focused charged beams. 12,13 The bunching action of the ponderomotive force in FELs indeed plays an equivalent role to the focusing action of the guiding magnetic field, and in both cases space-charge effects oppose the focusing drive.…”

Section: Introductionmentioning

confidence: 99%

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Mixing and space-charge effects in free-electron lasers

et al. 2013

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The present work revisits the subjects of mixing, saturation, and space-charge effects in free-electron lasers. Use is made of the compressibility factor, which proves to be a helpful tool in the related systems of charged beams confined by static magnetic fields. The compressibility allows to perform analytical estimates of the elapsed time until the onset of mixing, which in turn allows to estimate the saturated amplitude of the radiation field. In addition, the compressibility helps to pinpoint space-charge effects and the corresponding transition from Compton to Raman regimes. V C 2013 AIP Publishing LLC. [http://dx

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Section: B Space-charge Effectsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Mixing and space-charge effects in free-electron lasers

et al. 2013

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“…Thus phase mixing is a slow process that leads to wave breaking. Slow wave breaking of plasma oscillations is being studied extensively in various physical regimes [43][44][45][46] .…”

Section: Introductionmentioning

confidence: 99%

Nonlinear oscillations and waves in multi-species cold plasmas

Verma

2016

Physics of Plasmas

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The spatio-temporal evolution of nonlinear oscillations in multi-species plasma is revisited to provide more insight into the physics of phase mixing by constructing two sets of nonlinear solutions up to the second order. The first solution exhibits perfect oscillations in the linear regime and phase mixing appears only nonlinearly in the second order as a response to the ponderomotive forces.This response can be both direct and indirect. The indirect contribution of the ponderomotive forces appears through self-consistently generated low frequency fields. Furthermore, the direct and indirect contributions of the ponderomotive forces on the phase mixing process is explored and it is found that the indirect contribution is negligible in an electron-ion plasma and it disappears in the case of electron-positron plasma, yet represents an equal contribution in the electron-positron-ion plasma. However, the second solution does not exhibit any phase mixing due to the absence of ponderomotive forces but results in an undistorted nonlinear traveling wave. These investigations have relevance for laboratory/astrophysical multi-species plasma.

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“…The truncation is obtained by assuming a certain characteristic for the system dynamics which is expressed by an equation of state. Perhaps, the simplest used approximation is the cold fluid, which completely neglects thermal effects by assuming a vanishing temperature [6][7][8][9][10][11][12]. Other examples of largely used equations of state are isothermal [13][14][15][16][17] and adiabatic [18,19].…”

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Adiabatic-Nonadiabatic Transition in Warm Long-Range Interacting Systems: The Transport of Intense Inhomogeneous Beams

et al. 2012

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We investigate the role of the temperature in the onset of singularities and the consequent breakdown in a macroscopic fluid model for long-range interacting systems. In particular, we consider an adiabatic fluid description for the transport of intense inhomogeneous charged particle beams. We find that there exists a critical temperature below which the fluid model always develops a singularity and breaks down as the system evolves. As the critical temperature is approached, however, the time for the occurrence of the singularity diverges. Therefore, the critical temperature separates two distinct dynamical phases: a nonadiabatic transport at lower temperatures and a completely adiabatic evolution at higher temperatures. These findings are verified with the aid of self-consistent N-particle simulations. For long-range self-interacting systems, it is generally very difficult to obtain a fully kinetic description of the dynamics. This is the case in plasmas, charged particle beams, and self-gravitating systems among others, where the collision duration time diverges in the thermodynamic limit [1][2][3][4][5]. A largely used tool to overcome this difficulty is the employment of macroscopic fluid models. In contrast to the kinetic description that requires the knowledge of the evolution of the distribution function in the full phase space, the fluid description is simpler because it is based on local macroscopic variables obtained by averaging over the momentum space. Moreover, because the fluid variables consist of readily understood macroscopic quantities, the physical interpretation of the phenomena under investigation is generally more direct. Nevertheless, except for very specific cases, the fluid description leads to an infinite hierarchy of equations which, in practice, have to be truncated to be analyzed. The truncation is obtained by assuming a certain characteristic for the system dynamics which is expressed by an equation of state. Perhaps, the simplest used approximation is the cold fluid, which completely neglects thermal effects by assuming a vanishing temperature [6][7][8][9][10][11][12]. Other examples of largely used equations of state are isothermal [13][14][15][16][17] and adiabatic [18,19]. At any rate, the validity of the fluid description resides not only on the choice of equation of state but also on the fact that the infinite hierarchy has to be convergent; i.e., the macroscopic fluid variables may not present singularities. In the case of cold fluids, a wellknown cause of singularities is the onset of the so-called wave breaking where the fluid description looses its validity due to a divergence in the particles density at a certain position and time. This phenomenon is associated with a filamentation in the phase space and may have relevant consequences such as temperature increase, energy redistribution, and particle acceleration, depending on the system.In this Letter, we investigate the role of the temperature in the onset of singularities in the macroscopic quantities and the consequen...

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The controlling role of envelope mismatches in intense inhomogeneous charged beams

Cited by 16 publications

References 10 publications

Mixing and space-charge effects in free-electron lasers

Mixing and space-charge effects in free-electron lasers

Nonlinear oscillations and waves in multi-species cold plasmas

Adiabatic-Nonadiabatic Transition in Warm Long-Range Interacting Systems: The Transport of Intense Inhomogeneous Beams

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