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Title: Intense ion beam neutralization using underdense background plasma

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 1; Related Information: CHORUS Timestamp: 2016-12-26 05:21:10; Journal ID: ISSN 1070-664X
American Institute of Physics
Country of Publication:
United States

Citation Formats

Berdanier, William, Roy, Prabir K., and Kaganovich, Igor. Intense ion beam neutralization using underdense background plasma. United States: N. p., 2015. Web. doi:10.1063/1.4905631.
Berdanier, William, Roy, Prabir K., & Kaganovich, Igor. Intense ion beam neutralization using underdense background plasma. United States. doi:10.1063/1.4905631.
Berdanier, William, Roy, Prabir K., and Kaganovich, Igor. 2015. "Intense ion beam neutralization using underdense background plasma". United States. doi:10.1063/1.4905631.
title = {Intense ion beam neutralization using underdense background plasma},
author = {Berdanier, William and Roy, Prabir K. and Kaganovich, Igor},
abstractNote = {},
doi = {10.1063/1.4905631},
journal = {Physics of Plasmas},
number = 1,
volume = 22,
place = {United States},
year = 2015,
month = 1

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4905631

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Cited by: 2works
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  • Producing an overdense background plasma for neutralization purposes with a density that is high compared to the beam density is not always experimentally possible. We show that even an underdense background plasma with a small relative density can achieve high neutralization of intense ion beam pulses. Using particle-in-cell simulations, we show that if the total plasma electron charge is not sufficient to neutralize the beam charge, electron emitters are necessary for effective neutralization but are not needed if the plasma volume is so large that the total available charge in the electrons exceeds that of the ion beam. Several regimesmore » of possible underdense/tenuous neutralization plasma densities are investigated with and without electron emitters or dense plasma at periphery regions, including the case of electron emitters without plasma, which does not effectively neutralize the beam. Over 95% neutralization is achieved for even very underdense background plasma with plasma density 1/15th the beam density. We compare results of particle-in-cell simulations with an analytic model of neutralization and find close agreement with the particle-in-cell simulations. Further, we show experimental data from the National Drift Compression experiment-II group that verifies the result that underdense plasma can neutralize intense heavy ion beams effectively.« less
  • Time dependent large angular spreading and spectral broadening of an intense randomized laser beam propagating in an underdense, well-characterized plasma is measured. The two features are correlated and increase with laser intensity or plasma density. This spatial and temporal incoherence imposed upon the beam via the coupling with the plasma is interpreted, in agreement with recent numerical simulations, as due to the interplay between dynamical filamentation and strongly driven stimulated Brillouin forward scattering.
  • A scheme for electron self-injection in the laser wakefield acceleration is proposed. In this scheme, the transverse wave breaking of the wakefield and the tightly focused geometry of the laser beam play important roles. A large number of the background electrons are self-injected into the acceleration phase of the wakefield during the defocusing of the tightly focused laser beam as it propagates through an underdense plasma. Particle-in-cell simulations performed using a 2D3V code have shown generation of a collimated electron bunch with a total number of 1.4x10{sup 9} and energies up to 8 MeV.
  • The mechanism for the deneutralization of a positive ion beam during the excitation of plasma waves in a neutralizing electron background is studied. The deneutralization of extended fast beams which are not too dense is governed by not only the electron heating through Coulomb collisions with beam ions but also the longitudinal acceleration of electrons by the fields of the electron waves excited by the beam. Experimental data which have been obtained on the constant and varying beam potentials during a nonlinear ion-electron interaction are consistent with calculations based on the trapping of electrons by wave fields.
  • An analytical electron fluid model has been developed to describe the plasma response to a propagating ion beam. The model predicts very good charge neutralization during quasi-steady-state propagation, provided the beam pulse duration is much longer than the electron plasma period. In the opposite limit, the beam pulse excites large-amplitude plasma waves. Figure 1 shows the influence of a solenoidal magnetic field on charge and current neutralization. Analytical studies show that the solenoidal magnetic field begins to influence the radial electron motion when {omega}{sub ce} > {beta}{omega}{sub pe}. Here, {omega}{sub ce} is the electron gyrofrequency, {omega}{sub pe} is the electronmore » plasma frequency, and {beta} = V{sub b}/c is the ion beam velocity. If a solenoidal magnetic field is not applied, plasma waves do not propagate. In contrast, in the presence of a solenoidal magnetic field, whistler waves propagate ahead of the beam and can perturb the plasma ahead of the beam pulse. In the limit {omega}{sub ce} >> {beta}{omega}{sub pe}, the electron current completely neutralizes the ion beam current and the beam self magnetic field greatly diminishes. Application of an external solenoidal magnetic field clearly makes the collective processes of ion beam-plasma interactions rich in physics content. Many results of the PIC simulations remain to be explained by analytical theory. Four new papers have been published or submitted describing plasma neutralization of an intense ion beam pulse.« less