Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling

Vay, Jean‐Luc; Furman, M.A.; Seidl, P.A.; Cohen, R. H.; Friedman, A.; Grote, D.P.; Covo, M. Kireeff; Molvik, A.W.; Stoltz, Peter; Veitzer, Seth; Verboncoeur, John P.

doi:10.1109/pac.2005.1590486

Cited by 9 publications

(10 citation statements)

References 12 publications

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“…3.2. Self-consistent numerical simulations provide semi-quantitative agreement with the experimental results [44,48]. Quantitative agreement between the measured currents to the clearing electrodes in the last two drift regions between the quadrupole magnets has also been obtained with the simulations when the electron suppressor is turned off.…”

Section: Iiic Electron Cloud Physics In the High Current Experimentssupporting

confidence: 72%

US Heavy Ion Beam Research for High Energy Density Physics Applications and Fusion

Davidson¹,

Logan²,

Barnard³

et al. 2005

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Section: Iiic Electron Cloud Physics In the High Current Experimentssupporting

confidence: 72%

US Heavy Ion Beam Research for High Energy Density Physics Applications and Fusion

Davidson¹,

Logan²,

Barnard³

et al. 2005

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“…The physical limit corresponds to N s → ∞. We have benchmarked WARP/POSINST in QSM against the CERN code HEADTAIL for the case of the LHC beam, showing excellent agreement [11,12]. Fig.…”

Section: Electron Cloud Effects On the Beammentioning

confidence: 99%

HINS R&D Collaboration on Electron Cloud Effects: MidyearReport

Furman¹,

Sonnad²,

Vay³

2006

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We present a report on ongoing activities on electron-cloud R&D for the MI upgrade. These results update and extend those presented in Refs. 1, 2. In this report we have significantly expanded the parameter range explored in bunch intensity N b , RMS bunch length σz and peak secondary emission yield (SEY) δmax, but we have constrained our simulations to a field-free region. We describe the threshold behaviors in all of the above three parameters. For δmax ≥ 1.5 we find that, even for N b = 1 × 10 11 , the electron cloud density, when averaged over the entire chamber, exceeds the beam neutralization level, but remains significantly below the local neutralization level (ie., when the electron density is computed in the neighborhood of the beam). This "excess" of electrons is accounted for by narrow regions of high concentration of electrons very close to the chamber surface, especially at the top and bottom of the chamber, akin to virtual cathodes. These virtual cathodes are kept in equilibrium, on average, by a competition between space-charge forces (including their images) and secondary emission, a mechanism that shares some features with the space-charge saturation of the current in a diode at high fields. For N b = 3 × 10 11 the electron cloud build-up growth rate and saturation density have a strong dependence on σz as σz decreases below ∼ 0.4 m, when the average electron-wall impact energy roughly reaches the energy Emax where δ peaks. We also present improved results on emittance growth simulations of the beam obtained with the code WARP/POSINST in quasi-static mode, in which the beam-(electron cloud) interaction is lumped into Ns "stations" around the ring, where Ns = 1, 2, . . . , 9. The emittance shows a rapid growth of ∼ 20% during the first ∼ 100 turns, followed by a much slower growth rate of ∼ 0.03%/turn. Concerning the electron cloud detection technique using microwave transmission, we present an improved dispersion relation for the TE mode of the microwaves, and a corresponding analytic estimate of the phase shift. I. ELECTRON CLOUD BUILD-UP.A. Remarks on the simulations.We have replaced the Poisson solver of the code POSINST [3][4][5][6], used in the computation of the electron cloud space-charge forces, by a multigrid-type solver that is much faster and more accurate than the old one. We have carefully tested the new solver in stand-alone mode, and we are confident that it gives correct (indeed, quite accurate) results. Owing to its inefficiency, the old solver could realistically be used only for very coarse grids, leading to intermittent problems at high N b and/or high δ max that sometimes crashed the code. For MI simulations, the improved code yields results only a few percent different from the old ones [1] for those cases in which the above-mentioned problem did not materialize. For other cases, notably the simulation of an LHC * Work supported by the FNAL HINS R&D Effort and by the US DOE under contract DE-AC02-05CH11231.† Electronic address: mafurman@lbl.gov; URL: http://mafurman. lbl.go...

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“…The tools and numerical techniques are also proving very useful for a broad range of accelerator physics and particle trap applications. A comprehensive set of models [28] governing the interaction of positively-charged beams with electron clouds (eclouds) and gas has been developed and implemented in the WARP code. Secondary electron emission from walls, charge exchange, neutral emission, and other processes are now included.…”

Section: Advanced Theory and Simulation Toolsmentioning

confidence: 99%

Recent US advances in ion-beam-driven high energy density physics and heavy ion fusion

Logan

Bieniosek

Celata

et al. 2007

Nuclear Instruments and Methods in Physics Research Section A:

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During the past two years, significant experimental and theoretical progress has been made in the U.S. heavy ion fusion science program in longitudinal beam compression, ion-beam-driven warm dense matter, beam acceleration, high brightness beam transport, and advanced theory and numerical simulations. Innovations in longitudinal compression of intense ion beams by > 50 X propagating through background plasma enable initial beam target experiments in warm dense matter to begin within the next two years. We are assessing how these new techniques might apply to heavy ion fusion drivers for inertial fusion energy. IntroductionA coordinated heavy ion fusion science program by the Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and Princeton Plasma Physics Laboratory (the HeavyIon Fusion Science Virtual National Laboratory), together with collaborators at Voss Scientific and Sandia National Laboratories, pursues research on compressing heavy ion beams towards the high intensities required for creating high energy density matter and fusion energy. In previous research, experiments [1] and simulations [2] showed >100X increases in focused beam intensities in the Neutralized Transport Experiment by transverse compression of an intense ion beam propagating through a background plasma to neutralize >90% of the beam space charge. Section 2 describes recent work on longitudinal compression of an intense beam within neutralizing plasma, and in Sec. 3 we describe studies of initial warm dense matter target experiments that can begin in 2008 after transverse and longitudinal beam compression are combined. Progress in testing a novel Pulse Line Ion Accelerator (PLIA) is described in Sec. 4, e-cloud experiments, theory and simulations in Sec 5, advanced injectors in Sec 6, and advanced theory and simulation models in Sec 7. Section 8 discusses potential applications to heavy ion fusion drivers, and conclusions are given in Sec. 9.

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Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling

Cited by 9 publications

References 12 publications

US Heavy Ion Beam Research for High Energy Density Physics Applications and Fusion

US Heavy Ion Beam Research for High Energy Density Physics Applications and Fusion

HINS R&D Collaboration on Electron Cloud Effects: MidyearReport

Recent US advances in ion-beam-driven high energy density physics and heavy ion fusion

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