Chamber propagation physics for heavy ion fusion

Callahan, D. A.

doi:10.1016/s0920-3796(96)00500-5

Cited by 68 publications

(45 citation statements)

References 13 publications

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“…Indeed, in order to test the collective focusing, one needs to lower the final focus solenoid magnetic field from 8 T to several hundred gauss and turn off the cathodicarc plasma sources. It is then expected that the beam will drag the required neutralizing comoving electrons from the background plasma that fills the drift section [16][17][18][19][20][21] and will experience strong collective focusing inside the magnetic solenoid.…”

Section: -3mentioning

confidence: 99%

Collective focusing of intense ion beam pulses for high-energy density physics applications

Dorf¹,

Kaganovich²,

Startsev³

et al. 2011

Physics of Plasmas

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The collective focusing concept in which a weak magnetic lens provides strong focusing of an intense ion beam pulse carrying a neutralizing electron background is investigated by making use of advanced particle-in-cell simulations and reduced analytical models. The original analysis by Robertson ͓Phys. Rev. Lett. 48, 149 ͑1982͔͒ is extended to the parameter regimes of particular importance for several high-energy density physics applications. The present paper investigates ͑1͒ the effects of non-neutral collective focusing in a moderately strong magnetic field; ͑2͒ the diamagnetic effects leading to suppression of the applied magnetic field due to the presence of the beam pulse; and ͑3͒ the influence of a finite-radius conducting wall surrounding the beam cross-section on beam neutralization. In addition, it is demonstrated that the use of the collective focusing lens can significantly simplify the technical realization of the final focusing of ion beam pulses in the Neutralized Drift Compression Experiment-I ͑NDCX-I͒, and the conceptual designs of possible experiments on NDCX-I are investigated by making use of advanced numerical simulations.

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Section: -3mentioning

confidence: 99%

Collective focusing of intense ion beam pulses for high-energy density physics applications

Dorf¹,

Kaganovich²,

Startsev³

et al. 2011

Physics of Plasmas

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“…4. Gains are shown for targets without hydrogen in the fill gas (C5D!, for Nova and pure He for NIF) and for the basehe designs (C,Dl2 for Nova and equimolar H/He for NIF). The gasbag targets have somewhat higher peak gains than the Nova hohlraum targets for similar fill conditions, primarily because the plasma density is more homogeneous in the gasbags.…”

Section: Nova Target Designsmentioning

confidence: 99%

Inertial confinement fusion quarterly report: October--December 1995. Volume 6, Number 1

McEachern¹,

Carpenter²,

Miguel³

et al. 1996

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In this issue: Foreword Theory and Simulations of Nonlinear SBS in Multispecies PlasmasGas-filled hohlraums are the preferred targets for indirect-drive fusion experiments planned for the National Ignition Facility. However, instabilities like stimulated Brillouin scattering in the gas may reflect large amounts of laser light out of the hohlraum. We report on a method developed to control this instability-small amount of hydrogen added to the gas strongly decreases the reflected light. Modeling of Self-Focusing Experiments by Beam Propagation CodesTo validate the codes PROP1 and PROPZ, we used data from two 1053-nm self-focusing experiments in fused silica. Self-focusing damage in the sample was induced by placing a large wire in the beam in front of the silica sample. Using a small wire, damage to the sample was avoided, and induced lensing in the sample produced an intense image of the wire. Using the measured beam profiles and waveforms as input, and the value 2.7 x cm2/W for the selffocusing coefficient in silica, the codes successfully predicted the length of the self-focusing tracks and the intensity in the induced image.iii 1 7 Gas-Filled Target Designs Produce Ignition-Scale Plasma Conditions with Nova 15Gas-filled targets provide large, uniform underdense plasmas for laser-plasma interaction experiments on Nova. This article discusses design considerations for these targets and presents calculated plasma profiles, target characterization results, and comparisons with underdense plasma parameters in ignition hohlraum designs for the National Ignition FaciIity. Stimulated Brillouin Scattering in Multispecies PlasmasLaser light propagating through the underdense plasma in a hohlraum, or the corona of a direct-drive target, is subject to stimulated Brillouin scattering (SBS). Such scattering can cause significant loss of incident laser energy and/or affect the symmetry of the implosion. This article discusses the use of mixtures (e.g., H/He) to tailor the Landau damping of the SBS driven ion acoustic waves, thereby providing a powerful method to control the instability. Optical Scatter-A Diagnostic Tool to Investigate Laser Damage in KDP and DKDPDetermining and controlling the sources of laser-induced damage in crystals of KH,PO, and deuterated KDP is important for successful production of crystals for the National Ignition Facility. This article describes the implementation of a scatter diagnostic for in situ studies of laserinduced damage and initial results from these studies. Soft X-Ray Interferometry 32The short wavelength of existing soft x-ray lasers makes them well suited to probing lar e highdensity plasmas. We have combined a multilayer optic-based interferometer and a 155 1 x-ray laser source to measure the electron density profile in millimeter-size laser-produced plasmas. Metastable Crystal Structures of Solid HydrogenWe have determined the crystal structure of vapor deposited H, or D, crystals using Raman spectroscopy. While hcp is the equilibrium crystal structure, other metastable crystal s...

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“…In a heavy ion driver, intense beams of ions [1][2][3] are transported through a final-focus magnet system to the target chamber, where they must transversely focus onto the target with a final diameter of a few millimeters or less [4,5]. In addition, the ion beams need to be focused longitudinally in order to achieve large amounts of beam current in pulses with durations less than 10 nanoseconds.…”

Section: Introductionmentioning

confidence: 99%

Fast Faraday cup to measure neutralized drift compression in intense ion charge bunches

Sefkow

Davidson

Efthimion

et al. 2006

Phys. Rev. ST Accel. Beams

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Heavy ion drivers for heavy ion fusion and high energy density physics applications use space-chargedominated ion beams which must undergo longitudinal bunch compression in order to meet the requisite beam intensities desired at the target. The Neutralized Drift Compression Experiment-1A (NDCX-1A) at Lawrence Berkeley National Laboratory is used to determine the effective limits of neutralized drift compression, which occurs due to an imposed longitudinal velocity tilt on the drifting beam and subsequent neutralization of the beam's space charge with background plasma. The accurate and temporally resolved measurement of the ion beam's current and pulse length, which has been longitudinally compressed to a few nanoseconds duration at its focal plane, is a critical diagnostic. This paper describes the design and experimental results for a fast and accurate ion beam probe, which reliably measures the absolute beam current in the presence of high density plasma at the focal plane as a function of time. A particle-in-cell code has been used to model the propagation of the intense ion beam and to design the diagnostic probe.

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Chamber propagation physics for heavy ion fusion

Cited by 68 publications

References 13 publications

Collective focusing of intense ion beam pulses for high-energy density physics applications

Collective focusing of intense ion beam pulses for high-energy density physics applications

Inertial confinement fusion quarterly report: October--December 1995. Volume 6, Number 1

Fast Faraday cup to measure neutralized drift compression in intense ion charge bunches

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