E. M. Campbell

Bio: E. M. Campbell is an academic researcher from University of Rochester. The author has contributed to research in topics: Inertial confinement fusion & Laser. The author has an hindex of 38, co-authored 132 publications receiving 7170 citations. Previous affiliations of E. M. Campbell include University of California, Berkeley & General Atomics.

Intense High-Energy Proton Beams from Petawatt-Laser Irradiation of Solids

Abstract: An intense collimated beam of high-energy protons is emitted normal to the rear surface of thin solid targets irradiated at 1 PW power and peak intensity 3x10(20) W cm(-2). Up to 48 J ( 12%) of the laser energy is transferred to 2x10(13) protons of energy >10 MeV. The energy spectrum exhibits a sharp high-energy cutoff as high as 58 MeV on the axis of the beam which decreases in energy with increasing off axis angle. Proton induced nuclear processes have been observed and used to characterize the beam.

Fast ignition by intense laser-accelerated proton beams.

Abstract: The concept of fast ignition with inertial confinement fusion (ICF) is a way to reduce the energy required for ignition and burn and to maximize the gain produced by a single implosion. Based on recent experimental findings at the PETAWATT laser at Lawrence Livermore National Laboratory, an intense proton beam to achieve fast ignition is proposed. It is produced by direct laser acceleration and focused onto the pellet from the rear side of an irradiated target and can be integrated into a hohlraum for indirect drive ICF.

Demonstration of a soft x-ray amplifier.

Abstract: We report observations of amplified spontaneous emission at soft x-ray wavelengths. An optical laser ionized thin foils of selenium to produce a population inversion of the $2{p}^{5}3p$ and $2{p}^{5}3s$ levels of the neonlike ion. Using three time-resolved, spectroscopic measurements we demonstrated gain-length products up to 6.5 and gain coefficients of 5.5\ifmmode\pm\else\textpm\fi{}1.0 ${\mathrm{cm}}^{\ensuremath{-}1}$ for the $J=2 \mathrm{to} 1$ lines at 206.3 and 209.6 \AA{}. We also observed considerable amplification for the same transitions in yttrium at 155.0 and 157.1 \AA{}.

Exploding-Foil Technique for Achieving a Soft X-Ray Laser

Abstract: We describe a design for producing a soft x-ray laser via $3p\ensuremath{-}3s$ transitions in Ne-like selenium (wavelength of about 200 \AA{}). A 0.53-\ensuremath{\mu} m laser, focused in a 1.2\ifmmode\times\else\texttimes\fi{}0.02-cm spot to \ensuremath{\sim} 5\ifmmode\times\else\texttimes\fi{}${10}^{13}$ W/${\mathrm{cm}}^{2}$, heats and burns through a thin foil of Se. Besides ionizing the Se to a Ne-like state, the laser explodes the foil, creating a region of uniform electron density. This allows propagation of the x rays down the 1-cm-long gain direction without debilitating refraction. Gains of 4 to 10 ${\mathrm{cm}}^{\ensuremath{-}1}$ are predicted for various transitions.

Review of progress in Fast Ignitiona)

Abstract: Marshall Rosenbluth’s extensive contributions included seminal analysis of the physics of the laser-plasma interaction and review and advocacy of the inertial fusion program. Over the last decade he avidly followed the efforts of many scientists around the world who have studied Fast Ignition, an alternate form of inertial fusion. In this scheme, the fuel is first compressed by a conventional inertial confinement fusion driver and then ignited by a short (∼10ps) pulse, high-power laser. Due to technological advances, such short-pulse lasers can focus power equivalent to that produced by the hydrodynamic stagnation of conventional inertial fusion capsules. This review will discuss the ignition requirements and gain curves starting from simple models and then describe how these are modified, as more detailed physics understanding is included. The critical design issues revolve around two questions: How can the compressed fuel be efficiently assembled? And how can power from the driver be delivered efficient...

Development of the indirect‐drive approach to inertial confinement fusion and the target physics basis for ignition and gain

Abstract: Inertial confinement fusion (ICF) is an approach to fusion that relies on the inertia of the fuel mass to provide confinement. To achieve conditions under which inertial confinement is sufficient for efficient thermonuclear burn, a capsule (generally a spherical shell) containing thermonuclear fuel is compressed in an implosion process to conditions of high density and temperature. ICF capsules rely on either electron conduction (direct drive) or x rays (indirect drive) for energy transport to drive an implosion. In direct drive, the laser beams (or charged particle beams) are aimed directly at a target. The laser energy is transferred to electrons by means of inverse bremsstrahlung or a variety of plasma collective processes. In indirect drive, the driver energy (from laser beams or ion beams) is first absorbed in a high‐Z enclosure (a hohlraum), which surrounds the capsule. The material heated by the driver emits x rays, which drive the capsule implosion. For optimally designed targets, 70%–80% of the d...

The physics basis for ignition using indirect-drive targets on the National Ignition Facility

Abstract: The 1990 National Academy of Science final report of its review of the Inertial Confinement Fusion Program recommended completion of a series of target physics objectives on the 10-beam Nova laser at the Lawrence Livermore National Laboratory as the highest-priority prerequisite for proceeding with construction of an ignition-scale laser facility, now called the National Ignition Facility (NIF). These objectives were chosen to demonstrate that there was sufficient understanding of the physics of ignition targets that the laser requirements for laboratory ignition could be accurately specified. This research on Nova, as well as additional research on the Omega laser at the University of Rochester, is the subject of this review. The objectives of the U.S. indirect-drive target physics program have been to experimentally demonstrate and predictively model hohlraum characteristics, as well as capsule performance in targets that have been scaled in key physics variables from NIF targets. To address the hohlrau...

Recycling lower continental crust in the North China craton

Abstract: Foundering of mafic lower continental crust into underlying convecting mantle has been proposed as one means to explain the unusually evolved chemical composition of Earth's continental crust, yet direct evidence of this process has been scarce. Here we report that Late Jurassic high-magnesium andesites, dacites and adakites (siliceous lavas with high strontium and low heavy-rare-earth element and yttrium contents) from the North China craton have chemical and petrographic features consistent with their origin as partial melts of eclogite that subsequently interacted with mantle peridotite. Similar features observed in adakites and some Archaean sodium-rich granitoids of the tonalite-trondhjemite-granodiorite series have been interpreted to result from interaction of slab melts with the mantle wedge. Unlike their arc-related counterparts, however, the Chinese magmas carry inherited Archaean zircons and have neodymium and strontium isotopic compositions overlapping those of eclogite xenoliths derived from the lower crust of the North China craton. Such features cannot be produced by crustal assimilation of slab melts, given the high Mg#, nickel and chromium contents of the lavas. We infer that the Chinese lavas derive from ancient mafic lower crust that foundered into the convecting mantle and subsequently melted and interacted with peridotite. We suggest that lower crustal foundering occurred within the North China craton during the Late Jurassic, and thus provides constraints on the timing of lithosphere removal beneath the North China craton.