Showing papers by "T. W. Phillips published in 1997"
TL;DR: In this paper, a review of recent progress on the design of a diagnostic system proposed for ignition target experiments on the National Ignition Facility (NIF) is presented, which includes an extensive suite of optical, x ray, gamma ray, and neutron diagnostics that enable measurements of the performance of both direct and indirect driven NIF targets.
Abstract: A review of recent progress on the design of a diagnostic system proposed for ignition target experiments on the National Ignition Facility (NIF) will be presented. This diagnostic package contains an extensive suite of optical, x ray, gamma ray, and neutron diagnostics that enable measurements of the performance of both direct and indirect driven NIF targets. The philosophy used in designing all of the diagnostics in the set has emphasized redundant and independent measurement of fundamental physical quantities relevant to the operation of the NIF target. A unique feature of these diagnostics is that they are being designed to be capable of operating in the high radiation, electromagnetic pulse, and debris backgrounds expected on the NIF facility. The diagnostic system proposed can be categorized into three broad areas: laser characterization, hohlraum characterization, and capsule performance diagnostics. The operating principles of a representative instrument from each class of diagnostic employed in this package will be summarized and illustrated with data obtained in recent prototype diagnostic tests.
41 citations
TL;DR: In this article, the design and fabrication of a new diagnostic that measures the energy spectra of charged particles from targets on the Omega Upgrade are actively underway, using seven 512×512 charge coupled devices (CCDs) and a 7.5 kG permanent magnet.
Abstract: The design and fabrication of a new diagnostic that measures the energy spectra of charged particles from targets on the Omega Upgrade are actively underway. Using seven 512×512 charge coupled devices (CCDs) and a 7.5 kG permanent magnet, this instrument will uniquely determine particle identities and measure particle energies from 1 MeV up to the maximum charged particle energies of interest for ρR measurements (10.6 MeV knock-on tritons, 12.5 MeV knock-on deuterons and 30.8 MeV tertiary protons). The resolution of the diagnostic will be better than 5%. We have tested the response of SITe back-illuminated CCDs to 1.2–13.6 MeV protons from our Cockcroft–Walton accelerator and to alpha particles from an Am241 source, and the results agree extremely well with predictions. With its high density picture elements, each CCD has 105 single-hit detectors. In the case of a low DT yield of 109 neutrons, about 100 knock-on charged particles will be detected when the spectrometer aperture is 60 cm from the implosion....
21 citations
TL;DR: In this paper, a low density, high temperature plasma buffer between the absorption and ablation layers of a directly driven inertial confinement fusion implosion capsule has been proposed as a means to reduce the early time imprint from laser nonuniformities.
Abstract: Creation of a low density, high temperature plasma buffer between the absorption and ablation layers of a directly driven inertial confinement fusion implosion capsule has been proposed as a means to reduce “early time” imprint from laser nonuniformities. This thermal smoothing blanket might be created from a low density foam layer wrapped around the deuterium–tritium filled microballoon. Preliminary spherical implosion tests of this concept using a polystyrene foam layer surrounding a glass microballoon were performed at the Nova laser [Rev. Sci. Instrum. 57, 2101 (1986)], using a 527 nm drive wavelength. Comparison of capsule yield and imploded core symmetry showed promising improvements in overall target performance, relative to one-dimensional undegraded hydrodynamic simulations, when the foam-buffer layer was present.
12 citations
TL;DR: In this article, the authors have exposed CR-39 track recording material to a number of NOVA implosions and quantitatively compared the DD neutron yield with the DD proton yield determined from the track.
Abstract: We have exposed CR-39 track recording material to a number of NOVA implosions. Radiation from the implosion passed through an array of ranging filters, which aided identification of the incident particles and their energies. The etching procedure was calibrated by including a piece of track exposed to DD protons from a small accelerator. For the same shots, we quantitatively compare the DD neutron yield with the DD proton yield determined from the track. In DT implosions, tracks produced by neutron interactions prevent observation of charged-particle tracks that are produced by the processes of knock on, secondary, or tertiary fusion.
8 citations
TL;DR: In this paper, the authors used charge-coupled devices (CCDs) for ρR and implosion symmetry diagnostics on OMEGA and NOVA, and performed comprehensive studies on several back-illuminated CCDs in order to establish their utility for determining particle energy and identity.
Abstract: Charge-coupled devices (CCDs) are to be utilized as charged-particle detectors for ρR and implosion symmetry diagnostics on OMEGA and NOVA. Using a large range of MeV charged particles, comprehensive studies have been performed on several back-illuminated CCDs in order to establish their utility for determining particle energy and identity (e.g., H, D, or T). Issues of signal and noise (i.e., especially from neutrons and gammas interacting with the CCDs) are also being investigated.
3 citations