Development of laser driven implosions of DT filled shells as thermonuclear particle sources

et al. 2002

Physics of Plasmas

Recent spectroscopic analysis of charged particles generated by fusion reactions in direct-drive implosion experiments at the OMEGA laser facility ͓T. R. Boehly et al., Opt. Commun. 133, 495 ͑1997͔͒ show the presence of low-mode-number asymmetries in compressed-capsule areal density (R) at the time of fusion burn. Experiments involved the acquisition and analysis of spectra of primary ͑14.7 MeV͒ protons, from capsules filled with deuterium and helium-3, and secondary ͑12.6-17.5 MeV͒ protons, from cryogenic deuterium capsules. The difference between the birth energy and measured energy of these protons provides a measure of the amount of material they passed through on their way out of a capsule, so measurements taken at different angles relative to a target provide information about angular variations in capsule areal density at burn time. Those variations have low-mode-number amplitudes as large as Ϯ50% about the mean ͑which is typically ϳ65 mg/cm 2 ͒; high-mode-number structure can lead to individual pathlengths through the shell that reach several times the mean. It was found that the observed R asymmetries are often similar for contiguous implosions, but change when the laser beam energy balance is significantly changed, indicating a direct connection between drive symmetry and implosion symmetry.

Section: A Note On the Structures Of Individual Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurements of ρR asymmetries at burn time in inertial-confinement-fusion capsules

et al. 2002

Physics of Plasmas

“…33 Attempts have also been made with DD protons. 21,24 Another method makes use of the fact that, if products of more than one reaction can be detected simultaneously, the possibility exists for comparing the ratio of their yields to the ratio of the theoretical rates for the reactions. Since these rate ratios often vary with ion temperature ͑see Figs.…”

Section: Ion Temperaturementioning

confidence: 99%

Spectrometry of charged particles from inertial-confinement-fusion plasmas

Review of Scientific Instruments

et al. 2003

230

133

High-resolution spectrometry of charged particles from inertial-confinement-fusion ͑ICF͒ experiments has become an important method of studying plasma conditions in laser-compressed capsules. In experiments at the 60-beam OMEGA laser facility ͓T. R. Boehly et al., Opt. Commun. 133, 495 ͑1997͔͒, utilizing capsules with D 2 , D 3 He, DT, or DTH fuel in a shell of plastic, glass, or D 2 ice, we now routinely make spectral measurements of primary fusion products ͑p, D, T, 3 He, ␣͒, secondary fusion products ͑p͒, ''knock-on'' particles ͑p, D, T͒ elastically scattered by primary neutrons, and ions from the shell. Use is made of several types of spectrometers that rely on detection and identification of particles with CR-39 nuclear track detectors in conjunction with magnets and/or special ranging filters. CR-39 is especially useful because of its insensitivity to electromagnetic noise and its ability to distinguish the types and energies of individual particles, as illustrated here by detailed calibrations of its response to 0.1-13.8 MeV protons from a Van de Graaff accelerator and to p, D, T, and ␣ from ICF experiments at OMEGA. A description of the spectrometers is accompanied by illustrations of their operating principles using data from OMEGA. Sample results and discussions illustrate the relationship of secondary-proton and knock-on spectra to capsule fuel and shell areal densities and radial compression ratios; the relationship of different primary fusion products to each other and to ion temperatures; the relationship of deviations from spherical symmetry in particle yields and energies to capsule structure; the acceleration of fusion products and the spectra of ions from the shell due to external fields; and other important physical characteristics of the laser-compressed capsules.

“…This approach has been used in imaging with DD protons and DT ␣ particles. [38][39][40][41] Section III describes a different direct, noniterative algorithum involving computation in the spatial domain only. It is computationally efficient, has no issues with filter singularities, and has a well-defined point-response function that allows calculation of simple and explicit scaling laws relating camera parameters and source type to the spatial resolution and signal-to-noise ratio of reconstructed source functions.…”

Section: Introductionmentioning

confidence: 99%

D 3 He -proton emission imaging for inertial-confinement-fusion experiments (invited)

Deciantis

Review of Scientific Instruments

et al. 2004

Proton emission imaging cameras, in combination with proton spectrometers and a proton temporal diagnostic, provide a great deal of information about the spatial structure and time evolution of inertial-confinement fusion capsule implosions. When used with D 3 He-filled capsules, multiple proton emission imaging cameras measure the spatial distribution of fusion burn, with three-dimensional information about burn symmetry. Simultaneously, multiple spectrometers measure areal density as a function of angle around the imploded capsule. Experiments at the OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have already proven the utility of this approach. An introduction to the hardware used for penumbral imaging, and algorithms used to create images of the burn region, are provided here along with simple scaling laws relating image resolution and signal-to-noise ratio to characteristics of the cameras and the burn region.