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.

Articles you may be interested inA compact neutron spectrometer for characterizing inertial confinement fusion implosions at OMEGA and the NIF Rev. Sci. Instrum. 85, 063502 (2014); 10.1063/1.4880203 Improving the hot-spot pressure and demonstrating ignition hydrodynamic equivalence in cryogenic deuterium-tritium implosions on OMEGAa) Phys. Plasmas 21, 056315 (2014); 10.1063/1.4876618 Dynamic symmetry of indirectly driven inertial confinement fusion capsules on the National Ignition Facilitya) Phys. Plasmas 21, 056313 (2014); 10.1063/1.4876609 High-resolution spectroscopy used to measure inertial confinement fusion neutron spectra on Omega (invited)a) Rev. Sci. Instrum. 83, 10D919 (2012); 10.1063/1.4742926Study of direct-drive, deuterium-tritium gas-filled plastic capsule implosions using nuclear diagnostics at OMEGA With new measurement techniques, high-resolution spectrometry of secondary fusion protons has been used to study compression and symmetry of imploded D 2 -filled capsules in direct-drive inertial-confinement-fusion experiments at the 60-beam OMEGA laser facility ͓T. R. Boehly et al., Opt. Commun. 133, 495 ͑1997͔͒. Data from target capsules with ϳ15 atmospheres of D 2 fuel, in CH shells 19-27 m thick, were acquired with a magnet-based, charged-particle spectrometer and with several new ''wedge-range-filter''-based spectrometers incorporating special filters and CR39 nuclear track detectors. Capsules with 19-m shells, imploded with similar laser energies ͑ϳ23 kJ͒ but different methods of single-beam laser smoothing, were studied and found to show different compression characteristics as indicated by the fuel areal density ͑determined by the ratio of secondary-proton yield to primary-neutron yield͒ and the total areal density ͑determined by the energy loss of protons due to slowing in the fuel and shell͒. In going from 0.3-THz SSD ͑smoothing by spectral dispersion͒ to 1-THz SSD and PS ͑polarization smoothing͒, the fuel areal density increased by at least 30%, while the total areal density increased by 40% ͑from ϳ52 to ϳ72 mg/cm 2 ͒. In addition, significant low-mode-number spatial asymmetries in implosions were indicated by spectra measured at different angles with respect to the target. The mean energies of protons, measured at different angles during the same shot, varied by as much as 1 MeV, implying angular variations in areal density of order 30 mg/cm 2 . To the best of our knowledge, this is the first experimental demonstration that capsule symmetry can be sensitively studied by measuring the energy loss of charged particles.