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Presents a technique for obtaining highly smooth focused laser beams. Strategy employed in the study; Implementation consideration for smoothing by spectral dispersion; Simulation results.

Presents a study that examined thermal transport, mass ablation rates and preheat in six-beam ultraviolet irradiation of spherical targets. Functionality of the thermal transport in laser-target interaction; Discussion of mass ablation and ablation pressure; Possible sources of the discrepancy between spectral and charge-collector measurements.

Proton radiography of the spatial structure and temporal evolution of plasma blowing off from a hohlraum wall reveals how the fill gas compresses the wall blow-off, inhibits plasma jet formation and impedes plasma stagnation in the hohlraum interior. The roles of spontaneously generated electric and magnetic fields in hohlraum dynamics and capsule implosions are demonstrated. The heat flux is shown to rapidly convect the magnetic field due to the Nernst effect, which is shown to be ~10 times faster than convection by the plasma fluid from expanded wall blow-off (νN ~ 10v). This leads to inhibition of heat transfer from the gas region in the laser beam paths to the surrounding cold gas, resulting in a local plasma temperature increase. The experiments show that interpenetration of the two materials (gas and wall) occurs due to the classical Rayleigh-Taylor instability as the lighter, decelerating ionized fill gas pushes against the heavier, expanding gold wall blow-off. This experiment provides physics insight into the effects of fill gas on x-ray-driven implosions, and would impact the ongoing ignition experiments at the National Ignition Facility. [ABSTRACT FROM AUTHOR]

Time-gated, monoenergetic-proton radiography provides unique measurements of the electric (E) and magnetic (B) fields produced in laser-foil interactions and during the implosion of inertial-confinement-fusion capsules. These experiments resulted in the first observations of several new and important features: (1) observations of the generation, decay dynamics, and instabilities of megagauss B fields in laser-driven planar plastic foils, (2) the observation of radial E fields inside an imploding capsule, which are initially directed inward, reverse direction during deceleration, and are likely related to the evolution of the electron pressure gradient, and (3) the observation of many radial filaments with complex electromagnetic field striations in the expanding coronal plasmas surrounding the capsule. The physics behind and implications of such observed fields are discussed. [ABSTRACT FROM AUTHOR]

Measurements from three classes of direct-drive implosions at the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] were combined with Monte Carlo simulations to investigate models for determining hot-fuel areal density (ρRhot) in compressed, D2-filled capsules, and to assess the impact of mix and other factors on the determination of ρRhot. The results of the Monte Carlo simulations were compared to predictions of simple, commonly used models that use ratios of either secondary D3He proton yields or secondary DT neutron yields to primary DD neutron yields to provide estimates ρRhot,2p or ρRhot,2n, respectively, for ρRhot. For the first class of implosion, where ρRhot is low (<=3 mg/cm2), ρRhot,2p and ρRhot,2n often agree with each other and are often good estimates of the actual ρRhot. For the second class of implosion, where ρRhot is of order 10 mg/cm2, ρRhot,2p often underestimates the actual value due to secondary proton yield saturation; in addition, fuel-shell mix causes ρRhot,2p to further underestimate, and ρRhot,2n to overestimate, ρRhot. As a result, values of ρRhot,2p and ρRhot,2n can be interpreted as lower and upper limits, respectively. For the third class of implosion, involving cryogenic capsules, secondary protons and neutrons are produced mainly in the hot and cold fuel regions, respectively, and the effects of the mixing of hot and cold fuel must be taken into account when interpreting the values of ρRhot,2p and ρRhot,2n. From these data sets, it is concluded that accurate inference of ρRhot requires comprehensive measurements and detailed modeling. © 2005 American Institute of Physics. [ABSTRACT FROM AUTHOR]

New experimental results describing the dynamics of D³He capsule implosions, performed at the 60 beam direct-drive OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], are presented. The capsules, nominally 940 μm in diameter and with 20-27 μm thick CH shells, were filled with 18 atm D³He gas and irradiated with 23 kJ of UV light. Simultaneous measurements of D³He burn history, DD burn history, and several time-integrated D³He proton energy spectra provided new results, such as shock-bang timing, shock-burn duration, evolution of the ion temperature, and evolution of ρR and ρR asymmetries. The shock-bang time measurements, when compared to calculation using the 1D LILAC code [J. Delettrez et al., Phys. Rev. A 36, 3926 (1987)], indicate that a varying flux limiter is required to explain the data, while the measured shock-burn duration is significantly shorter than 1D calculations, irrespective of flux limiter. The time evolution of ion temperature [Ti(t)] has been inferred from the ratio of the DD and the D³He burn histories, and a constant temperature is observed during the compression phase. The discrepancy between experimental data and 1D simulations during the final stages of the compression burn indicates that mix is significant, especially for the 20 and 24-μm capsule implosions. Evolution of ρR and ρR asymmetries show that the average ρR grows by a factor of ∼4 - 5 from shock-bang to compression-bang time, and that ρR asymmetries (l=1), primarily driven by capsule convergence, grows ∼2 times faster than the average ρR growth. [ABSTRACT FROM AUTHOR]

The evolution of shell modulations was measured in targets with titanium-doped layers using differential imaging [B. Yaakobi et al., Phys. Plasmas 7, 3727 (2000)] near peak compression of direct-drive spherical implosions. Inner-shell modulations grow throughout the deceleration phase of the implosion due to the Rayleigh-Taylor instability with relative modulation levels of ∼ 20% at peak neutron production and ∼50% at peak compression (∼100 ps later) in targets with 1-mm-diam, 20-μm-thick shells filled with 4 atm of D[SUP3] He gas. In addition, the shell modulations grow up to about 1.5 times due to Bell-Plesset convergent effects during the same period. At peak compression the inner part of the shell has a higher modulation level than other parts of the shell. [ABSTRACT FROM AUTHOR]

Capsule-areal-density (ρR) asymmetries are studied for direct-drive, spherical implosions on the OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Measurements of copious 14.7-MeV protons generated from D[SUP3] He fusion reactions in the imploded capsules are used to determine ρR. As they pass through the plasma, these protons lose energy, and this energy loss reflects the areal density of the transited plasma. Up to 11 proton spectrometers simultaneously view D[SUP3] He implosions on OMEGA from different directions. While the burn-averaged and spatially averaged ρR for each implosion is typically between 50 and 75 mg/cm[SUP2] for 20-μm plastic shells filled with 18 atm of D[SUP3] He gas, significant differences often exist between the individual spectra, and inferred ρR on a given shot (as large as ∼ ±640% about the mean). A number of sources inherent in the direct-drive approach to capsule implosions can lead to these measured ρR asymmetries. For example, in some circumstances these asymmetries can be attributed to beam-to-beam energy imbalance when this imbalance is relatively large (∼ 25% rms). However, for more uniform illumination the source of the asymmetries is still under investigation. [ABSTRACT FROM AUTHOR]

High-resolution spectrometry of charged particles from inertial-confinement-fusion (ICF) experiments has become an important method of studying plasma conditions in laser-compressed capsules. In experiments at the 60-beam OMEGA laser facility IT. R. Boehly et al., Opt. Commun. 133, 495 (1997)], utilizing capsules with D[sub 2], D³He, DT, or DTH fuel in a shell of plastic, glass, or D[sub 2] ice, we now routinely make spectral measurements of primary fusion products (p, D, T, ³He, α), secondary fusion products (p), "knock-on" particles (p, D, T) 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 α 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. [ABSTRACT FROM AUTHOR]

Implosions of capsules filled with small quantities of deuterium–tritium (DT) were studied using up to seven proton spectrometers on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Simultaneous measurements of elastically scattered protons, i.e., “knock-on” protons generated from DT neutrons were obtained in several directions. The capsules, nominally 945 μm in diameter and with CD shells of ∼20 μm thickness, were filled to about 15 atm and irradiated with 23 kJ of UV light. The high-energy protons from these implosions were used to infer fuel areal density (6.8±0.5 mg/cm[sup 2]), an average shell areal density (71±3 mg/cm[sup 2]), and shell asymmetries of up to about 25 mg/cm2. In addition to presenting new results, these measurements verify and significantly improve upon the accuracy of the fuel areal density results obtained utilizing knock-on deuterons from hydrodynamically equivalent, pure DT implosions [C. K. Li et al., Phys. Plasmas 8, 4902 (2001)]. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

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 (1997)] show the presence of low-mode-number asymmetries in compressed-capsule areal density (ρR) at the time of fusion burn. Experiments involved the acquisition and analysis of spectra of primary (14.7 MeV) protons, from capsules filled with deuterium and helium-3, and secondary (12.6-17.5 MeV) 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 bum time. Those variations have low-mode-number amplitudes as large as ±50% about the mean (which is typically ∼65 mg/cm²); high-mode-number structure can lead to individual pathlengths through the shell that reach several times the mean. It was found that the observed ρR 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. [ABSTRACT FROM AUTHOR]

The response of CR-39 track detectors to neutrons has been characterized and used to measure neutron yields from implosions of DD- and DT-filled targets at the OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], and the scaling of neutron fluence with R (the target-to-detector distance) has been used to characterize the fluence of backscattered neutrons in the target chamber. A Monte-Carlo code was developed to predict the CR-39 efficiency for detecting DD neutrons, and it agrees well with the measurements. Neutron detection efficiencies of (1.1 ± 0.2) × 10[sup -4] and (6.0 ± 0.7) × 10[sup -5] for the DD and DT cases, respectively, were determined for standard CR-39 etch conditions. In OMEGA experiments with both DD and DT targets, the neutron fluence was observed to decrease as R[sup -2] up to about 45 cm; at larger distances, a significant backscattered neutron component was seen. The measured backscattered component appears to be spatially uniform, and agrees with predictions of a neutron-transport code. As an additional application of the calibration results, it is shown that the neutron-induced signal in CR-39 used in charged-particle spectrometers on OMEGA can be used to determine DD and DT yields ranging from about 10[sup 10] up to 10[sup 14]. With further improvements in the processing and analysis of CR-39, this upper limit can be increased by at least two orders of magnitude. [ABSTRACT FROM AUTHOR]

With new measurement techniques, high-resolution spectrometry of secondary fusion protons has been used to study compression and symmetry of imploded D[sub 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 (1997)]. Data from target capsules with ∼15 atmospheres of D[sub 2] fuel, in CH shells 19-27 µm 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-µm shells, imploded with similar laser energies (∼23 kJ) 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 yield) and the total areal density (determined by the energy loss of protons due to slowing in the fuel and shell). In going from 0.3-THz SSD (smoothing by spectral dispersion) to 1-THz SSD and PS (polarization smoothing), the fuel areal density increased by at least 30%, while the total areal density increased by 40% (from ∼52 to ∼72 mg/cm²). 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/cm². 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. [ABSTRACT FROM AUTHOR]

Implosions of direct-drive, deuterium–tritium (DT) gas-filled plastic capsules are studied using nuclear diagnostics at the OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. In addition to traditional neutron measurements, comprehensive sets of spectra of deuterons, tritons, and protons elastically scattered from the fuel and shell by primary DT neutrons (“knock-on” particles) are, for the first time, obtained and used for characterizing target performance. It is shown with these measurements that, for 15-atm DT capsules with 20-μm CH shells, improvement of target performance is achieved when on-target irradiation nonuniformity is reduced. Specifically, with a two-dimensional (2D) single-color-cycle, 1-THz-bandwidth smoothing by spectral dispersion (SSD), plus polarization smoothing (PS), a primary neutron yield of ∼1×10[sup 13], a fuel areal density of ∼15 mg/cm2, and a shell areal density of ∼60 mg/cm2 are obtained; these are, respectively, ∼80%, ∼60%, and ∼35% higher than those achieved using 0.35-THz, 3-color-cycle, 2D SSD without PS. (In determining fuel areal density we assume the fuel to have equal numbers of D and T.) With full beam smoothing, implosions with moderate radial convergence (∼10–15) are shown to have ρR performance close to one-dimensional-code predictions, but a ratio of measured-to-predicted primary neutron yield of ∼0.3. Other capsules that are predicted to have much higher radial convergence (3.8-atm DT gas with 20-μm CH shell) are shown to have ρR[sub fuel]∼3 mg/cm[sup 2], falling short of prediction by about a factor of 5. The corresponding convergence ratios are similar to the values for 15-atm capsules. This indicates, not surprisingly, that the effects of mix are more deleterious for high-convergence implosions. A brief comparison of these moderate- and high-convergence implosions to those... [ABSTRACT FROM AUTHOR]

The performance of gas-filled, plastic-shell implosions has significantly improved with advances in on-target uniformity on the 60-beam OMEGA laser system [T. R. Boehly, D. L. Brown, R. S. Craxton et al., Opt. Commun. 133, 495 (1997)]. Polarization smoothing (PS) with birefringent wedges and 1-THz-bandwidth smoothing by spectral dispersion (SSD) have been installed on OMEGA. The beam-to-beam power imbalance is ≤ 5% rms. Implosions of 20-μm-thick CH shells (15 atm fill) using full beam smoothing (1-THz SSD and PS) have primary neutron yields and fuel areal densities that are ∼ 70% larger than those driven with 0.35-THz SSD without PS. They also produce ∼ 35% of the predicted one-dimensional neutron yield. The results described here suggest that individual-beam nonuniformity is no longer the primary cause of nonideal target performance. A highly constrained model of the core conditions and fuel-shell mix has been developed. It suggests that there is a “clean” fuel region, surrounded by a mixed region, that accounts for half of the fuel areal density. [ABSTRACT FROM AUTHOR]

Fast protons >=1 MeV have been observed on the 60-beam, 30 kJ OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] at an intensity I=10[sup 15] W/cm[sup 2] and a wavelength λ=0.35 μm. These energies are more than 5 times greater than those observed on previous, single-beam experiments at the same Iλ[sup 2]. The total energy in the proton spectrum above 0.2 MeV is ∼0.1% of the laser energy. Some of the proton spectra display intense, regular lines which may be related to ion acoustic perturbations in the expanding plasma. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A model independent method to determine fuel [ρR] is to measure the energy spectrum and yield of elastically scattered primary neutrons in deuterium–tritium (DT) plasmas. As is the case for complementary methods to measure fuel [ρR] (in particular from knock-on deuterons and tritons [S. Skupsky and S. Kacenjar, J. Appl. Phys. 52, 2608 (1981); C. K. Li et al. (unpublished)]), minimizing the background is critical for successful implementation. To achieve this objective, a novel spectrometer for measurements of neutrons in the energy range 10–18 MeV is proposed. From scattered neutrons (10–13 MeV), the DT fuel [ρR] will be measured; from primary neutrons (∼14 MeV), the ion temperature and neutron yield will be determined; and from secondary neutrons, in the energy range 12–18 MeV, the fuel [ρR] in deuterium plasmas will be inferred at the National Ignition Facility. The instrument is based on a magnetic spectrometer with a neutron-to-deuteron (nd) conversion foil for production of deuteron recoils at nearly forward scattered angles. In its initial phase of implementation, CR-39 track detectors will be used in the focal plane to detect the recoil deuterons with extremely high spatial resolution. Besides simplicity, CR-39 track detectors will facilitate a highly accurate energy calibration. However, in a later implementation of the spectrometer design, the recoils will also be detected by an array of fast scintillation counters functioning in current mode. In either detection scheme, the detection efficiency is about 10[sup -9] for measuring 14 MeV neutrons with an energy resolution of about 3%. Due to its large dynamic range, its relatively high efficiency, and a compliant design that allows for significant background rejection, this spectrometer can be effectively used, with very high resolution, at both OMEGA and the National Ignition Facility. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The effect of optical prepulses on the performance of imploding inertial confinement fusion (ICF) targets has been measured. The neutron yields from nearly identical spherical targets imploded by the OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] laser were measured as a function of prepulse fluences in the drive laser. These experiments indicate that the cumulative prepulse fluence on target must be less than ∼0.2 J/cm2, which corresponds to a prepulse intensity contrast of >=10[sup 7]. This effect is the result of damage to the Al barrier layer used on OMEGA ICF targets. To verify this, the effect of low-intensity irradiation on these Al layers was observed on planar targets using the time-resolved reflectivity and the time-integrated transmission measurements. These experiments show that damage to the Al layers begins at ∼0.1 J/cm2, consistent with the implosion performance results. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A new technique for diagnosing compression in multiple regions of inertial confinement fusion targets is discussed. This diagnostic uses knock-on deuterons and protons that have been elastically scattered by 14.1 MeV deuterium-tritium (DT) fusion neutrons. The target is composed of three different materials: DT gas contained in a plastic shell overcoated by deuterated plastic. The effect on the knock-on deuteron spectrum of mixing of these layers from hydrodynamic instabilities is also discussed. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Investigates the target performance of stagnation and dependence on beam smoothing and pulse shaping of the OMEGA laser system. Diagnosis of compressed core conditions; Use of x-ray and neutron spectroscopy; Application of near-uniform illumination of spherical fuel-bearing targets with high-power laser beams.

MEGA, a 60-beam, 351 nm, Nd:glass laser with an on-target energy capability of more than 40 kJ,is a flexible facility that can be used for both direct- and indirect-drive targets and is designed to ultimately achieve irradiation uniformity of 1% on direct-drive capsules with shaped laser pulses~dynamic range .400:1!. The OMEGA program for the next five years includes plasma physics experiments to investigate laser matter interaction physics at temperatures, densities, and scale lengths approaching those of direct-drive capsules designed for the 1.8 MJ National Ignition Facility~NIF!; experiments to characterize and mitigate the deleterious effects of hydrodynamic instabilities;and implosion experiments with capsules that are hydrodynamically equivalent to high-gain,direct-drive capsules. Details are presented of the OMEGA direct-drive experimental program and initial data from direct-drive implosion experiments that have achieved the highest thermonuclear yield ~1014 DT neutrons! and yield efficiency ~1% of scientific break even! ever attained inlaser-fusion experiments.. [ABSTRACT FROM AUTHOR]

Several methods involving x-ray spectroscopic methods for diagnosing laser-imploded targets are discussed. The first method involves the recording of absorption lines formed in the target tamper, out of the continuum emitted by a hotter compressed core. This method is applied to ablatively imploded targets having a thin KCl signature layer. The tamper ρΔR is deduced from the area within the absorption lines, whereas the tamper temperature is deduced from the intensity distribution among absorption lines of adjacent charge states. In a second method, doubly diffracting crystals can give two-dimensional monochromatic images of thin signature layers in spherical targets. Such information is useful in studying stability and mixing. Experimental results relevant to these methods will be shown and the limitations on their application to lasertarget experiments will be discussed. [ABSTRACT FROM AUTHOR]

Underdense foam targets were irradiated with a single UV laser beam at intensities up to 1015 W/cm2. The incident laser propagated into the foam a distance of 500–1000 μm, depending on the average target density. The backscattered Brillouin and 3ω0/2 radiation were observed to have the same dependence on the incident laser intensity, indicating a strong interrelation of these processes. A possible coupling mechanism is proposed. [ABSTRACT FROM AUTHOR]

The final stages in the compression of microencapsulated DT fueled ICF targets require detailed characterization for meaningful comparison with predictions of hydrodynamic codes. The determination of such parameters as the fuel and shell areal densities, the average ion temperature, and the impact of implosion nonuniformities in high-density target implosions present a strong challenge. We describe several approaches utilizing the self-generated neutrons to diagnose these conditions, including neutron spectrometry, neutron activation of tracer gas and shell materials, and neutron scattering techniques. The importance of making simultaneous measurements of several core parameters to limit ambiguity in interpretation is discussed. [ABSTRACT FROM AUTHOR]

The use of measured spectra of secondary fusion protons for studying physical characteristics of D[sub 2]-filled inertial confinement fusion capsules is described theoretically and demonstrated with data from implosions in the OMEGA 60-beam laser facility. Spectra were acquired with a magnet-based charged-particle spectrometer and with a range-filter-based spectrometer utilizing filters and CR39 nuclear track detectors. Measurement of mean proton energy makes possible the study of a capsule’s total areal density (ρR), since that is what affects the energy loss suffered by protons as they pass through fuel and shell while leaving the capsule. Details of specific shots will be presented. It is also shown that similar techniques should prove useful for diagnosis of future experiments with cryogenic D[sub 2]-filled capsules. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

With charged-particle spectroscopy implemented on OMEGA, we have been able to routinely measure the particle spectra (both nuclear lines and continua) from a variety of capsule implosions. Important parameters such as fusion yields, fuel and shell areal densities, and ion temperatures can be readily deduced. We will report on details of this work with emphasis on the implosion physics. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Spectral measurements have been made of charged fusion products produced in deuterium + helium-3 filled targets irradiated by the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Comparing the energy shifts of four particle types has allowed two distinct physical processes to be probed: Electrostatic acceleration in the low-density corona and energy loss in the high-density target. When the fusion burn occurred during the laser pulse, particle energy shifts were dominated by acceleration effects. Using a simple model for the accelerating field region, the time history of the target electrostatic potential was found and shown to decay to zero soon after laser irradiation was complete. When the fusion burn occurred after the pulse, particle energy shifts were dominated by energy losses in the target, allowing fundamental charged-particle stopping-power predictions to be tested. The results provide the first experimental verification of the general form of stopping power theories over a wide velocity range. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Recent work has resulted in the first high-resolution, spectroscopic measurements of energetic charged particles on OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 496 (1997)]. Energy spectra of charged fusion products have been obtained from two spectrometers, and have been used to deduce various physical quantities in imploded capsules. In this paper the first use of 14.7 MeV deuterium-helium3 (D-[sup 3]He) proton spectra for diagnosing shell areal density (ρR) and fuel ion temperature (T[sub i]) is discussed. For thick-plastic shell capsules, shell areal densities between 20 and 70 mg/cm2 and ion temperatures between 3 and 5 keV have been determined. The spectral linewidths associated with such capsules are found to be wider than the doppler widths. This effect, the focus of future study, is the result of ρR evolution during the burn; or is the result of an extended burn region; or results from nonuniformities in the shell. For thin-glass shell capsules, the spectral linewidths are dominated by the doppler width, and ion temperatures between 10 and 15 keV were determined. These measurements have been also compared and contrasted with the results from neutron measurements and from one-dimension hydrodynamic simulations. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]