High-efficiency full-surface defects detection for an ICF capsule based on a null interferometric microscope.

Laser inertial confinement fusion (ICF) triggers a nuclear fusion reaction via the evenly compressed capsule containing deuterium tritium fuel with a high-power laser. However, isolated defects on the surface of the capsules reduce the probability of ignition. In this paper, we present a full-surface defects detection method based on a null interferometric microscope (NIM) to achieve high-precision, high-efficiency, and full-surface defects detection on ICF capsules. A dynamic phase-shifting module is applied to the NIM to achieve a single-shot measurement in a single subaperture. With the capsule controlling system, the capsule is rotated and scanned along a planned lattice to get all subapertures measured. The eccentricity error can be measured from wavefront aberrations and compensated online to guarantee the measurement accuracy during the scanning process. After the scanning process, all of the surface defects are identified on the full-surface map. Theories and experimental results indicate that for the capsule with 875-µm-diameter, the lateral resolution could reach 0.7 µm and the measurement time is less than 1 h. The number of sampling points can reach about 50 million. To the best of our knowledge, our proposed system is the first to achieve full-surface defects detection of ICF capsules with such high efficiency and high resolution at the same time.

Null interferometric microscope for ICF-capsule surface-defect detection.

Isolated defects on the surface of the inertial confinement fusion (ICF) capsule reduce the probability of ignition. Here, to the best of our knowledge, we present the first null interferometric microscope (NIM) for direct and large-field surface defects detection on ICF capsules. The planar reference mirror in conventional interferometric microscopes is replaced by a spherical reference mirror to achieve null interference in the full field of view. Further, via the use of a short-coherence light source system, parasitic fringes are avoided. The feasibility of the NIM is verified via experiments on a 0.7 mm diameter capsule. A 1 mm diameter ICF capsule is also tested by the NIM to prove that the NIM has the ability to measure capsules with different diameters.

Speed of sound in hydrogen isotopes derived from the experimental pvt data and an improved quantum law of corresponding state.

The speed of sound in hydrogen isotopes can be applied to accurately determine the density, virial coefficient and equation of state. The functional relation between the speed of sound in a real gas and the experimental PVT data is derived from the virial equation of states. Utilizing the relation, the speed of sound in n-H2 is calculated from the experimental PVT data available. The calculated results illustrate that the presented method has an accuracy of better than 0.25% within the pressure range of below 1500 atm. However, there is little experimental PVT data available for n-T2, therefore, an improved quantum law of corresponding state (IQLCS) method, which is based on the physical nature that the different virial coefficients represent the interaction between the different number of molecules, is proposed for obtaining the speed of sound in n-T2. Utilizing the IQLCS method, the speed of sound in n-T2 can be obtained from the available speed of sound data in n-H2 or n-D2 via scaling the corresponding fitting coefficients at same temperature and pressure. The simulated results demonstrate that the IQLCS method is more accurate than the classical law of corresponding state(CLCS) and the maximum deviation is about 0.52% over the pressure range of below 1500 atm.

[Quantitative analysis of the concentration of Br-doping in micro-shell coating with XRF].

In inertial confinement fusion (ICF) physics experiment, the micro-shell that contains Br-doped CH coating must be characterized for doping Br concentration level. X-ray fluorescence (XRF), with its unique capability to quantitatively determine concentrations of most elements simultaneously and non-destructively, is generally the method of choice for total dopant (Z > 11) concentration. In the present paper, a method to determine the dopant concentration in ICF micro-shell coating with X-ray fluorescence spectrometry is described, and the calibration model is founded by the calculation of fluorescence intensity of film and micro-shell sample. Based on the calibration model, the fluorescence intensity vs concentration of Br-doped CH coating of micro-shell was obtained. The experiment result shows that X-ray fluorescence spectrometry is a nondestructive and accurate method of measurement of coating dopant in the inertial confinement fusion micro-shell sample, and the measuring error is about 5% for Br doped CH coating of micro-shells with 10 micron thickness coating.