Recent diagnostic developments at the 100 kJ-level laser facility in China

A 100 kJ-level laser facility has been designed to study inertial confinement fusion physics in China.This facility incorporates various diagnostic techniques,including optical,x-ray imaging,x-ray spectrum,and fusion product diagnostics,as well as general diagnostics assistance systems and central control and data acquisition systems.This paper describes recent developments in diagnostics at the facility.

High efficiency X-ray diffraction diagnostic spectrometer with multi-curvature bent crystal

In spectral diagnostic physics experiments of inertial confinement fusion, the spectral signal is weak due to the low diffraction efficiency when using bent crystals. A spectral diagnostic instrument with high efficiency and wide spectral range is urgently needed. A multi-curvature bent crystal with multi-energy focusing ability is proposed based on the traditional conical crystal geometry. It has advantages of wide spectral range, strong focusing ability, and high spectral resolution. It also can eliminate the imaging aberration in principle due to rotational symmetry for the incoming X rays. A spectral diagnostic experiment based on a fabricated multi-curvatureα-quartz crystal was accomplished using a titanium X-ray tube of the bent crystal, and the corresponding experimental data using a plane α-quartz crystal was also acquired to demonstrate the strong focusing ability.The result shows that the Kα intensity of the multi-curvature α-quartz crystal is 157 times greater than that of the plane crystal, and the corresponding energy range is about 4.51–5.14 keV. This diagnostic instrument could be combined with a streak camera at a vertical direction so as to intensify the diffracted X-ray signal with a wide spectral range.

Performance of completely autotrophic nitrogen removal over nitrite process under different aeration modes and dissolved oxygen

In this study,three sequential batch biofilm reactors(SBBRs)were operated for 155 days to evaluate the performance of completely autotrophic nitrogen removal over nitrite(CANON)process under different aeration modes and dissolved oxygen(DO).Synthetic wastewater with 160-mg NH_(4)^(+)-N/L was fed into the reactors.In the continuously-aerated reactor,the efficiency of the ammonium nitrogen conversion and total nitrogen(TN)removal reached 80% and 70%,respectively,with DO between 0.8–1.0 mg/L.Whereas in the intermittently-aerated reactor,at the aeration/non-aeration ratio of 1.0,ammonium was always under the detection limit and 86% of TN was removed with DO between 2.0–2.5 mg/L during the aeration time.Results show that CANON could be achieved in both continuous and intermittent aeration pattern.However,to achieve the same nitrogen removal efficiency,the DO needed in the intermittently-aerated sequential batch biofilm reactor(SBBR)during the aeration period was higher than that in the continuously-aerated SBBR.In addition,the DO in the CANON system should be adjusted to the aeration mode,and low DO was not a prerequisite to CANON process.

Designing a toroidal crystal for monochromatic X-ray imaging of a laser-produced He-like plasma

In this study,a toroidal quartz(2023)crystal is designed for monochromatic X-ray imaging at 72.3◦.The designed crystal produces excellent images of a laser-produced plasma emitting He-like Ti X-rays at 4.75 keV.Based on the simulations,the imaging resolutions of the spherical and toroidal crystals in the sagittal direction are found to be 15 and 5μm,respectively.Moreover,the simulation results show that a higher resolution image of the source can be obtained by using a toroidal crystal.An X-ray backlight imaging experiment is conducted using 4.75 keV He-like Ti X-rays,a 3×3 metal grid,an imaging plate and a toroidal quartz crystal with a lattice constant of 2d=0.2749 nm.The meridional and sagittal radii of the toroidalα-quartz crystal are 295.6 and 268.5 mm,respectively.A highly resolved image of the microgrid,with a spatial resolution of 10μm,is obtained in the experiment.By using similar toroidal crystal designs,the application of a spatially resolved spectrometer with high-resolution X-ray imaging ability is capable of providing imaging data with the same magnification ratio in the sagittal and meridional planes.