We report the nanofabrication and characterization of x-ray transmission gratings with a high aspect ratio and a feature size of down to 65 nm. Two nanofabrication methods, the combination of electron beam and optical lithography and the combination of electron beam, x-ray, and optical lithography, are presented in detail. In the former approach, the proximity effect of electron beam lithography based on a thin membrane of low-z material was investigated, and the x-ray transmission gratings with a line density of up to 6666 lines/mm were demonstrated. In the latter approach, which is suitable for low volume production, we investigated the x-ray mask pattern correction during the electron beam lithography process and the diffraction effect between the mask and wafer during the x-ray lithography process, and we demonstrated the precise control ability of line width and vertical side-wall profile. A large number of x-ray transmission gratings with a line density of 5000 lines/mm and Au absorber thickness of up to 580 nm were fabricated. The optical characterization results of the fabricated x-ray transmission gratings were given, suggesting that these two reliable approaches also promote the development of x-ray diffractive optical elements.
Areal density (ρR) is one of the crucial parameters in the inertial confinement fusion. Measurement of the fusion products is a more feasible method to diagnose ρR than other methods, such as X-ray. In the capsules filled with D2 fuel or D-3He fuel, proton is an ideal probe to diagnose the implosion ρR in different emission times and directions by measurements of the proton yields and spectra. By D-D reaction protons and D-3He reaction protons, the diagnostics of the total and fuel ρR, ρR evolution, implosion asymmetry and mix effect have been demonstrated at OMEGA and NIF facilities. Also some advanced proton diagnostics instruments are developed with a high level capability. Preliminary diagnosis of ρR in the deuterium involved fuel capsules by measurement of protons at SG-III facility was implemented. A fusion product emission and transport code by Monte-Carlo method was developed. The primary and secondary protons emission and transport in the fuel and shell plasmas were able to be simulated. The relations of the proton energy loss and the secondary proton yields with the areal density were inspected. Several proton spectrometers have been built up at SG-III facility, such as a step ranged filter (SRF) proton spectrometer and a wedged range filter (WRF) proton spectrometer. Some proton response simulation codes and the codes for proton spectra reconstruction were also developed. The demonstrations of ρR diagnostics at SG-III facility by D-D reaction and D-3He reaction proton spectra measurements are presented.
In the field of target diagnostics for Initial Confinement Fusion experiment, high resolution X-ray imaging system is
seriously necessary to record the evolution details of target ablation-front disturbance at different energy points of backlight
conditions. Kirkpatrick-Baez mirror is a wide used imaging system to achieve a large efficient field of view with high
spatial resolution and energy transmitting capability. In this paper, we designed a novel type of reflective microscope based
on Kirkpatrick-Baez structure, and this system can achieve 5μm spatial resolution at 600μm field of view specific energy
point in one dimension.
A large-field high-resolution x-ray microscope was developed for multi-keV time-resolved x-ray imaging diagnostics of laser plasma at the Shenguang-III prototype facility. The microscope consists of Kirkpatrick–Baez amélioré (KBA) bimirrors and a KB single mirror corresponding to the imaging and temporal directions of a streak camera, respectively. KBA bimirrors coated with an Ir single layer were used to obtain high spatial resolutions within the millimeter-range field of view, and a KB mirror coated with Cr/C multilayers was used to obtain a specific spectral resolution around 4.3 keV. This study describes details of the microscope with regard to its optical design, mirror coatings, and assembly method. The experimental imaging results of the grid with 3 to 5 μm spatial resolution are also shown.
In this paper, the anisotropic focusing technique is used to make a novel streak tube. The salient features are the introduction of both temporally focusing electrodes and spatially focusing electric quadrupole lens. The simulation showed that physical temporal dispersion of 0.38 ps and edge spatial resolution of 56 lp/mm can be achieved. The Nd:YLF 8ps pulse laser was used to calibrate the performance index of streak camera. The static and dynamic spatial resolutions are 35 lp/mm and 25 lp/mm respectively. The dynamic range more than 950:1 and time resolution 8ps can be reached. Furthermore, the magnifications in slit and scanning direction can be adjusted respectively, so it is very convenient to select amplification needed when it is coupled with KB microscope.
Dynamic distortion, which is caused by space-charge effect, widely exists in streak camera. When input light intensity
becomes too large, the electric field caused by electric beam turns out analogous to that caused by image converter tube,
which leads to the dynamic distortion. In this article, we analyze the theory of the dynamic distortion by experiments and
simulations upon CST Particle Studio software. Results show that: the intensity of current and the space position along
the photocathode shall affect the dynamic distortion, leading to defocusing effect and reduce both the spatial resolution
and the temporal resolution. All above assist us to better understand the electric-optic system of image converter tube,
and provide ideas for further experimental diagnose design.
High speed X-ray scanning camera (XSC) is an extra precision temporal and spatial diagnostic instrument in the inertial
confinement fusion (ICF) experiment. In order to quantitatively analyze the measurement results, the spectral sensitivity
of XSC, which depends on the response of the transmission photocathode, is necessary to be absolutely calibrated. A
method of measuring the spectral response of Au and CsI transmission photocathodes of XSC is described. Based on
Beijing Synchrotron Radiation Facility (BSRF), Au and CsI transmission photocathodes with slits are calibrated in the
photon energy range of 60 eV-1500 eV and 2.1 keV-5.5 keV. Utilizing the quantum efficiency of the standard detector
AXUV-100, the calibrated quantum efficiency of Au and CsI photocathodes are derived. The calibration data agree well
with the photoelectric emission theory of Henke.
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