X-ray framing camera (XFC) is usually used as the principal diagnostic tool in inertial confinement fusion research. The methods on how to precisely calibrate the temporal resolution are important topics for XFC with several picoseconds gate time. A method to measure the temporal resolution of XFCs is proposed based on a high-power subpicosecond ultraviolet laser facility called LLG-ultimate. In our method, series of duraluminium alloy stepped reflective surfaces are used to separate the incident laser beam into sequentially delayed beams with equal size, spacing, and time interval. The temporal resolution of XFC can be measured if the sequentially delayed beams irradiate a gold photocathode microstrip line while the high-voltage pulse transferring along the same area simultaneously. A Fabry–Perot etalon is placed in the light path, improving the probability of synchronization of the voltage pulse and laser pulse. The accuracy of this measurement method can be very high by reducing the time interval of the sequentially delayed beams.
The radial structure of core temperature and density is very important to benchmark theory simulation codes in Inertial confinement fusion (ICF) studies. In this article, we gave a method to determinate the radial structure of core temperature and density by using the normalized intensity of core experimental x-ray image. The core emission model uses the average atom model (AA) and the radiation transport model assumes the local thermo dynamic equilibrium model (LTE). Calculated results show that: the full width at half maximum of core temperature is about 39.4μm which indicate that the hot spot diameter is such value and the full width at half maximum of core density is about 5μm. The hot spot convergence and the shell in-flight aspect ratio (IFAR) can be deduced approximately 7 and 7.5 respectively. The above assist us to better understand the implosion physics, and provide more information for benchmarking the simulation codes.
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.
Micro-channel Plate (MCP), which can be served as electron multiplier achieved by the surface of micro-pores that has
some electrical conductivity and performs well in producing secondary electrons, is a fiberglass plate made of silicate
glass containing oxide of lead, bismuth and otherwise. Once coated with cathode film both sides, MCP is capable of
responding to ultraviolet (UV) of several eV and x-ray of several keV. When gold is applied as photocathode, it has good
stability of emission, photoelectric emission character would not be changed even though exposed in the air several
times, and the photoelectric current density distributes uniformly. This article introduces a special photo-detector, which
employs MCP as dielectric substrate, and evaporates a layer of thin Au on the front surface acted as the photocathode
and input electrode, while a layer of general electrode on the back surface. In addition, an electron receiver is also needed
to structure the photo-detector. Energy spectrum response at ultraviolet band of this Au coated MCP photo-detector was
measured through measuring the response current of the detector between 200~340 nm (3.66~6.22 eV) directly. The
selective photoemission of Au has been found, which had been found only for alkali metals.
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