Direct intensity calibration of X-ray grazing-incidence microscopes with home-lab source

Abstract

Direct intensity calibration of X-ray grazing-incidence microscopes is urgently needed in quantitative studies of X-ray emission from laser plasma sources in inertial confinement fusion. The existing calibration methods for single reflecting mirrors, crystals, gratings, filters, and X-ray detectors are not applicable for such X-ray microscopes due to the specific optical structure and the restrictions of object-image relation. This article presents a reliable and efficient method that can be performed using a divergent X-ray source and an energy dispersive Si-PIN (silicon positive-intrinsic-negative) detector in an ordinary X-ray laboratory. The transmission theory of X-ray flux in imaging diagnostics is introduced, and the quantities to be measured are defined. The calibration method is verified by a W/Si multilayer-coated Kirkpatrick-Baez microscope with a field of view of ∼95 μm at 17.48 keV. The mirror reflectance curve in the 1D coordinate is drawn with a peak value of 20.9% and an uncertainty of ∼6.0%.

Study on full-aperture intensity response measurement for x-ray Kirkpatrick–Baez microscope

“…3(e). A smaller image distance was not chosen for the purpose of avoiding the effect of direct rays on the 2D imaging 16 . The KB microscope assembly was mounted on a six-axis target positioning mount, and the position of KB was fixed when the optimum imaging position was determined.…”

“…A smaller image distance was not chosen for the purpose of avoiding the effect of direct rays on the 2D imaging. 16 The KB microscope assembly was mounted on a six-axis target positioning mount, and the position of KB was fixed when the optimum imaging position was determined. A silicon positive-intrinsic-negative (Si-PIN) detector (XR-100CR, Amptek) was used to measure the output spectrum with a detection area of 5 mm × 5 mm as shown in Fig.…”

“…However, the effective aperture of the grazing incidence system with an extended source is codetermined by the group of mirrors, and the response efficiency of the system cannot be characterized by a single reflector. Work done by our group has proposed a quantitative calibration theory 16 to characterize the system response. In this method, a 50 μm-diameter pinhole is placed in front of the mirror as an aperture diaphragm to ensure that all x-rays passing through the pinhole are reflected by the optical system mirrors.…”

“…[12][13][14] Quantitative diagnosis of the radiation intensity is necessary to provide a method to deduce the temperature information of plasma from the image plane. [15][16][17] Due to the optical characteristics of grazing incidence system, the intensity of image plane is modulated to some extent, which hinders the inversion of hot spot. Periodic multilayer microscopes, 18 for example, have high reflectivity and sensitive spectral resolution, but the narrow angular bandwidth inhibits the formation of uniform x-ray images over a wide FOV.…”

A four-channels reflective Kirkpatrick-Baez microscope for the hot spot diagnostic in the 100 kJ laser driven inertial confinement fusion in China

“…After the intensity and energy response calibration of the microscope and the recorder, it may be also used to study the mix in the hot spot. Some calibration methods are proposed [13,33,34]. The KB microscope was installed on a general diagnostics instrument manipulator (DIM) and inserted inside the vacuum chamber.…”