103 / 2023-04-13 21:15:22

Development and application of dual MCP gated image intensifier for high energy X-ray online imaging process

惯性约束聚变物理学 > 驱动器、制靶和诊断-II

Compression symmetry and process evolution of implosion is an important subject in inertial confinement fusion (ICF) research. The research of this subject is helpful to correctly understand ICF process and realize ignition. In order to understand the symmetry of implosion compression and accurately grasp its physical laws, a reliable backlight photographic diagnosis with high temporal and spatial resolution is needed to obtain the image information of compressed target at the maximum compression time. At near-ignition scale, however, the conventional K α-ray backlight source is no longer suitable for backlight photography because of its low energy and insufficient penetration ability. An alternative scheme is to use high-energy photons (50-200keV), which can ensure sufficient penetration to the high-density compression region on the one hand, and avoid the core self-luminescence energy region on the other hand. In the energy range of 50keV ~ 200keV, the attenuation of X-rays passing through the high-density fuel region mainly comes from Compton scattering, so this photographic scheme is called "Compton photography". Because the penetration ability of high-energy X-ray is too strong, the detection efficiency of traditional recording equipment is too low. In order to ensure sufficient image signal-to-noise ratio, on the one hand, it is necessary to use high-Z material medium to block high-energy photons and improve the detection efficiency; On the other hand, by using gating technology, the influence of background X-ray in non-time domain on signal is eliminated. Double MCP gating technology improves the conversion efficiency of high energy X-ray by using lead glass with high lead ratio as conversion medium. On the other hand, MCP itself can also provide gating function to improve signal-to-noise ratio. In order to verify this key technology, we specially developed a set of dual MCP gated image intensifier. MCP devices with different specifications with lead content of 37% and 51% have been obtained, and imaging intensifiers are further packaged to test the quantum detection efficiency. It was found that the highest quantum detection efficiency of 37% lead-containing dual MCP image intensifier is about 4.48%, which is equivalent to the quantum detection efficiency of AXIS system on NIF reported in literature. However, the quantum detection efficiency of 51% lead-containing dual MCP image intensifier is as high as 7.15%.