Study On Microchannel Plate And Microchannel Plate Based Imaging Detection Applications

As a channel electron multiplier array with two-dimensional spatial and temporal resolution, as well as the direct detection ability for several of radiations, Microchannel Plate (MCP) is a powerful multifunctional detector, so it has broad application prospects and scientific value.This dissertation is focus on the research of MCP glass material design, fabrication process, as well as MCP based imaging detector, there are four main research topics and achievements in this dissertation:1. The research of MCP with glass composition optimized and fabrication process improved specially for generation third (Gen. Ⅲ) image intensifier, providing which can be impose to a higher temperature bake and exceeding intensive electron scrubbing, and an larger open area ratio (OAR), to ensure the reliability while achieve an improved signal to noise ratio (SNR) of Gen.Ⅲ image intensifier.A25mm diameter6μm pore size format MCP with optimized glass composition was developed, the OAR of this MCP is up to68%, the mean time to failure (MTTF) of this MCP assembled Gen. Ⅲ image intensifier was achieved excess5,000hours, and noise factor is decreased to1.8, SNR is up to25:1. As a strange "memory" phenomenon was occurred on this MCP assumed image intensifiers, an attempt to explain the formation mechanism of this phenomenon was made and concluded conclusion that "memory" phenomenon of image intensifiers were the results of a thicker silicon-rich layer, which existed between emission layer and conduction layer of channel inner wall of this MCP, having much higher resistance compare with conduction layer, and this phenomenon was eliminated through a strictly controlled MCP manufacture process.2. Exploring the feasibility and approach for unfilmed or thin film MCP based Gen. Ⅲ image intensifiers. Completely removal of ion barrier film (IBF) can maximize the effective availability of photocathode quantum efficiency of Gen. Ⅲ image intensifiers, but increasing the risk of reliability, thinning the thickness of film is a more flexible approach.Theoretically, extension of MCP to a bulk conductive substrate was considered to be an effective approach to eliminate ion feedback problem, so a vanadium iron lead alumina phosphate glass was developed, although it was succeed in fabricating some experimental samples of25mm diameter rimless format MCP with10μm pore diameter and60:1length to diameter (L/D) ratio, but its gain is lower, and its mechanical strength is insufficient.Though further reformulation of MCP glass composition, to restrict ion poisoning resource formation within the substrate of MCP, making it possible for thinning the thickness of IBF, would further improve the SNR while maintain even enhance the reliability of Gen. Ⅲ image intensifier. A25mm diameter6μm pore size format MCP with reformulation of composition and devitrification remodification of microstructure was developed, this MCP assembled Gen.Ⅲ image intensifier demonstrated a noise factor of1.69, while the MTTF is also further improved.3. Development of lager area format low resistance small pore size MCP for steak camera and frame camera, and research of the temporal gain and dynamic property of MCP applied to instantaneous phenomenon imaging detection.A low resistance MCP glass was developed, this reduced lead silicate glass was tailored to have a minimum surface resistivity range of1012～1013Ω/□, and meet the technical details requirement of several of geometry specification low resistance MCP fabrication, at the same time, the influence of saturation effect of MCP on dynamic range of streak cameras, as well as the temporal gain and dynamic character of ultra-high speed gated MCP applied for X-ray framing camera were analyzed and investigated.4. Making MCP sensitive to neutrons, by direct addition of neutron-absorbing atoms into MCP glass, such as10B and155,157Gd, and thus extending the application of MCP to the field of imaging detection which use neutron as probe.A50mm diameter rimless10μm pore size format MCP doped with10mol%natB2O3,3mole%natGd2O3and3mole%natGd2O3+10mol%natB2O3, respectively, were fabricated, experimental tests proved the MCP doped with3mole%natGd2O3is capable of imaging thermal neutrons with35%detection efficiency. Theoretical modeling prediction that the detection efficiency of a MCP doped with3mole%of natGd2O3is equivalent even superior to a MCP doped with20mole%of10B2O3, and a potential of enhancement on detection efficiency of this MCP doped with3mole%natGd2O3can also be achieved through a geometry structure optimization.