Charged Particle Detector With Conversion Surface

The patent introduces a conversion surface as an intermediary between the transmitted charged particles and the detector. The conversion surface converts incident charged particles into secondary electrons, which then strike the detector. This intermediary protects the detector from direct exposure to high particle currents that would cause saturation and damage, while still enabling efficient detection through the secondary electron conversion process.

The patent modifies the geometric parameter of the conversion surface by tilting it at a specific angle (e.g., 45 degrees) relative to the incident particle direction. This parameter change increases the conversion factor from approximately 1 secondary electron per incident particle at normal incidence to approximately 2 secondary electrons per incident particle at 45-degree incidence. The tilted configuration is integrated into the detector structure with appropriate spacing, achieving enhanced detection efficiency without excessive complexity.

The patent changes the material parameter of the conversion surface by selecting materials with high secondary electron yield (SEY), such as platinum, tungsten, or tungsten alloys. These materials can produce 2 or more secondary electrons per incident charged particle, significantly improving the conversion factor. The patent balances manufacturing considerations by providing alternative materials like aluminum or stainless steel that offer lower but still acceptable SEY values, allowing selection based on specific application requirements and manufacturing capabilities.