Imaging quality of a pulse-dilation framing camera based on short magnetic lenses

The pulse-dilation X-ray framing camera is an important two-dimensional ultrafast imaging diagnostic tool for laser nuclear fusion research. To improve the spatial resolution of the camera, a pulse-dilation framing camera employing short magnetic lenses for imaging is designed. The short magnetic lens group consists of different numbers of short magnetic lenses. A theoretical model of the framing camera is established using the Monte Carlo method, finite difference method and finite element method to investigate its spatial resolution characteristics. The results show that, as the number of short magnetic lenses increases, the curvature radius of the imaging surface of the framing camera increases. And the spatial resolution of the framing camera improves with the increasing number of short magnetic lenses. When five short magnetic lenses are employed, the spatial resolution of the framing camera is better than 15.0 lp/mm within a 42 mm diameter imaging area. An experimental platform for the pulse-dilation framing camera is constructed. With two short magnetic lenses used for imaging, the spatial resolution of the framing camera is better than 10.0 lp/mm within an 18 mm diameter imaging range. In addition, the spatial resolution of the framing camera improves with the increasing of cathode voltage. The experimental results are consistent with the theoretical predictions. Although employing multiple short magnetic lenses can further enhance imaging quality, it also increases system complexity. Therefore, in practical applications, the number of magnetic lenses should be selected according to specific performance requirements.