The modern era of high-resolution solar EUV imaging at multiple wavelengths has unlocked a wealth of scientific discovery. Despite this, there are two fundamental issues that limit our ability to understand bright, rapidly evolving events on the Sun. These are 1) temporal cadence, and 2) image saturation. The combination of these two issues means that the fast dynamics on the Sun, particularly during eruptive events, are difficult to resolve in both time and space. This is problematic because models predict and observations show that during flares reconnection and particle acceleration processes can occur on < 1s timescales. These processes lead to rapidly varying thermal responses in chromospheric and coronal plasma.
We present the science case for the FISHA concept, a fast imager for the solar atmosphere. FISHA would image the Sun at high spatial resolution and sub-second temporal cadence, providing targeted observations of bright, transient features. This can be achieved while avoiding saturation effects using a combination of short exposure times and rapid readout detector capabilities. FISHA would also employ situational exposure and cadence control to allow observations of a wide range of solar phenomena. Here, we explore the potential science that FISHA could achieve and discuss methods of implementation.