fluence, $$F$$, $$\varPsi$$, $$H_{0}$$

https://doi.org/10.1351/goldbook.F02448
At a given point in space, the @[email protected] incident on a small sphere divided by the cross-sectional area of that sphere. It is used in @[email protected] to specify the energy delivered in a given time interval (for instance by a @[email protected] pulse).