Influence of Focal Spot Geometry on Stability of a Solid Graph ite Super-FRS Production Target for a Fast Extraction Mode

The Super-FRS experiments will use highest intensities of the heaviest projectiles, namely, 5.0 ◊ 10 11 uranium ions delivered in a 50 ns long bunch. Survival of the pro- duction target over an extended period of time during this experimental campaign carried out at a repetition rate of 1 Hz, is a very important but difficult problem. One of the requirements necessary to achieve this goal is to keep the thermally induced material stress below a critical value so that the von Mises parameter remains less than 1 which implies that the target material remains in an elastic state . In this contribution we report 2D numerical simulations of interaction of a solid graphite cylindrical target that is i rra- diated with a 1 GeV/u uranium beam along the axis. The target radius is 5 cm while the beam intensity is 10 10 ions per bunch with a bunch length of 50 ns. The main purpose of this work is to study the thermal stress generated by dif- ferent focal spot geometries. We respectively consider a circular focal spot with = 1.69 mm and an elliptic focal spot with X = 0.41 mm and Y = 4.1 mm so that the focal spot area is the same in both cases.