The amount of synchrotron radiation is proportional to the stored beam current. To keep the current high one has the reduce the loss of electrons. BESSY II is designed to permit a life-time of 8 to 10 hours. Since the electrons travel with light velocity (~300,000 km/s) they travel a distance of 1,000,000,000 km, i.e., 72 times the distance from the sun to the earth.