About a thousand electromagnets are used to bring the beam from the end of the North Linear Accelerator to the beginning of the South Linear Accelerator. If you look carefully, you can see that there are two types of magnets. The round, red magnets are used to keep the beam focused to the thickness of a human hair while the straight, blue magnets are used to bend the electrons around the arc.
The blue magnets are different sizes because the electrons in each pipe have been around the accelerator a different number of times. Those closest to the floor have been around the accelerator the most, so they have the most energy. The more energy an electron has, the stronger a magnet has to be to get it around the arc.