Dipole bending magnets at Diamond Light Source

 The Diamond Light Source produces X-rays from a beam of very fast electrons going round in a circle. Well, actually, it is not quite a circle. The picture above shows the path of the electrons painted on the shielding on top of the storage ring. Notice that the path is straight and then a bend and then a straight. We went down below...

 There are 3 types of magnet. The green magnets are responsible for the bending.

The bending magnets are dipoles. They have two poles - north and south. One is above and one below. They are electromagnets with two turns above and two turns below. One two turns?! Well, the current is 1500 A and the field strength is 1.4 Teslas. That's huge. So they don't use wires. They use fat lumps of copper. The bigger the cross-sectional area, the lower the resistance. The heating effect would be calculated by current squared x resistance so the resistance needs to be very small. I was told that copper was hollow so that cooling water can flow through it. The electron beam must be travelling away from us to produce light to go into the tangential hutch experiments. To bend the bend left to right in the middle picture, Fleming's Left Hand rule means that the top coil must be a north pole and the bottom a south pole.